IB Biology SL Flashcards: Complete Course Review
Review the current IB Biology Standard Level course with 960 independently written active-recall cards covering all 34 SL topics across molecules, cells, organisms, genetics, evolution, and ecology.
Par šo kavu
Study the current IB Biology SL course with 960 independently written English flashcards. The deck covers all 34 Standard Level topics through four broad groups: molecules and cells; metabolism and genetics; organisms and systems; and evolution and ecology.
Cards move from essential terms and structures to functions, mechanisms, comparisons, predictions, and compact interpretation prompts. Useful two-way term cards are separated by at least three unrelated cards, while explanatory answers are kept in the direction that supports meaningful recall. Every card carries the root tag ib-bio-sl and exactly one broad group tag.
The order introduces prerequisite ideas before dependent ones and progresses from simpler recall to more demanding reasoning within each topic. The deck is designed for ongoing spaced review. It does not replace data-heavy practice papers, extended-response practice, laboratory work, or the scientific investigation.
Reviewed in 2026 against the current Biology Standard Level course, first assessed in 2025.
Independent, unofficial study aid based on common biological knowledge. Not affiliated with or endorsed by the International Baccalaureate Organization. No copied IB examination questions, mark schemes, or curriculum text are included.
Check the official IB Biology course page for authoritative requirements.
Kartītes šajā kavā
1. kartīte
Jautājums
What is water polarity?
Atbilde
The unequal sharing of electrons in a water molecule, giving oxygen a partial negative charge and the hydrogens partial positive charges.
2. kartīte
Jautājums
What is a hydrogen bond?
Atbilde
A weak attraction between a partially positive hydrogen atom and a partially negative atom in another molecule.
3. kartīte
Jautājums
What is cohesion?
Atbilde
Attraction between molecules of the same substance.
4. kartīte
Jautājums
What is adhesion?
Atbilde
Attraction between molecules of different substances.
5. kartīte
Jautājums
Which term describes unequal charge distribution within a water molecule?
Atbilde
water polarity
6. kartīte
Jautājums
Which term describes the intermolecular attraction that links neighboring water molecules?
Atbilde
a hydrogen bond
7. kartīte
Jautājums
Which term describes attraction between molecules of the same substance?
Atbilde
cohesion
8. kartīte
Jautājums
Which term describes attraction between water and a different material?
Atbilde
adhesion
9. kartīte
Jautājums
What is a solvent?
Atbilde
A liquid that dissolves solutes to form a solution.
10. kartīte
Jautājums
What is specific heat capacity?
Atbilde
The energy required to raise the temperature of a unit mass of a substance by one degree.
11. kartīte
Jautājums
What is latent heat of vaporization?
Atbilde
The energy required to vaporize a specified amount of liquid without changing its temperature.
12. kartīte
Jautājums
Why does ice float on liquid water?
Atbilde
Hydrogen bonds hold water molecules in an open lattice in ice, making ice less dense than liquid water.
13. kartīte
Jautājums
Which term describes a liquid that dissolves solutes?
Atbilde
a solvent
14. kartīte
Jautājums
Which term describes the energy needed to raise a unit mass by one degree?
Atbilde
specific heat capacity
15. kartīte
Jautājums
Which term describes the energy needed to vaporize a liquid without a temperature change?
Atbilde
latent heat of vaporization
16. kartīte
Jautājums
Which property of water makes sweating an effective cooling mechanism?
Atbilde
Water absorbs substantial energy as it evaporates; the highest-energy molecules leave, carrying heat away from the skin.
17. kartīte
Jautājums
Why does water resist rapid temperature change?
Atbilde
Many hydrogen bonds must absorb energy before molecular motion increases substantially, giving water a high specific heat capacity.
18. kartīte
Jautājums
How do cohesion and adhesion support water transport in narrow tubes?
Atbilde
Cohesion keeps water molecules connected, while adhesion helps the water column cling to the tube wall.
19. kartīte
Jautājums
How does water participate differently in hydrolysis and condensation?
Atbilde
Hydrolysis consumes water to split a bond; condensation forms a bond and releases water.
20. kartīte
Jautājums
How does floating ice protect aquatic life in winter?
Atbilde
Surface ice insulates the liquid water below, slowing further heat loss and preventing the whole body of water from freezing rapidly.
21. kartīte
Jautājums
Why is water effective for transporting many biological solutes?
Atbilde
Its polarity allows ions and other polar molecules to become surrounded and dispersed in solution.
22. kartīte
Jautājums
Why do nonpolar substances tend to cluster in water?
Atbilde
Clustering reduces the nonpolar surface exposed to water, allowing more water molecules to maintain hydrogen-bond interactions.
23. kartīte
Jautājums
What is a nucleotide?
Atbilde
A nucleic-acid monomer made of a pentose sugar, a phosphate group, and a nitrogenous base.
24. kartīte
Jautājums
What is a nucleoside?
Atbilde
A nitrogenous base joined to a pentose sugar, without a phosphate group.
25. kartīte
Jautājums
What is a phosphodiester bond?
Atbilde
A covalent bond linking the phosphate of one nucleotide to the sugar of the next nucleotide.
26. kartīte
Jautājums
What is DNA?
Atbilde
A usually double-stranded nucleic acid that stores hereditary information in its base sequence.
27. kartīte
Jautājums
Which term describes a sugar-phosphate-base monomer?
Atbilde
a nucleotide
28. kartīte
Jautājums
Which term describes a base joined to a sugar but no phosphate?
Atbilde
a nucleoside
29. kartīte
Jautājums
Which term describes the covalent linkage in a nucleic-acid sugar-phosphate backbone?
Atbilde
a phosphodiester bond
30. kartīte
Jautājums
Which term describes the nucleic acid that usually stores hereditary information?
Atbilde
DNA
31. kartīte
Jautājums
What is RNA?
Atbilde
A usually single-stranded nucleic acid involved in expressing and regulating genetic information.
32. kartīte
Jautājums
What are antiparallel DNA strands?
Atbilde
Two DNA strands that run in opposite 5′ to 3′ directions.
33. kartīte
Jautājums
What is complementary base pairing?
Atbilde
Specific pairing in which adenine pairs with thymine in DNA, or uracil in RNA, and cytosine pairs with guanine.
34. kartīte
Jautājums
What is a purine?
Atbilde
A nitrogenous base with two fused rings; adenine and guanine are purines.
35. kartīte
Jautājums
Which term describes the usually single-stranded nucleic acid used in gene expression?
Atbilde
RNA
36. kartīte
Jautājums
Which term describes DNA strands running in opposite directions?
Atbilde
antiparallel DNA strands
37. kartīte
Jautājums
Which term describes specific A–T or A–U and C–G pairing?
Atbilde
complementary base pairing
38. kartīte
Jautājums
Which term describes a two-ring nitrogenous base?
Atbilde
a purine
39. kartīte
Jautājums
What is a pyrimidine?
Atbilde
A nitrogenous base with one ring; cytosine, thymine, and uracil are pyrimidines.
40. kartīte
Jautājums
What is a genome?
Atbilde
The complete genetic material of an organism or cell.
41. kartīte
Jautājums
What three structural features commonly distinguish RNA from DNA?
Atbilde
RNA usually contains ribose, uses uracil instead of thymine, and is single-stranded rather than double-stranded.
42. kartīte
Jautājums
What determines the base sequence of the second DNA strand?
Atbilde
Complementary base-pairing rules determine it: A pairs with T, and C pairs with G.
43. kartīte
Jautājums
Which term describes a one-ring nitrogenous base?
Atbilde
a pyrimidine
44. kartīte
Jautājums
Which term describes the complete genetic material of an organism?
Atbilde
a genome
45. kartīte
Jautājums
What do the 5′ and 3′ labels of a nucleic-acid strand refer to?
Atbilde
They refer to numbered carbon atoms in the pentose sugar and define the strand's chemical direction.
46. kartīte
Jautājums
Where is genetic information encoded in DNA?
Atbilde
In the order of nitrogenous bases along the DNA strand.
47. kartīte
Jautājums
Why is ATP classified as a nucleotide?
Atbilde
It contains adenine, ribose, and phosphate groups, the three component types of a nucleotide.
48. kartīte
Jautājums
How do mRNA, tRNA, and rRNA contribute to protein synthesis?
Atbilde
mRNA carries the coding sequence, tRNA delivers amino acids, and rRNA forms the catalytic and structural core of ribosomes.
49. kartīte
Jautājums
How are a gene and a chromosome related?
Atbilde
A gene is a DNA sequence with a biological function; a chromosome is one long DNA molecule containing many genes and other sequences.
50. kartīte
Jautājums
What happens to double-stranded DNA when it is denatured by heat?
Atbilde
Hydrogen bonds between complementary bases break and the two strands separate; the covalent backbones usually remain intact.
51. kartīte
Jautājums
Why can each DNA strand serve as a template during replication?
Atbilde
Its base sequence determines a complementary sequence through specific base pairing.
52. kartīte
Jautājums
In which direction are new nucleic-acid strands synthesized?
Atbilde
Nucleotides are added to the 3′ end, so synthesis proceeds 5′ to 3′.
53. kartīte
Jautājums
What is a monosaccharide?
Atbilde
A single sugar unit that can serve as a carbohydrate monomer.
54. kartīte
Jautājums
What is a disaccharide?
Atbilde
A carbohydrate formed from two monosaccharides joined by a glycosidic bond.
55. kartīte
Jautājums
What is a polysaccharide?
Atbilde
A polymer made from many monosaccharide units.
56. kartīte
Jautājums
What is a glycosidic bond?
Atbilde
A covalent bond joining monosaccharides in a carbohydrate.
57. kartīte
Jautājums
Which term describes a single sugar unit?
Atbilde
a monosaccharide
58. kartīte
Jautājums
Which term describes two monosaccharides joined together?
Atbilde
a disaccharide
59. kartīte
Jautājums
Which term describes a polymer of many sugar units?
Atbilde
a polysaccharide
60. kartīte
Jautājums
Which term describes the covalent linkage between monosaccharides?
Atbilde
a glycosidic bond
61. kartīte
Jautājums
What is a triglyceride?
Atbilde
A lipid formed from glycerol joined to three fatty acids.
62. kartīte
Jautājums
What is a fatty acid?
Atbilde
A hydrocarbon chain with a carboxyl group that can form part of many lipids.
63. kartīte
Jautājums
What is a saturated fatty acid?
Atbilde
A fatty acid with no carbon-carbon double bonds in its hydrocarbon chain.
64. kartīte
Jautājums
What is a phospholipid?
Atbilde
An amphipathic lipid with a phosphate-containing hydrophilic head and hydrophobic fatty-acid tails.
65. kartīte
Jautājums
Which term describes glycerol joined to three fatty acids?
Atbilde
a triglyceride
66. kartīte
Jautājums
Which term describes a hydrocarbon chain ending in a carboxyl group?
Atbilde
a fatty acid
67. kartīte
Jautājums
Which term describes a fatty acid without carbon-carbon double bonds?
Atbilde
a saturated fatty acid
68. kartīte
Jautājums
Which term describes a lipid with a polar head and nonpolar tails?
Atbilde
a phospholipid
69. kartīte
Jautājums
How is a glycosidic bond formed between two monosaccharides?
Atbilde
A condensation reaction joins them and releases a molecule of water.
70. kartīte
Jautājums
How is a polysaccharide broken into smaller sugars?
Atbilde
Hydrolysis adds water across glycosidic bonds, splitting the polymer.
71. kartīte
Jautājums
Which polysaccharides store glucose in plants and animals?
Atbilde
Starch stores glucose in plants; glycogen stores glucose in animals and fungi.
72. kartīte
Jautājums
Why is cellulose suitable for plant cell walls?
Atbilde
Its straight β-glucose chains hydrogen-bond into strong microfibrils that resist stretching.
73. kartīte
Jautājums
Why do lipids store more energy per gram than carbohydrates?
Atbilde
Lipids contain more energy-rich carbon-hydrogen bonds and are more reduced.
74. kartīte
Jautājums
Why do phospholipids form bilayers in water?
Atbilde
Hydrophilic heads interact with water while hydrophobic tails cluster away from water.
75. kartīte
Jautājums
Besides energy storage, what are three biological roles of lipids?
Atbilde
They form membranes, provide thermal insulation and cushioning, and can act as signaling molecules.
76. kartīte
Jautājums
How do cis double bonds affect fatty-acid packing and melting point?
Atbilde
They introduce bends that reduce close packing, usually lowering the melting point.
77. kartīte
Jautājums
What is an amino acid?
Atbilde
A protein monomer with an amino group, a carboxyl group, a hydrogen, and a variable R group attached to a central carbon.
78. kartīte
Jautājums
What is a peptide bond?
Atbilde
The covalent bond formed between the amino group of one amino acid and the carboxyl group of another.
79. kartīte
Jautājums
What is a polypeptide?
Atbilde
A chain of amino acids joined by peptide bonds.
80. kartīte
Jautājums
What is protein primary structure?
Atbilde
The amino-acid sequence of a polypeptide.
81. kartīte
Jautājums
Which term describes a protein monomer with amino, carboxyl, and variable R groups?
Atbilde
an amino acid
82. kartīte
Jautājums
Which term describes the covalent linkage between amino acids?
Atbilde
a peptide bond
83. kartīte
Jautājums
Which term describes a chain of peptide-linked amino acids?
Atbilde
a polypeptide
84. kartīte
Jautājums
Which term describes a protein's amino-acid sequence?
Atbilde
protein primary structure
85. kartīte
Jautājums
What is protein secondary structure?
Atbilde
Local folding such as α-helices and β-sheets stabilized mainly by backbone hydrogen bonds.
86. kartīte
Jautājums
What is protein tertiary structure?
Atbilde
The overall three-dimensional shape of one polypeptide produced by interactions among R groups and the backbone.
87. kartīte
Jautājums
What is protein quaternary structure?
Atbilde
The arrangement of multiple polypeptide subunits in one functional protein.
88. kartīte
Jautājums
What is protein denaturation?
Atbilde
Loss of a protein's normal three-dimensional shape and therefore usually its function.
89. kartīte
Jautājums
Which term describes local α-helix and β-sheet folding?
Atbilde
protein secondary structure
90. kartīte
Jautājums
Which term describes the overall three-dimensional shape of one polypeptide?
Atbilde
protein tertiary structure
91. kartīte
Jautājums
Which term describes the association of multiple polypeptide subunits?
Atbilde
protein quaternary structure
92. kartīte
Jautājums
Which term describes loss of a protein's native shape?
Atbilde
protein denaturation
93. kartīte
Jautājums
What mainly gives different amino acids their different chemical properties?
Atbilde
Their variable R groups.
94. kartīte
Jautājums
What reaction forms a peptide bond?
Atbilde
A condensation reaction releases water as the amino and carboxyl groups join.
95. kartīte
Jautājums
Why can high temperature denature a protein?
Atbilde
Increased molecular motion disrupts weak interactions that maintain the protein's shape.
96. kartīte
Jautājums
Why can extreme pH denature a protein?
Atbilde
It changes the charges of R groups and disrupts ionic and hydrogen-bond interactions.
97. kartīte
Jautājums
How do fibrous and globular proteins generally differ?
Atbilde
Fibrous proteins are elongated and mainly structural; globular proteins are compact and often perform dynamic functions.
98. kartīte
Jautājums
Why is three-dimensional shape crucial to protein function?
Atbilde
It creates specific binding, catalytic, structural, or interaction surfaces.
99. kartīte
Jautājums
Name four broad biological roles of proteins.
Atbilde
Catalysis, transport, signaling, defense, movement, and structural support are major roles; any four are sufficient.
100. kartīte
Jautājums
How can changing one amino acid alter protein function?
Atbilde
The substitution can change R-group interactions, folding, stability, or an active or binding site.
101. kartīte
Jautājums
What is cell theory?
Atbilde
The principles that living organisms are made of cells, cells are the basic units of life, and cells arise from pre-existing cells.
102. kartīte
Jautājums
What is a prokaryotic cell?
Atbilde
A cell without a nucleus or other membrane-bound organelles.
103. kartīte
Jautājums
What is a eukaryotic cell?
Atbilde
A cell with DNA enclosed in a nucleus and with membrane-bound organelles.
104. kartīte
Jautājums
What is the nucleus?
Atbilde
The double-membrane organelle that contains most of a eukaryotic cell's DNA.
105. kartīte
Jautājums
Which term describes the principles describing cells as life's basic units?
Atbilde
cell theory
106. kartīte
Jautājums
Which term describes a cell lacking a nucleus and membrane-bound organelles?
Atbilde
a prokaryotic cell
107. kartīte
Jautājums
Which term describes a cell with a nucleus and membrane-bound organelles?
Atbilde
a eukaryotic cell
108. kartīte
Jautājums
Which term describes the organelle containing most eukaryotic DNA?
Atbilde
the nucleus
109. kartīte
Jautājums
What is a ribosome?
Atbilde
A molecular complex of rRNA and proteins that synthesizes polypeptides.
110. kartīte
Jautājums
What is the cytoplasm?
Atbilde
The material inside the plasma membrane but outside the nucleus, including cytosol and organelles.
111. kartīte
Jautājums
What is the plasma membrane?
Atbilde
The selectively permeable boundary separating a cell from its environment.
112. kartīte
Jautājums
What is a cell wall?
Atbilde
A rigid extracellular layer that supports and protects cells in plants, fungi, and most prokaryotes.
113. kartīte
Jautājums
Which term describes the complex that synthesizes polypeptides?
Atbilde
a ribosome
114. kartīte
Jautājums
Which term describes cell contents inside the plasma membrane but outside the nucleus?
Atbilde
the cytoplasm
115. kartīte
Jautājums
Which term describes the selectively permeable cell boundary?
Atbilde
the plasma membrane
116. kartīte
Jautājums
Which term describes a rigid extracellular support layer?
Atbilde
a cell wall
117. kartīte
Jautājums
What is the nucleoid?
Atbilde
The non-membrane-bound region containing the main chromosome of a prokaryotic cell.
118. kartīte
Jautājums
What is the cytoskeleton?
Atbilde
A dynamic network of protein filaments involved in cell shape, transport, division, and movement.
119. kartīte
Jautājums
What structures are shared by all cells?
Atbilde
A plasma membrane, cytoplasm, genetic material, and ribosomes.
120. kartīte
Jautājums
Which structures distinguish a typical plant cell from a typical animal cell?
Atbilde
A plant cell has a cellulose wall, chloroplasts in photosynthetic tissues, and a large central vacuole; an animal cell lacks these.
121. kartīte
Jautājums
Which term describes the prokaryotic chromosome-containing region?
Atbilde
the nucleoid
122. kartīte
Jautājums
Which term describes the internal network of protein filaments?
Atbilde
the cytoskeleton
123. kartīte
Jautājums
How is genetic material commonly organized in a prokaryotic cell?
Atbilde
The main DNA is usually one circular chromosome in the nucleoid, often accompanied by smaller plasmids.
124. kartīte
Jautājums
How is microscope magnification calculated?
Atbilde
Magnification = image size ÷ actual size, using the same units.
125. kartīte
Jautājums
What does microscope resolution describe?
Atbilde
The ability to distinguish two close points as separate.
126. kartīte
Jautājums
Arrange these from smallest to largest: ribosome, bacterium, animal cell.
Atbilde
Ribosome, bacterium, animal cell.
127. kartīte
Jautājums
How does the cytoskeleton support intracellular transport?
Atbilde
Motor proteins move vesicles and other cargo along cytoskeletal filaments.
128. kartīte
Jautājums
Why does a small cell usually exchange materials more efficiently than a geometrically similar large cell?
Atbilde
It has a larger surface-area-to-volume ratio, providing more exchange surface per unit of cell contents.
129. kartīte
Jautājums
Why is a cell more than a collection of isolated molecules?
Atbilde
Organized interactions among components produce emergent functions such as metabolism, regulation, and reproduction.
130. kartīte
Jautājums
What major advantage do membrane-bound organelles give eukaryotic cells?
Atbilde
They separate incompatible reactions and create specialized local conditions.
131. kartīte
Jautājums
What is a phospholipid bilayer?
Atbilde
A double layer of phospholipids with hydrophilic heads facing water and hydrophobic tails facing inward.
132. kartīte
Jautājums
What is the fluid mosaic model?
Atbilde
A model describing membranes as mobile phospholipids containing a changing mosaic of proteins and other components.
133. kartīte
Jautājums
What is an integral membrane protein?
Atbilde
A protein embedded in the bilayer, often spanning it.
134. kartīte
Jautājums
What is a peripheral membrane protein?
Atbilde
A protein attached to a membrane surface rather than embedded in the bilayer.
135. kartīte
Jautājums
Which term describes a double phospholipid layer with inward-facing tails?
Atbilde
a phospholipid bilayer
136. kartīte
Jautājums
Which term describes the model of a mobile lipid layer containing varied proteins?
Atbilde
the fluid mosaic model
137. kartīte
Jautājums
Which term describes a protein embedded within the lipid bilayer?
Atbilde
an integral membrane protein
138. kartīte
Jautājums
Which term describes a protein attached to a membrane surface?
Atbilde
a peripheral membrane protein
139. kartīte
Jautājums
What is membrane cholesterol?
Atbilde
An amphipathic lipid that buffers membrane fluidity and reduces permeability in animal cells.
140. kartīte
Jautājums
What is a glycoprotein?
Atbilde
A protein with an attached carbohydrate chain, often used in recognition, adhesion, or signaling.
141. kartīte
Jautājums
What is diffusion?
Atbilde
Net movement of particles from a region of higher concentration to lower concentration due to random motion.
142. kartīte
Jautājums
What is osmosis?
Atbilde
Net movement of water across a selectively permeable membrane from higher water potential to lower water potential.
143. kartīte
Jautājums
Which term describes the animal-membrane lipid that buffers fluidity?
Atbilde
membrane cholesterol
144. kartīte
Jautājums
Which term describes a carbohydrate-bearing protein?
Atbilde
a glycoprotein
145. kartīte
Jautājums
Which term describes net movement down a concentration gradient?
Atbilde
diffusion
146. kartīte
Jautājums
Which term describes net water movement across a selectively permeable membrane?
Atbilde
osmosis
147. kartīte
Jautājums
What is facilitated diffusion?
Atbilde
Passive movement down a gradient through a membrane channel or carrier protein.
148. kartīte
Jautājums
What is active transport?
Atbilde
Energy-requiring movement of a substance against its concentration or electrochemical gradient.
149. kartīte
Jautājums
Why is the phospholipid bilayer selectively permeable?
Atbilde
Its hydrophobic interior allows small nonpolar molecules through more readily than ions and most large or polar molecules.
150. kartīte
Jautājums
How do simple diffusion and facilitated diffusion differ?
Atbilde
Both are passive, but facilitated diffusion uses specific membrane proteins while simple diffusion passes through the bilayer.
151. kartīte
Jautājums
Which term describes passive transport through a channel or carrier?
Atbilde
facilitated diffusion
152. kartīte
Jautājums
Which term describes energy-dependent transport against a gradient?
Atbilde
active transport
153. kartīte
Jautājums
How do channel and carrier proteins differ?
Atbilde
Channels provide hydrophilic pores; carriers bind solutes and change shape to move them.
154. kartīte
Jautājums
How can an ATP-driven pump maintain an ion gradient?
Atbilde
It couples ATP hydrolysis to a conformational change that moves ions against their electrochemical gradient.
155. kartīte
Jautājums
How does endocytosis move material into a cell?
Atbilde
The plasma membrane folds inward and pinches off a vesicle containing the material.
156. kartīte
Jautājums
How does exocytosis move material out of a cell?
Atbilde
An intracellular vesicle fuses with the plasma membrane and releases its contents outside.
157. kartīte
Jautājums
What happens to an animal cell in a strongly hypotonic solution?
Atbilde
Water enters by osmosis; without a cell wall, the cell may swell and lyse.
158. kartīte
Jautājums
Does molecular movement stop when diffusion reaches equilibrium?
Atbilde
No. Molecules continue moving randomly, but there is no net movement between regions.
159. kartīte
Jautājums
How does decreasing temperature generally affect membrane fluidity?
Atbilde
It reduces phospholipid movement and makes the membrane less fluid.
160. kartīte
Jautājums
Why do unsaturated fatty-acid tails increase membrane fluidity?
Atbilde
Their cis double-bond bends prevent phospholipids from packing tightly.
161. kartīte
Jautājums
What changes increase the rate of simple diffusion across a membrane?
Atbilde
A steeper gradient, larger surface area, higher temperature, shorter distance, and greater membrane permeability increase the rate.
162. kartīte
Jautājums
What is a mitochondrion?
Atbilde
A double-membrane organelle where most aerobic ATP production occurs.
163. kartīte
Jautājums
What is a chloroplast?
Atbilde
A double-membrane organelle where photosynthesis occurs in plants and algae.
164. kartīte
Jautājums
What is rough endoplasmic reticulum?
Atbilde
A membrane network bearing ribosomes that synthesizes and begins processing many secreted and membrane proteins.
165. kartīte
Jautājums
What is smooth endoplasmic reticulum?
Atbilde
A membrane network involved in lipid synthesis, detoxification, and calcium storage.
166. kartīte
Jautājums
Which term describes the main organelle of aerobic ATP production?
Atbilde
a mitochondrion
167. kartīte
Jautājums
Which term describes the photosynthetic organelle of plants and algae?
Atbilde
a chloroplast
168. kartīte
Jautājums
Which term describes the ribosome-studded membrane network?
Atbilde
rough endoplasmic reticulum
169. kartīte
Jautājums
Which term describes the membrane network that lacks ribosomes and synthesizes lipids?
Atbilde
smooth endoplasmic reticulum
170. kartīte
Jautājums
What is the Golgi apparatus?
Atbilde
Stacked membranes that modify, sort, and package proteins and lipids into vesicles.
171. kartīte
Jautājums
What is a lysosome?
Atbilde
An acidic enzyme-containing organelle that digests macromolecules and worn cellular components.
172. kartīte
Jautājums
What is a vesicle?
Atbilde
A small membrane-bound compartment used for transport, storage, or chemical reactions.
173. kartīte
Jautājums
What is the central vacuole?
Atbilde
A large plant-cell compartment that stores solutes and helps maintain turgor pressure.
174. kartīte
Jautājums
Which term describes the organelle that modifies and sorts cellular cargo?
Atbilde
the Golgi apparatus
175. kartīte
Jautājums
Which term describes the acidic digestive organelle?
Atbilde
a lysosome
176. kartīte
Jautājums
Which term describes a small membrane-bound transport compartment?
Atbilde
a vesicle
177. kartīte
Jautājums
Which term describes the large plant compartment that supports turgor?
Atbilde
the central vacuole
178. kartīte
Jautājums
Why can compartmentalization increase metabolic efficiency?
Atbilde
It concentrates enzymes and substrates, maintains suitable local conditions, and separates incompatible reactions.
179. kartīte
Jautājums
How do mitochondrial cristae support ATP production?
Atbilde
They increase inner-membrane area for electron transport chains and ATP synthase.
180. kartīte
Jautājums
Why are chloroplast thylakoids arranged as extensive membranes?
Atbilde
They provide a large surface for light-absorbing complexes, electron transport chains, and ATP synthase.
181. kartīte
Jautājums
What is the main function of the nucleolus?
Atbilde
It produces rRNA and assembles ribosomal subunits.
182. kartīte
Jautājums
Trace a secreted protein from synthesis to release.
Atbilde
Ribosome on rough ER → ER lumen → transport vesicle → Golgi apparatus → secretory vesicle → plasma membrane → exocytosis.
183. kartīte
Jautājums
Why does a lysosome maintain an acidic interior?
Atbilde
Its hydrolytic enzymes work best at low pH, and acidity helps confine their activity from the cytosol.
184. kartīte
Jautājums
How do the nucleus, ribosomes, ER, and Golgi cooperate in protein production?
Atbilde
DNA instructions are transcribed in the nucleus; ribosomes translate them; ER folds or modifies many products; Golgi further modifies and sorts them.
185. kartīte
Jautājums
How are transport vesicles directed to the correct target membrane?
Atbilde
Specific recognition proteins on vesicles and target membranes interact, allowing selective docking and fusion.
186. kartīte
Jautājums
What is cell differentiation?
Atbilde
The process by which a cell develops specialized structure and function.
187. kartīte
Jautājums
What is a stem cell?
Atbilde
An unspecialized cell able to self-renew and produce differentiated cells.
188. kartīte
Jautājums
What is gene expression?
Atbilde
Use of genetic information to produce a functional RNA or protein product.
189. kartīte
Jautājums
What is a tissue?
Atbilde
A coordinated group of similar or related cells performing a shared function.
190. kartīte
Jautājums
Which term describes development of specialized cell structure and function?
Atbilde
cell differentiation
191. kartīte
Jautājums
Which term describes an unspecialized self-renewing cell?
Atbilde
a stem cell
192. kartīte
Jautājums
Which term describes production of a functional product from genetic information?
Atbilde
gene expression
193. kartīte
Jautājums
Which term describes a group of coordinated cells with a shared function?
Atbilde
a tissue
194. kartīte
Jautājums
What is an organ?
Atbilde
A structure made of multiple tissues working together for particular functions.
195. kartīte
Jautājums
What is the organ-system level of biological organization?
Atbilde
A group of organs that coordinate to perform major functions for an organism.
196. kartīte
Jautājums
What is surface-area-to-volume ratio?
Atbilde
The amount of surface area available relative to the volume it must serve.
197. kartīte
Jautājums
How can two specialized cells have the same genome but different structures?
Atbilde
They express different sets and amounts of genes, producing different proteins and cellular features.
198. kartīte
Jautājums
Which term describes a structure composed of multiple tissue types?
Atbilde
an organ
199. kartīte
Jautājums
Which term describes the level of biological organization formed by coordinated organs?
Atbilde
an organ system
200. kartīte
Jautājums
Which term describes surface area available per unit volume?
Atbilde
surface-area-to-volume ratio
201. kartīte
Jautājums
How is a mammalian red blood cell specialized for oxygen transport?
Atbilde
Its biconcave shape increases exchange area, it is flexible, and loss of its nucleus leaves more space for hemoglobin.
202. kartīte
Jautājums
How is a sperm cell specialized for fertilization?
Atbilde
It has a flagellum for movement, many mitochondria for ATP, a haploid nucleus, and an acrosome containing enzymes.
203. kartīte
Jautājums
How is a neuron specialized for rapid communication?
Atbilde
Long processes carry signals over distance, branching dendrites receive inputs, and synaptic terminals transmit signals to other cells.
204. kartīte
Jautājums
How is a root hair cell specialized for mineral and water uptake?
Atbilde
Its long projection increases surface area, its thin wall shortens the pathway, and membrane transport proteins take up ions.
205. kartīte
Jautājums
How is a palisade mesophyll cell specialized for photosynthesis?
Atbilde
It contains many chloroplasts and is positioned near the upper leaf surface where light is strongest.
206. kartīte
Jautājums
How do ciliated epithelial cells help protect airways?
Atbilde
Their cilia move mucus containing trapped particles and microbes toward the throat.
207. kartīte
Jautājums
Why can extreme specialization reduce a cell's independence?
Atbilde
Resources and structures are committed to a narrow role, so the cell depends on other cells for functions it no longer performs well.
208. kartīte
Jautājums
What is water potential?
Atbilde
The potential energy of water per unit volume relative to pure water, used to predict the direction of water movement.
209. kartīte
Jautājums
What is solute potential?
Atbilde
The negative contribution of dissolved solutes to water potential.
210. kartīte
Jautājums
What is pressure potential?
Atbilde
The contribution of physical pressure to water potential.
211. kartīte
Jautājums
What is turgor pressure?
Atbilde
Outward pressure of a plant-cell interior against its cell wall after water uptake.
212. kartīte
Jautājums
Which term describes the tendency of water to move relative to pure water?
Atbilde
water potential
213. kartīte
Jautājums
Which term describes the water-potential component lowered by dissolved solutes?
Atbilde
solute potential
214. kartīte
Jautājums
Which term describes the water-potential component caused by physical pressure?
Atbilde
pressure potential
215. kartīte
Jautājums
Which term describes pressure of plant-cell contents against the wall?
Atbilde
turgor pressure
216. kartīte
Jautājums
What is plasmolysis?
Atbilde
Separation of the plasma membrane from the cell wall after a plant cell loses water.
217. kartīte
Jautājums
What is a flaccid plant cell?
Atbilde
A plant cell with insufficient turgor pressure to be firm.
218. kartīte
Jautājums
What is an isotonic condition?
Atbilde
A condition in which two solutions have equal effective water potential and no net water movement occurs.
219. kartīte
Jautājums
In which direction does water move across a permeable membrane?
Atbilde
From higher water potential to lower water potential.
220. kartīte
Jautājums
Which term describes membrane separation from the plant cell wall after water loss?
Atbilde
plasmolysis
221. kartīte
Jautājums
Which term describes a plant cell lacking firm turgor?
Atbilde
a flaccid plant cell
222. kartīte
Jautājums
Which term describes equal effective water potential across a membrane?
Atbilde
an isotonic condition
223. kartīte
Jautājums
What is the water potential of pure water at standard pressure?
Atbilde
Zero; adding solute makes water potential more negative.
224. kartīte
Jautājums
How are water potential, solute potential, and pressure potential related?
Atbilde
Water potential equals solute potential plus pressure potential: Ψ = Ψs + Ψp.
225. kartīte
Jautājums
Why does a plant cell usually become turgid rather than burst in a hypotonic solution?
Atbilde
Water entry raises pressure potential, while the rigid cell wall resists further expansion.
226. kartīte
Jautājums
What happens to a plant cell placed in a solution with much lower water potential?
Atbilde
Water leaves the cell, turgor falls, and severe loss can cause plasmolysis.
227. kartīte
Jautājums
Can two solutions have different solute concentrations but equal water potential?
Atbilde
Yes. A difference in pressure potential can offset a difference in solute potential.
228. kartīte
Jautājums
What is an enzyme?
Atbilde
A biological catalyst that increases reaction rate without being consumed.
229. kartīte
Jautājums
What is an active site?
Atbilde
The region of an enzyme where substrate binds and catalysis occurs.
230. kartīte
Jautājums
What is a substrate?
Atbilde
A reactant molecule on which an enzyme acts.
231. kartīte
Jautājums
What is activation energy?
Atbilde
The minimum energy input needed for a reaction to begin.
232. kartīte
Jautājums
Which term describes a biological catalyst?
Atbilde
an enzyme
233. kartīte
Jautājums
Which term describes the substrate-binding catalytic region of an enzyme?
Atbilde
an active site
234. kartīte
Jautājums
Which term describes a reactant bound and changed by an enzyme?
Atbilde
a substrate
235. kartīte
Jautājums
Which term describes the energy barrier that must be overcome for a reaction?
Atbilde
activation energy
236. kartīte
Jautājums
What is the induced-fit model?
Atbilde
The model in which substrate binding changes active-site shape to improve catalytic interactions.
237. kartīte
Jautājums
What is enzyme denaturation?
Atbilde
Loss of the active three-dimensional shape of an enzyme, usually causing loss of activity.
238. kartīte
Jautājums
What is competitive inhibition?
Atbilde
Inhibition caused by a molecule competing with substrate for the active site.
239. kartīte
Jautājums
What is noncompetitive inhibition?
Atbilde
Inhibition caused by binding away from the active site and reducing catalytic function.
240. kartīte
Jautājums
Which term describes the model where substrate binding reshapes the active site?
Atbilde
the induced-fit model
241. kartīte
Jautājums
Which term describes loss of an enzyme's functional shape?
Atbilde
enzyme denaturation
242. kartīte
Jautājums
Which term describes inhibition by active-site competition?
Atbilde
competitive inhibition
243. kartīte
Jautājums
Which term describes inhibition by binding outside the active site?
Atbilde
noncompetitive inhibition
244. kartīte
Jautājums
What is an enzyme optimum?
Atbilde
The condition, such as temperature or pH, at which an enzyme's activity is highest.
245. kartīte
Jautājums
What is feedback inhibition?
Atbilde
Control in which a pathway product inhibits an enzyme acting earlier in the pathway.
246. kartīte
Jautājums
How does an enzyme increase reaction rate?
Atbilde
It stabilizes the transition state and provides a pathway with lower activation energy.
247. kartīte
Jautājums
Why does enzyme activity often rise and then fall as temperature increases?
Atbilde
Molecular collisions initially increase, but excessive heat disrupts enzyme shape and denatures the active site.
248. kartīte
Jautājums
Which term describes the condition producing maximum enzyme activity?
Atbilde
an enzyme optimum
249. kartīte
Jautājums
Which term describes pathway control by inhibition from an end product?
Atbilde
feedback inhibition
250. kartīte
Jautājums
Why does each enzyme have a characteristic pH range?
Atbilde
pH changes the ionization of amino-acid side chains, affecting active-site shape and chemical interactions.
251. kartīte
Jautājums
Why does increasing substrate concentration eventually stop increasing enzyme rate?
Atbilde
At saturation, nearly all active sites are occupied and enzyme concentration limits the maximum rate.
252. kartīte
Jautājums
How does increasing enzyme concentration affect rate when substrate is abundant?
Atbilde
More active sites are available, so the initial rate increases roughly in proportion to enzyme concentration.
253. kartīte
Jautājums
What gives an enzyme substrate specificity?
Atbilde
The active site's shape, charge, polarity, and chemical groups complement particular substrates and transition states.
254. kartīte
Jautājums
What is one practical advantage of immobilizing an enzyme?
Atbilde
The enzyme can be separated from products and reused while conditions around it are controlled.
255. kartīte
Jautājums
Does an enzyme change a reaction's equilibrium position?
Atbilde
No. It speeds forward and reverse reactions but does not change the equilibrium constant or final equilibrium position.
256. kartīte
Jautājums
How can high substrate concentration reduce competitive inhibition?
Atbilde
More substrate molecules increase the chance that substrate rather than inhibitor occupies the active site.
257. kartīte
Jautājums
Why are metabolic reactions commonly organized into pathways?
Atbilde
A sequence of enzyme-controlled steps allows energy changes and intermediates to be controlled and coupled.
258. kartīte
Jautājums
What is ATP?
Atbilde
A nucleotide that transfers usable energy through coupling of its hydrolysis to cellular processes.
259. kartīte
Jautājums
What is cellular respiration?
Atbilde
Controlled release of energy from organic molecules to produce ATP.
260. kartīte
Jautājums
What is glycolysis?
Atbilde
A cytosolic pathway that splits glucose into two pyruvate molecules and yields a small amount of ATP and reduced electron carriers.
261. kartīte
Jautājums
What is pyruvate?
Atbilde
The three-carbon product of glycolysis that can enter aerobic or anaerobic pathways.
262. kartīte
Jautājums
Which term describes the cell's immediate phosphoryl-group energy carrier?
Atbilde
ATP
263. kartīte
Jautājums
Which term describes controlled ATP-producing breakdown of organic molecules?
Atbilde
cellular respiration
264. kartīte
Jautājums
Which term describes the cytosolic splitting of glucose into pyruvate?
Atbilde
glycolysis
265. kartīte
Jautājums
Which term describes the three-carbon product of glycolysis?
Atbilde
pyruvate
266. kartīte
Jautājums
What is aerobic respiration?
Atbilde
Respiration that uses oxygen as the final electron acceptor and produces much more ATP than fermentation.
267. kartīte
Jautājums
What is anaerobic metabolism?
Atbilde
ATP-producing metabolism that proceeds without oxygen.
268. kartīte
Jautājums
What is fermentation?
Atbilde
An anaerobic pathway that regenerates oxidized electron carriers so glycolysis can continue.
269. kartīte
Jautājums
What is oxidation?
Atbilde
Loss of electrons, often accompanied in biology by loss of hydrogen or gain of oxygen.
270. kartīte
Jautājums
Which term describes respiration using oxygen as final electron acceptor?
Atbilde
aerobic respiration
271. kartīte
Jautājums
Which term describes ATP-producing metabolism without oxygen?
Atbilde
anaerobic metabolism
272. kartīte
Jautājums
Which term describes anaerobic regeneration of electron carriers after glycolysis?
Atbilde
fermentation
273. kartīte
Jautājums
Which term describes loss of electrons?
Atbilde
oxidation
274. kartīte
Jautājums
What is reduction?
Atbilde
Gain of electrons, often accompanied in biology by gain of hydrogen or loss of oxygen.
275. kartīte
Jautājums
What is a reduced electron carrier?
Atbilde
A molecule such as NADH that carries high-energy electrons and hydrogen from one reaction to another.
276. kartīte
Jautājums
What is chemiosmosis?
Atbilde
ATP production driven by ions moving down an electrochemical gradient through ATP synthase.
277. kartīte
Jautājums
What is the overall word equation for aerobic respiration of glucose?
Atbilde
Glucose + oxygen → carbon dioxide + water + energy transferred to ATP and heat.
278. kartīte
Jautājums
Which term describes gain of electrons?
Atbilde
reduction
279. kartīte
Jautājums
Which term describes a molecule carrying high-energy electrons between reactions?
Atbilde
a reduced electron carrier
280. kartīte
Jautājums
Which term describes ATP production powered by an ion gradient?
Atbilde
chemiosmosis
281. kartīte
Jautājums
Where does glycolysis occur?
Atbilde
In the cytosol.
282. kartīte
Jautājums
What major stages of aerobic respiration occur in mitochondria?
Atbilde
Pyruvate oxidation and the citric acid cycle occur in the matrix; electron transport and chemiosmosis occur at the inner membrane.
283. kartīte
Jautājums
What is oxygen's direct role in aerobic respiration?
Atbilde
It accepts electrons and hydrogen ions at the end of the electron transport chain, forming water.
284. kartīte
Jautājums
Why does aerobic respiration yield much more ATP per glucose than fermentation?
Atbilde
It transfers electrons through an electron transport chain and uses oxidative phosphorylation, extracting far more of glucose's energy.
285. kartīte
Jautājums
What is the purpose of lactate formation in oxygen-limited animal cells?
Atbilde
It regenerates NAD⁺ so glycolysis can continue producing a small amount of ATP.
286. kartīte
Jautājums
What products are formed during alcoholic fermentation in yeast?
Atbilde
Ethanol and carbon dioxide, while NAD⁺ is regenerated.
287. kartīte
Jautājums
Why is some energy released by respiration transferred as heat rather than captured in ATP?
Atbilde
Energy conversions are not fully efficient, so part of the chemical energy becomes disordered molecular motion.
288. kartīte
Jautājums
What is substrate-level phosphorylation?
Atbilde
Direct transfer of a phosphate group from a metabolic intermediate to ADP to form ATP.
289. kartīte
Jautājums
How does electron transport lead to ATP synthesis in mitochondria?
Atbilde
Electron energy pumps protons across the inner membrane; proton flow back through ATP synthase drives ATP formation.
290. kartīte
Jautājums
Why can intense exercise increase lactate production?
Atbilde
ATP demand can exceed oxygen delivery and aerobic capacity, so cells regenerate NAD⁺ through lactate formation to sustain glycolysis.
291. kartīte
Jautājums
What is photosynthesis?
Atbilde
Conversion of light energy into chemical energy used to synthesize organic molecules from carbon dioxide.
292. kartīte
Jautājums
What is chlorophyll?
Atbilde
A green pigment that absorbs light energy for photosynthesis.
293. kartīte
Jautājums
What is an absorption spectrum?
Atbilde
A graph showing how strongly a pigment absorbs different wavelengths of light.
294. kartīte
Jautājums
What is an action spectrum?
Atbilde
A graph showing the rate or effectiveness of photosynthesis at different wavelengths.
295. kartīte
Jautājums
Which term describes light-driven synthesis of organic molecules from carbon dioxide?
Atbilde
photosynthesis
296. kartīte
Jautājums
Which term describes the principal green photosynthetic pigment?
Atbilde
chlorophyll
297. kartīte
Jautājums
Which term describes a graph of pigment absorption versus wavelength?
Atbilde
an absorption spectrum
298. kartīte
Jautājums
Which term describes a graph of photosynthetic effectiveness versus wavelength?
Atbilde
an action spectrum
299. kartīte
Jautājums
What is photolysis of water?
Atbilde
Light-driven splitting of water that supplies electrons and hydrogen ions and releases oxygen.
300. kartīte
Jautājums
What are light-dependent reactions?
Atbilde
Photosynthetic reactions that use light to generate ATP and reduced electron carriers while releasing oxygen.
301. kartīte
Jautājums
What is the Calvin cycle?
Atbilde
A set of chloroplast reactions that uses ATP and reduced electron carriers to convert carbon dioxide into carbohydrate precursors.
302. kartīte
Jautājums
What is carbon fixation?
Atbilde
Incorporation of inorganic carbon dioxide into an organic molecule.
303. kartīte
Jautājums
Which term describes light-driven splitting of water?
Atbilde
photolysis of water
304. kartīte
Jautājums
Which term describes photosynthetic reactions that directly capture light energy?
Atbilde
light-dependent reactions
305. kartīte
Jautājums
Which term describes the carbon-reduction cycle of photosynthesis?
Atbilde
the Calvin cycle
306. kartīte
Jautājums
Which term describes incorporation of carbon dioxide into organic matter?
Atbilde
carbon fixation
307. kartīte
Jautājums
What is the role of a stoma in photosynthesis?
Atbilde
A pore in the leaf epidermis that regulates carbon-dioxide entry as well as water loss.
308. kartīte
Jautājums
What is a limiting factor of photosynthesis?
Atbilde
The environmental factor whose availability currently restricts the photosynthetic rate.
309. kartīte
Jautājums
What is the light compensation point?
Atbilde
The light intensity at which photosynthetic carbon uptake equals respiratory carbon release.
310. kartīte
Jautājums
What is the overall word equation for oxygenic photosynthesis?
Atbilde
Carbon dioxide + water → carbohydrate + oxygen, using light energy.
311. kartīte
Jautājums
Which term describes the regulated leaf pore controlling carbon-dioxide entry for photosynthesis?
Atbilde
a stoma
312. kartīte
Jautājums
Which term describes the factor currently restricting photosynthetic rate?
Atbilde
a limiting factor
313. kartīte
Jautājums
Which term describes the light level where photosynthesis and respiration balance?
Atbilde
the light compensation point
314. kartīte
Jautājums
Where do the main stages of photosynthesis occur in a chloroplast?
Atbilde
Light-dependent reactions occur in thylakoid membranes; carbon-fixation reactions occur in the stroma.
315. kartīte
Jautājums
What energy conversion occurs during photosynthesis?
Atbilde
Light energy is converted into chemical energy stored first in ATP and reduced carriers and ultimately in organic molecules.
316. kartīte
Jautājums
From which reactant does the oxygen released by photosynthesis originate?
Atbilde
Water.
317. kartīte
Jautājums
What role does RuBisCO play in photosynthesis?
Atbilde
It catalyzes fixation of carbon dioxide by adding it to an organic acceptor molecule.
318. kartīte
Jautājums
What tradeoff is controlled when stomata open?
Atbilde
Opening permits carbon dioxide entry but increases water loss by transpiration.
319. kartīte
Jautājums
Name three leaf features that support photosynthesis.
Atbilde
A broad surface captures light, a thin structure shortens diffusion paths, and veins supply water and remove sugars; chloroplast-rich cells and stomata also help.
320. kartīte
Jautājums
What can a plant do with carbohydrate made by photosynthesis?
Atbilde
Use it in respiration, convert it to storage or structural carbohydrates, or use its carbon to make lipids, amino acids, and other molecules.
321. kartīte
Jautājums
How are products of the light-dependent reactions used in carbon fixation?
Atbilde
ATP supplies energy and NADPH supplies reducing power for conversion of fixed carbon into carbohydrate precursors.
322. kartīte
Jautājums
Why does increasing light intensity eventually stop increasing photosynthetic rate?
Atbilde
Another factor, such as carbon dioxide supply, temperature, or biochemical capacity, becomes limiting.
323. kartīte
Jautājums
How can increasing carbon dioxide concentration affect photosynthetic rate?
Atbilde
It can increase the rate until another factor becomes limiting.
324. kartīte
Jautājums
Why does photosynthetic rate usually have a temperature optimum?
Atbilde
Enzyme-controlled reactions accelerate with temperature up to an optimum, then decline as enzymes and membranes lose effective function.
325. kartīte
Jautājums
Why does an action spectrum broadly resemble the combined absorption spectra of photosynthetic pigments?
Atbilde
Wavelengths absorbed by the pigments supply more energy for photosynthesis than poorly absorbed wavelengths.
326. kartīte
Jautājums
What is semiconservative replication?
Atbilde
DNA replication in which each daughter molecule contains one parental strand and one newly synthesized strand.
327. kartīte
Jautājums
What is DNA helicase?
Atbilde
An enzyme that unwinds the double helix and separates the strands by disrupting base pairing.
328. kartīte
Jautājums
What is DNA polymerase?
Atbilde
An enzyme that adds nucleotides to a growing DNA strand using a template.
329. kartīte
Jautājums
What is a primer?
Atbilde
A short nucleic-acid segment providing a free 3′ end from which DNA polymerase can extend.
330. kartīte
Jautājums
Which term describes replication producing one old and one new strand per DNA molecule?
Atbilde
semiconservative replication
331. kartīte
Jautājums
Which term describes the enzyme that separates DNA strands?
Atbilde
DNA helicase
332. kartīte
Jautājums
Which term describes the enzyme that builds DNA from a template?
Atbilde
DNA polymerase
333. kartīte
Jautājums
Which term describes the short segment providing a starting 3′ end?
Atbilde
a primer
334. kartīte
Jautājums
What is the leading strand?
Atbilde
The new DNA strand synthesized continuously toward the replication fork.
335. kartīte
Jautājums
What is the lagging strand?
Atbilde
The new DNA strand synthesized discontinuously away from the replication fork.
336. kartīte
Jautājums
What is an Okazaki fragment?
Atbilde
A short DNA segment synthesized on the lagging strand.
337. kartīte
Jautājums
What is DNA ligase?
Atbilde
An enzyme that seals breaks in the sugar-phosphate backbone, joining DNA fragments.
338. kartīte
Jautājums
Which term describes the continuously synthesized daughter strand?
Atbilde
the leading strand
339. kartīte
Jautājums
Which term describes the discontinuously synthesized daughter strand?
Atbilde
the lagging strand
340. kartīte
Jautājums
Which term describes a short newly made segment of lagging-strand DNA?
Atbilde
an Okazaki fragment
341. kartīte
Jautājums
Which term describes the enzyme that joins DNA fragments by sealing the backbone?
Atbilde
DNA ligase
342. kartīte
Jautājums
How does complementary base pairing ensure accurate DNA copying?
Atbilde
Each template base specifies the nucleotide added opposite it: A pairs with T, and C pairs with G.
343. kartīte
Jautājums
Why does DNA polymerase synthesize DNA only 5′ to 3′?
Atbilde
It can add a nucleotide only to the free 3′ hydroxyl group of the growing strand.
344. kartīte
Jautājums
When in the cell cycle is nuclear DNA replicated?
Atbilde
During S phase of interphase, before cell division.
345. kartīte
Jautājums
How can a replication error become a permanent mutation?
Atbilde
If it escapes proofreading and repair, the altered sequence can be copied in later cell generations.
346. kartīte
Jautājums
Why are leading and lagging strands synthesized differently?
Atbilde
The templates are antiparallel while DNA polymerase works only 5′ to 3′, forcing one strand to be made discontinuously.
347. kartīte
Jautājums
How do proofreading and repair reduce replication errors?
Atbilde
Incorrectly paired nucleotides are recognized, removed, and replaced before or after replication continues.
348. kartīte
Jautājums
What three repeating steps amplify DNA in PCR?
Atbilde
Strand separation by heating, primer annealing during cooling, and DNA extension by a heat-stable polymerase.
349. kartīte
Jautājums
What determines which DNA region PCR amplifies?
Atbilde
The sequences and positions of the two primers flanking the target region.
350. kartīte
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What is transcription?
Atbilde
Synthesis of RNA from a DNA template.
351. kartīte
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What is RNA polymerase?
Atbilde
The enzyme that synthesizes RNA complementary to a DNA template strand.
352. kartīte
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What is messenger RNA?
Atbilde
RNA carrying a coding sequence from DNA to ribosomes.
353. kartīte
Jautājums
What is a codon?
Atbilde
A three-base sequence in mRNA that specifies an amino acid or a translation signal.
354. kartīte
Jautājums
Which term describes RNA synthesis from DNA?
Atbilde
transcription
355. kartīte
Jautājums
Which term describes the enzyme that builds RNA from a DNA template?
Atbilde
RNA polymerase
356. kartīte
Jautājums
Which term describes RNA that carries coding information to ribosomes?
Atbilde
messenger RNA
357. kartīte
Jautājums
Which term describes a three-base mRNA unit?
Atbilde
a codon
358. kartīte
Jautājums
What is translation?
Atbilde
Synthesis of a polypeptide using the codon sequence of mRNA.
359. kartīte
Jautājums
What does a ribosome do during translation?
Atbilde
It reads mRNA and catalyzes polypeptide synthesis using its rRNA-protein machinery.
360. kartīte
Jautājums
What is transfer RNA?
Atbilde
RNA that carries a specific amino acid and pairs its anticodon with an mRNA codon.
361. kartīte
Jautājums
What is an anticodon?
Atbilde
A three-base tRNA sequence complementary to an mRNA codon.
362. kartīte
Jautājums
Which term describes polypeptide synthesis from an mRNA sequence?
Atbilde
translation
363. kartīte
Jautājums
Which term describes the translation complex that reads mRNA and builds a polypeptide?
Atbilde
a ribosome
364. kartīte
Jautājums
Which term describes the adaptor RNA carrying an amino acid?
Atbilde
transfer RNA
365. kartīte
Jautājums
Which term describes the tRNA triplet that pairs with a codon?
Atbilde
an anticodon
366. kartīte
Jautājums
What is the genetic code?
Atbilde
The set of rules relating mRNA codons to amino acids and translation signals.
367. kartīte
Jautājums
What are start and stop codons?
Atbilde
mRNA signals that establish the reading frame or terminate translation.
368. kartīte
Jautājums
Where do transcription and translation occur in a eukaryotic cell?
Atbilde
Transcription occurs in the nucleus; translation occurs on ribosomes in the cytoplasm or on rough ER.
369. kartīte
Jautājums
How is an mRNA sequence related to its DNA template strand?
Atbilde
It is complementary and antiparallel, with uracil in RNA opposite adenine in DNA.
370. kartīte
Jautājums
Which term describes the codon-to-amino-acid rule set?
Atbilde
the genetic code
371. kartīte
Jautājums
Which term describes codons that begin or end translation?
Atbilde
start and stop codons
372. kartīte
Jautājums
What reaction does the ribosome catalyze as a polypeptide grows?
Atbilde
Formation of peptide bonds between adjacent amino acids.
373. kartīte
Jautājums
What does it mean that the genetic code is degenerate?
Atbilde
Most amino acids are specified by more than one codon.
374. kartīte
Jautājums
How can one mRNA produce many polypeptides quickly?
Atbilde
Multiple ribosomes can translate the same mRNA simultaneously as a polyribosome.
375. kartīte
Jautājums
Why is translation not the final step in producing many functional proteins?
Atbilde
The polypeptide must fold and may undergo cleavage, chemical modification, or assembly with other subunits.
376. kartīte
Jautājums
How does mRNA compare with the DNA coding strand?
Atbilde
It has the same base sequence except that RNA contains uracil where DNA contains thymine.
377. kartīte
Jautājums
What happens during eukaryotic RNA splicing?
Atbilde
Introns are removed and exons are joined to form mature mRNA.
378. kartīte
Jautājums
Why must codons be read in the correct reading frame?
Atbilde
Changing the starting position changes every downstream triplet and therefore the amino-acid sequence.
379. kartīte
Jautājums
How is the correct amino acid matched to each mRNA codon?
Atbilde
Each tRNA is charged with a particular amino acid, and its anticodon pairs with the complementary codon.
380. kartīte
Jautājums
How can a base substitution affect a protein?
Atbilde
It may be silent, change one amino acid, create a stop codon, or sometimes alter RNA processing.
381. kartīte
Jautājums
What is a mutation?
Atbilde
A change in a DNA sequence or chromosome structure that can be passed to daughter cells.
382. kartīte
Jautājums
What is a base substitution?
Atbilde
Replacement of one nucleotide pair by another.
383. kartīte
Jautājums
What is an insertion mutation?
Atbilde
Addition of one or more nucleotides to a DNA sequence.
384. kartīte
Jautājums
What is a deletion mutation?
Atbilde
Loss of one or more nucleotides from a DNA sequence.
385. kartīte
Jautājums
Which term describes a lasting DNA-sequence or chromosome change?
Atbilde
a mutation
386. kartīte
Jautājums
Which term describes replacement of one DNA base pair?
Atbilde
a base substitution
387. kartīte
Jautājums
Which term describes addition of nucleotides to DNA?
Atbilde
an insertion mutation
388. kartīte
Jautājums
Which term describes loss of nucleotides from DNA?
Atbilde
a deletion mutation
389. kartīte
Jautājums
What is a frameshift mutation?
Atbilde
A coding-sequence insertion or deletion not divisible by three that changes downstream codon grouping.
390. kartīte
Jautājums
What is a silent mutation?
Atbilde
A sequence change that does not alter the encoded amino acid.
391. kartīte
Jautājums
What is a missense mutation?
Atbilde
A mutation that changes a codon so a different amino acid is incorporated.
392. kartīte
Jautājums
What is a nonsense mutation?
Atbilde
A mutation that changes an amino-acid codon into a stop codon.
393. kartīte
Jautājums
Which term describes a mutation that shifts downstream codon grouping?
Atbilde
a frameshift mutation
394. kartīte
Jautājums
Which term describes a coding change that leaves the amino acid unchanged?
Atbilde
a silent mutation
395. kartīte
Jautājums
Which term describes a mutation causing one amino-acid substitution?
Atbilde
a missense mutation
396. kartīte
Jautājums
Which term describes a mutation creating a premature stop codon?
Atbilde
a nonsense mutation
397. kartīte
Jautājums
How do germline and somatic mutations differ in inheritance?
Atbilde
Germline mutations can enter gametes and be inherited; somatic mutations affect a cell lineage within the individual.
398. kartīte
Jautājums
What can cause mutations?
Atbilde
Replication errors, spontaneous chemical changes, radiation, and mutagenic chemicals can alter DNA.
399. kartīte
Jautājums
How does DNA repair protect genome stability?
Atbilde
Repair systems detect damaged or mismatched DNA and restore the correct structure or sequence when possible.
400. kartīte
Jautājums
Why are mutations essential to evolution despite often being neutral or harmful?
Atbilde
They create new alleles, providing the heritable variation on which selection and drift act.
401. kartīte
Jautājums
What is the basic role of guide RNA in CRISPR gene editing?
Atbilde
It directs a nuclease to a complementary DNA sequence.
402. kartīte
Jautājums
Why can the same type of DNA mutation have effects ranging from none to severe?
Atbilde
Effects depend on location, genetic-code redundancy, protein role, cell type, and environmental context.
403. kartīte
Jautājums
How can accumulated mutations contribute to cancer?
Atbilde
Mutations can activate growth-promoting genes or disable genes that restrain division, repair DNA, or trigger cell death.
404. kartīte
Jautājums
Why can repairing a CRISPR-induced DNA break produce different editing outcomes?
Atbilde
Different cellular repair pathways may disrupt the target sequence or use a supplied template for a specific change.
405. kartīte
Jautājums
What is an off-target effect in gene editing?
Atbilde
An unintended DNA change at a site sufficiently similar to the intended target.
406. kartīte
Jautājums
Why does heritable human genome editing raise additional ethical concerns?
Atbilde
Changes could pass to future generations who cannot consent, with uncertain long-term biological and social effects.
407. kartīte
Jautājums
What is the cell cycle?
Atbilde
The ordered sequence of cell growth, DNA replication, nuclear division, and cell division.
408. kartīte
Jautājums
What is interphase?
Atbilde
The period of growth, normal activity, and DNA replication between nuclear divisions.
409. kartīte
Jautājums
What is mitosis?
Atbilde
Nuclear division that usually produces genetically equivalent daughter nuclei.
410. kartīte
Jautājums
What is cytokinesis?
Atbilde
Division of the cytoplasm to form separate daughter cells.
411. kartīte
Jautājums
Which term describes the ordered sequence from one cell division to the next?
Atbilde
the cell cycle
412. kartīte
Jautājums
Which term describes the growth and DNA-replication period between divisions?
Atbilde
interphase
413. kartīte
Jautājums
Which term describes division producing genetically equivalent nuclei?
Atbilde
mitosis
414. kartīte
Jautājums
Which term describes physical division of the cytoplasm?
Atbilde
cytokinesis
415. kartīte
Jautājums
What is a chromosome?
Atbilde
One DNA molecule packaged with associated proteins.
416. kartīte
Jautājums
What are sister chromatids?
Atbilde
The two replicated copies of a chromosome joined before separation.
417. kartīte
Jautājums
What is a centromere?
Atbilde
The chromosome region that holds sister chromatids together and organizes kinetochore attachment.
418. kartīte
Jautājums
What is the mitotic spindle?
Atbilde
A microtubule system that attaches to and separates chromosomes during cell division.
419. kartīte
Jautājums
Which term describes a protein-packaged DNA molecule?
Atbilde
a chromosome
420. kartīte
Jautājums
Which term describes joined replicated copies of one chromosome?
Atbilde
sister chromatids
421. kartīte
Jautājums
Which term describes the chromosome region joining sister chromatids?
Atbilde
a centromere
422. kartīte
Jautājums
Which term describes the chromosome-separating microtubule system?
Atbilde
the mitotic spindle
423. kartīte
Jautājums
What is the basic sequence of mitosis?
Atbilde
Chromosomes condense, align at the cell equator, sister chromatids separate to opposite poles, and new nuclei form.
424. kartīte
Jautājums
Why must DNA replicate before mitosis?
Atbilde
Each chromosome must have two copies so each daughter nucleus can receive a complete genome.
425. kartīte
Jautājums
Why are daughter cells from mitosis usually genetically similar?
Atbilde
Replicated sister chromatids are separated so each daughter receives one copy of every chromosome.
426. kartīte
Jautājums
What are major roles of mitosis in multicellular organisms?
Atbilde
Growth, tissue repair, cell replacement, and some forms of asexual reproduction.
427. kartīte
Jautājums
How do homologous chromosomes differ from sister chromatids?
Atbilde
Homologs carry the same gene loci but may have different alleles; sister chromatids are replicated copies of one chromosome.
428. kartīte
Jautājums
What key outcome distinguishes mitosis from meiosis?
Atbilde
Mitosis usually preserves chromosome number and similarity; meiosis halves chromosome number and generates genetically varied haploid cells.
429. kartīte
Jautājums
How does cytokinesis commonly occur in animal cells?
Atbilde
A contractile ring tightens the plasma membrane into a cleavage furrow.
430. kartīte
Jautājums
How does cytokinesis commonly occur in plant cells?
Atbilde
Vesicles fuse at the center to form a cell plate that develops into new membranes and a cell wall.
431. kartīte
Jautājums
What is the purpose of cell-cycle checkpoints?
Atbilde
They delay progression when conditions are unsuitable or DNA and chromosome attachment are defective.
432. kartīte
Jautājums
How is loss of cell-cycle control related to cancer?
Atbilde
Cells can divide despite damage or growth restraints, producing an expanding abnormal clone.
433. kartīte
Jautājums
What is a gene?
Atbilde
A DNA sequence that contributes to a functional product and influences a characteristic or cellular process.
434. kartīte
Jautājums
What is an allele?
Atbilde
One of the alternative DNA-sequence forms at a gene locus.
435. kartīte
Jautājums
What is a gene locus?
Atbilde
The physical position of a gene on a chromosome.
436. kartīte
Jautājums
What is a genotype?
Atbilde
The allele combination of an organism at one or more loci.
437. kartīte
Jautājums
Which term describes a functional DNA sequence?
Atbilde
a gene
438. kartīte
Jautājums
Which term describes an alternative form of a gene?
Atbilde
an allele
439. kartīte
Jautājums
Which term describes a gene's chromosome position?
Atbilde
a gene locus
440. kartīte
Jautājums
Which term describes an organism's allele combination?
Atbilde
a genotype
441. kartīte
Jautājums
What is a phenotype?
Atbilde
An observable or measurable trait produced by genotype and environment.
442. kartīte
Jautājums
What is homozygous?
Atbilde
Having two identical alleles at a diploid locus.
443. kartīte
Jautājums
What is heterozygous?
Atbilde
Having two different alleles at a diploid locus.
444. kartīte
Jautājums
What is a dominant allele?
Atbilde
An allele expressed in the phenotype of a heterozygote under a specified inheritance model.
445. kartīte
Jautājums
Which term describes an observable trait resulting from genes and environment?
Atbilde
a phenotype
446. kartīte
Jautājums
Which term describes having two identical alleles at a locus?
Atbilde
homozygous
447. kartīte
Jautājums
Which term describes having two different alleles at a locus?
Atbilde
heterozygous
448. kartīte
Jautājums
Which term describes an allele expressed in a heterozygote?
Atbilde
a dominant allele
449. kartīte
Jautājums
What is a recessive allele?
Atbilde
An allele whose phenotype is masked by a dominant allele in a heterozygote.
450. kartīte
Jautājums
What is a genetic carrier?
Atbilde
An unaffected heterozygote who can transmit a recessive disease allele.
451. kartīte
Jautājums
What is a test cross?
Atbilde
A cross with a homozygous recessive individual used to infer an unknown dominant phenotype's genotype.
452. kartīte
Jautājums
What is a pedigree?
Atbilde
A diagram showing biological relationships and occurrence of a trait across generations.
453. kartīte
Jautājums
Which term describes an allele masked in a heterozygote?
Atbilde
a recessive allele
454. kartīte
Jautājums
Which term describes an unaffected heterozygote carrying a recessive disease allele?
Atbilde
a genetic carrier
455. kartīte
Jautājums
Which term describes a cross used to reveal an unknown dominant genotype?
Atbilde
a test cross
456. kartīte
Jautājums
Which term describes a family diagram tracking a trait across generations?
Atbilde
a pedigree
457. kartīte
Jautājums
What does allele segregation mean during gamete formation?
Atbilde
The two alleles at a diploid locus separate so each gamete receives one.
458. kartīte
Jautājums
What does a Punnett square predict?
Atbilde
Expected genotype and phenotype probabilities from specified parental gametes, not guaranteed family outcomes.
459. kartīte
Jautājums
What phenotypic ratio is expected from Aa × Aa with complete dominance?
Atbilde
Approximately 3 dominant phenotype : 1 recessive phenotype.
460. kartīte
Jautājums
What genotypic ratio is expected from Aa × Aa?
Atbilde
1 AA : 2 Aa : 1 aa.
461. kartīte
Jautājums
What happens in codominance?
Atbilde
Both alleles contribute distinctly to the heterozygous phenotype.
462. kartīte
Jautājums
What happens in incomplete dominance?
Atbilde
The heterozygote has a phenotype intermediate between the two homozygotes.
463. kartīte
Jautājums
How can environment affect phenotype without changing genotype?
Atbilde
Conditions alter development, physiology, or gene expression, changing the observed trait.
464. kartīte
Jautājums
What is the ultimate source of new alleles?
Atbilde
Mutation.
465. kartīte
Jautājums
Why are X-linked recessive traits more common in XY individuals?
Atbilde
They have only one X chromosome, so one recessive allele on it can determine the phenotype.
466. kartīte
Jautājums
When is the product rule used in genetic probability?
Atbilde
For independent events that must both occur; multiply their probabilities.
467. kartīte
Jautājums
When is the sum rule used in genetic probability?
Atbilde
For mutually exclusive alternative outcomes; add their probabilities.
468. kartīte
Jautājums
Why do polygenic traits often show continuous variation?
Atbilde
Many loci contribute small effects, creating many possible genotypes and phenotypes, often further influenced by environment.
469. kartīte
Jautājums
What pedigree pattern can suggest an autosomal recessive trait?
Atbilde
Unaffected parents can have affected children, and all sexes are affected at similar frequencies.
470. kartīte
Jautājums
What is a species?
Atbilde
A group of organisms whose members can potentially interbreed and produce fertile offspring under natural conditions.
471. kartīte
Jautājums
What is binomial nomenclature?
Atbilde
The two-part scientific naming system using a genus name followed by a specific epithet.
472. kartīte
Jautājums
What is taxonomy?
Atbilde
The naming and classification of organisms.
473. kartīte
Jautājums
What is a biological domain?
Atbilde
The broadest commonly used taxonomic rank, separating Bacteria, Archaea, and Eukarya.
474. kartīte
Jautājums
Which term describes a naturally interbreeding group producing fertile offspring?
Atbilde
a species
475. kartīte
Jautājums
Which term describes the genus-plus-specific-epithet naming system?
Atbilde
binomial nomenclature
476. kartīte
Jautājums
Which term describes the science of naming and classifying organisms?
Atbilde
taxonomy
477. kartīte
Jautājums
Which term describes the broadest common taxonomic rank?
Atbilde
a biological domain
478. kartīte
Jautājums
What is biodiversity?
Atbilde
Variation of life at genetic, species, and ecosystem levels.
479. kartīte
Jautājums
What is an autotroph?
Atbilde
An organism that makes organic compounds from inorganic carbon using light or chemical energy.
480. kartīte
Jautājums
What is a heterotroph?
Atbilde
An organism that obtains organic carbon by consuming other organisms or their products.
960 kartīšu
IB Biology SL Flashcards: Complete Course Review
Mācies šo kavu bez maksasAtvērsies Nibomo, lai vari sākt mācīties.
481. kartīte
Jautājums
What is a unicellular organism?
Atbilde
An organism consisting of one cell that carries out all essential life functions.
482. kartīte
Jautājums
Which term describes variation of life across genes, species, and ecosystems?
Atbilde
biodiversity
483. kartīte
Jautājums
Which term describes an organism that builds organic matter from inorganic carbon?
Atbilde
an autotroph
484. kartīte
Jautājums
Which term describes an organism obtaining organic carbon from other organisms?
Atbilde
a heterotroph
485. kartīte
Jautājums
Which term describes an organism made of one cell?
Atbilde
a unicellular organism
486. kartīte
Jautājums
What is a multicellular organism?
Atbilde
An organism composed of many cooperating cells, often with specialized cell types.
487. kartīte
Jautājums
What is a karyotype?
Atbilde
An ordered display of chromosomes used to examine their number and large-scale structure.
488. kartīte
Jautājums
What broad feature distinguishes both Bacteria and Archaea from Eukarya?
Atbilde
Their cells lack a nucleus and other membrane-bound organelles.
489. kartīte
Jautājums
What features characterize most plant cells?
Atbilde
Cellulose walls, chloroplasts in photosynthetic tissues, and large vacuoles are typical features.
490. kartīte
Jautājums
Which term describes an organism made of many cooperating cells?
Atbilde
a multicellular organism
491. kartīte
Jautājums
Which term describes an ordered display of an individual's chromosomes?
Atbilde
a karyotype
492. kartīte
Jautājums
How do fungi obtain nutrients?
Atbilde
They secrete digestive enzymes and absorb soluble products; their cells usually have chitin-containing walls.
493. kartīte
Jautājums
What distinguishes animal nutrition and cell structure?
Atbilde
Animals ingest organic material, and their cells lack cell walls and chloroplasts.
494. kartīte
Jautājums
Why are scientific names useful across languages?
Atbilde
A standardized name identifies the same organism internationally and reduces ambiguity from local common names.
495. kartīte
Jautājums
Why can genetic diversity improve a population's resilience?
Atbilde
More heritable variation increases the chance that some individuals tolerate new diseases or environmental changes.
496. kartīte
Jautājums
What does ecosystem diversity measure?
Atbilde
The variety of habitats, communities, and ecological processes within a region.
497. kartīte
Jautājums
Why are Archaea classified separately from Bacteria?
Atbilde
They differ in genetic sequences, membrane chemistry, cell-wall composition, and aspects of molecular machinery.
498. kartīte
Jautājums
Why is the biological species concept difficult to apply to fossils or asexual organisms?
Atbilde
Their ability to interbreed and produce fertile offspring cannot be tested in the usual way.
499. kartīte
Jautājums
Does a larger chromosome number necessarily mean a more complex organism?
Atbilde
No. Chromosome number varies through fusion, fission, and duplication and does not directly measure biological complexity.
500. kartīte
Jautājums
Does genome size reliably predict organismal complexity?
Atbilde
No. Large amounts of noncoding and repeated DNA make genome size a poor simple measure of complexity.
501. kartīte
Jautājums
What evidence can be combined when classifying organisms?
Atbilde
Molecular sequences, cell structure, anatomy, development, physiology, and reproductive evidence can all contribute.
502. kartīte
Jautājums
What is gas exchange?
Atbilde
Diffusion of respiratory gases between an organism and its environment or transport fluid.
503. kartīte
Jautājums
What is ventilation?
Atbilde
Bulk movement of air or water over a gas-exchange surface.
504. kartīte
Jautājums
What is an alveolus?
Atbilde
A microscopic air sac in the lung where gases diffuse between air and blood.
505. kartīte
Jautājums
What is pulmonary surfactant?
Atbilde
A substance lining alveoli that lowers surface tension and reduces collapse.
506. kartīte
Jautājums
Which term describes diffusion of oxygen and carbon dioxide across a respiratory surface?
Atbilde
gas exchange
507. kartīte
Jautājums
Which term describes bulk movement of respiratory medium over an exchange surface?
Atbilde
ventilation
508. kartīte
Jautājums
Which term describes a microscopic lung air sac?
Atbilde
an alveolus
509. kartīte
Jautājums
Which term describes the alveolar lining that lowers surface tension?
Atbilde
pulmonary surfactant
510. kartīte
Jautājums
What is the diaphragm?
Atbilde
A sheet of skeletal muscle whose contraction increases thoracic volume during inhalation.
511. kartīte
Jautājums
What is tidal volume?
Atbilde
The volume of air moved in or out during a normal breath.
512. kartīte
Jautājums
What is a stoma?
Atbilde
A regulated epidermal pore through which gases diffuse in leaves.
513. kartīte
Jautājums
What is countercurrent exchange?
Atbilde
Exchange between fluids moving in opposite directions, maintaining a gradient along most of the surface.
514. kartīte
Jautājums
Which term describes the muscle sheet that expands the thorax during inhalation?
Atbilde
the diaphragm
515. kartīte
Jautājums
Which term describes air volume moved in one normal breath?
Atbilde
tidal volume
516. kartīte
Jautājums
Which term describes a regulated leaf gas-exchange pore?
Atbilde
a stoma
517. kartīte
Jautājums
Which term describes opposite fluid flow that maintains an exchange gradient?
Atbilde
countercurrent exchange
518. kartīte
Jautājums
What features make an efficient gas-exchange surface?
Atbilde
Large area, short diffusion distance, permeability, and maintained concentration gradients.
519. kartīte
Jautājums
How is a steep oxygen gradient maintained across alveoli?
Atbilde
Ventilation replenishes alveolar oxygen and blood flow removes absorbed oxygen.
520. kartīte
Jautājums
How does diaphragm contraction cause inhalation?
Atbilde
Thoracic volume increases, lung pressure falls below atmospheric pressure, and air flows inward.
521. kartīte
Jautājums
What drives quiet exhalation?
Atbilde
The diaphragm relaxes and elastic recoil reduces thoracic and lung volume, raising pressure and pushing air out.
522. kartīte
Jautājums
Why do ventilation rate and depth increase during exercise?
Atbilde
They increase oxygen uptake and carbon dioxide removal to support higher cellular respiration.
523. kartīte
Jautājums
How does leaf structure shorten the pathway for carbon dioxide diffusion?
Atbilde
Stomata open into air spaces, and mesophyll cells expose moist surfaces close to those spaces.
524. kartīte
Jautājums
Why does carbon dioxide diffuse from tissues into blood?
Atbilde
Respiring cells produce carbon dioxide, making its partial pressure higher in tissues than in incoming blood.
525. kartīte
Jautājums
How does countercurrent flow improve oxygen uptake at fish gills?
Atbilde
Blood continually meets water with a higher oxygen concentration, preserving diffusion along the lamella.
526. kartīte
Jautājums
Why does closing stomata reduce both water loss and photosynthesis?
Atbilde
It limits water-vapor diffusion out but also restricts carbon dioxide diffusion into the leaf.
527. kartīte
Jautājums
What is a circulatory system?
Atbilde
A transport system that moves a fluid carrying gases, nutrients, wastes, hormones, and heat through an organism.
528. kartīte
Jautājums
What is an artery?
Atbilde
A blood vessel carrying blood away from the heart under relatively high pressure.
529. kartīte
Jautājums
What is a vein?
Atbilde
A blood vessel carrying blood toward the heart, usually with low pressure and often valves.
530. kartīte
Jautājums
What is a capillary?
Atbilde
A microscopic thin-walled vessel where substances exchange between blood and tissues.
531. kartīte
Jautājums
Which term describes an internal fluid-transport system?
Atbilde
a circulatory system
532. kartīte
Jautājums
Which term describes a vessel carrying blood away from the heart?
Atbilde
an artery
533. kartīte
Jautājums
Which term describes a vessel carrying blood toward the heart?
Atbilde
a vein
534. kartīte
Jautājums
Which term describes a microscopic exchange blood vessel?
Atbilde
a capillary
535. kartīte
Jautājums
What is the cardiac cycle?
Atbilde
The repeating sequence of heart-chamber contraction and relaxation that pumps blood.
536. kartīte
Jautājums
What is hemoglobin?
Atbilde
An iron-containing protein in red blood cells that binds oxygen reversibly.
537. kartīte
Jautājums
What is xylem?
Atbilde
Plant vascular tissue that transports water and mineral ions and provides structural support.
538. kartīte
Jautājums
What is phloem?
Atbilde
Plant vascular tissue that transports sucrose and other organic solutes between sources and sinks.
539. kartīte
Jautājums
Which term describes the repeating pumping sequence of the heart?
Atbilde
the cardiac cycle
540. kartīte
Jautājums
Which term describes the oxygen-carrying protein of red blood cells?
Atbilde
hemoglobin
541. kartīte
Jautājums
Which term describes plant tissue carrying water and minerals?
Atbilde
xylem
542. kartīte
Jautājums
Which term describes plant tissue carrying organic solutes?
Atbilde
phloem
543. kartīte
Jautājums
What is transpiration?
Atbilde
Loss of water vapor from plant surfaces, mainly through stomata.
544. kartīte
Jautājums
What is phloem translocation?
Atbilde
Movement of organic solutes through phloem from sources to sinks.
545. kartīte
Jautājums
How do a source and a sink differ in plant transport?
Atbilde
A source releases assimilates to phloem; a sink removes them for use or storage.
546. kartīte
Jautājums
What makes human circulation a double circulation?
Atbilde
Blood passes through the heart once in the pulmonary circuit and again in the systemic circuit during one complete journey.
547. kartīte
Jautājums
Which term describes water-vapor loss from plant surfaces?
Atbilde
transpiration
548. kartīte
Jautājums
Which term describes movement of organic solutes through phloem?
Atbilde
phloem translocation
549. kartīte
Jautājums
Which term describes the exporting and importing regions of phloem transport?
Atbilde
source and sink
550. kartīte
Jautājums
How is an artery adapted to high pressure?
Atbilde
It has thick elastic and muscular walls and a relatively narrow lumen.
551. kartīte
Jautājums
How is a vein adapted to return low-pressure blood?
Atbilde
It has a wide lumen, thinner walls, and valves that reduce backflow.
552. kartīte
Jautājums
How does capillary structure support exchange?
Atbilde
One-cell-thick walls give a short diffusion distance; extensive branching gives a large total area; narrow lumens slow flow and keep blood close to tissues.
553. kartīte
Jautājums
What determines whether a heart valve opens or closes?
Atbilde
Pressure differences across the valve.
554. kartīte
Jautājums
Trace water from soil to the atmosphere through a plant.
Atbilde
Soil → root hairs → root tissues → xylem → leaf mesophyll → leaf air spaces → stomata → atmosphere.
555. kartīte
Jautājums
Why may root cells use active transport to absorb mineral ions?
Atbilde
Ion concentrations can be lower in soil than in root cells, so uptake must occur against a gradient.
556. kartīte
Jautājums
Why do large multicellular organisms need bulk transport systems?
Atbilde
Their low surface-area-to-volume ratio and long diffusion distances make diffusion alone too slow for whole-body supply.
557. kartīte
Jautājums
Why does hemoglobin unload more oxygen in actively respiring tissues?
Atbilde
Lower oxygen and often higher carbon dioxide and acidity reduce hemoglobin's oxygen affinity.
558. kartīte
Jautājums
How does transpiration pull water upward through xylem?
Atbilde
Evaporation lowers leaf water potential and creates tension; cohesion transmits the pull through the continuous water column.
559. kartīte
Jautājums
How do wind and low humidity generally affect transpiration?
Atbilde
Both maintain a steep water-vapor gradient outside the leaf, increasing transpiration if stomata remain open.
560. kartīte
Jautājums
What drives mass flow in phloem?
Atbilde
Sugar loading draws in water and raises pressure at a source; unloading lowers pressure at a sink, producing bulk flow.
561. kartīte
Jautājums
Can the same plant organ be a source at one time and a sink at another?
Atbilde
Yes. A storage organ may import sugars while filling and export them later during growth or germination.
562. kartīte
Jautājums
What is a neuron?
Atbilde
An excitable cell specialized to receive, process, and transmit information.
563. kartīte
Jautājums
What is a sensory neuron?
Atbilde
A neuron carrying information from a receptor toward the central nervous system.
564. kartīte
Jautājums
What is a motor neuron?
Atbilde
A neuron carrying commands from the central nervous system to an effector.
565. kartīte
Jautājums
What is the resting potential?
Atbilde
The voltage difference across an unstimulated neuron's membrane, with the inside negative relative to outside.
566. kartīte
Jautājums
Which term describes an excitable information-transmitting cell?
Atbilde
a neuron
567. kartīte
Jautājums
Which term describes a neuron carrying receptor information to the CNS?
Atbilde
a sensory neuron
568. kartīte
Jautājums
Which term describes a neuron carrying CNS commands to an effector?
Atbilde
a motor neuron
569. kartīte
Jautājums
Which term describes the negative-inside voltage of an unstimulated neuron?
Atbilde
the resting potential
570. kartīte
Jautājums
What is an action potential?
Atbilde
A brief, self-propagating reversal and restoration of membrane potential along an excitable membrane.
571. kartīte
Jautājums
What is depolarization?
Atbilde
A change that makes membrane potential less negative, and during an action potential often positive.
572. kartīte
Jautājums
What is repolarization?
Atbilde
Return of membrane potential toward its resting negative value after depolarization.
573. kartīte
Jautājums
What is a synapse?
Atbilde
A junction where one cell communicates with another cell.
574. kartīte
Jautājums
Which term describes a brief propagating change in neuron membrane voltage?
Atbilde
an action potential
575. kartīte
Jautājums
Which term describes a membrane-voltage change toward a less negative value?
Atbilde
depolarization
576. kartīte
Jautājums
Which term describes return toward resting membrane voltage?
Atbilde
repolarization
577. kartīte
Jautājums
Which term describes a communication junction between cells?
Atbilde
a synapse
578. kartīte
Jautājums
What is a neurotransmitter?
Atbilde
A chemical released by a neuron that changes the activity of a target cell.
579. kartīte
Jautājums
What is the refractory period?
Atbilde
A brief period after an action potential when another is impossible or requires a stronger stimulus.
580. kartīte
Jautājums
What is myelin?
Atbilde
An insulating sheath around some axons that speeds impulse conduction.
581. kartīte
Jautājums
What happens when membrane depolarization reaches threshold?
Atbilde
Voltage-gated channels trigger the self-amplifying events of an action potential.
582. kartīte
Jautājums
Which term describes a neuron-released signaling chemical?
Atbilde
a neurotransmitter
583. kartīte
Jautājums
Which term describes the recovery interval after an action potential?
Atbilde
the refractory period
584. kartīte
Jautājums
Which term describes the insulating axon sheath?
Atbilde
myelin
585. kartīte
Jautājums
What does the all-or-none principle mean for an action potential?
Atbilde
Once threshold is reached, the action potential has a characteristic size; stronger stimuli increase frequency, not its amplitude.
586. kartīte
Jautājums
How does myelin increase conduction speed?
Atbilde
Depolarizing current travels rapidly beneath myelin and action potentials regenerate mainly at gaps in the sheath.
587. kartīte
Jautājums
What is the basic sequence at a chemical synapse?
Atbilde
An impulse triggers neurotransmitter release; it diffuses across the cleft, binds receptors, and alters the postsynaptic cell.
588. kartīte
Jautājums
Why can a reflex response be rapid?
Atbilde
A short neural pathway produces an automatic response without waiting for conscious processing.
589. kartīte
Jautājums
What is sensory transduction?
Atbilde
Conversion of a physical or chemical stimulus into an electrical signal in a receptor cell.
590. kartīte
Jautājums
How does an action potential propagate along an axon?
Atbilde
Local current depolarizes the next membrane region to threshold, opening voltage-gated channels there.
591. kartīte
Jautājums
Why does an action potential normally travel in one direction along an axon?
Atbilde
The membrane just behind it is refractory and cannot immediately fire again.
592. kartīte
Jautājums
How is neurotransmitter action ended?
Atbilde
The transmitter is removed by enzymatic breakdown, reuptake, or diffusion away.
593. kartīte
Jautājums
What is sensory adaptation?
Atbilde
Reduced receptor or neural response during a constant, unchanging stimulus.
594. kartīte
Jautājums
How can a drug alter synaptic transmission?
Atbilde
It may mimic or block a transmitter, change its release, or change its removal from the synaptic cleft.
595. kartīte
Jautājums
What is an organ system?
Atbilde
A group of organs coordinating to perform major functions for an organism.
596. kartīte
Jautājums
What is a hormone?
Atbilde
A signaling molecule released into transport fluid and acting on target cells with suitable receptors.
597. kartīte
Jautājums
What is an endocrine gland?
Atbilde
A gland that secretes hormones into extracellular fluid and blood rather than through a duct.
598. kartīte
Jautājums
What is a hormone target cell?
Atbilde
A cell able to respond because it has the appropriate receptor.
599. kartīte
Jautājums
Which term describes a coordinated group of organs?
Atbilde
an organ system
600. kartīte
Jautājums
Which term describes a long-distance chemical messenger carried in body fluid?
Atbilde
a hormone
601. kartīte
Jautājums
Which term describes a ductless hormone-secreting gland?
Atbilde
an endocrine gland
602. kartīte
Jautājums
Which term describes a cell with a receptor for a particular hormone?
Atbilde
a hormone target cell
603. kartīte
Jautājums
What is digestion?
Atbilde
Mechanical and chemical breakdown of food into molecules small enough to absorb.
604. kartīte
Jautājums
What is absorption?
Atbilde
Movement of digested nutrients across an exchange surface into blood or lymph.
605. kartīte
Jautājums
What is peristalsis?
Atbilde
Coordinated waves of smooth-muscle contraction that move material through the digestive tract.
606. kartīte
Jautājums
What is an intestinal villus?
Atbilde
A finger-like projection increasing the absorptive surface of the small intestine.
607. kartīte
Jautājums
Which term describes breakdown of food into absorbable molecules?
Atbilde
digestion
608. kartīte
Jautājums
Which term describes movement of digested nutrients into transport fluids?
Atbilde
absorption
609. kartīte
Jautājums
Which term describes wave-like gut contractions moving contents?
Atbilde
peristalsis
610. kartīte
Jautājums
Which term describes a finger-like intestinal absorption projection?
Atbilde
an intestinal villus
611. kartīte
Jautājums
What is excretion?
Atbilde
Removal of metabolic waste products from the body.
612. kartīte
Jautājums
What is a nephron?
Atbilde
The microscopic functional unit of the kidney that filters blood and modifies filtrate into urine.
613. kartīte
Jautājums
What is ultrafiltration?
Atbilde
Pressure-driven filtration of small molecules from blood into a kidney capsule while cells and most proteins remain in blood.
614. kartīte
Jautājums
What is selective reabsorption?
Atbilde
Recovery of useful substances and regulated amounts of water and ions from kidney filtrate into blood.
615. kartīte
Jautājums
Which term describes removal of metabolic wastes?
Atbilde
excretion
616. kartīte
Jautājums
Which term describes the kidney's microscopic functional unit?
Atbilde
a nephron
617. kartīte
Jautājums
Which term describes pressure filtration at the start of a nephron?
Atbilde
ultrafiltration
618. kartīte
Jautājums
Which term describes return of useful substances from kidney filtrate to blood?
Atbilde
selective reabsorption
619. kartīte
Jautājums
What is skeletal muscle?
Atbilde
Striated voluntary muscle attached to the skeleton and used for movement and posture.
620. kartīte
Jautājums
What is an antagonistic muscle pair?
Atbilde
Two muscles producing opposite movements at a joint because muscles pull but do not push.
621. kartīte
Jautājums
How do nervous and endocrine signaling generally differ?
Atbilde
Neural signals are rapid and targeted; hormonal signals are usually slower, longer-lasting, and distributed through body fluids.
622. kartīte
Jautājums
Why does a circulating hormone affect only some cells?
Atbilde
Only target cells express receptors that recognize the hormone and activate a response.
623. kartīte
Jautājums
Which term describes voluntary striated muscle that moves the skeleton?
Atbilde
skeletal muscle
624. kartīte
Jautājums
Which term describes two muscles producing opposite joint movements?
Atbilde
an antagonistic muscle pair
625. kartīte
Jautājums
What is the final absorbable product of most dietary carbohydrate digestion?
Atbilde
Monosaccharides, especially glucose.
626. kartīte
Jautājums
What are the main absorbable products of protein digestion?
Atbilde
Amino acids and small peptides that are completed to amino acids during absorption.
627. kartīte
Jautājums
How is the small intestine adapted for absorption?
Atbilde
Folds, villi, and microvilli increase area; a thin epithelium, rich blood supply, and lymph vessels support transport.
628. kartīte
Jautājums
Name three integrative roles of the liver.
Atbilde
It processes absorbed nutrients, regulates blood chemistry, detoxifies substances, produces bile, and converts ammonia to urea; any three are sufficient.
629. kartīte
Jautājums
Why are blood cells and most plasma proteins absent from normal kidney filtrate?
Atbilde
They are too large to cross the filtration barrier.
630. kartīte
Jautājums
How do muscles move a bone at a joint?
Atbilde
Contraction shortens the muscle, pulling through a tendon on the bone.
631. kartīte
Jautājums
Why are antagonistic muscles needed at many joints?
Atbilde
A muscle can pull in one direction but cannot push itself back, so an opposing muscle produces the reverse movement.
632. kartīte
Jautājums
Why must organ systems be integrated rather than acting independently?
Atbilde
Each system depends on materials, signals, waste removal, and stable conditions supplied by other systems.
633. kartīte
Jautājums
Why do many absorbed lipids enter lymph before blood?
Atbilde
Intestinal cells package them into lipoprotein particles too large to enter ordinary blood capillaries directly.
634. kartīte
Jautājums
Why is glucose normally absent from final urine?
Atbilde
Filtered glucose is selectively reabsorbed into blood when transporter capacity is not exceeded.
635. kartīte
Jautājums
How do respiratory, circulatory, and muscular systems cooperate during exercise?
Atbilde
Ventilation supplies oxygen, circulation transports gases and fuels, and muscles use ATP while returning carbon dioxide, heat, and metabolites.
636. kartīte
Jautājums
How do liver, circulation, and kidneys cooperate in nitrogen-waste removal?
Atbilde
The liver converts toxic ammonia to urea, blood carries urea, and kidneys filter and excrete it.
637. kartīte
Jautājums
What is a pathogen?
Atbilde
A biological agent capable of causing disease.
638. kartīte
Jautājums
What is an antigen?
Atbilde
A molecule recognized specifically by an antibody or lymphocyte receptor.
639. kartīte
Jautājums
What is innate immunity?
Atbilde
Rapid, nonspecific defense mechanisms present without prior exposure.
640. kartīte
Jautājums
What is adaptive immunity?
Atbilde
Specific defense that develops through lymphocyte activation and can form memory.
641. kartīte
Jautājums
Which term describes a disease-causing biological agent?
Atbilde
a pathogen
642. kartīte
Jautājums
Which term describes a molecule specifically recognized by adaptive immune receptors?
Atbilde
an antigen
643. kartīte
Jautājums
Which term describes rapid nonspecific immune defense?
Atbilde
innate immunity
644. kartīte
Jautājums
Which term describes specific immune defense capable of memory?
Atbilde
adaptive immunity
645. kartīte
Jautājums
What is a phagocyte?
Atbilde
A cell that engulfs and digests microbes, particles, or damaged cells.
646. kartīte
Jautājums
What is a lymphocyte?
Atbilde
An adaptive immune cell with receptors specific to particular antigens.
647. kartīte
Jautājums
What is an antibody?
Atbilde
A secreted immunoglobulin that binds a specific antigen.
648. kartīte
Jautājums
What is a B lymphocyte?
Atbilde
A lymphocyte that can differentiate into antibody-secreting plasma cells and memory cells.
649. kartīte
Jautājums
Which term describes an engulfing immune cell?
Atbilde
a phagocyte
650. kartīte
Jautājums
Which term describes an antigen-specific adaptive immune cell?
Atbilde
a lymphocyte
651. kartīte
Jautājums
Which term describes a secreted antigen-binding immunoglobulin?
Atbilde
an antibody
652. kartīte
Jautājums
Which term describes the lymphocyte lineage that produces antibody-secreting cells?
Atbilde
a B lymphocyte
653. kartīte
Jautājums
What is a helper T cell?
Atbilde
A lymphocyte that coordinates immune responses through contact signals and cytokines.
654. kartīte
Jautājums
What is an immune memory cell?
Atbilde
A long-lived lymphocyte that responds rapidly after re-exposure to its antigen.
655. kartīte
Jautājums
What is vaccination?
Atbilde
Deliberate exposure to a safe form or component of an antigen to generate protective immune memory.
656. kartīte
Jautājums
What is an antibiotic?
Atbilde
A substance that kills bacteria or inhibits their growth at clinically useful doses.
657. kartīte
Jautājums
Which term describes the T cell that coordinates other immune cells?
Atbilde
a helper T cell
658. kartīte
Jautājums
Which term describes a long-lived lymphocyte enabling faster re-exposure response?
Atbilde
an immune memory cell
659. kartīte
Jautājums
Which term describes safe antigen exposure used to create immune memory?
Atbilde
vaccination
660. kartīte
Jautājums
Which term describes a drug acting against bacteria?
Atbilde
an antibiotic
661. kartīte
Jautājums
What are examples of first-line defenses against pathogens?
Atbilde
Intact skin, mucus, cilia, antimicrobial secretions, stomach acidity, and competing microbiota.
662. kartīte
Jautājums
How does inflammation help defend damaged tissue?
Atbilde
It increases local blood flow and vessel permeability and recruits immune cells and defensive molecules.
663. kartīte
Jautājums
What happens during phagocytosis?
Atbilde
A cell surrounds a particle in a vesicle, then fuses it with digestive compartments to destroy or process it.
664. kartīte
Jautājums
How can antibodies help eliminate a pathogen?
Atbilde
They can neutralize targets, block attachment, clump particles, and mark them for phagocytosis or complement attack.
665. kartīte
Jautājums
Why can a vaccine generate protection without causing the full disease?
Atbilde
It presents antigen in a weakened, inactivated, partial, or encoded form that stimulates immunity with much lower risk.
666. kartīte
Jautājums
Why do antibiotics not treat viral infections?
Atbilde
Viruses lack the bacterial structures and independent metabolic processes targeted by antibiotics.
667. kartīte
Jautājums
What determines the antigen specificity of a lymphocyte?
Atbilde
The molecular shape and chemistry of its unique surface receptor.
668. kartīte
Jautājums
What is clonal selection?
Atbilde
An antigen activates lymphocytes with matching receptors, causing them to proliferate and differentiate.
669. kartīte
Jautājums
Why is a secondary adaptive immune response usually faster and stronger?
Atbilde
Memory cells are more numerous and activate rapidly, producing effective cells and antibodies sooner.
670. kartīte
Jautājums
How can high vaccination coverage protect some unvaccinated people?
Atbilde
Reduced transmission makes encounters with infectious individuals less likely, though protection is incomplete and pathogen-dependent.
671. kartīte
Jautājums
How does antibiotic use select for resistant bacteria?
Atbilde
Susceptible bacteria are removed while resistant variants survive and reproduce, increasing resistance-allele frequency.
672. kartīte
Jautājums
Why can unnecessary or incomplete antibiotic exposure promote resistance?
Atbilde
It creates selection favoring resistant cells while potentially leaving surviving bacteria to multiply and spread.
673. kartīte
Jautājums
What is an allergy?
Atbilde
An immune response to a normally harmless antigen that causes tissue symptoms or damage.
674. kartīte
Jautājums
What is asexual reproduction?
Atbilde
Production of offspring from one parent without fusion of gametes.
675. kartīte
Jautājums
What is sexual reproduction?
Atbilde
Production of offspring involving fusion of haploid gametes.
676. kartīte
Jautājums
What is a gamete?
Atbilde
A haploid reproductive cell able to fuse with another gamete.
677. kartīte
Jautājums
What is fertilization?
Atbilde
Fusion of gamete nuclei to form a diploid zygote.
678. kartīte
Jautājums
Which term describes reproduction without gamete fusion?
Atbilde
asexual reproduction
679. kartīte
Jautājums
Which term describes reproduction involving gamete fusion?
Atbilde
sexual reproduction
680. kartīte
Jautājums
Which term describes a haploid reproductive cell?
Atbilde
a gamete
681. kartīte
Jautājums
Which term describes fusion of gamete nuclei?
Atbilde
fertilization
682. kartīte
Jautājums
What is a zygote?
Atbilde
The diploid cell formed by fertilization.
683. kartīte
Jautājums
What is meiosis?
Atbilde
Cell division that halves chromosome number and usually produces genetically varied haploid cells.
684. kartīte
Jautājums
What is ovulation?
Atbilde
Release of a secondary oocyte from an ovary.
685. kartīte
Jautājums
What is implantation?
Atbilde
Attachment and embedding of an early embryo in the uterine lining.
686. kartīte
Jautājums
Which term describes the first diploid cell after fertilization?
Atbilde
a zygote
687. kartīte
Jautājums
Which term describes division producing varied haploid cells?
Atbilde
meiosis
688. kartīte
Jautājums
Which term describes release of an oocyte from an ovary?
Atbilde
ovulation
689. kartīte
Jautājums
Which term describes embedding of an early embryo in the uterine lining?
Atbilde
implantation
690. kartīte
Jautājums
What is the placenta?
Atbilde
A temporary organ that exchanges materials between maternal and fetal blood supplies without normally mixing them directly.
691. kartīte
Jautājums
What is pollination?
Atbilde
Transfer of pollen from an anther to a receptive stigma.
692. kartīte
Jautājums
Why does sexual reproduction usually produce more genetic variation than asexual reproduction?
Atbilde
Meiosis reshuffles alleles and random fertilization combines genomes from two gametes.
693. kartīte
Jautājums
Why must gametes be haploid?
Atbilde
Fusion of two haploid gametes restores the diploid chromosome number instead of doubling it each generation.
694. kartīte
Jautājums
Which term describes the maternal-fetal exchange organ?
Atbilde
the placenta
695. kartīte
Jautājums
Which term describes transfer of pollen to a stigma?
Atbilde
pollination
696. kartīte
Jautājums
What are major roles of FSH in the ovarian cycle?
Atbilde
It stimulates follicle development and supports estrogen secretion.
697. kartīte
Jautājums
What is a major role of the mid-cycle LH surge?
Atbilde
It triggers ovulation and formation of the corpus luteum.
698. kartīte
Jautājums
How does estrogen contribute to the uterine cycle?
Atbilde
It promotes repair and thickening of the uterine lining after menstruation.
699. kartīte
Jautājums
How does progesterone contribute to the uterine cycle?
Atbilde
It maintains a thick, secretory uterine lining after ovulation.
700. kartīte
Jautājums
Where does human fertilization usually occur?
Atbilde
In an oviduct, before the early embryo reaches the uterus.
701. kartīte
Jautājums
What happens after compatible pollen reaches a flower's stigma?
Atbilde
A pollen tube grows toward an ovule and delivers male nuclei for fertilization.
702. kartīte
Jautājums
Why does menstruation usually begin if pregnancy does not occur?
Atbilde
The corpus luteum degenerates, progesterone and estrogen fall, and the uterine lining is no longer maintained.
703. kartīte
Jautājums
What substances commonly cross the placenta between mother and fetus?
Atbilde
Oxygen and nutrients move toward the fetus; carbon dioxide and nitrogenous wastes move toward the mother.
704. kartīte
Jautājums
How can contraception prevent pregnancy in different ways?
Atbilde
Methods can inhibit ovulation, block sperm from reaching an egg, prevent fertilization, or permanently interrupt the reproductive ducts.
705. kartīte
Jautājums
What is homeostasis?
Atbilde
Maintenance of internal conditions within ranges compatible with normal function despite change.
706. kartīte
Jautājums
What is negative feedback?
Atbilde
Control in which a deviation triggers responses that oppose the original change.
707. kartīte
Jautājums
What is a set point?
Atbilde
The target value or range around which a regulated variable is maintained.
708. kartīte
Jautājums
What is a homeostatic receptor?
Atbilde
A sensor that detects a change in a regulated variable.
709. kartīte
Jautājums
Which term describes maintenance of a stable functional internal environment?
Atbilde
homeostasis
710. kartīte
Jautājums
Which term describes feedback that counteracts a deviation?
Atbilde
negative feedback
711. kartīte
Jautājums
Which term describes the target around which a variable is regulated?
Atbilde
a set point
712. kartīte
Jautājums
Which term describes the sensor in a feedback system?
Atbilde
a homeostatic receptor
713. kartīte
Jautājums
What is a control center?
Atbilde
The component that compares information with a target and coordinates a response.
714. kartīte
Jautājums
What is an effector?
Atbilde
A muscle, gland, or other component that carries out a control response.
715. kartīte
Jautājums
What is thermoregulation?
Atbilde
Control of body temperature within a functional range.
716. kartīte
Jautājums
What is vasodilation?
Atbilde
Widening of blood vessels, often increasing blood flow near the skin.
717. kartīte
Jautājums
Which term describes the feedback component that evaluates input and directs a response?
Atbilde
a control center
718. kartīte
Jautājums
Which term describes the component that executes a physiological response?
Atbilde
an effector
719. kartīte
Jautājums
Which term describes physiological regulation of body temperature?
Atbilde
thermoregulation
720. kartīte
Jautājums
Which term describes widening of blood vessels?
Atbilde
vasodilation
721. kartīte
Jautājums
What is vasoconstriction?
Atbilde
Narrowing of blood vessels, often reducing blood flow near the skin.
722. kartīte
Jautājums
What is insulin?
Atbilde
A pancreatic hormone that lowers elevated blood glucose by promoting uptake and storage.
723. kartīte
Jautājums
What is glucagon?
Atbilde
A pancreatic hormone that raises low blood glucose by promoting release of stored fuel.
724. kartīte
Jautājums
What are the main components of a homeostatic feedback loop?
Atbilde
A regulated variable, receptor, control center, effectors, and responses that alter the variable.
725. kartīte
Jautājums
Which term describes narrowing of blood vessels?
Atbilde
vasoconstriction
726. kartīte
Jautājums
Which term describes the pancreatic hormone that lowers blood glucose?
Atbilde
insulin
727. kartīte
Jautājums
Which term describes the pancreatic hormone that raises blood glucose?
Atbilde
glucagon
728. kartīte
Jautājums
What happens when blood glucose rises after a meal?
Atbilde
Insulin secretion increases, promoting glucose uptake and storage so blood glucose falls toward its normal range.
729. kartīte
Jautājums
What happens when blood glucose falls during fasting?
Atbilde
Glucagon secretion increases, promoting glycogen breakdown and glucose release by the liver.
730. kartīte
Jautājums
How does sweating cool the body?
Atbilde
Evaporation of water from skin transfers heat to the environment.
731. kartīte
Jautājums
How does skin vasodilation increase heat loss?
Atbilde
It brings more warm blood near the surface, increasing transfer of heat to the environment.
732. kartīte
Jautājums
How does shivering warm the body?
Atbilde
Rapid involuntary muscle contractions increase respiration and heat production.
733. kartīte
Jautājums
Does homeostasis keep internal conditions perfectly constant?
Atbilde
No. Variables fluctuate within controlled ranges around target values.
734. kartīte
Jautājums
How does ADH help conserve water?
Atbilde
It increases water permeability in kidney collecting ducts, so more water is reabsorbed and urine becomes more concentrated.
735. kartīte
Jautājums
How should ADH secretion change during dehydration?
Atbilde
It should increase, promoting greater water reabsorption by the kidneys.
736. kartīte
Jautājums
How does positive feedback differ from negative feedback?
Atbilde
Positive feedback amplifies a change until an endpoint; negative feedback opposes a change and stabilizes a variable.
737. kartīte
Jautājums
Why can diabetes mellitus cause persistently high blood glucose?
Atbilde
Insulin production may be insufficient or target cells may respond poorly to insulin.
738. kartīte
Jautājums
What is biological evolution?
Atbilde
Change in heritable characteristics or allele frequencies of a population across generations.
739. kartīte
Jautājums
What is allele frequency?
Atbilde
The proportion of gene copies in a population represented by a particular allele.
740. kartīte
Jautājums
What is microevolution?
Atbilde
Evolutionary change in allele frequencies within populations over relatively short timescales.
741. kartīte
Jautājums
What is speciation?
Atbilde
Evolutionary formation of new species.
742. kartīte
Jautājums
Which term describes change in a population's heritable composition across generations?
Atbilde
biological evolution
743. kartīte
Jautājums
Which term describes the proportion of a population's gene copies that are one allele?
Atbilde
allele frequency
744. kartīte
Jautājums
Which term describes short-timescale allele-frequency change within populations?
Atbilde
microevolution
745. kartīte
Jautājums
Which term describes formation of new species?
Atbilde
speciation
746. kartīte
Jautājums
What is reproductive isolation?
Atbilde
Barriers that prevent or greatly reduce gene flow between populations.
747. kartīte
Jautājums
What is allopatric speciation?
Atbilde
Speciation after populations become geographically separated and diverge.
748. kartīte
Jautājums
What is sympatric speciation?
Atbilde
Speciation without geographic separation, through reproductive isolation within the same area.
749. kartīte
Jautājums
What are homologous structures?
Atbilde
Structures similar because they were inherited from a common ancestor, even if their functions differ.
750. kartīte
Jautājums
Which term describes barriers reducing gene flow between populations?
Atbilde
reproductive isolation
751. kartīte
Jautājums
Which term describes speciation following geographic separation?
Atbilde
allopatric speciation
752. kartīte
Jautājums
Which term describes speciation within the same geographic area?
Atbilde
sympatric speciation
753. kartīte
Jautājums
Which term describes structures similar through common ancestry?
Atbilde
homologous structures
754. kartīte
Jautājums
What are analogous structures?
Atbilde
Structures with similar functions that evolved independently rather than from the same ancestral structure.
755. kartīte
Jautājums
What is a common ancestor?
Atbilde
An ancestral population from which two or more descendant lineages evolved.
756. kartīte
Jautājums
How does the fossil record provide evidence for evolution?
Atbilde
It documents organisms from different times, including appearance, change, persistence, and extinction of lineages.
757. kartīte
Jautājums
How do DNA and protein sequences provide evidence of common ancestry?
Atbilde
Shared sequences are inherited; greater similarity generally indicates more recent common ancestry.
758. kartīte
Jautājums
Which term describes functionally similar structures of independent evolutionary origin?
Atbilde
analogous structures
759. kartīte
Jautājums
Which term describes an ancestral population shared by descendant lineages?
Atbilde
a common ancestor
760. kartīte
Jautājums
What is the evolutionary significance of extinction?
Atbilde
It permanently ends a lineage and can alter ecological opportunities and the future diversification of survivors.
761. kartīte
Jautājums
Do individual organisms evolve during their lifetimes?
Atbilde
No. Individuals develop and acclimate; evolution is heritable change in populations across generations.
762. kartīte
Jautājums
Why is evolution represented as a branching tree rather than a ladder?
Atbilde
Lineages split from common ancestors; living species are not arranged as stages toward a single goal.
763. kartīte
Jautājums
How can island species support evolutionary explanations?
Atbilde
Their similarities to nearby mainland ancestors and unique local adaptations fit divergence after colonization and isolation.
764. kartīte
Jautājums
How can geographic isolation lead to reproductive isolation?
Atbilde
Separated populations accumulate different mutations and experience different selection and drift until interbreeding is reduced.
765. kartīte
Jautājums
Why can continuing gene flow slow speciation?
Atbilde
Movement of alleles between populations counteracts genetic divergence.
766. kartīte
Jautājums
Why can unrelated species evolve similar traits?
Atbilde
Similar environmental challenges can favor similar functional solutions through convergent evolution.
767. kartīte
Jautājums
Which parts of evolution are random and which are nonrandom?
Atbilde
Mutation and many sampling effects are random with respect to need; natural selection nonrandomly favors variants that reproduce better in a given environment.
768. kartīte
Jautājums
What is conservation biology?
Atbilde
The science and practice of protecting biodiversity, ecological processes, and evolutionary potential.
769. kartīte
Jautājums
What is habitat fragmentation?
Atbilde
Division of continuous habitat into smaller, isolated patches.
770. kartīte
Jautājums
What is an endangered species?
Atbilde
A species facing a high risk of extinction in the wild.
771. kartīte
Jautājums
What is in situ conservation?
Atbilde
Protection of species in their natural habitats and ecological communities.
772. kartīte
Jautājums
Which term describes the protection of biodiversity and ecological processes?
Atbilde
conservation biology
773. kartīte
Jautājums
Which term describes division of habitat into isolated patches?
Atbilde
habitat fragmentation
774. kartīte
Jautājums
Which term describes a species at high risk of extinction?
Atbilde
an endangered species
775. kartīte
Jautājums
Which term describes conservation within natural habitat?
Atbilde
in situ conservation
776. kartīte
Jautājums
What is ex situ conservation?
Atbilde
Protection of organisms or genetic material outside the natural habitat.
777. kartīte
Jautājums
What is a population bottleneck?
Atbilde
A sharp population reduction that can remove genetic variation by chance.
778. kartīte
Jautājums
What is a wildlife corridor?
Atbilde
Habitat connecting isolated patches to permit movement and gene flow.
779. kartīte
Jautājums
What major human-driven processes threaten biodiversity?
Atbilde
Habitat loss, overexploitation, invasive species, pollution, and climate change.
780. kartīte
Jautājums
Which term describes conservation outside natural habitat?
Atbilde
ex situ conservation
781. kartīte
Jautājums
Which term describes a severe population reduction that loses genetic diversity?
Atbilde
a population bottleneck
782. kartīte
Jautājums
Which term describes habitat linking isolated populations?
Atbilde
a wildlife corridor
783. kartīte
Jautājums
What makes a protected area more effective than a boundary alone?
Atbilde
Adequate size, representative habitat, enforcement, connectivity, local support, and management of external threats.
784. kartīte
Jautājums
Why is long-term population monitoring important in conservation?
Atbilde
It reveals trends, tests whether management works, and provides early warning of decline.
785. kartīte
Jautājums
How can ecosystem services support the case for conservation?
Atbilde
Healthy ecosystems provide benefits such as pollination, water purification, carbon storage, soil formation, and cultural value.
786. kartīte
Jautājums
Why are very small populations especially vulnerable to extinction?
Atbilde
Chance events, inbreeding, low genetic diversity, and difficulty finding mates can reinforce decline.
787. kartīte
Jautājums
What are benefits and limits of captive-breeding programs?
Atbilde
They can prevent immediate extinction and manage breeding, but may lose diversity, alter behavior, and fail without safe habitat for release.
788. kartīte
Jautājums
Why can controlling an invasive species aid conservation?
Atbilde
It can reduce predation, competition, disease, or habitat alteration affecting native species.
789. kartīte
Jautājums
Why must conservation priorities consider more than species count?
Atbilde
Endemism, evolutionary distinctness, ecological roles, threat severity, feasibility, and human needs also matter.
790. kartīte
Jautājums
What is an adaptation?
Atbilde
A heritable characteristic that increases reproductive success in a particular environment.
791. kartīte
Jautājums
What is acclimation?
Atbilde
A reversible physiological or behavioral adjustment by an individual to environmental change.
792. kartīte
Jautājums
What is a structural adaptation?
Atbilde
An inherited anatomical feature that improves performance in an environment.
793. kartīte
Jautājums
What is a physiological adaptation?
Atbilde
An inherited functional or biochemical feature that improves performance in an environment.
794. kartīte
Jautājums
Which term describes a heritable trait improving reproductive success in context?
Atbilde
an adaptation
795. kartīte
Jautājums
Which term describes an individual's reversible adjustment to environmental change?
Atbilde
acclimation
796. kartīte
Jautājums
Which term describes an adaptive anatomical feature?
Atbilde
a structural adaptation
797. kartīte
Jautājums
Which term describes an adaptive functional or biochemical feature?
Atbilde
a physiological adaptation
798. kartīte
Jautājums
What is a behavioral adaptation?
Atbilde
An inherited behavior pattern that improves survival or reproduction.
799. kartīte
Jautājums
What is an environmental tolerance range?
Atbilde
The range of an abiotic condition within which an organism can survive and reproduce.
800. kartīte
Jautājums
What is evolutionary fitness?
Atbilde
Relative contribution of an individual or genotype to future generations.
801. kartīte
Jautājums
How can a thick cuticle and reduced leaves help a desert plant?
Atbilde
The cuticle lowers surface permeability, while smaller leaves reduce the area from which water can evaporate.
802. kartīte
Jautājums
Which term describes an adaptive behavior pattern?
Atbilde
a behavioral adaptation
803. kartīte
Jautājums
Which term describes the survivable range of an abiotic condition?
Atbilde
an environmental tolerance range
804. kartīte
Jautājums
Which term describes relative reproductive contribution to future generations?
Atbilde
evolutionary fitness
805. kartīte
Jautājums
How can a streamlined body adapt an aquatic animal to movement?
Atbilde
It reduces drag, lowering the energy needed to move through water.
806. kartīte
Jautājums
Does an organism develop an adaptation because it needs one?
Atbilde
No. Heritable variants arise without regard to need, and selection changes their frequencies across generations.
807. kartīte
Jautājums
Why may organisms from different thermal environments have enzymes with different temperature optima?
Atbilde
Selection favors protein structures that balance flexibility and stability under local temperatures.
808. kartīte
Jautājums
Why is an adaptation rarely beneficial in every environment?
Atbilde
Traits carry costs and their advantage depends on local resources, competitors, predators, and physical conditions.
809. kartīte
Jautājums
How does phenotypic plasticity differ from genetic adaptation?
Atbilde
Plasticity lets one genotype produce different phenotypes; adaptation is a heritable population trait shaped across generations.
810. kartīte
Jautājums
What is local adaptation?
Atbilde
A population has higher fitness in its home environment than foreign populations because selection favored local traits.
811. kartīte
Jautājums
What is an ecological niche?
Atbilde
The set of environmental conditions, resources, interactions, and functional roles associated with a species.
812. kartīte
Jautājums
What is a habitat?
Atbilde
The physical place or environment where an organism lives.
813. kartīte
Jautājums
What is a fundamental niche?
Atbilde
The full range of conditions and resources a species could use without limiting biotic interactions.
814. kartīte
Jautājums
What is a realized niche?
Atbilde
The conditions and resources a species actually uses after competition and other interactions.
815. kartīte
Jautājums
Which term describes a species' environmental requirements and ecological role?
Atbilde
an ecological niche
816. kartīte
Jautājums
Which term describes the place where an organism lives?
Atbilde
a habitat
817. kartīte
Jautājums
Which term describes the potential niche without limiting biotic interactions?
Atbilde
a fundamental niche
818. kartīte
Jautājums
Which term describes the niche actually occupied in nature?
Atbilde
a realized niche
819. kartīte
Jautājums
What is competition?
Atbilde
An interaction in which organisms reduce one another's access to a limited resource.
820. kartīte
Jautājums
What is mutualism?
Atbilde
An interaction in which both participating species benefit.
821. kartīte
Jautājums
What is predation?
Atbilde
An interaction in which one organism kills and consumes another.
822. kartīte
Jautājums
How does a habitat differ from a niche?
Atbilde
A habitat is where an organism lives; a niche includes how it uses conditions and resources and interacts there.
823. kartīte
Jautājums
Which term describes an interaction over a limited resource that harms both competitors?
Atbilde
competition
824. kartīte
Jautājums
Which term describes an interspecific interaction benefiting both partners?
Atbilde
mutualism
825. kartīte
Jautājums
Which term describes an interaction where one organism kills and eats another?
Atbilde
predation
826. kartīte
Jautājums
What kinds of factors define a niche?
Atbilde
Abiotic factors such as temperature and moisture, plus biotic factors such as food, competitors, predators, and partners.
827. kartīte
Jautājums
What does competitive exclusion predict?
Atbilde
Species with effectively identical niches cannot coexist indefinitely under stable conditions; one is excluded or niches diverge.
828. kartīte
Jautājums
How can resource partitioning reduce competition?
Atbilde
Species use different resources, places, or times, reducing niche overlap.
829. kartīte
Jautājums
What is a keystone species?
Atbilde
A species whose effect on community structure is disproportionately large relative to its abundance.
830. kartīte
Jautājums
Why can an introduced species expand rapidly in a new community?
Atbilde
It may encounter abundant resources, suitable climate, and fewer predators, pathogens, or competitors.
831. kartīte
Jautājums
Can an organism alter the niche conditions of other species?
Atbilde
Yes. Ecosystem engineers modify habitat structure or resource availability, changing opportunities for other organisms.
832. kartīte
Jautājums
What is a population?
Atbilde
Individuals of the same species living in the same area at the same time.
833. kartīte
Jautājums
What is an ecological community?
Atbilde
Populations of different species living and interacting in an area.
834. kartīte
Jautājums
What is an ecosystem?
Atbilde
A community together with its physical environment and their interactions.
835. kartīte
Jautājums
What is carrying capacity?
Atbilde
The population size an environment can sustain over time under given conditions.
836. kartīte
Jautājums
Which term describes same-species individuals sharing an area and time?
Atbilde
a population
837. kartīte
Jautājums
Which term describes interacting populations of different species?
Atbilde
an ecological community
838. kartīte
Jautājums
Which term describes a community plus its abiotic environment?
Atbilde
an ecosystem
839. kartīte
Jautājums
Which term describes the long-term supportable population size?
Atbilde
carrying capacity
840. kartīte
Jautājums
What is population density?
Atbilde
The number of individuals per unit area or volume.
841. kartīte
Jautājums
What is a limiting factor?
Atbilde
A resource or condition that restricts population growth or distribution.
842. kartīte
Jautājums
What is a density-dependent factor?
Atbilde
A factor whose effect strengthens as population density increases.
843. kartīte
Jautājums
What is a density-independent factor?
Atbilde
A factor whose effect is not primarily determined by population density.
844. kartīte
Jautājums
Which term describes individuals per unit area or volume?
Atbilde
population density
845. kartīte
Jautājums
Which term describes a resource or condition restricting a population?
Atbilde
a limiting factor
846. kartīte
Jautājums
Which term describes a factor with stronger effects at higher density?
Atbilde
a density-dependent factor
847. kartīte
Jautājums
Which term describes a factor acting largely regardless of population density?
Atbilde
a density-independent factor
848. kartīte
Jautājums
What is exponential population growth?
Atbilde
Growth at a constant per-capita rate, producing a J-shaped curve under ideal conditions.
849. kartīte
Jautājums
What is logistic population growth?
Atbilde
Growth that slows as population size approaches carrying capacity, producing an S-shaped model.
850. kartīte
Jautājums
What four processes directly change population size?
Atbilde
Births and immigration increase it; deaths and emigration decrease it.
851. kartīte
Jautājums
Under what conditions can exponential growth occur temporarily?
Atbilde
Resources are abundant and limiting effects such as competition, disease, and predation are weak.
852. kartīte
Jautājums
Which term describes J-shaped growth at constant per-capita rate?
Atbilde
exponential population growth
853. kartīte
Jautājums
Which term describes S-shaped growth that slows near carrying capacity?
Atbilde
logistic population growth
854. kartīte
Jautājums
Why is infectious disease often density dependent?
Atbilde
Close or frequent contact at high density increases transmission opportunities.
855. kartīte
Jautājums
Give an example of a density-independent population factor.
Atbilde
A severe storm, wildfire, drought, or freeze can affect populations regardless of their initial density.
856. kartīte
Jautājums
When is quadrat sampling useful?
Atbilde
For estimating abundance or frequency of sessile or slow-moving organisms in defined areas.
857. kartīte
Jautājums
What can a transect reveal?
Atbilde
How species occurrence or abundance changes along an environmental gradient.
858. kartīte
Jautājums
What can happen when a population overshoots carrying capacity?
Atbilde
Resource depletion may raise mortality or lower reproduction, causing decline or oscillation.
859. kartīte
Jautājums
What is the basic mark–recapture estimate of population size?
Atbilde
First sample marked × second sample total ÷ marked individuals recaptured.
860. kartīte
Jautājums
What assumptions improve a mark–recapture estimate?
Atbilde
Marks persist and do not affect survival, marked individuals mix, capture probability is similar, and the population is effectively closed.
861. kartīte
Jautājums
Why does a correlation between two population variables not prove causation?
Atbilde
A third factor, reverse influence, chance, or biased sampling could produce the association.
862. kartīte
Jautājums
What is a trophic level?
Atbilde
A feeding position in a food chain or web.
863. kartīte
Jautājums
What is a producer?
Atbilde
An autotroph that converts inorganic carbon into organic matter.
864. kartīte
Jautājums
What is a consumer?
Atbilde
An organism obtaining energy and matter by eating other organisms or organic material.
865. kartīte
Jautājums
What is a decomposer?
Atbilde
An organism that externally digests dead material and wastes and absorbs the products.
866. kartīte
Jautājums
Which term describes a feeding position in an ecosystem?
Atbilde
a trophic level
867. kartīte
Jautājums
Which term describes an autotroph forming organic matter?
Atbilde
a producer
868. kartīte
Jautājums
Which term describes an organism feeding on other organic matter?
Atbilde
a consumer
869. kartīte
Jautājums
Which term describes an organism digesting dead organic matter externally?
Atbilde
a decomposer
870. kartīte
Jautājums
What is a food chain?
Atbilde
A linear representation of feeding and energy-transfer relationships.
871. kartīte
Jautājums
What is a food web?
Atbilde
A network of interconnected feeding relationships in a community.
872. kartīte
Jautājums
What is gross primary productivity?
Atbilde
The total rate at which producers capture energy into organic matter.
873. kartīte
Jautājums
What is net primary productivity?
Atbilde
Producer energy stored as new biomass after subtracting producer respiration from gross primary productivity.
874. kartīte
Jautājums
Which term describes a linear feeding sequence?
Atbilde
a food chain
875. kartīte
Jautājums
Which term describes a network of connected food chains?
Atbilde
a food web
876. kartīte
Jautājums
Which term describes the total producer energy-capture rate?
Atbilde
gross primary productivity
877. kartīte
Jautājums
Which term describes producer biomass gain after respiration?
Atbilde
net primary productivity
878. kartīte
Jautājums
What is ecological productivity?
Atbilde
The rate of biomass or energy production per unit area or volume.
879. kartīte
Jautājums
What is a biogeochemical cycle?
Atbilde
Movement of an element or compound through organisms and the physical environment.
880. kartīte
Jautājums
Why is less energy available at each higher trophic level?
Atbilde
Not all biomass is eaten or digested, and organisms use energy in respiration, movement, maintenance, and heat loss.
881. kartīte
Jautājums
Why does energy flow rather than cycle through an ecosystem?
Atbilde
Energy enters mainly as light and ultimately disperses as heat, which ecosystems cannot fully recycle.
882. kartīte
Jautājums
Which term describes the rate of biomass or energy production?
Atbilde
ecological productivity
883. kartīte
Jautājums
Which term describes cycling of matter through living and nonliving reservoirs?
Atbilde
a biogeochemical cycle
884. kartīte
Jautājums
Why can matter cycle through an ecosystem?
Atbilde
Atoms are conserved and repeatedly transferred among organisms, detritus, soil, water, and atmosphere.
885. kartīte
Jautājums
Why is a pyramid of energy always upright?
Atbilde
Usable energy decreases between trophic levels because every transfer includes losses.
886. kartīte
Jautājums
How are gross and net primary productivity related?
Atbilde
NPP = GPP − producer respiration.
887. kartīte
Jautājums
How do decomposers support nutrient cycling?
Atbilde
They break down dead material and wastes, releasing inorganic nutrients for reuse.
888. kartīte
Jautājums
What processes move carbon rapidly between organisms and the atmosphere?
Atbilde
Photosynthesis removes carbon dioxide; respiration, decomposition, and combustion release it.
889. kartīte
Jautājums
Why is nitrogen fixation important?
Atbilde
It converts atmospheric nitrogen gas into forms that can enter biological nitrogen metabolism.
890. kartīte
Jautājums
How can excess nitrogen or phosphorus cause eutrophication?
Atbilde
Nutrient enrichment drives algal growth; decomposition of the biomass consumes oxygen and can create hypoxic water.
891. kartīte
Jautājums
Why can a persistent pollutant reach higher concentrations at higher trophic levels?
Atbilde
Predators consume contaminant stored in many prey, and the substance is not readily broken down or excreted.
892. kartīte
Jautājums
How is trophic-transfer efficiency calculated?
Atbilde
Energy or biomass gained by the higher trophic level ÷ energy or biomass available at the lower level × 100%.
893. kartīte
Jautājums
What is phenotypic variation?
Atbilde
Differences in observable traits among individuals of a population.
894. kartīte
Jautājums
What is heritable variation?
Atbilde
Trait differences that can be transmitted genetically to offspring.
895. kartīte
Jautājums
What is a selection pressure?
Atbilde
An environmental factor causing differences in survival or reproduction among phenotypes.
896. kartīte
Jautājums
What is relative fitness?
Atbilde
An individual's reproductive success compared with others in the population.
897. kartīte
Jautājums
Which term describes observable differences among individuals?
Atbilde
phenotypic variation
898. kartīte
Jautājums
Which term describes genetically transmissible trait differences?
Atbilde
heritable variation
899. kartīte
Jautājums
Which term describes an environmental factor producing differential reproductive success?
Atbilde
a selection pressure
900. kartīte
Jautājums
Which term describes reproductive success relative to other individuals?
Atbilde
relative fitness
901. kartīte
Jautājums
What is directional selection?
Atbilde
Selection favoring one extreme phenotype and shifting a population's trait distribution.
902. kartīte
Jautājums
What is stabilizing selection?
Atbilde
Selection favoring intermediate phenotypes and acting against extremes.
903. kartīte
Jautājums
What is disruptive selection?
Atbilde
Selection favoring both extreme phenotypes over intermediates.
904. kartīte
Jautājums
What is sexual selection?
Atbilde
Selection arising from differences in mating success.
905. kartīte
Jautājums
Which term describes selection shifting a trait toward one extreme?
Atbilde
directional selection
906. kartīte
Jautājums
Which term describes selection favoring intermediate phenotypes?
Atbilde
stabilizing selection
907. kartīte
Jautājums
Which term describes selection favoring both trait extremes?
Atbilde
disruptive selection
908. kartīte
Jautājums
Which term describes selection caused by unequal mating success?
Atbilde
sexual selection
909. kartīte
Jautājums
What conditions are required for natural selection?
Atbilde
Individuals vary, some variation is heritable, more offspring are produced than can reproduce, and variants differ in reproductive success.
910. kartīte
Jautājums
How does natural selection produce antibiotic-resistant bacterial populations?
Atbilde
Existing resistant variants survive treatment and reproduce more than susceptible bacteria.
911. kartīte
Jautājums
Does an antibiotic cause bacteria to mutate specifically toward resistance?
Atbilde
No. Resistance variants arise without regard to need; treatment selects among them.
912. kartīte
Jautājums
Can an individual become genetically adapted through natural selection?
Atbilde
No. Selection acts on individuals, but adaptation is a population change across generations.
913. kartīte
Jautājums
How does artificial selection differ from natural selection?
Atbilde
Humans choose breeding traits in artificial selection; environmental conditions determine differential reproduction in natural selection.
914. kartīte
Jautājums
How does natural selection change a population?
Atbilde
Individuals with advantageous heritable variants leave more offspring, increasing those alleles over generations.
915. kartīte
Jautājums
Why is fitness environment-dependent?
Atbilde
A trait that improves reproduction in one environment may be neutral or costly in another.
916. kartīte
Jautājums
How does genetic drift differ from natural selection?
Atbilde
Drift changes allele frequencies by chance sampling; selection changes them through consistent fitness differences.
917. kartīte
Jautājums
What is ecosystem stability?
Atbilde
The capacity of an ecosystem to maintain or recover its structure and functions despite disturbance.
918. kartīte
Jautājums
What is an ecological tipping point?
Atbilde
A threshold beyond which feedbacks can drive a large and difficult-to-reverse ecosystem shift.
919. kartīte
Jautājums
What is a mesocosm?
Atbilde
A controlled, simplified ecosystem used to investigate ecological processes under more realistic conditions than a small laboratory vessel.
920. kartīte
Jautājums
What is a sustainable yield?
Atbilde
A harvest rate that can continue without causing long-term resource decline under prevailing conditions.
921. kartīte
Jautājums
Which term describes the capacity of an ecosystem to persist or recover after disturbance?
Atbilde
ecosystem stability
922. kartīte
Jautājums
Which term describes a threshold triggering a major hard-to-reverse ecosystem shift?
Atbilde
an ecological tipping point
923. kartīte
Jautājums
Which term describes a controlled model ecosystem used for experiments?
Atbilde
a mesocosm
924. kartīte
Jautājums
Which term describes a harvest rate that avoids long-term depletion?
Atbilde
a sustainable yield
925. kartīte
Jautājums
What is eutrophication?
Atbilde
Nutrient enrichment of water that stimulates excess primary production and can lead to oxygen depletion.
926. kartīte
Jautājums
What is biomagnification?
Atbilde
Increase in concentration of a persistent pollutant at successively higher trophic levels.
927. kartīte
Jautājums
What is rewilding?
Atbilde
Ecosystem restoration that rebuilds natural processes, species interactions, and self-sustaining ecological function.
928. kartīte
Jautājums
What features can make an ecosystem more stable?
Atbilde
Diverse functional roles, connected habitats, intact food webs, nutrient cycling, and balancing feedbacks can help the system resist or recover from disturbance.
929. kartīte
Jautājums
Which term describes nutrient enrichment that can deplete oxygen in water?
Atbilde
eutrophication
930. kartīte
Jautājums
Which term describes increasing pollutant concentration up a food chain?
Atbilde
biomagnification
931. kartīte
Jautājums
Which term describes restoration focused on natural processes and self-sustaining ecosystems?
Atbilde
rewilding
932. kartīte
Jautājums
How could extensive Amazon deforestation push the ecosystem toward a tipping point?
Atbilde
Loss of trees can reduce rainfall recycling and increase heat and fire, which cause further forest loss and may shift large areas toward a drier state.
933. kartīte
Jautājums
What are a benefit and a limitation of using a mesocosm?
Atbilde
It allows controlled experiments with interacting organisms, but its simplified scale cannot reproduce every process or long-term influence in a natural ecosystem.
934. kartīte
Jautājums
Why should a fishery harvest below an uncertain maximum sustainable yield?
Atbilde
Population estimates and recruitment vary, so a safety margin reduces the chance that error or a poor breeding year drives long-term decline.
935. kartīte
Jautājums
How can intensive agriculture reduce ecosystem stability?
Atbilde
Habitat loss, low crop diversity, soil degradation, heavy water use, pesticides, and nutrient runoff can weaken food webs and ecosystem processes.
936. kartīte
Jautājums
Why can microplastic pollution harm aquatic ecosystems?
Atbilde
Small persistent particles can be ingested, carry additives or other pollutants, damage feeding and tissues, and move through food webs.
937. kartīte
Jautājums
How can rewilding improve ecosystem stability?
Atbilde
Restoring native species, habitat connections, and natural disturbance or grazing processes can rebuild feedbacks and allow the ecosystem to maintain itself with less intervention.
938. kartīte
Jautājums
What is the greenhouse effect?
Atbilde
Warming caused when atmospheric gases absorb and re-emit outgoing infrared radiation.
939. kartīte
Jautājums
What is a greenhouse gas?
Atbilde
An atmospheric gas that absorbs infrared radiation at wavelengths emitted by Earth.
940. kartīte
Jautājums
What is carbon dioxide (CO₂)?
Atbilde
A long-lived greenhouse gas increased mainly by fossil-fuel combustion, cement production, and land-use change.
941. kartīte
Jautājums
What is methane (CH₄)?
Atbilde
A potent greenhouse gas emitted by sources including fossil-fuel systems, livestock, rice cultivation, wetlands, and waste.
942. kartīte
Jautājums
Which term describes warming from absorption and re-emission of infrared radiation?
Atbilde
the greenhouse effect
943. kartīte
Jautājums
Which term describes an atmospheric infrared-absorbing gas?
Atbilde
a greenhouse gas
944. kartīte
Jautājums
Which term describes the long-lived greenhouse gas strongly increased by fossil fuels?
Atbilde
carbon dioxide (CO₂)
945. kartīte
Jautājums
Which term describes the potent short-lived greenhouse gas from biological and fossil sources?
Atbilde
methane (CH₄)
946. kartīte
Jautājums
What is albedo?
Atbilde
The fraction of incoming radiation reflected by a surface.
947. kartīte
Jautājums
What is a carbon sink?
Atbilde
A reservoir that absorbs more carbon than it releases over a specified period.
948. kartīte
Jautājums
What is ocean acidification?
Atbilde
Decline in seawater pH caused mainly by absorption of human-emitted carbon dioxide.
949. kartīte
Jautājums
What is climate change?
Atbilde
A persistent change in the statistical patterns of climate over decades or longer.
950. kartīte
Jautājums
Which term describes surface reflectivity?
Atbilde
albedo
951. kartīte
Jautājums
Which term describes a reservoir with net carbon uptake?
Atbilde
a carbon sink
952. kartīte
Jautājums
Which term describes seawater pH decline from absorbed carbon dioxide?
Atbilde
ocean acidification
953. kartīte
Jautājums
Which term describes long-term change in climate patterns?
Atbilde
climate change
954. kartīte
Jautājums
What is the enhanced greenhouse effect?
Atbilde
Additional warming caused by human-driven increases in greenhouse-gas concentrations.
955. kartīte
Jautājums
How do climate mitigation and climate adaptation differ?
Atbilde
Mitigation limits the magnitude of climate change; adaptation reduces harm from changes that occur.
956. kartīte
Jautājums
How does increasing greenhouse-gas concentration alter Earth's energy balance?
Atbilde
Less outgoing infrared energy initially escapes to space, so the climate warms until energy balance is restored at a higher temperature.
957. kartīte
Jautājums
How can melting ice amplify warming?
Atbilde
Less bright ice lowers albedo, so darker land or water absorbs more solar energy and causes further warming.
958. kartīte
Jautājums
How can climate change alter species distributions?
Atbilde
Temperature, rainfall, seasons, sea level, and interactions shift, moving or shrinking areas with suitable conditions.
959. kartīte
Jautājums
Why can ocean acidification harm calcifying organisms?
Atbilde
Carbonate chemistry changes, reducing availability of carbonate ions used to build calcium-carbonate structures.
960. kartīte
Jautājums
How can ecosystem protection contribute to climate mitigation?
Atbilde
Protecting forests, wetlands, soils, and coastal habitats can avoid emissions and maintain or increase carbon storage.
960 kartīšu
IB Biology SL Flashcards: Complete Course Review
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