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.
या संचाविषयी
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.
या संचातील कार्डे
कार्ड १
प्रश्न
What is water polarity?
उत्तर
The unequal sharing of electrons in a water molecule, giving oxygen a partial negative charge and the hydrogens partial positive charges.
कार्ड २
प्रश्न
What is a hydrogen bond?
उत्तर
A weak attraction between a partially positive hydrogen atom and a partially negative atom in another molecule.
कार्ड ३
प्रश्न
What is cohesion?
उत्तर
Attraction between molecules of the same substance.
कार्ड ४
प्रश्न
What is adhesion?
उत्तर
Attraction between molecules of different substances.
कार्ड ५
प्रश्न
Which term describes unequal charge distribution within a water molecule?
उत्तर
water polarity
कार्ड ६
प्रश्न
Which term describes the intermolecular attraction that links neighboring water molecules?
उत्तर
a hydrogen bond
कार्ड ७
प्रश्न
Which term describes attraction between molecules of the same substance?
उत्तर
cohesion
कार्ड ८
प्रश्न
Which term describes attraction between water and a different material?
उत्तर
adhesion
कार्ड ९
प्रश्न
What is a solvent?
उत्तर
A liquid that dissolves solutes to form a solution.
कार्ड १०
प्रश्न
What is specific heat capacity?
उत्तर
The energy required to raise the temperature of a unit mass of a substance by one degree.
कार्ड ११
प्रश्न
What is latent heat of vaporization?
उत्तर
The energy required to vaporize a specified amount of liquid without changing its temperature.
कार्ड १२
प्रश्न
Why does ice float on liquid water?
उत्तर
Hydrogen bonds hold water molecules in an open lattice in ice, making ice less dense than liquid water.
कार्ड १३
प्रश्न
Which term describes a liquid that dissolves solutes?
उत्तर
a solvent
कार्ड १४
प्रश्न
Which term describes the energy needed to raise a unit mass by one degree?
उत्तर
specific heat capacity
कार्ड १५
प्रश्न
Which term describes the energy needed to vaporize a liquid without a temperature change?
उत्तर
latent heat of vaporization
कार्ड १६
प्रश्न
Which property of water makes sweating an effective cooling mechanism?
उत्तर
Water absorbs substantial energy as it evaporates; the highest-energy molecules leave, carrying heat away from the skin.
कार्ड १७
प्रश्न
Why does water resist rapid temperature change?
उत्तर
Many hydrogen bonds must absorb energy before molecular motion increases substantially, giving water a high specific heat capacity.
कार्ड १८
प्रश्न
How do cohesion and adhesion support water transport in narrow tubes?
उत्तर
Cohesion keeps water molecules connected, while adhesion helps the water column cling to the tube wall.
कार्ड १९
प्रश्न
How does water participate differently in hydrolysis and condensation?
उत्तर
Hydrolysis consumes water to split a bond; condensation forms a bond and releases water.
कार्ड २०
प्रश्न
How does floating ice protect aquatic life in winter?
उत्तर
Surface ice insulates the liquid water below, slowing further heat loss and preventing the whole body of water from freezing rapidly.
कार्ड २१
प्रश्न
Why is water effective for transporting many biological solutes?
उत्तर
Its polarity allows ions and other polar molecules to become surrounded and dispersed in solution.
कार्ड २२
प्रश्न
Why do nonpolar substances tend to cluster in water?
उत्तर
Clustering reduces the nonpolar surface exposed to water, allowing more water molecules to maintain hydrogen-bond interactions.
कार्ड २३
प्रश्न
What is a nucleotide?
उत्तर
A nucleic-acid monomer made of a pentose sugar, a phosphate group, and a nitrogenous base.
कार्ड २४
प्रश्न
What is a nucleoside?
उत्तर
A nitrogenous base joined to a pentose sugar, without a phosphate group.
कार्ड २५
प्रश्न
What is a phosphodiester bond?
उत्तर
A covalent bond linking the phosphate of one nucleotide to the sugar of the next nucleotide.
कार्ड २६
प्रश्न
What is DNA?
उत्तर
A usually double-stranded nucleic acid that stores hereditary information in its base sequence.
कार्ड २७
प्रश्न
Which term describes a sugar-phosphate-base monomer?
उत्तर
a nucleotide
कार्ड २८
प्रश्न
Which term describes a base joined to a sugar but no phosphate?
उत्तर
a nucleoside
कार्ड २९
प्रश्न
Which term describes the covalent linkage in a nucleic-acid sugar-phosphate backbone?
उत्तर
a phosphodiester bond
कार्ड ३०
प्रश्न
Which term describes the nucleic acid that usually stores hereditary information?
उत्तर
DNA
कार्ड ३१
प्रश्न
What is RNA?
उत्तर
A usually single-stranded nucleic acid involved in expressing and regulating genetic information.
कार्ड ३२
प्रश्न
What are antiparallel DNA strands?
उत्तर
Two DNA strands that run in opposite 5′ to 3′ directions.
कार्ड ३३
प्रश्न
What is complementary base pairing?
उत्तर
Specific pairing in which adenine pairs with thymine in DNA, or uracil in RNA, and cytosine pairs with guanine.
कार्ड ३४
प्रश्न
What is a purine?
उत्तर
A nitrogenous base with two fused rings; adenine and guanine are purines.
कार्ड ३५
प्रश्न
Which term describes the usually single-stranded nucleic acid used in gene expression?
उत्तर
RNA
कार्ड ३६
प्रश्न
Which term describes DNA strands running in opposite directions?
उत्तर
antiparallel DNA strands
कार्ड ३७
प्रश्न
Which term describes specific A–T or A–U and C–G pairing?
उत्तर
complementary base pairing
कार्ड ३८
प्रश्न
Which term describes a two-ring nitrogenous base?
उत्तर
a purine
कार्ड ३९
प्रश्न
What is a pyrimidine?
उत्तर
A nitrogenous base with one ring; cytosine, thymine, and uracil are pyrimidines.
कार्ड ४०
प्रश्न
What is a genome?
उत्तर
The complete genetic material of an organism or cell.
कार्ड ४१
प्रश्न
What three structural features commonly distinguish RNA from DNA?
उत्तर
RNA usually contains ribose, uses uracil instead of thymine, and is single-stranded rather than double-stranded.
कार्ड ४२
प्रश्न
What determines the base sequence of the second DNA strand?
उत्तर
Complementary base-pairing rules determine it: A pairs with T, and C pairs with G.
कार्ड ४३
प्रश्न
Which term describes a one-ring nitrogenous base?
उत्तर
a pyrimidine
कार्ड ४४
प्रश्न
Which term describes the complete genetic material of an organism?
उत्तर
a genome
कार्ड ४५
प्रश्न
What do the 5′ and 3′ labels of a nucleic-acid strand refer to?
उत्तर
They refer to numbered carbon atoms in the pentose sugar and define the strand's chemical direction.
कार्ड ४६
प्रश्न
Where is genetic information encoded in DNA?
उत्तर
In the order of nitrogenous bases along the DNA strand.
कार्ड ४७
प्रश्न
Why is ATP classified as a nucleotide?
उत्तर
It contains adenine, ribose, and phosphate groups, the three component types of a nucleotide.
कार्ड ४८
प्रश्न
How do mRNA, tRNA, and rRNA contribute to protein synthesis?
उत्तर
mRNA carries the coding sequence, tRNA delivers amino acids, and rRNA forms the catalytic and structural core of ribosomes.
कार्ड ४९
प्रश्न
How are a gene and a chromosome related?
उत्तर
A gene is a DNA sequence with a biological function; a chromosome is one long DNA molecule containing many genes and other sequences.
कार्ड ५०
प्रश्न
What happens to double-stranded DNA when it is denatured by heat?
उत्तर
Hydrogen bonds between complementary bases break and the two strands separate; the covalent backbones usually remain intact.
कार्ड ५१
प्रश्न
Why can each DNA strand serve as a template during replication?
उत्तर
Its base sequence determines a complementary sequence through specific base pairing.
कार्ड ५२
प्रश्न
In which direction are new nucleic-acid strands synthesized?
उत्तर
Nucleotides are added to the 3′ end, so synthesis proceeds 5′ to 3′.
कार्ड ५३
प्रश्न
What is a monosaccharide?
उत्तर
A single sugar unit that can serve as a carbohydrate monomer.
कार्ड ५४
प्रश्न
What is a disaccharide?
उत्तर
A carbohydrate formed from two monosaccharides joined by a glycosidic bond.
कार्ड ५५
प्रश्न
What is a polysaccharide?
उत्तर
A polymer made from many monosaccharide units.
कार्ड ५६
प्रश्न
What is a glycosidic bond?
उत्तर
A covalent bond joining monosaccharides in a carbohydrate.
कार्ड ५७
प्रश्न
Which term describes a single sugar unit?
उत्तर
a monosaccharide
कार्ड ५८
प्रश्न
Which term describes two monosaccharides joined together?
उत्तर
a disaccharide
कार्ड ५९
प्रश्न
Which term describes a polymer of many sugar units?
उत्तर
a polysaccharide
कार्ड ६०
प्रश्न
Which term describes the covalent linkage between monosaccharides?
उत्तर
a glycosidic bond
कार्ड ६१
प्रश्न
What is a triglyceride?
उत्तर
A lipid formed from glycerol joined to three fatty acids.
कार्ड ६२
प्रश्न
What is a fatty acid?
उत्तर
A hydrocarbon chain with a carboxyl group that can form part of many lipids.
कार्ड ६३
प्रश्न
What is a saturated fatty acid?
उत्तर
A fatty acid with no carbon-carbon double bonds in its hydrocarbon chain.
कार्ड ६४
प्रश्न
What is a phospholipid?
उत्तर
An amphipathic lipid with a phosphate-containing hydrophilic head and hydrophobic fatty-acid tails.
कार्ड ६५
प्रश्न
Which term describes glycerol joined to three fatty acids?
उत्तर
a triglyceride
कार्ड ६६
प्रश्न
Which term describes a hydrocarbon chain ending in a carboxyl group?
उत्तर
a fatty acid
कार्ड ६७
प्रश्न
Which term describes a fatty acid without carbon-carbon double bonds?
उत्तर
a saturated fatty acid
कार्ड ६८
प्रश्न
Which term describes a lipid with a polar head and nonpolar tails?
उत्तर
a phospholipid
कार्ड ६९
प्रश्न
How is a glycosidic bond formed between two monosaccharides?
उत्तर
A condensation reaction joins them and releases a molecule of water.
कार्ड ७०
प्रश्न
How is a polysaccharide broken into smaller sugars?
उत्तर
Hydrolysis adds water across glycosidic bonds, splitting the polymer.
कार्ड ७१
प्रश्न
Which polysaccharides store glucose in plants and animals?
उत्तर
Starch stores glucose in plants; glycogen stores glucose in animals and fungi.
कार्ड ७२
प्रश्न
Why is cellulose suitable for plant cell walls?
उत्तर
Its straight β-glucose chains hydrogen-bond into strong microfibrils that resist stretching.
कार्ड ७३
प्रश्न
Why do lipids store more energy per gram than carbohydrates?
उत्तर
Lipids contain more energy-rich carbon-hydrogen bonds and are more reduced.
कार्ड ७४
प्रश्न
Why do phospholipids form bilayers in water?
उत्तर
Hydrophilic heads interact with water while hydrophobic tails cluster away from water.
कार्ड ७५
प्रश्न
Besides energy storage, what are three biological roles of lipids?
उत्तर
They form membranes, provide thermal insulation and cushioning, and can act as signaling molecules.
कार्ड ७६
प्रश्न
How do cis double bonds affect fatty-acid packing and melting point?
उत्तर
They introduce bends that reduce close packing, usually lowering the melting point.
कार्ड ७७
प्रश्न
What is an amino acid?
उत्तर
A protein monomer with an amino group, a carboxyl group, a hydrogen, and a variable R group attached to a central carbon.
कार्ड ७८
प्रश्न
What is a peptide bond?
उत्तर
The covalent bond formed between the amino group of one amino acid and the carboxyl group of another.
कार्ड ७९
प्रश्न
What is a polypeptide?
उत्तर
A chain of amino acids joined by peptide bonds.
कार्ड ८०
प्रश्न
What is protein primary structure?
उत्तर
The amino-acid sequence of a polypeptide.
कार्ड ८१
प्रश्न
Which term describes a protein monomer with amino, carboxyl, and variable R groups?
उत्तर
an amino acid
कार्ड ८२
प्रश्न
Which term describes the covalent linkage between amino acids?
उत्तर
a peptide bond
कार्ड ८३
प्रश्न
Which term describes a chain of peptide-linked amino acids?
उत्तर
a polypeptide
कार्ड ८४
प्रश्न
Which term describes a protein's amino-acid sequence?
उत्तर
protein primary structure
कार्ड ८५
प्रश्न
What is protein secondary structure?
उत्तर
Local folding such as α-helices and β-sheets stabilized mainly by backbone hydrogen bonds.
कार्ड ८६
प्रश्न
What is protein tertiary structure?
उत्तर
The overall three-dimensional shape of one polypeptide produced by interactions among R groups and the backbone.
कार्ड ८७
प्रश्न
What is protein quaternary structure?
उत्तर
The arrangement of multiple polypeptide subunits in one functional protein.
कार्ड ८८
प्रश्न
What is protein denaturation?
उत्तर
Loss of a protein's normal three-dimensional shape and therefore usually its function.
कार्ड ८९
प्रश्न
Which term describes local α-helix and β-sheet folding?
उत्तर
protein secondary structure
कार्ड ९०
प्रश्न
Which term describes the overall three-dimensional shape of one polypeptide?
उत्तर
protein tertiary structure
कार्ड ९१
प्रश्न
Which term describes the association of multiple polypeptide subunits?
उत्तर
protein quaternary structure
कार्ड ९२
प्रश्न
Which term describes loss of a protein's native shape?
उत्तर
protein denaturation
कार्ड ९३
प्रश्न
What mainly gives different amino acids their different chemical properties?
उत्तर
Their variable R groups.
कार्ड ९४
प्रश्न
What reaction forms a peptide bond?
उत्तर
A condensation reaction releases water as the amino and carboxyl groups join.
कार्ड ९५
प्रश्न
Why can high temperature denature a protein?
उत्तर
Increased molecular motion disrupts weak interactions that maintain the protein's shape.
कार्ड ९६
प्रश्न
Why can extreme pH denature a protein?
उत्तर
It changes the charges of R groups and disrupts ionic and hydrogen-bond interactions.
कार्ड ९७
प्रश्न
How do fibrous and globular proteins generally differ?
उत्तर
Fibrous proteins are elongated and mainly structural; globular proteins are compact and often perform dynamic functions.
कार्ड ९८
प्रश्न
Why is three-dimensional shape crucial to protein function?
उत्तर
It creates specific binding, catalytic, structural, or interaction surfaces.
कार्ड ९९
प्रश्न
Name four broad biological roles of proteins.
उत्तर
Catalysis, transport, signaling, defense, movement, and structural support are major roles; any four are sufficient.
कार्ड १००
प्रश्न
How can changing one amino acid alter protein function?
उत्तर
The substitution can change R-group interactions, folding, stability, or an active or binding site.
कार्ड १०१
प्रश्न
What is cell theory?
उत्तर
The principles that living organisms are made of cells, cells are the basic units of life, and cells arise from pre-existing cells.
कार्ड १०२
प्रश्न
What is a prokaryotic cell?
उत्तर
A cell without a nucleus or other membrane-bound organelles.
कार्ड १०३
प्रश्न
What is a eukaryotic cell?
उत्तर
A cell with DNA enclosed in a nucleus and with membrane-bound organelles.
कार्ड १०४
प्रश्न
What is the nucleus?
उत्तर
The double-membrane organelle that contains most of a eukaryotic cell's DNA.
कार्ड १०५
प्रश्न
Which term describes the principles describing cells as life's basic units?
उत्तर
cell theory
कार्ड १०६
प्रश्न
Which term describes a cell lacking a nucleus and membrane-bound organelles?
उत्तर
a prokaryotic cell
कार्ड १०७
प्रश्न
Which term describes a cell with a nucleus and membrane-bound organelles?
उत्तर
a eukaryotic cell
कार्ड १०८
प्रश्न
Which term describes the organelle containing most eukaryotic DNA?
उत्तर
the nucleus
कार्ड १०९
प्रश्न
What is a ribosome?
उत्तर
A molecular complex of rRNA and proteins that synthesizes polypeptides.
कार्ड ११०
प्रश्न
What is the cytoplasm?
उत्तर
The material inside the plasma membrane but outside the nucleus, including cytosol and organelles.
कार्ड १११
प्रश्न
What is the plasma membrane?
उत्तर
The selectively permeable boundary separating a cell from its environment.
कार्ड ११२
प्रश्न
What is a cell wall?
उत्तर
A rigid extracellular layer that supports and protects cells in plants, fungi, and most prokaryotes.
कार्ड ११३
प्रश्न
Which term describes the complex that synthesizes polypeptides?
उत्तर
a ribosome
कार्ड ११४
प्रश्न
Which term describes cell contents inside the plasma membrane but outside the nucleus?
उत्तर
the cytoplasm
कार्ड ११५
प्रश्न
Which term describes the selectively permeable cell boundary?
उत्तर
the plasma membrane
कार्ड ११६
प्रश्न
Which term describes a rigid extracellular support layer?
उत्तर
a cell wall
कार्ड ११७
प्रश्न
What is the nucleoid?
उत्तर
The non-membrane-bound region containing the main chromosome of a prokaryotic cell.
कार्ड ११८
प्रश्न
What is the cytoskeleton?
उत्तर
A dynamic network of protein filaments involved in cell shape, transport, division, and movement.
कार्ड ११९
प्रश्न
What structures are shared by all cells?
उत्तर
A plasma membrane, cytoplasm, genetic material, and ribosomes.
कार्ड १२०
प्रश्न
Which structures distinguish a typical plant cell from a typical animal cell?
उत्तर
A plant cell has a cellulose wall, chloroplasts in photosynthetic tissues, and a large central vacuole; an animal cell lacks these.
कार्ड १२१
प्रश्न
Which term describes the prokaryotic chromosome-containing region?
उत्तर
the nucleoid
कार्ड १२२
प्रश्न
Which term describes the internal network of protein filaments?
उत्तर
the cytoskeleton
कार्ड १२३
प्रश्न
How is genetic material commonly organized in a prokaryotic cell?
उत्तर
The main DNA is usually one circular chromosome in the nucleoid, often accompanied by smaller plasmids.
कार्ड १२४
प्रश्न
How is microscope magnification calculated?
उत्तर
Magnification = image size ÷ actual size, using the same units.
कार्ड १२५
प्रश्न
What does microscope resolution describe?
उत्तर
The ability to distinguish two close points as separate.
कार्ड १२६
प्रश्न
Arrange these from smallest to largest: ribosome, bacterium, animal cell.
उत्तर
Ribosome, bacterium, animal cell.
कार्ड १२७
प्रश्न
How does the cytoskeleton support intracellular transport?
उत्तर
Motor proteins move vesicles and other cargo along cytoskeletal filaments.
कार्ड १२८
प्रश्न
Why does a small cell usually exchange materials more efficiently than a geometrically similar large cell?
उत्तर
It has a larger surface-area-to-volume ratio, providing more exchange surface per unit of cell contents.
कार्ड १२९
प्रश्न
Why is a cell more than a collection of isolated molecules?
उत्तर
Organized interactions among components produce emergent functions such as metabolism, regulation, and reproduction.
कार्ड १३०
प्रश्न
What major advantage do membrane-bound organelles give eukaryotic cells?
उत्तर
They separate incompatible reactions and create specialized local conditions.
कार्ड १३१
प्रश्न
What is a phospholipid bilayer?
उत्तर
A double layer of phospholipids with hydrophilic heads facing water and hydrophobic tails facing inward.
कार्ड १३२
प्रश्न
What is the fluid mosaic model?
उत्तर
A model describing membranes as mobile phospholipids containing a changing mosaic of proteins and other components.
कार्ड १३३
प्रश्न
What is an integral membrane protein?
उत्तर
A protein embedded in the bilayer, often spanning it.
कार्ड १३४
प्रश्न
What is a peripheral membrane protein?
उत्तर
A protein attached to a membrane surface rather than embedded in the bilayer.
कार्ड १३५
प्रश्न
Which term describes a double phospholipid layer with inward-facing tails?
उत्तर
a phospholipid bilayer
कार्ड १३६
प्रश्न
Which term describes the model of a mobile lipid layer containing varied proteins?
उत्तर
the fluid mosaic model
कार्ड १३७
प्रश्न
Which term describes a protein embedded within the lipid bilayer?
उत्तर
an integral membrane protein
कार्ड १३८
प्रश्न
Which term describes a protein attached to a membrane surface?
उत्तर
a peripheral membrane protein
कार्ड १३९
प्रश्न
What is membrane cholesterol?
उत्तर
An amphipathic lipid that buffers membrane fluidity and reduces permeability in animal cells.
कार्ड १४०
प्रश्न
What is a glycoprotein?
उत्तर
A protein with an attached carbohydrate chain, often used in recognition, adhesion, or signaling.
कार्ड १४१
प्रश्न
What is diffusion?
उत्तर
Net movement of particles from a region of higher concentration to lower concentration due to random motion.
कार्ड १४२
प्रश्न
What is osmosis?
उत्तर
Net movement of water across a selectively permeable membrane from higher water potential to lower water potential.
कार्ड १४३
प्रश्न
Which term describes the animal-membrane lipid that buffers fluidity?
उत्तर
membrane cholesterol
कार्ड १४४
प्रश्न
Which term describes a carbohydrate-bearing protein?
उत्तर
a glycoprotein
कार्ड १४५
प्रश्न
Which term describes net movement down a concentration gradient?
उत्तर
diffusion
कार्ड १४६
प्रश्न
Which term describes net water movement across a selectively permeable membrane?
उत्तर
osmosis
कार्ड १४७
प्रश्न
What is facilitated diffusion?
उत्तर
Passive movement down a gradient through a membrane channel or carrier protein.
कार्ड १४८
प्रश्न
What is active transport?
उत्तर
Energy-requiring movement of a substance against its concentration or electrochemical gradient.
कार्ड १४९
प्रश्न
Why is the phospholipid bilayer selectively permeable?
उत्तर
Its hydrophobic interior allows small nonpolar molecules through more readily than ions and most large or polar molecules.
कार्ड १५०
प्रश्न
How do simple diffusion and facilitated diffusion differ?
उत्तर
Both are passive, but facilitated diffusion uses specific membrane proteins while simple diffusion passes through the bilayer.
कार्ड १५१
प्रश्न
Which term describes passive transport through a channel or carrier?
उत्तर
facilitated diffusion
कार्ड १५२
प्रश्न
Which term describes energy-dependent transport against a gradient?
उत्तर
active transport
कार्ड १५३
प्रश्न
How do channel and carrier proteins differ?
उत्तर
Channels provide hydrophilic pores; carriers bind solutes and change shape to move them.
कार्ड १५४
प्रश्न
How can an ATP-driven pump maintain an ion gradient?
उत्तर
It couples ATP hydrolysis to a conformational change that moves ions against their electrochemical gradient.
कार्ड १५५
प्रश्न
How does endocytosis move material into a cell?
उत्तर
The plasma membrane folds inward and pinches off a vesicle containing the material.
कार्ड १५६
प्रश्न
How does exocytosis move material out of a cell?
उत्तर
An intracellular vesicle fuses with the plasma membrane and releases its contents outside.
कार्ड १५७
प्रश्न
What happens to an animal cell in a strongly hypotonic solution?
उत्तर
Water enters by osmosis; without a cell wall, the cell may swell and lyse.
कार्ड १५८
प्रश्न
Does molecular movement stop when diffusion reaches equilibrium?
उत्तर
No. Molecules continue moving randomly, but there is no net movement between regions.
कार्ड १५९
प्रश्न
How does decreasing temperature generally affect membrane fluidity?
उत्तर
It reduces phospholipid movement and makes the membrane less fluid.
कार्ड १६०
प्रश्न
Why do unsaturated fatty-acid tails increase membrane fluidity?
उत्तर
Their cis double-bond bends prevent phospholipids from packing tightly.
कार्ड १६१
प्रश्न
What changes increase the rate of simple diffusion across a membrane?
उत्तर
A steeper gradient, larger surface area, higher temperature, shorter distance, and greater membrane permeability increase the rate.
कार्ड १६२
प्रश्न
What is a mitochondrion?
उत्तर
A double-membrane organelle where most aerobic ATP production occurs.
कार्ड १६३
प्रश्न
What is a chloroplast?
उत्तर
A double-membrane organelle where photosynthesis occurs in plants and algae.
कार्ड १६४
प्रश्न
What is rough endoplasmic reticulum?
उत्तर
A membrane network bearing ribosomes that synthesizes and begins processing many secreted and membrane proteins.
कार्ड १६५
प्रश्न
What is smooth endoplasmic reticulum?
उत्तर
A membrane network involved in lipid synthesis, detoxification, and calcium storage.
कार्ड १६६
प्रश्न
Which term describes the main organelle of aerobic ATP production?
उत्तर
a mitochondrion
कार्ड १६७
प्रश्न
Which term describes the photosynthetic organelle of plants and algae?
उत्तर
a chloroplast
कार्ड १६८
प्रश्न
Which term describes the ribosome-studded membrane network?
उत्तर
rough endoplasmic reticulum
कार्ड १६९
प्रश्न
Which term describes the membrane network that lacks ribosomes and synthesizes lipids?
उत्तर
smooth endoplasmic reticulum
कार्ड १७०
प्रश्न
What is the Golgi apparatus?
उत्तर
Stacked membranes that modify, sort, and package proteins and lipids into vesicles.
कार्ड १७१
प्रश्न
What is a lysosome?
उत्तर
An acidic enzyme-containing organelle that digests macromolecules and worn cellular components.
कार्ड १७२
प्रश्न
What is a vesicle?
उत्तर
A small membrane-bound compartment used for transport, storage, or chemical reactions.
कार्ड १७३
प्रश्न
What is the central vacuole?
उत्तर
A large plant-cell compartment that stores solutes and helps maintain turgor pressure.
कार्ड १७४
प्रश्न
Which term describes the organelle that modifies and sorts cellular cargo?
उत्तर
the Golgi apparatus
कार्ड १७५
प्रश्न
Which term describes the acidic digestive organelle?
उत्तर
a lysosome
कार्ड १७६
प्रश्न
Which term describes a small membrane-bound transport compartment?
उत्तर
a vesicle
कार्ड १७७
प्रश्न
Which term describes the large plant compartment that supports turgor?
उत्तर
the central vacuole
कार्ड १७८
प्रश्न
Why can compartmentalization increase metabolic efficiency?
उत्तर
It concentrates enzymes and substrates, maintains suitable local conditions, and separates incompatible reactions.
कार्ड १७९
प्रश्न
How do mitochondrial cristae support ATP production?
उत्तर
They increase inner-membrane area for electron transport chains and ATP synthase.
कार्ड १८०
प्रश्न
Why are chloroplast thylakoids arranged as extensive membranes?
उत्तर
They provide a large surface for light-absorbing complexes, electron transport chains, and ATP synthase.
कार्ड १८१
प्रश्न
What is the main function of the nucleolus?
उत्तर
It produces rRNA and assembles ribosomal subunits.
कार्ड १८२
प्रश्न
Trace a secreted protein from synthesis to release.
उत्तर
Ribosome on rough ER → ER lumen → transport vesicle → Golgi apparatus → secretory vesicle → plasma membrane → exocytosis.
कार्ड १८३
प्रश्न
Why does a lysosome maintain an acidic interior?
उत्तर
Its hydrolytic enzymes work best at low pH, and acidity helps confine their activity from the cytosol.
कार्ड १८४
प्रश्न
How do the nucleus, ribosomes, ER, and Golgi cooperate in protein production?
उत्तर
DNA instructions are transcribed in the nucleus; ribosomes translate them; ER folds or modifies many products; Golgi further modifies and sorts them.
कार्ड १८५
प्रश्न
How are transport vesicles directed to the correct target membrane?
उत्तर
Specific recognition proteins on vesicles and target membranes interact, allowing selective docking and fusion.
कार्ड १८६
प्रश्न
What is cell differentiation?
उत्तर
The process by which a cell develops specialized structure and function.
कार्ड १८७
प्रश्न
What is a stem cell?
उत्तर
An unspecialized cell able to self-renew and produce differentiated cells.
कार्ड १८८
प्रश्न
What is gene expression?
उत्तर
Use of genetic information to produce a functional RNA or protein product.
कार्ड १८९
प्रश्न
What is a tissue?
उत्तर
A coordinated group of similar or related cells performing a shared function.
कार्ड १९०
प्रश्न
Which term describes development of specialized cell structure and function?
उत्तर
cell differentiation
कार्ड १९१
प्रश्न
Which term describes an unspecialized self-renewing cell?
उत्तर
a stem cell
कार्ड १९२
प्रश्न
Which term describes production of a functional product from genetic information?
उत्तर
gene expression
कार्ड १९३
प्रश्न
Which term describes a group of coordinated cells with a shared function?
उत्तर
a tissue
कार्ड १९४
प्रश्न
What is an organ?
उत्तर
A structure made of multiple tissues working together for particular functions.
कार्ड १९५
प्रश्न
What is the organ-system level of biological organization?
उत्तर
A group of organs that coordinate to perform major functions for an organism.
कार्ड १९६
प्रश्न
What is surface-area-to-volume ratio?
उत्तर
The amount of surface area available relative to the volume it must serve.
कार्ड १९७
प्रश्न
How can two specialized cells have the same genome but different structures?
उत्तर
They express different sets and amounts of genes, producing different proteins and cellular features.
कार्ड १९८
प्रश्न
Which term describes a structure composed of multiple tissue types?
उत्तर
an organ
कार्ड १९९
प्रश्न
Which term describes the level of biological organization formed by coordinated organs?
उत्तर
an organ system
कार्ड २००
प्रश्न
Which term describes surface area available per unit volume?
उत्तर
surface-area-to-volume ratio
कार्ड २०१
प्रश्न
How is a mammalian red blood cell specialized for oxygen transport?
उत्तर
Its biconcave shape increases exchange area, it is flexible, and loss of its nucleus leaves more space for hemoglobin.
कार्ड २०२
प्रश्न
How is a sperm cell specialized for fertilization?
उत्तर
It has a flagellum for movement, many mitochondria for ATP, a haploid nucleus, and an acrosome containing enzymes.
कार्ड २०३
प्रश्न
How is a neuron specialized for rapid communication?
उत्तर
Long processes carry signals over distance, branching dendrites receive inputs, and synaptic terminals transmit signals to other cells.
कार्ड २०४
प्रश्न
How is a root hair cell specialized for mineral and water uptake?
उत्तर
Its long projection increases surface area, its thin wall shortens the pathway, and membrane transport proteins take up ions.
कार्ड २०५
प्रश्न
How is a palisade mesophyll cell specialized for photosynthesis?
उत्तर
It contains many chloroplasts and is positioned near the upper leaf surface where light is strongest.
कार्ड २०६
प्रश्न
How do ciliated epithelial cells help protect airways?
उत्तर
Their cilia move mucus containing trapped particles and microbes toward the throat.
कार्ड २०७
प्रश्न
Why can extreme specialization reduce a cell's independence?
उत्तर
Resources and structures are committed to a narrow role, so the cell depends on other cells for functions it no longer performs well.
कार्ड २०८
प्रश्न
What is water potential?
उत्तर
The potential energy of water per unit volume relative to pure water, used to predict the direction of water movement.
कार्ड २०९
प्रश्न
What is solute potential?
उत्तर
The negative contribution of dissolved solutes to water potential.
कार्ड २१०
प्रश्न
What is pressure potential?
उत्तर
The contribution of physical pressure to water potential.
कार्ड २११
प्रश्न
What is turgor pressure?
उत्तर
Outward pressure of a plant-cell interior against its cell wall after water uptake.
कार्ड २१२
प्रश्न
Which term describes the tendency of water to move relative to pure water?
उत्तर
water potential
कार्ड २१३
प्रश्न
Which term describes the water-potential component lowered by dissolved solutes?
उत्तर
solute potential
कार्ड २१४
प्रश्न
Which term describes the water-potential component caused by physical pressure?
उत्तर
pressure potential
कार्ड २१५
प्रश्न
Which term describes pressure of plant-cell contents against the wall?
उत्तर
turgor pressure
कार्ड २१६
प्रश्न
What is plasmolysis?
उत्तर
Separation of the plasma membrane from the cell wall after a plant cell loses water.
कार्ड २१७
प्रश्न
What is a flaccid plant cell?
उत्तर
A plant cell with insufficient turgor pressure to be firm.
कार्ड २१८
प्रश्न
What is an isotonic condition?
उत्तर
A condition in which two solutions have equal effective water potential and no net water movement occurs.
कार्ड २१९
प्रश्न
In which direction does water move across a permeable membrane?
उत्तर
From higher water potential to lower water potential.
कार्ड २२०
प्रश्न
Which term describes membrane separation from the plant cell wall after water loss?
उत्तर
plasmolysis
कार्ड २२१
प्रश्न
Which term describes a plant cell lacking firm turgor?
उत्तर
a flaccid plant cell
कार्ड २२२
प्रश्न
Which term describes equal effective water potential across a membrane?
उत्तर
an isotonic condition
कार्ड २२३
प्रश्न
What is the water potential of pure water at standard pressure?
उत्तर
Zero; adding solute makes water potential more negative.
कार्ड २२४
प्रश्न
How are water potential, solute potential, and pressure potential related?
उत्तर
Water potential equals solute potential plus pressure potential: Ψ = Ψs + Ψp.
कार्ड २२५
प्रश्न
Why does a plant cell usually become turgid rather than burst in a hypotonic solution?
उत्तर
Water entry raises pressure potential, while the rigid cell wall resists further expansion.
कार्ड २२६
प्रश्न
What happens to a plant cell placed in a solution with much lower water potential?
उत्तर
Water leaves the cell, turgor falls, and severe loss can cause plasmolysis.
कार्ड २२७
प्रश्न
Can two solutions have different solute concentrations but equal water potential?
उत्तर
Yes. A difference in pressure potential can offset a difference in solute potential.
कार्ड २२८
प्रश्न
What is an enzyme?
उत्तर
A biological catalyst that increases reaction rate without being consumed.
कार्ड २२९
प्रश्न
What is an active site?
उत्तर
The region of an enzyme where substrate binds and catalysis occurs.
कार्ड २३०
प्रश्न
What is a substrate?
उत्तर
A reactant molecule on which an enzyme acts.
कार्ड २३१
प्रश्न
What is activation energy?
उत्तर
The minimum energy input needed for a reaction to begin.
कार्ड २३२
प्रश्न
Which term describes a biological catalyst?
उत्तर
an enzyme
कार्ड २३३
प्रश्न
Which term describes the substrate-binding catalytic region of an enzyme?
उत्तर
an active site
कार्ड २३४
प्रश्न
Which term describes a reactant bound and changed by an enzyme?
उत्तर
a substrate
कार्ड २३५
प्रश्न
Which term describes the energy barrier that must be overcome for a reaction?
उत्तर
activation energy
कार्ड २३६
प्रश्न
What is the induced-fit model?
उत्तर
The model in which substrate binding changes active-site shape to improve catalytic interactions.
कार्ड २३७
प्रश्न
What is enzyme denaturation?
उत्तर
Loss of the active three-dimensional shape of an enzyme, usually causing loss of activity.
कार्ड २३८
प्रश्न
What is competitive inhibition?
उत्तर
Inhibition caused by a molecule competing with substrate for the active site.
कार्ड २३९
प्रश्न
What is noncompetitive inhibition?
उत्तर
Inhibition caused by binding away from the active site and reducing catalytic function.
कार्ड २४०
प्रश्न
Which term describes the model where substrate binding reshapes the active site?
उत्तर
the induced-fit model
कार्ड २४१
प्रश्न
Which term describes loss of an enzyme's functional shape?
उत्तर
enzyme denaturation
कार्ड २४२
प्रश्न
Which term describes inhibition by active-site competition?
उत्तर
competitive inhibition
कार्ड २४३
प्रश्न
Which term describes inhibition by binding outside the active site?
उत्तर
noncompetitive inhibition
कार्ड २४४
प्रश्न
What is an enzyme optimum?
उत्तर
The condition, such as temperature or pH, at which an enzyme's activity is highest.
कार्ड २४५
प्रश्न
What is feedback inhibition?
उत्तर
Control in which a pathway product inhibits an enzyme acting earlier in the pathway.
कार्ड २४६
प्रश्न
How does an enzyme increase reaction rate?
उत्तर
It stabilizes the transition state and provides a pathway with lower activation energy.
कार्ड २४७
प्रश्न
Why does enzyme activity often rise and then fall as temperature increases?
उत्तर
Molecular collisions initially increase, but excessive heat disrupts enzyme shape and denatures the active site.
कार्ड २४८
प्रश्न
Which term describes the condition producing maximum enzyme activity?
उत्तर
an enzyme optimum
कार्ड २४९
प्रश्न
Which term describes pathway control by inhibition from an end product?
उत्तर
feedback inhibition
कार्ड २५०
प्रश्न
Why does each enzyme have a characteristic pH range?
उत्तर
pH changes the ionization of amino-acid side chains, affecting active-site shape and chemical interactions.
कार्ड २५१
प्रश्न
Why does increasing substrate concentration eventually stop increasing enzyme rate?
उत्तर
At saturation, nearly all active sites are occupied and enzyme concentration limits the maximum rate.
कार्ड २५२
प्रश्न
How does increasing enzyme concentration affect rate when substrate is abundant?
उत्तर
More active sites are available, so the initial rate increases roughly in proportion to enzyme concentration.
कार्ड २५३
प्रश्न
What gives an enzyme substrate specificity?
उत्तर
The active site's shape, charge, polarity, and chemical groups complement particular substrates and transition states.
कार्ड २५४
प्रश्न
What is one practical advantage of immobilizing an enzyme?
उत्तर
The enzyme can be separated from products and reused while conditions around it are controlled.
कार्ड २५५
प्रश्न
Does an enzyme change a reaction's equilibrium position?
उत्तर
No. It speeds forward and reverse reactions but does not change the equilibrium constant or final equilibrium position.
कार्ड २५६
प्रश्न
How can high substrate concentration reduce competitive inhibition?
उत्तर
More substrate molecules increase the chance that substrate rather than inhibitor occupies the active site.
कार्ड २५७
प्रश्न
Why are metabolic reactions commonly organized into pathways?
उत्तर
A sequence of enzyme-controlled steps allows energy changes and intermediates to be controlled and coupled.
कार्ड २५८
प्रश्न
What is ATP?
उत्तर
A nucleotide that transfers usable energy through coupling of its hydrolysis to cellular processes.
कार्ड २५९
प्रश्न
What is cellular respiration?
उत्तर
Controlled release of energy from organic molecules to produce ATP.
कार्ड २६०
प्रश्न
What is glycolysis?
उत्तर
A cytosolic pathway that splits glucose into two pyruvate molecules and yields a small amount of ATP and reduced electron carriers.
कार्ड २६१
प्रश्न
What is pyruvate?
उत्तर
The three-carbon product of glycolysis that can enter aerobic or anaerobic pathways.
कार्ड २६२
प्रश्न
Which term describes the cell's immediate phosphoryl-group energy carrier?
उत्तर
ATP
कार्ड २६३
प्रश्न
Which term describes controlled ATP-producing breakdown of organic molecules?
उत्तर
cellular respiration
कार्ड २६४
प्रश्न
Which term describes the cytosolic splitting of glucose into pyruvate?
उत्तर
glycolysis
कार्ड २६५
प्रश्न
Which term describes the three-carbon product of glycolysis?
उत्तर
pyruvate
कार्ड २६६
प्रश्न
What is aerobic respiration?
उत्तर
Respiration that uses oxygen as the final electron acceptor and produces much more ATP than fermentation.
कार्ड २६७
प्रश्न
What is anaerobic metabolism?
उत्तर
ATP-producing metabolism that proceeds without oxygen.
कार्ड २६८
प्रश्न
What is fermentation?
उत्तर
An anaerobic pathway that regenerates oxidized electron carriers so glycolysis can continue.
कार्ड २६९
प्रश्न
What is oxidation?
उत्तर
Loss of electrons, often accompanied in biology by loss of hydrogen or gain of oxygen.
कार्ड २७०
प्रश्न
Which term describes respiration using oxygen as final electron acceptor?
उत्तर
aerobic respiration
कार्ड २७१
प्रश्न
Which term describes ATP-producing metabolism without oxygen?
उत्तर
anaerobic metabolism
कार्ड २७२
प्रश्न
Which term describes anaerobic regeneration of electron carriers after glycolysis?
उत्तर
fermentation
कार्ड २७३
प्रश्न
Which term describes loss of electrons?
उत्तर
oxidation
कार्ड २७४
प्रश्न
What is reduction?
उत्तर
Gain of electrons, often accompanied in biology by gain of hydrogen or loss of oxygen.
कार्ड २७५
प्रश्न
What is a reduced electron carrier?
उत्तर
A molecule such as NADH that carries high-energy electrons and hydrogen from one reaction to another.
कार्ड २७६
प्रश्न
What is chemiosmosis?
उत्तर
ATP production driven by ions moving down an electrochemical gradient through ATP synthase.
कार्ड २७७
प्रश्न
What is the overall word equation for aerobic respiration of glucose?
उत्तर
Glucose + oxygen → carbon dioxide + water + energy transferred to ATP and heat.
कार्ड २७८
प्रश्न
Which term describes gain of electrons?
उत्तर
reduction
कार्ड २७९
प्रश्न
Which term describes a molecule carrying high-energy electrons between reactions?
उत्तर
a reduced electron carrier
कार्ड २८०
प्रश्न
Which term describes ATP production powered by an ion gradient?
उत्तर
chemiosmosis
कार्ड २८१
प्रश्न
Where does glycolysis occur?
उत्तर
In the cytosol.
कार्ड २८२
प्रश्न
What major stages of aerobic respiration occur in mitochondria?
उत्तर
Pyruvate oxidation and the citric acid cycle occur in the matrix; electron transport and chemiosmosis occur at the inner membrane.
कार्ड २८३
प्रश्न
What is oxygen's direct role in aerobic respiration?
उत्तर
It accepts electrons and hydrogen ions at the end of the electron transport chain, forming water.
कार्ड २८४
प्रश्न
Why does aerobic respiration yield much more ATP per glucose than fermentation?
उत्तर
It transfers electrons through an electron transport chain and uses oxidative phosphorylation, extracting far more of glucose's energy.
कार्ड २८५
प्रश्न
What is the purpose of lactate formation in oxygen-limited animal cells?
उत्तर
It regenerates NAD⁺ so glycolysis can continue producing a small amount of ATP.
कार्ड २८६
प्रश्न
What products are formed during alcoholic fermentation in yeast?
उत्तर
Ethanol and carbon dioxide, while NAD⁺ is regenerated.
कार्ड २८७
प्रश्न
Why is some energy released by respiration transferred as heat rather than captured in ATP?
उत्तर
Energy conversions are not fully efficient, so part of the chemical energy becomes disordered molecular motion.
कार्ड २८८
प्रश्न
What is substrate-level phosphorylation?
उत्तर
Direct transfer of a phosphate group from a metabolic intermediate to ADP to form ATP.
कार्ड २८९
प्रश्न
How does electron transport lead to ATP synthesis in mitochondria?
उत्तर
Electron energy pumps protons across the inner membrane; proton flow back through ATP synthase drives ATP formation.
कार्ड २९०
प्रश्न
Why can intense exercise increase lactate production?
उत्तर
ATP demand can exceed oxygen delivery and aerobic capacity, so cells regenerate NAD⁺ through lactate formation to sustain glycolysis.
कार्ड २९१
प्रश्न
What is photosynthesis?
उत्तर
Conversion of light energy into chemical energy used to synthesize organic molecules from carbon dioxide.
कार्ड २९२
प्रश्न
What is chlorophyll?
उत्तर
A green pigment that absorbs light energy for photosynthesis.
कार्ड २९३
प्रश्न
What is an absorption spectrum?
उत्तर
A graph showing how strongly a pigment absorbs different wavelengths of light.
कार्ड २९४
प्रश्न
What is an action spectrum?
उत्तर
A graph showing the rate or effectiveness of photosynthesis at different wavelengths.
कार्ड २९५
प्रश्न
Which term describes light-driven synthesis of organic molecules from carbon dioxide?
उत्तर
photosynthesis
कार्ड २९६
प्रश्न
Which term describes the principal green photosynthetic pigment?
उत्तर
chlorophyll
कार्ड २९७
प्रश्न
Which term describes a graph of pigment absorption versus wavelength?
उत्तर
an absorption spectrum
कार्ड २९८
प्रश्न
Which term describes a graph of photosynthetic effectiveness versus wavelength?
उत्तर
an action spectrum
कार्ड २९९
प्रश्न
What is photolysis of water?
उत्तर
Light-driven splitting of water that supplies electrons and hydrogen ions and releases oxygen.
कार्ड ३००
प्रश्न
What are light-dependent reactions?
उत्तर
Photosynthetic reactions that use light to generate ATP and reduced electron carriers while releasing oxygen.
कार्ड ३०१
प्रश्न
What is the Calvin cycle?
उत्तर
A set of chloroplast reactions that uses ATP and reduced electron carriers to convert carbon dioxide into carbohydrate precursors.
कार्ड ३०२
प्रश्न
What is carbon fixation?
उत्तर
Incorporation of inorganic carbon dioxide into an organic molecule.
कार्ड ३०३
प्रश्न
Which term describes light-driven splitting of water?
उत्तर
photolysis of water
कार्ड ३०४
प्रश्न
Which term describes photosynthetic reactions that directly capture light energy?
उत्तर
light-dependent reactions
कार्ड ३०५
प्रश्न
Which term describes the carbon-reduction cycle of photosynthesis?
उत्तर
the Calvin cycle
कार्ड ३०६
प्रश्न
Which term describes incorporation of carbon dioxide into organic matter?
उत्तर
carbon fixation
कार्ड ३०७
प्रश्न
What is the role of a stoma in photosynthesis?
उत्तर
A pore in the leaf epidermis that regulates carbon-dioxide entry as well as water loss.
कार्ड ३०८
प्रश्न
What is a limiting factor of photosynthesis?
उत्तर
The environmental factor whose availability currently restricts the photosynthetic rate.
कार्ड ३०९
प्रश्न
What is the light compensation point?
उत्तर
The light intensity at which photosynthetic carbon uptake equals respiratory carbon release.
कार्ड ३१०
प्रश्न
What is the overall word equation for oxygenic photosynthesis?
उत्तर
Carbon dioxide + water → carbohydrate + oxygen, using light energy.
कार्ड ३११
प्रश्न
Which term describes the regulated leaf pore controlling carbon-dioxide entry for photosynthesis?
उत्तर
a stoma
कार्ड ३१२
प्रश्न
Which term describes the factor currently restricting photosynthetic rate?
उत्तर
a limiting factor
कार्ड ३१३
प्रश्न
Which term describes the light level where photosynthesis and respiration balance?
उत्तर
the light compensation point
कार्ड ३१४
प्रश्न
Where do the main stages of photosynthesis occur in a chloroplast?
उत्तर
Light-dependent reactions occur in thylakoid membranes; carbon-fixation reactions occur in the stroma.
कार्ड ३१५
प्रश्न
What energy conversion occurs during photosynthesis?
उत्तर
Light energy is converted into chemical energy stored first in ATP and reduced carriers and ultimately in organic molecules.
कार्ड ३१६
प्रश्न
From which reactant does the oxygen released by photosynthesis originate?
उत्तर
Water.
कार्ड ३१७
प्रश्न
What role does RuBisCO play in photosynthesis?
उत्तर
It catalyzes fixation of carbon dioxide by adding it to an organic acceptor molecule.
कार्ड ३१८
प्रश्न
What tradeoff is controlled when stomata open?
उत्तर
Opening permits carbon dioxide entry but increases water loss by transpiration.
कार्ड ३१९
प्रश्न
Name three leaf features that support photosynthesis.
उत्तर
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.
कार्ड ३२०
प्रश्न
What can a plant do with carbohydrate made by photosynthesis?
उत्तर
Use it in respiration, convert it to storage or structural carbohydrates, or use its carbon to make lipids, amino acids, and other molecules.
कार्ड ३२१
प्रश्न
How are products of the light-dependent reactions used in carbon fixation?
उत्तर
ATP supplies energy and NADPH supplies reducing power for conversion of fixed carbon into carbohydrate precursors.
कार्ड ३२२
प्रश्न
Why does increasing light intensity eventually stop increasing photosynthetic rate?
उत्तर
Another factor, such as carbon dioxide supply, temperature, or biochemical capacity, becomes limiting.
कार्ड ३२३
प्रश्न
How can increasing carbon dioxide concentration affect photosynthetic rate?
उत्तर
It can increase the rate until another factor becomes limiting.
कार्ड ३२४
प्रश्न
Why does photosynthetic rate usually have a temperature optimum?
उत्तर
Enzyme-controlled reactions accelerate with temperature up to an optimum, then decline as enzymes and membranes lose effective function.
कार्ड ३२५
प्रश्न
Why does an action spectrum broadly resemble the combined absorption spectra of photosynthetic pigments?
उत्तर
Wavelengths absorbed by the pigments supply more energy for photosynthesis than poorly absorbed wavelengths.
कार्ड ३२६
प्रश्न
What is semiconservative replication?
उत्तर
DNA replication in which each daughter molecule contains one parental strand and one newly synthesized strand.
कार्ड ३२७
प्रश्न
What is DNA helicase?
उत्तर
An enzyme that unwinds the double helix and separates the strands by disrupting base pairing.
कार्ड ३२८
प्रश्न
What is DNA polymerase?
उत्तर
An enzyme that adds nucleotides to a growing DNA strand using a template.
कार्ड ३२९
प्रश्न
What is a primer?
उत्तर
A short nucleic-acid segment providing a free 3′ end from which DNA polymerase can extend.
कार्ड ३३०
प्रश्न
Which term describes replication producing one old and one new strand per DNA molecule?
उत्तर
semiconservative replication
कार्ड ३३१
प्रश्न
Which term describes the enzyme that separates DNA strands?
उत्तर
DNA helicase
कार्ड ३३२
प्रश्न
Which term describes the enzyme that builds DNA from a template?
उत्तर
DNA polymerase
कार्ड ३३३
प्रश्न
Which term describes the short segment providing a starting 3′ end?
उत्तर
a primer
कार्ड ३३४
प्रश्न
What is the leading strand?
उत्तर
The new DNA strand synthesized continuously toward the replication fork.
कार्ड ३३५
प्रश्न
What is the lagging strand?
उत्तर
The new DNA strand synthesized discontinuously away from the replication fork.
कार्ड ३३६
प्रश्न
What is an Okazaki fragment?
उत्तर
A short DNA segment synthesized on the lagging strand.
कार्ड ३३७
प्रश्न
What is DNA ligase?
उत्तर
An enzyme that seals breaks in the sugar-phosphate backbone, joining DNA fragments.
कार्ड ३३८
प्रश्न
Which term describes the continuously synthesized daughter strand?
उत्तर
the leading strand
कार्ड ३३९
प्रश्न
Which term describes the discontinuously synthesized daughter strand?
उत्तर
the lagging strand
कार्ड ३४०
प्रश्न
Which term describes a short newly made segment of lagging-strand DNA?
उत्तर
an Okazaki fragment
कार्ड ३४१
प्रश्न
Which term describes the enzyme that joins DNA fragments by sealing the backbone?
उत्तर
DNA ligase
कार्ड ३४२
प्रश्न
How does complementary base pairing ensure accurate DNA copying?
उत्तर
Each template base specifies the nucleotide added opposite it: A pairs with T, and C pairs with G.
कार्ड ३४३
प्रश्न
Why does DNA polymerase synthesize DNA only 5′ to 3′?
उत्तर
It can add a nucleotide only to the free 3′ hydroxyl group of the growing strand.
कार्ड ३४४
प्रश्न
When in the cell cycle is nuclear DNA replicated?
उत्तर
During S phase of interphase, before cell division.
कार्ड ३४५
प्रश्न
How can a replication error become a permanent mutation?
उत्तर
If it escapes proofreading and repair, the altered sequence can be copied in later cell generations.
कार्ड ३४६
प्रश्न
Why are leading and lagging strands synthesized differently?
उत्तर
The templates are antiparallel while DNA polymerase works only 5′ to 3′, forcing one strand to be made discontinuously.
कार्ड ३४७
प्रश्न
How do proofreading and repair reduce replication errors?
उत्तर
Incorrectly paired nucleotides are recognized, removed, and replaced before or after replication continues.
कार्ड ३४८
प्रश्न
What three repeating steps amplify DNA in PCR?
उत्तर
Strand separation by heating, primer annealing during cooling, and DNA extension by a heat-stable polymerase.
कार्ड ३४९
प्रश्न
What determines which DNA region PCR amplifies?
उत्तर
The sequences and positions of the two primers flanking the target region.
कार्ड ३५०
प्रश्न
What is transcription?
उत्तर
Synthesis of RNA from a DNA template.
कार्ड ३५१
प्रश्न
What is RNA polymerase?
उत्तर
The enzyme that synthesizes RNA complementary to a DNA template strand.
कार्ड ३५२
प्रश्न
What is messenger RNA?
उत्तर
RNA carrying a coding sequence from DNA to ribosomes.
कार्ड ३५३
प्रश्न
What is a codon?
उत्तर
A three-base sequence in mRNA that specifies an amino acid or a translation signal.
कार्ड ३५४
प्रश्न
Which term describes RNA synthesis from DNA?
उत्तर
transcription
कार्ड ३५५
प्रश्न
Which term describes the enzyme that builds RNA from a DNA template?
उत्तर
RNA polymerase
कार्ड ३५६
प्रश्न
Which term describes RNA that carries coding information to ribosomes?
उत्तर
messenger RNA
कार्ड ३५७
प्रश्न
Which term describes a three-base mRNA unit?
उत्तर
a codon
कार्ड ३५८
प्रश्न
What is translation?
उत्तर
Synthesis of a polypeptide using the codon sequence of mRNA.
कार्ड ३५९
प्रश्न
What does a ribosome do during translation?
उत्तर
It reads mRNA and catalyzes polypeptide synthesis using its rRNA-protein machinery.
कार्ड ३६०
प्रश्न
What is transfer RNA?
उत्तर
RNA that carries a specific amino acid and pairs its anticodon with an mRNA codon.
कार्ड ३६१
प्रश्न
What is an anticodon?
उत्तर
A three-base tRNA sequence complementary to an mRNA codon.
कार्ड ३६२
प्रश्न
Which term describes polypeptide synthesis from an mRNA sequence?
उत्तर
translation
कार्ड ३६३
प्रश्न
Which term describes the translation complex that reads mRNA and builds a polypeptide?
उत्तर
a ribosome
कार्ड ३६४
प्रश्न
Which term describes the adaptor RNA carrying an amino acid?
उत्तर
transfer RNA
कार्ड ३६५
प्रश्न
Which term describes the tRNA triplet that pairs with a codon?
उत्तर
an anticodon
कार्ड ३६६
प्रश्न
What is the genetic code?
उत्तर
The set of rules relating mRNA codons to amino acids and translation signals.
कार्ड ३६७
प्रश्न
What are start and stop codons?
उत्तर
mRNA signals that establish the reading frame or terminate translation.
कार्ड ३६८
प्रश्न
Where do transcription and translation occur in a eukaryotic cell?
उत्तर
Transcription occurs in the nucleus; translation occurs on ribosomes in the cytoplasm or on rough ER.
कार्ड ३६९
प्रश्न
How is an mRNA sequence related to its DNA template strand?
उत्तर
It is complementary and antiparallel, with uracil in RNA opposite adenine in DNA.
कार्ड ३७०
प्रश्न
Which term describes the codon-to-amino-acid rule set?
उत्तर
the genetic code
कार्ड ३७१
प्रश्न
Which term describes codons that begin or end translation?
उत्तर
start and stop codons
कार्ड ३७२
प्रश्न
What reaction does the ribosome catalyze as a polypeptide grows?
उत्तर
Formation of peptide bonds between adjacent amino acids.
कार्ड ३७३
प्रश्न
What does it mean that the genetic code is degenerate?
उत्तर
Most amino acids are specified by more than one codon.
कार्ड ३७४
प्रश्न
How can one mRNA produce many polypeptides quickly?
उत्तर
Multiple ribosomes can translate the same mRNA simultaneously as a polyribosome.
कार्ड ३७५
प्रश्न
Why is translation not the final step in producing many functional proteins?
उत्तर
The polypeptide must fold and may undergo cleavage, chemical modification, or assembly with other subunits.
कार्ड ३७६
प्रश्न
How does mRNA compare with the DNA coding strand?
उत्तर
It has the same base sequence except that RNA contains uracil where DNA contains thymine.
कार्ड ३७७
प्रश्न
What happens during eukaryotic RNA splicing?
उत्तर
Introns are removed and exons are joined to form mature mRNA.
कार्ड ३७८
प्रश्न
Why must codons be read in the correct reading frame?
उत्तर
Changing the starting position changes every downstream triplet and therefore the amino-acid sequence.
कार्ड ३७९
प्रश्न
How is the correct amino acid matched to each mRNA codon?
उत्तर
Each tRNA is charged with a particular amino acid, and its anticodon pairs with the complementary codon.
कार्ड ३८०
प्रश्न
How can a base substitution affect a protein?
उत्तर
It may be silent, change one amino acid, create a stop codon, or sometimes alter RNA processing.
कार्ड ३८१
प्रश्न
What is a mutation?
उत्तर
A change in a DNA sequence or chromosome structure that can be passed to daughter cells.
कार्ड ३८२
प्रश्न
What is a base substitution?
उत्तर
Replacement of one nucleotide pair by another.
कार्ड ३८३
प्रश्न
What is an insertion mutation?
उत्तर
Addition of one or more nucleotides to a DNA sequence.
कार्ड ३८४
प्रश्न
What is a deletion mutation?
उत्तर
Loss of one or more nucleotides from a DNA sequence.
कार्ड ३८५
प्रश्न
Which term describes a lasting DNA-sequence or chromosome change?
उत्तर
a mutation
कार्ड ३८६
प्रश्न
Which term describes replacement of one DNA base pair?
उत्तर
a base substitution
कार्ड ३८७
प्रश्न
Which term describes addition of nucleotides to DNA?
उत्तर
an insertion mutation
कार्ड ३८८
प्रश्न
Which term describes loss of nucleotides from DNA?
उत्तर
a deletion mutation
कार्ड ३८९
प्रश्न
What is a frameshift mutation?
उत्तर
A coding-sequence insertion or deletion not divisible by three that changes downstream codon grouping.
कार्ड ३९०
प्रश्न
What is a silent mutation?
उत्तर
A sequence change that does not alter the encoded amino acid.
कार्ड ३९१
प्रश्न
What is a missense mutation?
उत्तर
A mutation that changes a codon so a different amino acid is incorporated.
कार्ड ३९२
प्रश्न
What is a nonsense mutation?
उत्तर
A mutation that changes an amino-acid codon into a stop codon.
कार्ड ३९३
प्रश्न
Which term describes a mutation that shifts downstream codon grouping?
उत्तर
a frameshift mutation
कार्ड ३९४
प्रश्न
Which term describes a coding change that leaves the amino acid unchanged?
उत्तर
a silent mutation
कार्ड ३९५
प्रश्न
Which term describes a mutation causing one amino-acid substitution?
उत्तर
a missense mutation
कार्ड ३९६
प्रश्न
Which term describes a mutation creating a premature stop codon?
उत्तर
a nonsense mutation
कार्ड ३९७
प्रश्न
How do germline and somatic mutations differ in inheritance?
उत्तर
Germline mutations can enter gametes and be inherited; somatic mutations affect a cell lineage within the individual.
कार्ड ३९८
प्रश्न
What can cause mutations?
उत्तर
Replication errors, spontaneous chemical changes, radiation, and mutagenic chemicals can alter DNA.
कार्ड ३९९
प्रश्न
How does DNA repair protect genome stability?
उत्तर
Repair systems detect damaged or mismatched DNA and restore the correct structure or sequence when possible.
कार्ड ४००
प्रश्न
Why are mutations essential to evolution despite often being neutral or harmful?
उत्तर
They create new alleles, providing the heritable variation on which selection and drift act.
कार्ड ४०१
प्रश्न
What is the basic role of guide RNA in CRISPR gene editing?
उत्तर
It directs a nuclease to a complementary DNA sequence.
कार्ड ४०२
प्रश्न
Why can the same type of DNA mutation have effects ranging from none to severe?
उत्तर
Effects depend on location, genetic-code redundancy, protein role, cell type, and environmental context.
कार्ड ४०३
प्रश्न
How can accumulated mutations contribute to cancer?
उत्तर
Mutations can activate growth-promoting genes or disable genes that restrain division, repair DNA, or trigger cell death.
कार्ड ४०४
प्रश्न
Why can repairing a CRISPR-induced DNA break produce different editing outcomes?
उत्तर
Different cellular repair pathways may disrupt the target sequence or use a supplied template for a specific change.
कार्ड ४०५
प्रश्न
What is an off-target effect in gene editing?
उत्तर
An unintended DNA change at a site sufficiently similar to the intended target.
कार्ड ४०६
प्रश्न
Why does heritable human genome editing raise additional ethical concerns?
उत्तर
Changes could pass to future generations who cannot consent, with uncertain long-term biological and social effects.
कार्ड ४०७
प्रश्न
What is the cell cycle?
उत्तर
The ordered sequence of cell growth, DNA replication, nuclear division, and cell division.
कार्ड ४०८
प्रश्न
What is interphase?
उत्तर
The period of growth, normal activity, and DNA replication between nuclear divisions.
कार्ड ४०९
प्रश्न
What is mitosis?
उत्तर
Nuclear division that usually produces genetically equivalent daughter nuclei.
कार्ड ४१०
प्रश्न
What is cytokinesis?
उत्तर
Division of the cytoplasm to form separate daughter cells.
कार्ड ४११
प्रश्न
Which term describes the ordered sequence from one cell division to the next?
उत्तर
the cell cycle
कार्ड ४१२
प्रश्न
Which term describes the growth and DNA-replication period between divisions?
उत्तर
interphase
कार्ड ४१३
प्रश्न
Which term describes division producing genetically equivalent nuclei?
उत्तर
mitosis
कार्ड ४१४
प्रश्न
Which term describes physical division of the cytoplasm?
उत्तर
cytokinesis
कार्ड ४१५
प्रश्न
What is a chromosome?
उत्तर
One DNA molecule packaged with associated proteins.
कार्ड ४१६
प्रश्न
What are sister chromatids?
उत्तर
The two replicated copies of a chromosome joined before separation.
कार्ड ४१७
प्रश्न
What is a centromere?
उत्तर
The chromosome region that holds sister chromatids together and organizes kinetochore attachment.
कार्ड ४१८
प्रश्न
What is the mitotic spindle?
उत्तर
A microtubule system that attaches to and separates chromosomes during cell division.
कार्ड ४१९
प्रश्न
Which term describes a protein-packaged DNA molecule?
उत्तर
a chromosome
कार्ड ४२०
प्रश्न
Which term describes joined replicated copies of one chromosome?
उत्तर
sister chromatids
कार्ड ४२१
प्रश्न
Which term describes the chromosome region joining sister chromatids?
उत्तर
a centromere
कार्ड ४२२
प्रश्न
Which term describes the chromosome-separating microtubule system?
उत्तर
the mitotic spindle
कार्ड ४२३
प्रश्न
What is the basic sequence of mitosis?
उत्तर
Chromosomes condense, align at the cell equator, sister chromatids separate to opposite poles, and new nuclei form.
कार्ड ४२४
प्रश्न
Why must DNA replicate before mitosis?
उत्तर
Each chromosome must have two copies so each daughter nucleus can receive a complete genome.
कार्ड ४२५
प्रश्न
Why are daughter cells from mitosis usually genetically similar?
उत्तर
Replicated sister chromatids are separated so each daughter receives one copy of every chromosome.
कार्ड ४२६
प्रश्न
What are major roles of mitosis in multicellular organisms?
उत्तर
Growth, tissue repair, cell replacement, and some forms of asexual reproduction.
कार्ड ४२७
प्रश्न
How do homologous chromosomes differ from sister chromatids?
उत्तर
Homologs carry the same gene loci but may have different alleles; sister chromatids are replicated copies of one chromosome.
कार्ड ४२८
प्रश्न
What key outcome distinguishes mitosis from meiosis?
उत्तर
Mitosis usually preserves chromosome number and similarity; meiosis halves chromosome number and generates genetically varied haploid cells.
कार्ड ४२९
प्रश्न
How does cytokinesis commonly occur in animal cells?
उत्तर
A contractile ring tightens the plasma membrane into a cleavage furrow.
कार्ड ४३०
प्रश्न
How does cytokinesis commonly occur in plant cells?
उत्तर
Vesicles fuse at the center to form a cell plate that develops into new membranes and a cell wall.
कार्ड ४३१
प्रश्न
What is the purpose of cell-cycle checkpoints?
उत्तर
They delay progression when conditions are unsuitable or DNA and chromosome attachment are defective.
कार्ड ४३२
प्रश्न
How is loss of cell-cycle control related to cancer?
उत्तर
Cells can divide despite damage or growth restraints, producing an expanding abnormal clone.
कार्ड ४३३
प्रश्न
What is a gene?
उत्तर
A DNA sequence that contributes to a functional product and influences a characteristic or cellular process.
कार्ड ४३४
प्रश्न
What is an allele?
उत्तर
One of the alternative DNA-sequence forms at a gene locus.
कार्ड ४३५
प्रश्न
What is a gene locus?
उत्तर
The physical position of a gene on a chromosome.
कार्ड ४३६
प्रश्न
What is a genotype?
उत्तर
The allele combination of an organism at one or more loci.
कार्ड ४३७
प्रश्न
Which term describes a functional DNA sequence?
उत्तर
a gene
कार्ड ४३८
प्रश्न
Which term describes an alternative form of a gene?
उत्तर
an allele
कार्ड ४३९
प्रश्न
Which term describes a gene's chromosome position?
उत्तर
a gene locus
कार्ड ४४०
प्रश्न
Which term describes an organism's allele combination?
उत्तर
a genotype
कार्ड ४४१
प्रश्न
What is a phenotype?
उत्तर
An observable or measurable trait produced by genotype and environment.
कार्ड ४४२
प्रश्न
What is homozygous?
उत्तर
Having two identical alleles at a diploid locus.
कार्ड ४४३
प्रश्न
What is heterozygous?
उत्तर
Having two different alleles at a diploid locus.
कार्ड ४४४
प्रश्न
What is a dominant allele?
उत्तर
An allele expressed in the phenotype of a heterozygote under a specified inheritance model.
कार्ड ४४५
प्रश्न
Which term describes an observable trait resulting from genes and environment?
उत्तर
a phenotype
कार्ड ४४६
प्रश्न
Which term describes having two identical alleles at a locus?
उत्तर
homozygous
कार्ड ४४७
प्रश्न
Which term describes having two different alleles at a locus?
उत्तर
heterozygous
कार्ड ४४८
प्रश्न
Which term describes an allele expressed in a heterozygote?
उत्तर
a dominant allele
कार्ड ४४९
प्रश्न
What is a recessive allele?
उत्तर
An allele whose phenotype is masked by a dominant allele in a heterozygote.
कार्ड ४५०
प्रश्न
What is a genetic carrier?
उत्तर
An unaffected heterozygote who can transmit a recessive disease allele.
कार्ड ४५१
प्रश्न
What is a test cross?
उत्तर
A cross with a homozygous recessive individual used to infer an unknown dominant phenotype's genotype.
कार्ड ४५२
प्रश्न
What is a pedigree?
उत्तर
A diagram showing biological relationships and occurrence of a trait across generations.
कार्ड ४५३
प्रश्न
Which term describes an allele masked in a heterozygote?
उत्तर
a recessive allele
कार्ड ४५४
प्रश्न
Which term describes an unaffected heterozygote carrying a recessive disease allele?
उत्तर
a genetic carrier
कार्ड ४५५
प्रश्न
Which term describes a cross used to reveal an unknown dominant genotype?
उत्तर
a test cross
कार्ड ४५६
प्रश्न
Which term describes a family diagram tracking a trait across generations?
उत्तर
a pedigree
कार्ड ४५७
प्रश्न
What does allele segregation mean during gamete formation?
उत्तर
The two alleles at a diploid locus separate so each gamete receives one.
कार्ड ४५८
प्रश्न
What does a Punnett square predict?
उत्तर
Expected genotype and phenotype probabilities from specified parental gametes, not guaranteed family outcomes.
कार्ड ४५९
प्रश्न
What phenotypic ratio is expected from Aa × Aa with complete dominance?
उत्तर
Approximately 3 dominant phenotype : 1 recessive phenotype.
कार्ड ४६०
प्रश्न
What genotypic ratio is expected from Aa × Aa?
उत्तर
1 AA : 2 Aa : 1 aa.
कार्ड ४६१
प्रश्न
What happens in codominance?
उत्तर
Both alleles contribute distinctly to the heterozygous phenotype.
कार्ड ४६२
प्रश्न
What happens in incomplete dominance?
उत्तर
The heterozygote has a phenotype intermediate between the two homozygotes.
कार्ड ४६३
प्रश्न
How can environment affect phenotype without changing genotype?
उत्तर
Conditions alter development, physiology, or gene expression, changing the observed trait.
कार्ड ४६४
प्रश्न
What is the ultimate source of new alleles?
उत्तर
Mutation.
कार्ड ४६५
प्रश्न
Why are X-linked recessive traits more common in XY individuals?
उत्तर
They have only one X chromosome, so one recessive allele on it can determine the phenotype.
कार्ड ४६६
प्रश्न
When is the product rule used in genetic probability?
उत्तर
For independent events that must both occur; multiply their probabilities.
कार्ड ४६७
प्रश्न
When is the sum rule used in genetic probability?
उत्तर
For mutually exclusive alternative outcomes; add their probabilities.
कार्ड ४६८
प्रश्न
Why do polygenic traits often show continuous variation?
उत्तर
Many loci contribute small effects, creating many possible genotypes and phenotypes, often further influenced by environment.
कार्ड ४६९
प्रश्न
What pedigree pattern can suggest an autosomal recessive trait?
उत्तर
Unaffected parents can have affected children, and all sexes are affected at similar frequencies.
कार्ड ४७०
प्रश्न
What is a species?
उत्तर
A group of organisms whose members can potentially interbreed and produce fertile offspring under natural conditions.
कार्ड ४७१
प्रश्न
What is binomial nomenclature?
उत्तर
The two-part scientific naming system using a genus name followed by a specific epithet.
कार्ड ४७२
प्रश्न
What is taxonomy?
उत्तर
The naming and classification of organisms.
कार्ड ४७३
प्रश्न
What is a biological domain?
उत्तर
The broadest commonly used taxonomic rank, separating Bacteria, Archaea, and Eukarya.
कार्ड ४७४
प्रश्न
Which term describes a naturally interbreeding group producing fertile offspring?
उत्तर
a species
कार्ड ४७५
प्रश्न
Which term describes the genus-plus-specific-epithet naming system?
उत्तर
binomial nomenclature
कार्ड ४७६
प्रश्न
Which term describes the science of naming and classifying organisms?
उत्तर
taxonomy
कार्ड ४७७
प्रश्न
Which term describes the broadest common taxonomic rank?
उत्तर
a biological domain
कार्ड ४७८
प्रश्न
What is biodiversity?
उत्तर
Variation of life at genetic, species, and ecosystem levels.
कार्ड ४७९
प्रश्न
What is an autotroph?
उत्तर
An organism that makes organic compounds from inorganic carbon using light or chemical energy.
कार्ड ४८०
प्रश्न
What is a heterotroph?
उत्तर
An organism that obtains organic carbon by consuming other organisms or their products.
९६० कार्डे
IB Biology SL Flashcards: Complete Course Review
हा संच मोफत अभ्यासाअभ्यास सुरू करण्यासाठी Nibomo उघडेल.
कार्ड ४८१
प्रश्न
What is a unicellular organism?
उत्तर
An organism consisting of one cell that carries out all essential life functions.
कार्ड ४८२
प्रश्न
Which term describes variation of life across genes, species, and ecosystems?
उत्तर
biodiversity
कार्ड ४८३
प्रश्न
Which term describes an organism that builds organic matter from inorganic carbon?
उत्तर
an autotroph
कार्ड ४८४
प्रश्न
Which term describes an organism obtaining organic carbon from other organisms?
उत्तर
a heterotroph
कार्ड ४८५
प्रश्न
Which term describes an organism made of one cell?
उत्तर
a unicellular organism
कार्ड ४८६
प्रश्न
What is a multicellular organism?
उत्तर
An organism composed of many cooperating cells, often with specialized cell types.
कार्ड ४८७
प्रश्न
What is a karyotype?
उत्तर
An ordered display of chromosomes used to examine their number and large-scale structure.
कार्ड ४८८
प्रश्न
What broad feature distinguishes both Bacteria and Archaea from Eukarya?
उत्तर
Their cells lack a nucleus and other membrane-bound organelles.
कार्ड ४८९
प्रश्न
What features characterize most plant cells?
उत्तर
Cellulose walls, chloroplasts in photosynthetic tissues, and large vacuoles are typical features.
कार्ड ४९०
प्रश्न
Which term describes an organism made of many cooperating cells?
उत्तर
a multicellular organism
कार्ड ४९१
प्रश्न
Which term describes an ordered display of an individual's chromosomes?
उत्तर
a karyotype
कार्ड ४९२
प्रश्न
How do fungi obtain nutrients?
उत्तर
They secrete digestive enzymes and absorb soluble products; their cells usually have chitin-containing walls.
कार्ड ४९३
प्रश्न
What distinguishes animal nutrition and cell structure?
उत्तर
Animals ingest organic material, and their cells lack cell walls and chloroplasts.
कार्ड ४९४
प्रश्न
Why are scientific names useful across languages?
उत्तर
A standardized name identifies the same organism internationally and reduces ambiguity from local common names.
कार्ड ४९५
प्रश्न
Why can genetic diversity improve a population's resilience?
उत्तर
More heritable variation increases the chance that some individuals tolerate new diseases or environmental changes.
कार्ड ४९६
प्रश्न
What does ecosystem diversity measure?
उत्तर
The variety of habitats, communities, and ecological processes within a region.
कार्ड ४९७
प्रश्न
Why are Archaea classified separately from Bacteria?
उत्तर
They differ in genetic sequences, membrane chemistry, cell-wall composition, and aspects of molecular machinery.
कार्ड ४९८
प्रश्न
Why is the biological species concept difficult to apply to fossils or asexual organisms?
उत्तर
Their ability to interbreed and produce fertile offspring cannot be tested in the usual way.
कार्ड ४९९
प्रश्न
Does a larger chromosome number necessarily mean a more complex organism?
उत्तर
No. Chromosome number varies through fusion, fission, and duplication and does not directly measure biological complexity.
कार्ड ५००
प्रश्न
Does genome size reliably predict organismal complexity?
उत्तर
No. Large amounts of noncoding and repeated DNA make genome size a poor simple measure of complexity.
कार्ड ५०१
प्रश्न
What evidence can be combined when classifying organisms?
उत्तर
Molecular sequences, cell structure, anatomy, development, physiology, and reproductive evidence can all contribute.
कार्ड ५०२
प्रश्न
What is gas exchange?
उत्तर
Diffusion of respiratory gases between an organism and its environment or transport fluid.
कार्ड ५०३
प्रश्न
What is ventilation?
उत्तर
Bulk movement of air or water over a gas-exchange surface.
कार्ड ५०४
प्रश्न
What is an alveolus?
उत्तर
A microscopic air sac in the lung where gases diffuse between air and blood.
कार्ड ५०५
प्रश्न
What is pulmonary surfactant?
उत्तर
A substance lining alveoli that lowers surface tension and reduces collapse.
कार्ड ५०६
प्रश्न
Which term describes diffusion of oxygen and carbon dioxide across a respiratory surface?
उत्तर
gas exchange
कार्ड ५०७
प्रश्न
Which term describes bulk movement of respiratory medium over an exchange surface?
उत्तर
ventilation
कार्ड ५०८
प्रश्न
Which term describes a microscopic lung air sac?
उत्तर
an alveolus
कार्ड ५०९
प्रश्न
Which term describes the alveolar lining that lowers surface tension?
उत्तर
pulmonary surfactant
कार्ड ५१०
प्रश्न
What is the diaphragm?
उत्तर
A sheet of skeletal muscle whose contraction increases thoracic volume during inhalation.
कार्ड ५११
प्रश्न
What is tidal volume?
उत्तर
The volume of air moved in or out during a normal breath.
कार्ड ५१२
प्रश्न
What is a stoma?
उत्तर
A regulated epidermal pore through which gases diffuse in leaves.
कार्ड ५१३
प्रश्न
What is countercurrent exchange?
उत्तर
Exchange between fluids moving in opposite directions, maintaining a gradient along most of the surface.
कार्ड ५१४
प्रश्न
Which term describes the muscle sheet that expands the thorax during inhalation?
उत्तर
the diaphragm
कार्ड ५१५
प्रश्न
Which term describes air volume moved in one normal breath?
उत्तर
tidal volume
कार्ड ५१६
प्रश्न
Which term describes a regulated leaf gas-exchange pore?
उत्तर
a stoma
कार्ड ५१७
प्रश्न
Which term describes opposite fluid flow that maintains an exchange gradient?
उत्तर
countercurrent exchange
कार्ड ५१८
प्रश्न
What features make an efficient gas-exchange surface?
उत्तर
Large area, short diffusion distance, permeability, and maintained concentration gradients.
कार्ड ५१९
प्रश्न
How is a steep oxygen gradient maintained across alveoli?
उत्तर
Ventilation replenishes alveolar oxygen and blood flow removes absorbed oxygen.
कार्ड ५२०
प्रश्न
How does diaphragm contraction cause inhalation?
उत्तर
Thoracic volume increases, lung pressure falls below atmospheric pressure, and air flows inward.
कार्ड ५२१
प्रश्न
What drives quiet exhalation?
उत्तर
The diaphragm relaxes and elastic recoil reduces thoracic and lung volume, raising pressure and pushing air out.
कार्ड ५२२
प्रश्न
Why do ventilation rate and depth increase during exercise?
उत्तर
They increase oxygen uptake and carbon dioxide removal to support higher cellular respiration.
कार्ड ५२३
प्रश्न
How does leaf structure shorten the pathway for carbon dioxide diffusion?
उत्तर
Stomata open into air spaces, and mesophyll cells expose moist surfaces close to those spaces.
कार्ड ५२४
प्रश्न
Why does carbon dioxide diffuse from tissues into blood?
उत्तर
Respiring cells produce carbon dioxide, making its partial pressure higher in tissues than in incoming blood.
कार्ड ५२५
प्रश्न
How does countercurrent flow improve oxygen uptake at fish gills?
उत्तर
Blood continually meets water with a higher oxygen concentration, preserving diffusion along the lamella.
कार्ड ५२६
प्रश्न
Why does closing stomata reduce both water loss and photosynthesis?
उत्तर
It limits water-vapor diffusion out but also restricts carbon dioxide diffusion into the leaf.
कार्ड ५२७
प्रश्न
What is a circulatory system?
उत्तर
A transport system that moves a fluid carrying gases, nutrients, wastes, hormones, and heat through an organism.
कार्ड ५२८
प्रश्न
What is an artery?
उत्तर
A blood vessel carrying blood away from the heart under relatively high pressure.
कार्ड ५२९
प्रश्न
What is a vein?
उत्तर
A blood vessel carrying blood toward the heart, usually with low pressure and often valves.
कार्ड ५३०
प्रश्न
What is a capillary?
उत्तर
A microscopic thin-walled vessel where substances exchange between blood and tissues.
कार्ड ५३१
प्रश्न
Which term describes an internal fluid-transport system?
उत्तर
a circulatory system
कार्ड ५३२
प्रश्न
Which term describes a vessel carrying blood away from the heart?
उत्तर
an artery
कार्ड ५३३
प्रश्न
Which term describes a vessel carrying blood toward the heart?
उत्तर
a vein
कार्ड ५३४
प्रश्न
Which term describes a microscopic exchange blood vessel?
उत्तर
a capillary
कार्ड ५३५
प्रश्न
What is the cardiac cycle?
उत्तर
The repeating sequence of heart-chamber contraction and relaxation that pumps blood.
कार्ड ५३६
प्रश्न
What is hemoglobin?
उत्तर
An iron-containing protein in red blood cells that binds oxygen reversibly.
कार्ड ५३७
प्रश्न
What is xylem?
उत्तर
Plant vascular tissue that transports water and mineral ions and provides structural support.
कार्ड ५३८
प्रश्न
What is phloem?
उत्तर
Plant vascular tissue that transports sucrose and other organic solutes between sources and sinks.
कार्ड ५३९
प्रश्न
Which term describes the repeating pumping sequence of the heart?
उत्तर
the cardiac cycle
कार्ड ५४०
प्रश्न
Which term describes the oxygen-carrying protein of red blood cells?
उत्तर
hemoglobin
कार्ड ५४१
प्रश्न
Which term describes plant tissue carrying water and minerals?
उत्तर
xylem
कार्ड ५४२
प्रश्न
Which term describes plant tissue carrying organic solutes?
उत्तर
phloem
कार्ड ५४३
प्रश्न
What is transpiration?
उत्तर
Loss of water vapor from plant surfaces, mainly through stomata.
कार्ड ५४४
प्रश्न
What is phloem translocation?
उत्तर
Movement of organic solutes through phloem from sources to sinks.
कार्ड ५४५
प्रश्न
How do a source and a sink differ in plant transport?
उत्तर
A source releases assimilates to phloem; a sink removes them for use or storage.
कार्ड ५४६
प्रश्न
What makes human circulation a double circulation?
उत्तर
Blood passes through the heart once in the pulmonary circuit and again in the systemic circuit during one complete journey.
कार्ड ५४७
प्रश्न
Which term describes water-vapor loss from plant surfaces?
उत्तर
transpiration
कार्ड ५४८
प्रश्न
Which term describes movement of organic solutes through phloem?
उत्तर
phloem translocation
कार्ड ५४९
प्रश्न
Which term describes the exporting and importing regions of phloem transport?
उत्तर
source and sink
कार्ड ५५०
प्रश्न
How is an artery adapted to high pressure?
उत्तर
It has thick elastic and muscular walls and a relatively narrow lumen.
कार्ड ५५१
प्रश्न
How is a vein adapted to return low-pressure blood?
उत्तर
It has a wide lumen, thinner walls, and valves that reduce backflow.
कार्ड ५५२
प्रश्न
How does capillary structure support exchange?
उत्तर
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.
कार्ड ५५३
प्रश्न
What determines whether a heart valve opens or closes?
उत्तर
Pressure differences across the valve.
कार्ड ५५४
प्रश्न
Trace water from soil to the atmosphere through a plant.
उत्तर
Soil → root hairs → root tissues → xylem → leaf mesophyll → leaf air spaces → stomata → atmosphere.
कार्ड ५५५
प्रश्न
Why may root cells use active transport to absorb mineral ions?
उत्तर
Ion concentrations can be lower in soil than in root cells, so uptake must occur against a gradient.
कार्ड ५५६
प्रश्न
Why do large multicellular organisms need bulk transport systems?
उत्तर
Their low surface-area-to-volume ratio and long diffusion distances make diffusion alone too slow for whole-body supply.
कार्ड ५५७
प्रश्न
Why does hemoglobin unload more oxygen in actively respiring tissues?
उत्तर
Lower oxygen and often higher carbon dioxide and acidity reduce hemoglobin's oxygen affinity.
कार्ड ५५८
प्रश्न
How does transpiration pull water upward through xylem?
उत्तर
Evaporation lowers leaf water potential and creates tension; cohesion transmits the pull through the continuous water column.
कार्ड ५५९
प्रश्न
How do wind and low humidity generally affect transpiration?
उत्तर
Both maintain a steep water-vapor gradient outside the leaf, increasing transpiration if stomata remain open.
कार्ड ५६०
प्रश्न
What drives mass flow in phloem?
उत्तर
Sugar loading draws in water and raises pressure at a source; unloading lowers pressure at a sink, producing bulk flow.
कार्ड ५६१
प्रश्न
Can the same plant organ be a source at one time and a sink at another?
उत्तर
Yes. A storage organ may import sugars while filling and export them later during growth or germination.
कार्ड ५६२
प्रश्न
What is a neuron?
उत्तर
An excitable cell specialized to receive, process, and transmit information.
कार्ड ५६३
प्रश्न
What is a sensory neuron?
उत्तर
A neuron carrying information from a receptor toward the central nervous system.
कार्ड ५६४
प्रश्न
What is a motor neuron?
उत्तर
A neuron carrying commands from the central nervous system to an effector.
कार्ड ५६५
प्रश्न
What is the resting potential?
उत्तर
The voltage difference across an unstimulated neuron's membrane, with the inside negative relative to outside.
कार्ड ५६६
प्रश्न
Which term describes an excitable information-transmitting cell?
उत्तर
a neuron
कार्ड ५६७
प्रश्न
Which term describes a neuron carrying receptor information to the CNS?
उत्तर
a sensory neuron
कार्ड ५६८
प्रश्न
Which term describes a neuron carrying CNS commands to an effector?
उत्तर
a motor neuron
कार्ड ५६९
प्रश्न
Which term describes the negative-inside voltage of an unstimulated neuron?
उत्तर
the resting potential
कार्ड ५७०
प्रश्न
What is an action potential?
उत्तर
A brief, self-propagating reversal and restoration of membrane potential along an excitable membrane.
कार्ड ५७१
प्रश्न
What is depolarization?
उत्तर
A change that makes membrane potential less negative, and during an action potential often positive.
कार्ड ५७२
प्रश्न
What is repolarization?
उत्तर
Return of membrane potential toward its resting negative value after depolarization.
कार्ड ५७३
प्रश्न
What is a synapse?
उत्तर
A junction where one cell communicates with another cell.
कार्ड ५७४
प्रश्न
Which term describes a brief propagating change in neuron membrane voltage?
उत्तर
an action potential
कार्ड ५७५
प्रश्न
Which term describes a membrane-voltage change toward a less negative value?
उत्तर
depolarization
कार्ड ५७६
प्रश्न
Which term describes return toward resting membrane voltage?
उत्तर
repolarization
कार्ड ५७७
प्रश्न
Which term describes a communication junction between cells?
उत्तर
a synapse
कार्ड ५७८
प्रश्न
What is a neurotransmitter?
उत्तर
A chemical released by a neuron that changes the activity of a target cell.
कार्ड ५७९
प्रश्न
What is the refractory period?
उत्तर
A brief period after an action potential when another is impossible or requires a stronger stimulus.
कार्ड ५८०
प्रश्न
What is myelin?
उत्तर
An insulating sheath around some axons that speeds impulse conduction.
कार्ड ५८१
प्रश्न
What happens when membrane depolarization reaches threshold?
उत्तर
Voltage-gated channels trigger the self-amplifying events of an action potential.
कार्ड ५८२
प्रश्न
Which term describes a neuron-released signaling chemical?
उत्तर
a neurotransmitter
कार्ड ५८३
प्रश्न
Which term describes the recovery interval after an action potential?
उत्तर
the refractory period
कार्ड ५८४
प्रश्न
Which term describes the insulating axon sheath?
उत्तर
myelin
कार्ड ५८५
प्रश्न
What does the all-or-none principle mean for an action potential?
उत्तर
Once threshold is reached, the action potential has a characteristic size; stronger stimuli increase frequency, not its amplitude.
कार्ड ५८६
प्रश्न
How does myelin increase conduction speed?
उत्तर
Depolarizing current travels rapidly beneath myelin and action potentials regenerate mainly at gaps in the sheath.
कार्ड ५८७
प्रश्न
What is the basic sequence at a chemical synapse?
उत्तर
An impulse triggers neurotransmitter release; it diffuses across the cleft, binds receptors, and alters the postsynaptic cell.
कार्ड ५८८
प्रश्न
Why can a reflex response be rapid?
उत्तर
A short neural pathway produces an automatic response without waiting for conscious processing.
कार्ड ५८९
प्रश्न
What is sensory transduction?
उत्तर
Conversion of a physical or chemical stimulus into an electrical signal in a receptor cell.
कार्ड ५९०
प्रश्न
How does an action potential propagate along an axon?
उत्तर
Local current depolarizes the next membrane region to threshold, opening voltage-gated channels there.
कार्ड ५९१
प्रश्न
Why does an action potential normally travel in one direction along an axon?
उत्तर
The membrane just behind it is refractory and cannot immediately fire again.
कार्ड ५९२
प्रश्न
How is neurotransmitter action ended?
उत्तर
The transmitter is removed by enzymatic breakdown, reuptake, or diffusion away.
कार्ड ५९३
प्रश्न
What is sensory adaptation?
उत्तर
Reduced receptor or neural response during a constant, unchanging stimulus.
कार्ड ५९४
प्रश्न
How can a drug alter synaptic transmission?
उत्तर
It may mimic or block a transmitter, change its release, or change its removal from the synaptic cleft.
कार्ड ५९५
प्रश्न
What is an organ system?
उत्तर
A group of organs coordinating to perform major functions for an organism.
कार्ड ५९६
प्रश्न
What is a hormone?
उत्तर
A signaling molecule released into transport fluid and acting on target cells with suitable receptors.
कार्ड ५९७
प्रश्न
What is an endocrine gland?
उत्तर
A gland that secretes hormones into extracellular fluid and blood rather than through a duct.
कार्ड ५९८
प्रश्न
What is a hormone target cell?
उत्तर
A cell able to respond because it has the appropriate receptor.
कार्ड ५९९
प्रश्न
Which term describes a coordinated group of organs?
उत्तर
an organ system
कार्ड ६००
प्रश्न
Which term describes a long-distance chemical messenger carried in body fluid?
उत्तर
a hormone
कार्ड ६०१
प्रश्न
Which term describes a ductless hormone-secreting gland?
उत्तर
an endocrine gland
कार्ड ६०२
प्रश्न
Which term describes a cell with a receptor for a particular hormone?
उत्तर
a hormone target cell
कार्ड ६०३
प्रश्न
What is digestion?
उत्तर
Mechanical and chemical breakdown of food into molecules small enough to absorb.
कार्ड ६०४
प्रश्न
What is absorption?
उत्तर
Movement of digested nutrients across an exchange surface into blood or lymph.
कार्ड ६०५
प्रश्न
What is peristalsis?
उत्तर
Coordinated waves of smooth-muscle contraction that move material through the digestive tract.
कार्ड ६०६
प्रश्न
What is an intestinal villus?
उत्तर
A finger-like projection increasing the absorptive surface of the small intestine.
कार्ड ६०७
प्रश्न
Which term describes breakdown of food into absorbable molecules?
उत्तर
digestion
कार्ड ६०८
प्रश्न
Which term describes movement of digested nutrients into transport fluids?
उत्तर
absorption
कार्ड ६०९
प्रश्न
Which term describes wave-like gut contractions moving contents?
उत्तर
peristalsis
कार्ड ६१०
प्रश्न
Which term describes a finger-like intestinal absorption projection?
उत्तर
an intestinal villus
कार्ड ६११
प्रश्न
What is excretion?
उत्तर
Removal of metabolic waste products from the body.
कार्ड ६१२
प्रश्न
What is a nephron?
उत्तर
The microscopic functional unit of the kidney that filters blood and modifies filtrate into urine.
कार्ड ६१३
प्रश्न
What is ultrafiltration?
उत्तर
Pressure-driven filtration of small molecules from blood into a kidney capsule while cells and most proteins remain in blood.
कार्ड ६१४
प्रश्न
What is selective reabsorption?
उत्तर
Recovery of useful substances and regulated amounts of water and ions from kidney filtrate into blood.
कार्ड ६१५
प्रश्न
Which term describes removal of metabolic wastes?
उत्तर
excretion
कार्ड ६१६
प्रश्न
Which term describes the kidney's microscopic functional unit?
उत्तर
a nephron
कार्ड ६१७
प्रश्न
Which term describes pressure filtration at the start of a nephron?
उत्तर
ultrafiltration
कार्ड ६१८
प्रश्न
Which term describes return of useful substances from kidney filtrate to blood?
उत्तर
selective reabsorption
कार्ड ६१९
प्रश्न
What is skeletal muscle?
उत्तर
Striated voluntary muscle attached to the skeleton and used for movement and posture.
कार्ड ६२०
प्रश्न
What is an antagonistic muscle pair?
उत्तर
Two muscles producing opposite movements at a joint because muscles pull but do not push.
कार्ड ६२१
प्रश्न
How do nervous and endocrine signaling generally differ?
उत्तर
Neural signals are rapid and targeted; hormonal signals are usually slower, longer-lasting, and distributed through body fluids.
कार्ड ६२२
प्रश्न
Why does a circulating hormone affect only some cells?
उत्तर
Only target cells express receptors that recognize the hormone and activate a response.
कार्ड ६२३
प्रश्न
Which term describes voluntary striated muscle that moves the skeleton?
उत्तर
skeletal muscle
कार्ड ६२४
प्रश्न
Which term describes two muscles producing opposite joint movements?
उत्तर
an antagonistic muscle pair
कार्ड ६२५
प्रश्न
What is the final absorbable product of most dietary carbohydrate digestion?
उत्तर
Monosaccharides, especially glucose.
कार्ड ६२६
प्रश्न
What are the main absorbable products of protein digestion?
उत्तर
Amino acids and small peptides that are completed to amino acids during absorption.
कार्ड ६२७
प्रश्न
How is the small intestine adapted for absorption?
उत्तर
Folds, villi, and microvilli increase area; a thin epithelium, rich blood supply, and lymph vessels support transport.
कार्ड ६२८
प्रश्न
Name three integrative roles of the liver.
उत्तर
It processes absorbed nutrients, regulates blood chemistry, detoxifies substances, produces bile, and converts ammonia to urea; any three are sufficient.
कार्ड ६२९
प्रश्न
Why are blood cells and most plasma proteins absent from normal kidney filtrate?
उत्तर
They are too large to cross the filtration barrier.
कार्ड ६३०
प्रश्न
How do muscles move a bone at a joint?
उत्तर
Contraction shortens the muscle, pulling through a tendon on the bone.
कार्ड ६३१
प्रश्न
Why are antagonistic muscles needed at many joints?
उत्तर
A muscle can pull in one direction but cannot push itself back, so an opposing muscle produces the reverse movement.
कार्ड ६३२
प्रश्न
Why must organ systems be integrated rather than acting independently?
उत्तर
Each system depends on materials, signals, waste removal, and stable conditions supplied by other systems.
कार्ड ६३३
प्रश्न
Why do many absorbed lipids enter lymph before blood?
उत्तर
Intestinal cells package them into lipoprotein particles too large to enter ordinary blood capillaries directly.
कार्ड ६३४
प्रश्न
Why is glucose normally absent from final urine?
उत्तर
Filtered glucose is selectively reabsorbed into blood when transporter capacity is not exceeded.
कार्ड ६३५
प्रश्न
How do respiratory, circulatory, and muscular systems cooperate during exercise?
उत्तर
Ventilation supplies oxygen, circulation transports gases and fuels, and muscles use ATP while returning carbon dioxide, heat, and metabolites.
कार्ड ६३६
प्रश्न
How do liver, circulation, and kidneys cooperate in nitrogen-waste removal?
उत्तर
The liver converts toxic ammonia to urea, blood carries urea, and kidneys filter and excrete it.
कार्ड ६३७
प्रश्न
What is a pathogen?
उत्तर
A biological agent capable of causing disease.
कार्ड ६३८
प्रश्न
What is an antigen?
उत्तर
A molecule recognized specifically by an antibody or lymphocyte receptor.
कार्ड ६३९
प्रश्न
What is innate immunity?
उत्तर
Rapid, nonspecific defense mechanisms present without prior exposure.
कार्ड ६४०
प्रश्न
What is adaptive immunity?
उत्तर
Specific defense that develops through lymphocyte activation and can form memory.
कार्ड ६४१
प्रश्न
Which term describes a disease-causing biological agent?
उत्तर
a pathogen
कार्ड ६४२
प्रश्न
Which term describes a molecule specifically recognized by adaptive immune receptors?
उत्तर
an antigen
कार्ड ६४३
प्रश्न
Which term describes rapid nonspecific immune defense?
उत्तर
innate immunity
कार्ड ६४४
प्रश्न
Which term describes specific immune defense capable of memory?
उत्तर
adaptive immunity
कार्ड ६४५
प्रश्न
What is a phagocyte?
उत्तर
A cell that engulfs and digests microbes, particles, or damaged cells.
कार्ड ६४६
प्रश्न
What is a lymphocyte?
उत्तर
An adaptive immune cell with receptors specific to particular antigens.
कार्ड ६४७
प्रश्न
What is an antibody?
उत्तर
A secreted immunoglobulin that binds a specific antigen.
कार्ड ६४८
प्रश्न
What is a B lymphocyte?
उत्तर
A lymphocyte that can differentiate into antibody-secreting plasma cells and memory cells.
कार्ड ६४९
प्रश्न
Which term describes an engulfing immune cell?
उत्तर
a phagocyte
कार्ड ६५०
प्रश्न
Which term describes an antigen-specific adaptive immune cell?
उत्तर
a lymphocyte
कार्ड ६५१
प्रश्न
Which term describes a secreted antigen-binding immunoglobulin?
उत्तर
an antibody
कार्ड ६५२
प्रश्न
Which term describes the lymphocyte lineage that produces antibody-secreting cells?
उत्तर
a B lymphocyte
कार्ड ६५३
प्रश्न
What is a helper T cell?
उत्तर
A lymphocyte that coordinates immune responses through contact signals and cytokines.
कार्ड ६५४
प्रश्न
What is an immune memory cell?
उत्तर
A long-lived lymphocyte that responds rapidly after re-exposure to its antigen.
कार्ड ६५५
प्रश्न
What is vaccination?
उत्तर
Deliberate exposure to a safe form or component of an antigen to generate protective immune memory.
कार्ड ६५६
प्रश्न
What is an antibiotic?
उत्तर
A substance that kills bacteria or inhibits their growth at clinically useful doses.
कार्ड ६५७
प्रश्न
Which term describes the T cell that coordinates other immune cells?
उत्तर
a helper T cell
कार्ड ६५८
प्रश्न
Which term describes a long-lived lymphocyte enabling faster re-exposure response?
उत्तर
an immune memory cell
कार्ड ६५९
प्रश्न
Which term describes safe antigen exposure used to create immune memory?
उत्तर
vaccination
कार्ड ६६०
प्रश्न
Which term describes a drug acting against bacteria?
उत्तर
an antibiotic
कार्ड ६६१
प्रश्न
What are examples of first-line defenses against pathogens?
उत्तर
Intact skin, mucus, cilia, antimicrobial secretions, stomach acidity, and competing microbiota.
कार्ड ६६२
प्रश्न
How does inflammation help defend damaged tissue?
उत्तर
It increases local blood flow and vessel permeability and recruits immune cells and defensive molecules.
कार्ड ६६३
प्रश्न
What happens during phagocytosis?
उत्तर
A cell surrounds a particle in a vesicle, then fuses it with digestive compartments to destroy or process it.
कार्ड ६६४
प्रश्न
How can antibodies help eliminate a pathogen?
उत्तर
They can neutralize targets, block attachment, clump particles, and mark them for phagocytosis or complement attack.
कार्ड ६६५
प्रश्न
Why can a vaccine generate protection without causing the full disease?
उत्तर
It presents antigen in a weakened, inactivated, partial, or encoded form that stimulates immunity with much lower risk.
कार्ड ६६६
प्रश्न
Why do antibiotics not treat viral infections?
उत्तर
Viruses lack the bacterial structures and independent metabolic processes targeted by antibiotics.
कार्ड ६६७
प्रश्न
What determines the antigen specificity of a lymphocyte?
उत्तर
The molecular shape and chemistry of its unique surface receptor.
कार्ड ६६८
प्रश्न
What is clonal selection?
उत्तर
An antigen activates lymphocytes with matching receptors, causing them to proliferate and differentiate.
कार्ड ६६९
प्रश्न
Why is a secondary adaptive immune response usually faster and stronger?
उत्तर
Memory cells are more numerous and activate rapidly, producing effective cells and antibodies sooner.
कार्ड ६७०
प्रश्न
How can high vaccination coverage protect some unvaccinated people?
उत्तर
Reduced transmission makes encounters with infectious individuals less likely, though protection is incomplete and pathogen-dependent.
कार्ड ६७१
प्रश्न
How does antibiotic use select for resistant bacteria?
उत्तर
Susceptible bacteria are removed while resistant variants survive and reproduce, increasing resistance-allele frequency.
कार्ड ६७२
प्रश्न
Why can unnecessary or incomplete antibiotic exposure promote resistance?
उत्तर
It creates selection favoring resistant cells while potentially leaving surviving bacteria to multiply and spread.
कार्ड ६७३
प्रश्न
What is an allergy?
उत्तर
An immune response to a normally harmless antigen that causes tissue symptoms or damage.
कार्ड ६७४
प्रश्न
What is asexual reproduction?
उत्तर
Production of offspring from one parent without fusion of gametes.
कार्ड ६७५
प्रश्न
What is sexual reproduction?
उत्तर
Production of offspring involving fusion of haploid gametes.
कार्ड ६७६
प्रश्न
What is a gamete?
उत्तर
A haploid reproductive cell able to fuse with another gamete.
कार्ड ६७७
प्रश्न
What is fertilization?
उत्तर
Fusion of gamete nuclei to form a diploid zygote.
कार्ड ६७८
प्रश्न
Which term describes reproduction without gamete fusion?
उत्तर
asexual reproduction
कार्ड ६७९
प्रश्न
Which term describes reproduction involving gamete fusion?
उत्तर
sexual reproduction
कार्ड ६८०
प्रश्न
Which term describes a haploid reproductive cell?
उत्तर
a gamete
कार्ड ६८१
प्रश्न
Which term describes fusion of gamete nuclei?
उत्तर
fertilization
कार्ड ६८२
प्रश्न
What is a zygote?
उत्तर
The diploid cell formed by fertilization.
कार्ड ६८३
प्रश्न
What is meiosis?
उत्तर
Cell division that halves chromosome number and usually produces genetically varied haploid cells.
कार्ड ६८४
प्रश्न
What is ovulation?
उत्तर
Release of a secondary oocyte from an ovary.
कार्ड ६८५
प्रश्न
What is implantation?
उत्तर
Attachment and embedding of an early embryo in the uterine lining.
कार्ड ६८६
प्रश्न
Which term describes the first diploid cell after fertilization?
उत्तर
a zygote
कार्ड ६८७
प्रश्न
Which term describes division producing varied haploid cells?
उत्तर
meiosis
कार्ड ६८८
प्रश्न
Which term describes release of an oocyte from an ovary?
उत्तर
ovulation
कार्ड ६८९
प्रश्न
Which term describes embedding of an early embryo in the uterine lining?
उत्तर
implantation
कार्ड ६९०
प्रश्न
What is the placenta?
उत्तर
A temporary organ that exchanges materials between maternal and fetal blood supplies without normally mixing them directly.
कार्ड ६९१
प्रश्न
What is pollination?
उत्तर
Transfer of pollen from an anther to a receptive stigma.
कार्ड ६९२
प्रश्न
Why does sexual reproduction usually produce more genetic variation than asexual reproduction?
उत्तर
Meiosis reshuffles alleles and random fertilization combines genomes from two gametes.
कार्ड ६९३
प्रश्न
Why must gametes be haploid?
उत्तर
Fusion of two haploid gametes restores the diploid chromosome number instead of doubling it each generation.
कार्ड ६९४
प्रश्न
Which term describes the maternal-fetal exchange organ?
उत्तर
the placenta
कार्ड ६९५
प्रश्न
Which term describes transfer of pollen to a stigma?
उत्तर
pollination
कार्ड ६९६
प्रश्न
What are major roles of FSH in the ovarian cycle?
उत्तर
It stimulates follicle development and supports estrogen secretion.
कार्ड ६९७
प्रश्न
What is a major role of the mid-cycle LH surge?
उत्तर
It triggers ovulation and formation of the corpus luteum.
कार्ड ६९८
प्रश्न
How does estrogen contribute to the uterine cycle?
उत्तर
It promotes repair and thickening of the uterine lining after menstruation.
कार्ड ६९९
प्रश्न
How does progesterone contribute to the uterine cycle?
उत्तर
It maintains a thick, secretory uterine lining after ovulation.
कार्ड ७००
प्रश्न
Where does human fertilization usually occur?
उत्तर
In an oviduct, before the early embryo reaches the uterus.
कार्ड ७०१
प्रश्न
What happens after compatible pollen reaches a flower's stigma?
उत्तर
A pollen tube grows toward an ovule and delivers male nuclei for fertilization.
कार्ड ७०२
प्रश्न
Why does menstruation usually begin if pregnancy does not occur?
उत्तर
The corpus luteum degenerates, progesterone and estrogen fall, and the uterine lining is no longer maintained.
कार्ड ७०३
प्रश्न
What substances commonly cross the placenta between mother and fetus?
उत्तर
Oxygen and nutrients move toward the fetus; carbon dioxide and nitrogenous wastes move toward the mother.
कार्ड ७०४
प्रश्न
How can contraception prevent pregnancy in different ways?
उत्तर
Methods can inhibit ovulation, block sperm from reaching an egg, prevent fertilization, or permanently interrupt the reproductive ducts.
कार्ड ७०५
प्रश्न
What is homeostasis?
उत्तर
Maintenance of internal conditions within ranges compatible with normal function despite change.
कार्ड ७०६
प्रश्न
What is negative feedback?
उत्तर
Control in which a deviation triggers responses that oppose the original change.
कार्ड ७०७
प्रश्न
What is a set point?
उत्तर
The target value or range around which a regulated variable is maintained.
कार्ड ७०८
प्रश्न
What is a homeostatic receptor?
उत्तर
A sensor that detects a change in a regulated variable.
कार्ड ७०९
प्रश्न
Which term describes maintenance of a stable functional internal environment?
उत्तर
homeostasis
कार्ड ७१०
प्रश्न
Which term describes feedback that counteracts a deviation?
उत्तर
negative feedback
कार्ड ७११
प्रश्न
Which term describes the target around which a variable is regulated?
उत्तर
a set point
कार्ड ७१२
प्रश्न
Which term describes the sensor in a feedback system?
उत्तर
a homeostatic receptor
कार्ड ७१३
प्रश्न
What is a control center?
उत्तर
The component that compares information with a target and coordinates a response.
कार्ड ७१४
प्रश्न
What is an effector?
उत्तर
A muscle, gland, or other component that carries out a control response.
कार्ड ७१५
प्रश्न
What is thermoregulation?
उत्तर
Control of body temperature within a functional range.
कार्ड ७१६
प्रश्न
What is vasodilation?
उत्तर
Widening of blood vessels, often increasing blood flow near the skin.
कार्ड ७१७
प्रश्न
Which term describes the feedback component that evaluates input and directs a response?
उत्तर
a control center
कार्ड ७१८
प्रश्न
Which term describes the component that executes a physiological response?
उत्तर
an effector
कार्ड ७१९
प्रश्न
Which term describes physiological regulation of body temperature?
उत्तर
thermoregulation
कार्ड ७२०
प्रश्न
Which term describes widening of blood vessels?
उत्तर
vasodilation
कार्ड ७२१
प्रश्न
What is vasoconstriction?
उत्तर
Narrowing of blood vessels, often reducing blood flow near the skin.
कार्ड ७२२
प्रश्न
What is insulin?
उत्तर
A pancreatic hormone that lowers elevated blood glucose by promoting uptake and storage.
कार्ड ७२३
प्रश्न
What is glucagon?
उत्तर
A pancreatic hormone that raises low blood glucose by promoting release of stored fuel.
कार्ड ७२४
प्रश्न
What are the main components of a homeostatic feedback loop?
उत्तर
A regulated variable, receptor, control center, effectors, and responses that alter the variable.
कार्ड ७२५
प्रश्न
Which term describes narrowing of blood vessels?
उत्तर
vasoconstriction
कार्ड ७२६
प्रश्न
Which term describes the pancreatic hormone that lowers blood glucose?
उत्तर
insulin
कार्ड ७२७
प्रश्न
Which term describes the pancreatic hormone that raises blood glucose?
उत्तर
glucagon
कार्ड ७२८
प्रश्न
What happens when blood glucose rises after a meal?
उत्तर
Insulin secretion increases, promoting glucose uptake and storage so blood glucose falls toward its normal range.
कार्ड ७२९
प्रश्न
What happens when blood glucose falls during fasting?
उत्तर
Glucagon secretion increases, promoting glycogen breakdown and glucose release by the liver.
कार्ड ७३०
प्रश्न
How does sweating cool the body?
उत्तर
Evaporation of water from skin transfers heat to the environment.
कार्ड ७३१
प्रश्न
How does skin vasodilation increase heat loss?
उत्तर
It brings more warm blood near the surface, increasing transfer of heat to the environment.
कार्ड ७३२
प्रश्न
How does shivering warm the body?
उत्तर
Rapid involuntary muscle contractions increase respiration and heat production.
कार्ड ७३३
प्रश्न
Does homeostasis keep internal conditions perfectly constant?
उत्तर
No. Variables fluctuate within controlled ranges around target values.
कार्ड ७३४
प्रश्न
How does ADH help conserve water?
उत्तर
It increases water permeability in kidney collecting ducts, so more water is reabsorbed and urine becomes more concentrated.
कार्ड ७३५
प्रश्न
How should ADH secretion change during dehydration?
उत्तर
It should increase, promoting greater water reabsorption by the kidneys.
कार्ड ७३६
प्रश्न
How does positive feedback differ from negative feedback?
उत्तर
Positive feedback amplifies a change until an endpoint; negative feedback opposes a change and stabilizes a variable.
कार्ड ७३७
प्रश्न
Why can diabetes mellitus cause persistently high blood glucose?
उत्तर
Insulin production may be insufficient or target cells may respond poorly to insulin.
कार्ड ७३८
प्रश्न
What is biological evolution?
उत्तर
Change in heritable characteristics or allele frequencies of a population across generations.
कार्ड ७३९
प्रश्न
What is allele frequency?
उत्तर
The proportion of gene copies in a population represented by a particular allele.
कार्ड ७४०
प्रश्न
What is microevolution?
उत्तर
Evolutionary change in allele frequencies within populations over relatively short timescales.
कार्ड ७४१
प्रश्न
What is speciation?
उत्तर
Evolutionary formation of new species.
कार्ड ७४२
प्रश्न
Which term describes change in a population's heritable composition across generations?
उत्तर
biological evolution
कार्ड ७४३
प्रश्न
Which term describes the proportion of a population's gene copies that are one allele?
उत्तर
allele frequency
कार्ड ७४४
प्रश्न
Which term describes short-timescale allele-frequency change within populations?
उत्तर
microevolution
कार्ड ७४५
प्रश्न
Which term describes formation of new species?
उत्तर
speciation
कार्ड ७४६
प्रश्न
What is reproductive isolation?
उत्तर
Barriers that prevent or greatly reduce gene flow between populations.
कार्ड ७४७
प्रश्न
What is allopatric speciation?
उत्तर
Speciation after populations become geographically separated and diverge.
कार्ड ७४८
प्रश्न
What is sympatric speciation?
उत्तर
Speciation without geographic separation, through reproductive isolation within the same area.
कार्ड ७४९
प्रश्न
What are homologous structures?
उत्तर
Structures similar because they were inherited from a common ancestor, even if their functions differ.
कार्ड ७५०
प्रश्न
Which term describes barriers reducing gene flow between populations?
उत्तर
reproductive isolation
कार्ड ७५१
प्रश्न
Which term describes speciation following geographic separation?
उत्तर
allopatric speciation
कार्ड ७५२
प्रश्न
Which term describes speciation within the same geographic area?
उत्तर
sympatric speciation
कार्ड ७५३
प्रश्न
Which term describes structures similar through common ancestry?
उत्तर
homologous structures
कार्ड ७५४
प्रश्न
What are analogous structures?
उत्तर
Structures with similar functions that evolved independently rather than from the same ancestral structure.
कार्ड ७५५
प्रश्न
What is a common ancestor?
उत्तर
An ancestral population from which two or more descendant lineages evolved.
कार्ड ७५६
प्रश्न
How does the fossil record provide evidence for evolution?
उत्तर
It documents organisms from different times, including appearance, change, persistence, and extinction of lineages.
कार्ड ७५७
प्रश्न
How do DNA and protein sequences provide evidence of common ancestry?
उत्तर
Shared sequences are inherited; greater similarity generally indicates more recent common ancestry.
कार्ड ७५८
प्रश्न
Which term describes functionally similar structures of independent evolutionary origin?
उत्तर
analogous structures
कार्ड ७५९
प्रश्न
Which term describes an ancestral population shared by descendant lineages?
उत्तर
a common ancestor
कार्ड ७६०
प्रश्न
What is the evolutionary significance of extinction?
उत्तर
It permanently ends a lineage and can alter ecological opportunities and the future diversification of survivors.
कार्ड ७६१
प्रश्न
Do individual organisms evolve during their lifetimes?
उत्तर
No. Individuals develop and acclimate; evolution is heritable change in populations across generations.
कार्ड ७६२
प्रश्न
Why is evolution represented as a branching tree rather than a ladder?
उत्तर
Lineages split from common ancestors; living species are not arranged as stages toward a single goal.
कार्ड ७६३
प्रश्न
How can island species support evolutionary explanations?
उत्तर
Their similarities to nearby mainland ancestors and unique local adaptations fit divergence after colonization and isolation.
कार्ड ७६४
प्रश्न
How can geographic isolation lead to reproductive isolation?
उत्तर
Separated populations accumulate different mutations and experience different selection and drift until interbreeding is reduced.
कार्ड ७६५
प्रश्न
Why can continuing gene flow slow speciation?
उत्तर
Movement of alleles between populations counteracts genetic divergence.
कार्ड ७६६
प्रश्न
Why can unrelated species evolve similar traits?
उत्तर
Similar environmental challenges can favor similar functional solutions through convergent evolution.
कार्ड ७६७
प्रश्न
Which parts of evolution are random and which are nonrandom?
उत्तर
Mutation and many sampling effects are random with respect to need; natural selection nonrandomly favors variants that reproduce better in a given environment.
कार्ड ७६८
प्रश्न
What is conservation biology?
उत्तर
The science and practice of protecting biodiversity, ecological processes, and evolutionary potential.
कार्ड ७६९
प्रश्न
What is habitat fragmentation?
उत्तर
Division of continuous habitat into smaller, isolated patches.
कार्ड ७७०
प्रश्न
What is an endangered species?
उत्तर
A species facing a high risk of extinction in the wild.
कार्ड ७७१
प्रश्न
What is in situ conservation?
उत्तर
Protection of species in their natural habitats and ecological communities.
कार्ड ७७२
प्रश्न
Which term describes the protection of biodiversity and ecological processes?
उत्तर
conservation biology
कार्ड ७७३
प्रश्न
Which term describes division of habitat into isolated patches?
उत्तर
habitat fragmentation
कार्ड ७७४
प्रश्न
Which term describes a species at high risk of extinction?
उत्तर
an endangered species
कार्ड ७७५
प्रश्न
Which term describes conservation within natural habitat?
उत्तर
in situ conservation
कार्ड ७७६
प्रश्न
What is ex situ conservation?
उत्तर
Protection of organisms or genetic material outside the natural habitat.
कार्ड ७७७
प्रश्न
What is a population bottleneck?
उत्तर
A sharp population reduction that can remove genetic variation by chance.
कार्ड ७७८
प्रश्न
What is a wildlife corridor?
उत्तर
Habitat connecting isolated patches to permit movement and gene flow.
कार्ड ७७९
प्रश्न
What major human-driven processes threaten biodiversity?
उत्तर
Habitat loss, overexploitation, invasive species, pollution, and climate change.
कार्ड ७८०
प्रश्न
Which term describes conservation outside natural habitat?
उत्तर
ex situ conservation
कार्ड ७८१
प्रश्न
Which term describes a severe population reduction that loses genetic diversity?
उत्तर
a population bottleneck
कार्ड ७८२
प्रश्न
Which term describes habitat linking isolated populations?
उत्तर
a wildlife corridor
कार्ड ७८३
प्रश्न
What makes a protected area more effective than a boundary alone?
उत्तर
Adequate size, representative habitat, enforcement, connectivity, local support, and management of external threats.
कार्ड ७८४
प्रश्न
Why is long-term population monitoring important in conservation?
उत्तर
It reveals trends, tests whether management works, and provides early warning of decline.
कार्ड ७८५
प्रश्न
How can ecosystem services support the case for conservation?
उत्तर
Healthy ecosystems provide benefits such as pollination, water purification, carbon storage, soil formation, and cultural value.
कार्ड ७८६
प्रश्न
Why are very small populations especially vulnerable to extinction?
उत्तर
Chance events, inbreeding, low genetic diversity, and difficulty finding mates can reinforce decline.
कार्ड ७८७
प्रश्न
What are benefits and limits of captive-breeding programs?
उत्तर
They can prevent immediate extinction and manage breeding, but may lose diversity, alter behavior, and fail without safe habitat for release.
कार्ड ७८८
प्रश्न
Why can controlling an invasive species aid conservation?
उत्तर
It can reduce predation, competition, disease, or habitat alteration affecting native species.
कार्ड ७८९
प्रश्न
Why must conservation priorities consider more than species count?
उत्तर
Endemism, evolutionary distinctness, ecological roles, threat severity, feasibility, and human needs also matter.
कार्ड ७९०
प्रश्न
What is an adaptation?
उत्तर
A heritable characteristic that increases reproductive success in a particular environment.
कार्ड ७९१
प्रश्न
What is acclimation?
उत्तर
A reversible physiological or behavioral adjustment by an individual to environmental change.
कार्ड ७९२
प्रश्न
What is a structural adaptation?
उत्तर
An inherited anatomical feature that improves performance in an environment.
कार्ड ७९३
प्रश्न
What is a physiological adaptation?
उत्तर
An inherited functional or biochemical feature that improves performance in an environment.
कार्ड ७९४
प्रश्न
Which term describes a heritable trait improving reproductive success in context?
उत्तर
an adaptation
कार्ड ७९५
प्रश्न
Which term describes an individual's reversible adjustment to environmental change?
उत्तर
acclimation
कार्ड ७९६
प्रश्न
Which term describes an adaptive anatomical feature?
उत्तर
a structural adaptation
कार्ड ७९७
प्रश्न
Which term describes an adaptive functional or biochemical feature?
उत्तर
a physiological adaptation
कार्ड ७९८
प्रश्न
What is a behavioral adaptation?
उत्तर
An inherited behavior pattern that improves survival or reproduction.
कार्ड ७९९
प्रश्न
What is an environmental tolerance range?
उत्तर
The range of an abiotic condition within which an organism can survive and reproduce.
कार्ड ८००
प्रश्न
What is evolutionary fitness?
उत्तर
Relative contribution of an individual or genotype to future generations.
कार्ड ८०१
प्रश्न
How can a thick cuticle and reduced leaves help a desert plant?
उत्तर
The cuticle lowers surface permeability, while smaller leaves reduce the area from which water can evaporate.
कार्ड ८०२
प्रश्न
Which term describes an adaptive behavior pattern?
उत्तर
a behavioral adaptation
कार्ड ८०३
प्रश्न
Which term describes the survivable range of an abiotic condition?
उत्तर
an environmental tolerance range
कार्ड ८०४
प्रश्न
Which term describes relative reproductive contribution to future generations?
उत्तर
evolutionary fitness
कार्ड ८०५
प्रश्न
How can a streamlined body adapt an aquatic animal to movement?
उत्तर
It reduces drag, lowering the energy needed to move through water.
कार्ड ८०६
प्रश्न
Does an organism develop an adaptation because it needs one?
उत्तर
No. Heritable variants arise without regard to need, and selection changes their frequencies across generations.
कार्ड ८०७
प्रश्न
Why may organisms from different thermal environments have enzymes with different temperature optima?
उत्तर
Selection favors protein structures that balance flexibility and stability under local temperatures.
कार्ड ८०८
प्रश्न
Why is an adaptation rarely beneficial in every environment?
उत्तर
Traits carry costs and their advantage depends on local resources, competitors, predators, and physical conditions.
कार्ड ८०९
प्रश्न
How does phenotypic plasticity differ from genetic adaptation?
उत्तर
Plasticity lets one genotype produce different phenotypes; adaptation is a heritable population trait shaped across generations.
कार्ड ८१०
प्रश्न
What is local adaptation?
उत्तर
A population has higher fitness in its home environment than foreign populations because selection favored local traits.
कार्ड ८११
प्रश्न
What is an ecological niche?
उत्तर
The set of environmental conditions, resources, interactions, and functional roles associated with a species.
कार्ड ८१२
प्रश्न
What is a habitat?
उत्तर
The physical place or environment where an organism lives.
कार्ड ८१३
प्रश्न
What is a fundamental niche?
उत्तर
The full range of conditions and resources a species could use without limiting biotic interactions.
कार्ड ८१४
प्रश्न
What is a realized niche?
उत्तर
The conditions and resources a species actually uses after competition and other interactions.
कार्ड ८१५
प्रश्न
Which term describes a species' environmental requirements and ecological role?
उत्तर
an ecological niche
कार्ड ८१६
प्रश्न
Which term describes the place where an organism lives?
उत्तर
a habitat
कार्ड ८१७
प्रश्न
Which term describes the potential niche without limiting biotic interactions?
उत्तर
a fundamental niche
कार्ड ८१८
प्रश्न
Which term describes the niche actually occupied in nature?
उत्तर
a realized niche
कार्ड ८१९
प्रश्न
What is competition?
उत्तर
An interaction in which organisms reduce one another's access to a limited resource.
कार्ड ८२०
प्रश्न
What is mutualism?
उत्तर
An interaction in which both participating species benefit.
कार्ड ८२१
प्रश्न
What is predation?
उत्तर
An interaction in which one organism kills and consumes another.
कार्ड ८२२
प्रश्न
How does a habitat differ from a niche?
उत्तर
A habitat is where an organism lives; a niche includes how it uses conditions and resources and interacts there.
कार्ड ८२३
प्रश्न
Which term describes an interaction over a limited resource that harms both competitors?
उत्तर
competition
कार्ड ८२४
प्रश्न
Which term describes an interspecific interaction benefiting both partners?
उत्तर
mutualism
कार्ड ८२५
प्रश्न
Which term describes an interaction where one organism kills and eats another?
उत्तर
predation
कार्ड ८२६
प्रश्न
What kinds of factors define a niche?
उत्तर
Abiotic factors such as temperature and moisture, plus biotic factors such as food, competitors, predators, and partners.
कार्ड ८२७
प्रश्न
What does competitive exclusion predict?
उत्तर
Species with effectively identical niches cannot coexist indefinitely under stable conditions; one is excluded or niches diverge.
कार्ड ८२८
प्रश्न
How can resource partitioning reduce competition?
उत्तर
Species use different resources, places, or times, reducing niche overlap.
कार्ड ८२९
प्रश्न
What is a keystone species?
उत्तर
A species whose effect on community structure is disproportionately large relative to its abundance.
कार्ड ८३०
प्रश्न
Why can an introduced species expand rapidly in a new community?
उत्तर
It may encounter abundant resources, suitable climate, and fewer predators, pathogens, or competitors.
कार्ड ८३१
प्रश्न
Can an organism alter the niche conditions of other species?
उत्तर
Yes. Ecosystem engineers modify habitat structure or resource availability, changing opportunities for other organisms.
कार्ड ८३२
प्रश्न
What is a population?
उत्तर
Individuals of the same species living in the same area at the same time.
कार्ड ८३३
प्रश्न
What is an ecological community?
उत्तर
Populations of different species living and interacting in an area.
कार्ड ८३४
प्रश्न
What is an ecosystem?
उत्तर
A community together with its physical environment and their interactions.
कार्ड ८३५
प्रश्न
What is carrying capacity?
उत्तर
The population size an environment can sustain over time under given conditions.
कार्ड ८३६
प्रश्न
Which term describes same-species individuals sharing an area and time?
उत्तर
a population
कार्ड ८३७
प्रश्न
Which term describes interacting populations of different species?
उत्तर
an ecological community
कार्ड ८३८
प्रश्न
Which term describes a community plus its abiotic environment?
उत्तर
an ecosystem
कार्ड ८३९
प्रश्न
Which term describes the long-term supportable population size?
उत्तर
carrying capacity
कार्ड ८४०
प्रश्न
What is population density?
उत्तर
The number of individuals per unit area or volume.
कार्ड ८४१
प्रश्न
What is a limiting factor?
उत्तर
A resource or condition that restricts population growth or distribution.
कार्ड ८४२
प्रश्न
What is a density-dependent factor?
उत्तर
A factor whose effect strengthens as population density increases.
कार्ड ८४३
प्रश्न
What is a density-independent factor?
उत्तर
A factor whose effect is not primarily determined by population density.
कार्ड ८४४
प्रश्न
Which term describes individuals per unit area or volume?
उत्तर
population density
कार्ड ८४५
प्रश्न
Which term describes a resource or condition restricting a population?
उत्तर
a limiting factor
कार्ड ८४६
प्रश्न
Which term describes a factor with stronger effects at higher density?
उत्तर
a density-dependent factor
कार्ड ८४७
प्रश्न
Which term describes a factor acting largely regardless of population density?
उत्तर
a density-independent factor
कार्ड ८४८
प्रश्न
What is exponential population growth?
उत्तर
Growth at a constant per-capita rate, producing a J-shaped curve under ideal conditions.
कार्ड ८४९
प्रश्न
What is logistic population growth?
उत्तर
Growth that slows as population size approaches carrying capacity, producing an S-shaped model.
कार्ड ८५०
प्रश्न
What four processes directly change population size?
उत्तर
Births and immigration increase it; deaths and emigration decrease it.
कार्ड ८५१
प्रश्न
Under what conditions can exponential growth occur temporarily?
उत्तर
Resources are abundant and limiting effects such as competition, disease, and predation are weak.
कार्ड ८५२
प्रश्न
Which term describes J-shaped growth at constant per-capita rate?
उत्तर
exponential population growth
कार्ड ८५३
प्रश्न
Which term describes S-shaped growth that slows near carrying capacity?
उत्तर
logistic population growth
कार्ड ८५४
प्रश्न
Why is infectious disease often density dependent?
उत्तर
Close or frequent contact at high density increases transmission opportunities.
कार्ड ८५५
प्रश्न
Give an example of a density-independent population factor.
उत्तर
A severe storm, wildfire, drought, or freeze can affect populations regardless of their initial density.
कार्ड ८५६
प्रश्न
When is quadrat sampling useful?
उत्तर
For estimating abundance or frequency of sessile or slow-moving organisms in defined areas.
कार्ड ८५७
प्रश्न
What can a transect reveal?
उत्तर
How species occurrence or abundance changes along an environmental gradient.
कार्ड ८५८
प्रश्न
What can happen when a population overshoots carrying capacity?
उत्तर
Resource depletion may raise mortality or lower reproduction, causing decline or oscillation.
कार्ड ८५९
प्रश्न
What is the basic mark–recapture estimate of population size?
उत्तर
First sample marked × second sample total ÷ marked individuals recaptured.
कार्ड ८६०
प्रश्न
What assumptions improve a mark–recapture estimate?
उत्तर
Marks persist and do not affect survival, marked individuals mix, capture probability is similar, and the population is effectively closed.
कार्ड ८६१
प्रश्न
Why does a correlation between two population variables not prove causation?
उत्तर
A third factor, reverse influence, chance, or biased sampling could produce the association.
कार्ड ८६२
प्रश्न
What is a trophic level?
उत्तर
A feeding position in a food chain or web.
कार्ड ८६३
प्रश्न
What is a producer?
उत्तर
An autotroph that converts inorganic carbon into organic matter.
कार्ड ८६४
प्रश्न
What is a consumer?
उत्तर
An organism obtaining energy and matter by eating other organisms or organic material.
कार्ड ८६५
प्रश्न
What is a decomposer?
उत्तर
An organism that externally digests dead material and wastes and absorbs the products.
कार्ड ८६६
प्रश्न
Which term describes a feeding position in an ecosystem?
उत्तर
a trophic level
कार्ड ८६७
प्रश्न
Which term describes an autotroph forming organic matter?
उत्तर
a producer
कार्ड ८६८
प्रश्न
Which term describes an organism feeding on other organic matter?
उत्तर
a consumer
कार्ड ८६९
प्रश्न
Which term describes an organism digesting dead organic matter externally?
उत्तर
a decomposer
कार्ड ८७०
प्रश्न
What is a food chain?
उत्तर
A linear representation of feeding and energy-transfer relationships.
कार्ड ८७१
प्रश्न
What is a food web?
उत्तर
A network of interconnected feeding relationships in a community.
कार्ड ८७२
प्रश्न
What is gross primary productivity?
उत्तर
The total rate at which producers capture energy into organic matter.
कार्ड ८७३
प्रश्न
What is net primary productivity?
उत्तर
Producer energy stored as new biomass after subtracting producer respiration from gross primary productivity.
कार्ड ८७४
प्रश्न
Which term describes a linear feeding sequence?
उत्तर
a food chain
कार्ड ८७५
प्रश्न
Which term describes a network of connected food chains?
उत्तर
a food web
कार्ड ८७६
प्रश्न
Which term describes the total producer energy-capture rate?
उत्तर
gross primary productivity
कार्ड ८७७
प्रश्न
Which term describes producer biomass gain after respiration?
उत्तर
net primary productivity
कार्ड ८७८
प्रश्न
What is ecological productivity?
उत्तर
The rate of biomass or energy production per unit area or volume.
कार्ड ८७९
प्रश्न
What is a biogeochemical cycle?
उत्तर
Movement of an element or compound through organisms and the physical environment.
कार्ड ८८०
प्रश्न
Why is less energy available at each higher trophic level?
उत्तर
Not all biomass is eaten or digested, and organisms use energy in respiration, movement, maintenance, and heat loss.
कार्ड ८८१
प्रश्न
Why does energy flow rather than cycle through an ecosystem?
उत्तर
Energy enters mainly as light and ultimately disperses as heat, which ecosystems cannot fully recycle.
कार्ड ८८२
प्रश्न
Which term describes the rate of biomass or energy production?
उत्तर
ecological productivity
कार्ड ८८३
प्रश्न
Which term describes cycling of matter through living and nonliving reservoirs?
उत्तर
a biogeochemical cycle
कार्ड ८८४
प्रश्न
Why can matter cycle through an ecosystem?
उत्तर
Atoms are conserved and repeatedly transferred among organisms, detritus, soil, water, and atmosphere.
कार्ड ८८५
प्रश्न
Why is a pyramid of energy always upright?
उत्तर
Usable energy decreases between trophic levels because every transfer includes losses.
कार्ड ८८६
प्रश्न
How are gross and net primary productivity related?
उत्तर
NPP = GPP − producer respiration.
कार्ड ८८७
प्रश्न
How do decomposers support nutrient cycling?
उत्तर
They break down dead material and wastes, releasing inorganic nutrients for reuse.
कार्ड ८८८
प्रश्न
What processes move carbon rapidly between organisms and the atmosphere?
उत्तर
Photosynthesis removes carbon dioxide; respiration, decomposition, and combustion release it.
कार्ड ८८९
प्रश्न
Why is nitrogen fixation important?
उत्तर
It converts atmospheric nitrogen gas into forms that can enter biological nitrogen metabolism.
कार्ड ८९०
प्रश्न
How can excess nitrogen or phosphorus cause eutrophication?
उत्तर
Nutrient enrichment drives algal growth; decomposition of the biomass consumes oxygen and can create hypoxic water.
कार्ड ८९१
प्रश्न
Why can a persistent pollutant reach higher concentrations at higher trophic levels?
उत्तर
Predators consume contaminant stored in many prey, and the substance is not readily broken down or excreted.
कार्ड ८९२
प्रश्न
How is trophic-transfer efficiency calculated?
उत्तर
Energy or biomass gained by the higher trophic level ÷ energy or biomass available at the lower level × 100%.
कार्ड ८९३
प्रश्न
What is phenotypic variation?
उत्तर
Differences in observable traits among individuals of a population.
कार्ड ८९४
प्रश्न
What is heritable variation?
उत्तर
Trait differences that can be transmitted genetically to offspring.
कार्ड ८९५
प्रश्न
What is a selection pressure?
उत्तर
An environmental factor causing differences in survival or reproduction among phenotypes.
कार्ड ८९६
प्रश्न
What is relative fitness?
उत्तर
An individual's reproductive success compared with others in the population.
कार्ड ८९७
प्रश्न
Which term describes observable differences among individuals?
उत्तर
phenotypic variation
कार्ड ८९८
प्रश्न
Which term describes genetically transmissible trait differences?
उत्तर
heritable variation
कार्ड ८९९
प्रश्न
Which term describes an environmental factor producing differential reproductive success?
उत्तर
a selection pressure
कार्ड ९००
प्रश्न
Which term describes reproductive success relative to other individuals?
उत्तर
relative fitness
कार्ड ९०१
प्रश्न
What is directional selection?
उत्तर
Selection favoring one extreme phenotype and shifting a population's trait distribution.
कार्ड ९०२
प्रश्न
What is stabilizing selection?
उत्तर
Selection favoring intermediate phenotypes and acting against extremes.
कार्ड ९०३
प्रश्न
What is disruptive selection?
उत्तर
Selection favoring both extreme phenotypes over intermediates.
कार्ड ९०४
प्रश्न
What is sexual selection?
उत्तर
Selection arising from differences in mating success.
कार्ड ९०५
प्रश्न
Which term describes selection shifting a trait toward one extreme?
उत्तर
directional selection
कार्ड ९०६
प्रश्न
Which term describes selection favoring intermediate phenotypes?
उत्तर
stabilizing selection
कार्ड ९०७
प्रश्न
Which term describes selection favoring both trait extremes?
उत्तर
disruptive selection
कार्ड ९०८
प्रश्न
Which term describes selection caused by unequal mating success?
उत्तर
sexual selection
कार्ड ९०९
प्रश्न
What conditions are required for natural selection?
उत्तर
Individuals vary, some variation is heritable, more offspring are produced than can reproduce, and variants differ in reproductive success.
कार्ड ९१०
प्रश्न
How does natural selection produce antibiotic-resistant bacterial populations?
उत्तर
Existing resistant variants survive treatment and reproduce more than susceptible bacteria.
कार्ड ९११
प्रश्न
Does an antibiotic cause bacteria to mutate specifically toward resistance?
उत्तर
No. Resistance variants arise without regard to need; treatment selects among them.
कार्ड ९१२
प्रश्न
Can an individual become genetically adapted through natural selection?
उत्तर
No. Selection acts on individuals, but adaptation is a population change across generations.
कार्ड ९१३
प्रश्न
How does artificial selection differ from natural selection?
उत्तर
Humans choose breeding traits in artificial selection; environmental conditions determine differential reproduction in natural selection.
कार्ड ९१४
प्रश्न
How does natural selection change a population?
उत्तर
Individuals with advantageous heritable variants leave more offspring, increasing those alleles over generations.
कार्ड ९१५
प्रश्न
Why is fitness environment-dependent?
उत्तर
A trait that improves reproduction in one environment may be neutral or costly in another.
कार्ड ९१६
प्रश्न
How does genetic drift differ from natural selection?
उत्तर
Drift changes allele frequencies by chance sampling; selection changes them through consistent fitness differences.
कार्ड ९१७
प्रश्न
What is ecosystem stability?
उत्तर
The capacity of an ecosystem to maintain or recover its structure and functions despite disturbance.
कार्ड ९१८
प्रश्न
What is an ecological tipping point?
उत्तर
A threshold beyond which feedbacks can drive a large and difficult-to-reverse ecosystem shift.
कार्ड ९१९
प्रश्न
What is a mesocosm?
उत्तर
A controlled, simplified ecosystem used to investigate ecological processes under more realistic conditions than a small laboratory vessel.
कार्ड ९२०
प्रश्न
What is a sustainable yield?
उत्तर
A harvest rate that can continue without causing long-term resource decline under prevailing conditions.
कार्ड ९२१
प्रश्न
Which term describes the capacity of an ecosystem to persist or recover after disturbance?
उत्तर
ecosystem stability
कार्ड ९२२
प्रश्न
Which term describes a threshold triggering a major hard-to-reverse ecosystem shift?
उत्तर
an ecological tipping point
कार्ड ९२३
प्रश्न
Which term describes a controlled model ecosystem used for experiments?
उत्तर
a mesocosm
कार्ड ९२४
प्रश्न
Which term describes a harvest rate that avoids long-term depletion?
उत्तर
a sustainable yield
कार्ड ९२५
प्रश्न
What is eutrophication?
उत्तर
Nutrient enrichment of water that stimulates excess primary production and can lead to oxygen depletion.
कार्ड ९२६
प्रश्न
What is biomagnification?
उत्तर
Increase in concentration of a persistent pollutant at successively higher trophic levels.
कार्ड ९२७
प्रश्न
What is rewilding?
उत्तर
Ecosystem restoration that rebuilds natural processes, species interactions, and self-sustaining ecological function.
कार्ड ९२८
प्रश्न
What features can make an ecosystem more stable?
उत्तर
Diverse functional roles, connected habitats, intact food webs, nutrient cycling, and balancing feedbacks can help the system resist or recover from disturbance.
कार्ड ९२९
प्रश्न
Which term describes nutrient enrichment that can deplete oxygen in water?
उत्तर
eutrophication
कार्ड ९३०
प्रश्न
Which term describes increasing pollutant concentration up a food chain?
उत्तर
biomagnification
कार्ड ९३१
प्रश्न
Which term describes restoration focused on natural processes and self-sustaining ecosystems?
उत्तर
rewilding
कार्ड ९३२
प्रश्न
How could extensive Amazon deforestation push the ecosystem toward a tipping point?
उत्तर
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.
कार्ड ९३३
प्रश्न
What are a benefit and a limitation of using a mesocosm?
उत्तर
It allows controlled experiments with interacting organisms, but its simplified scale cannot reproduce every process or long-term influence in a natural ecosystem.
कार्ड ९३४
प्रश्न
Why should a fishery harvest below an uncertain maximum sustainable yield?
उत्तर
Population estimates and recruitment vary, so a safety margin reduces the chance that error or a poor breeding year drives long-term decline.
कार्ड ९३५
प्रश्न
How can intensive agriculture reduce ecosystem stability?
उत्तर
Habitat loss, low crop diversity, soil degradation, heavy water use, pesticides, and nutrient runoff can weaken food webs and ecosystem processes.
कार्ड ९३६
प्रश्न
Why can microplastic pollution harm aquatic ecosystems?
उत्तर
Small persistent particles can be ingested, carry additives or other pollutants, damage feeding and tissues, and move through food webs.
कार्ड ९३७
प्रश्न
How can rewilding improve ecosystem stability?
उत्तर
Restoring native species, habitat connections, and natural disturbance or grazing processes can rebuild feedbacks and allow the ecosystem to maintain itself with less intervention.
कार्ड ९३८
प्रश्न
What is the greenhouse effect?
उत्तर
Warming caused when atmospheric gases absorb and re-emit outgoing infrared radiation.
कार्ड ९३९
प्रश्न
What is a greenhouse gas?
उत्तर
An atmospheric gas that absorbs infrared radiation at wavelengths emitted by Earth.
कार्ड ९४०
प्रश्न
What is carbon dioxide (CO₂)?
उत्तर
A long-lived greenhouse gas increased mainly by fossil-fuel combustion, cement production, and land-use change.
कार्ड ९४१
प्रश्न
What is methane (CH₄)?
उत्तर
A potent greenhouse gas emitted by sources including fossil-fuel systems, livestock, rice cultivation, wetlands, and waste.
कार्ड ९४२
प्रश्न
Which term describes warming from absorption and re-emission of infrared radiation?
उत्तर
the greenhouse effect
कार्ड ९४३
प्रश्न
Which term describes an atmospheric infrared-absorbing gas?
उत्तर
a greenhouse gas
कार्ड ९४४
प्रश्न
Which term describes the long-lived greenhouse gas strongly increased by fossil fuels?
उत्तर
carbon dioxide (CO₂)
कार्ड ९४५
प्रश्न
Which term describes the potent short-lived greenhouse gas from biological and fossil sources?
उत्तर
methane (CH₄)
कार्ड ९४६
प्रश्न
What is albedo?
उत्तर
The fraction of incoming radiation reflected by a surface.
कार्ड ९४७
प्रश्न
What is a carbon sink?
उत्तर
A reservoir that absorbs more carbon than it releases over a specified period.
कार्ड ९४८
प्रश्न
What is ocean acidification?
उत्तर
Decline in seawater pH caused mainly by absorption of human-emitted carbon dioxide.
कार्ड ९४९
प्रश्न
What is climate change?
उत्तर
A persistent change in the statistical patterns of climate over decades or longer.
कार्ड ९५०
प्रश्न
Which term describes surface reflectivity?
उत्तर
albedo
कार्ड ९५१
प्रश्न
Which term describes a reservoir with net carbon uptake?
उत्तर
a carbon sink
कार्ड ९५२
प्रश्न
Which term describes seawater pH decline from absorbed carbon dioxide?
उत्तर
ocean acidification
कार्ड ९५३
प्रश्न
Which term describes long-term change in climate patterns?
उत्तर
climate change
कार्ड ९५४
प्रश्न
What is the enhanced greenhouse effect?
उत्तर
Additional warming caused by human-driven increases in greenhouse-gas concentrations.
कार्ड ९५५
प्रश्न
How do climate mitigation and climate adaptation differ?
उत्तर
Mitigation limits the magnitude of climate change; adaptation reduces harm from changes that occur.
कार्ड ९५६
प्रश्न
How does increasing greenhouse-gas concentration alter Earth's energy balance?
उत्तर
Less outgoing infrared energy initially escapes to space, so the climate warms until energy balance is restored at a higher temperature.
कार्ड ९५७
प्रश्न
How can melting ice amplify warming?
उत्तर
Less bright ice lowers albedo, so darker land or water absorbs more solar energy and causes further warming.
कार्ड ९५८
प्रश्न
How can climate change alter species distributions?
उत्तर
Temperature, rainfall, seasons, sea level, and interactions shift, moving or shrinking areas with suitable conditions.
कार्ड ९५९
प्रश्न
Why can ocean acidification harm calcifying organisms?
उत्तर
Carbonate chemistry changes, reducing availability of carbonate ions used to build calcium-carbonate structures.
कार्ड ९६०
प्रश्न
How can ecosystem protection contribute to climate mitigation?
उत्तर
Protecting forests, wetlands, soils, and coastal habitats can avoid emissions and maintain or increase carbon storage.
९६० कार्डे
IB Biology SL Flashcards: Complete Course Review
अभ्यास सुरू करण्यासाठी Nibomo उघडेल.