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