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