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