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