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