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