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