Multiple choice: Which property is shared by all living organisms?
A) They all have cell walls
B) They all perform photosynthesis
C) They all maintain homeostasis
D) They all are multicellular
Correct answer: C) They all maintain homeostasis
Explanation: Homeostasis, the regulation of internal conditions, is a common feature of all living organisms, regardless of structure or nutrition.

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Short answer: Describe the main difference between prokaryotic cells and eukaryotic cells.
Correct answer: Prokaryotic cells lack a membrane-bound nucleus and membrane-bound organelles, while eukaryotic cells have a nucleus and membrane-bound organelles.
Explanation: The presence of internal membrane compartments, especially the nucleus, distinguishes eukaryotes from prokaryotes.

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Fill in: The basic unit of heredity that encodes a functional product is a __________.
Correct answer: gene
Explanation: A gene is a segment of deoxyribonucleic acid that carries the information to produce a functional RNA or protein.

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True or False: The cell theory states that all cells come from preexisting cells.
Correct answer: True.
Explanation: One of the three core statements of cell theory is that new cells arise from the division of existing cells.

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Multiple choice: Which organelle is primarily responsible for producing most cellular adenosine triphosphate?
A) Golgi apparatus
B) Lysosome
C) Mitochondrion
D) Smooth endoplasmic reticulum
Correct answer: C) Mitochondrion
Explanation: Mitochondria carry out aerobic respiration and oxidative phosphorylation, generating most adenosine triphosphate in eukaryotic cells.

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Short answer: Define osmosis in one clear sentence.
Correct answer: Osmosis is the passive movement of water across a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration.
Explanation: Osmosis is driven by a concentration gradient of solutes and does not require energy.

 

Fill in: The phospholipid bilayer of cell membranes has hydrophilic __________ and hydrophobic __________.
Correct answer: heads; tails
Explanation: Polar phosphate heads face aqueous environments, while nonpolar fatty acid tails face inward.

 

True or False: Simple diffusion requires a membrane transport protein.
Correct answer: False.
Explanation: Simple diffusion is the movement of small, nonpolar molecules directly through the lipid bilayer without transport proteins.

 

Multiple choice: Which macromolecule is primarily responsible for catalyzing biochemical reactions in cells?
A) Carbohydrates
B) Proteins
C) Lipids
D) Nucleic acids
Correct answer: B) Proteins
Explanation: Most enzymes are proteins that lower activation energy and speed up reactions.

 

Short answer: What is the role of ribosomes in the cell?
Correct answer: Ribosomes are the sites of protein synthesis, where messenger RNA is translated into polypeptide chains.
Explanation: Ribosomes link amino acids together in an order specified by messenger RNA.

 

Fill in: In eukaryotic cells, transcription occurs in the __________ and translation occurs in the __________.
Correct answer: nucleus; cytoplasm
Explanation: DNA is transcribed into RNA in the nucleus, and ribosomes in the cytoplasm translate RNA into protein.

 

True or False: Hydrogen bonds are stronger than covalent bonds within a molecule.
Correct answer: False.
Explanation: Hydrogen bonds are weaker, noncovalent interactions compared to covalent bonds, which involve shared electron pairs.

 

Multiple choice: Which statement correctly describes an enzyme active site?
A) It is a rigid structure that fits all substrates equally well
B) It is a flexible region that forms a specific fit with the substrate
C) It is located only on membrane proteins
D) It is consumed during the reaction
Correct answer: B) It is a flexible region that forms a specific fit with the substrate
Explanation: The induced-fit model describes a flexible active site that shapes around the substrate for specificity.

 

Short answer: Define genome in simple terms.
Correct answer: A genome is the complete set of genetic material of an organism, including all of its genes and noncoding sequences.
Explanation: It represents the total deoxyribonucleic acid content for an organism or organelle.

 

Fill in: During mitosis, sister chromatids separate during __________.
Correct answer: anaphase
Explanation: Anaphase is the stage when spindle fibers pull sister chromatids to opposite poles.

 

True or False: Meiosis results in daughter cells that are genetically identical to the parent cell.
Correct answer: False.
Explanation: Meiosis produces haploid gametes that are genetically diverse due to crossing over and independent assortment.

 

Multiple choice: Which process increases genetic variation during meiosis?
A) Cytokinesis
B) DNA replication
C) Crossing over between homologous chromosomes
D) Binary fission
Correct answer: C) Crossing over between homologous chromosomes
Explanation: Exchange of genetic material between homologous chromosomes creates new allele combinations.

 

Short answer: What is the central dogma of molecular biology?
Correct answer: The central dogma states that genetic information flows from deoxyribonucleic acid to ribonucleic acid to protein.
Explanation: DNA is transcribed to RNA, which is translated into protein.

 

Fill in: The three-base sequence in messenger RNA that specifies an amino acid is called a __________.
Correct answer: codon
Explanation: Each codon corresponds to a specific amino acid or a stop signal during translation.

 

True or False: All mutations in DNA lead to a change in the amino acid sequence of a protein.
Correct answer: False.
Explanation: Some mutations are silent due to redundancy in the genetic code or occur in noncoding regions.

 

Multiple choice: Which component of the cytoskeleton is primarily involved in chromosome movement during cell division?
A) Microfilaments
B) Intermediate filaments
C) Microtubules
D) Actin cortex
Correct answer: C) Microtubules
Explanation: Microtubules form the mitotic spindle that moves chromosomes.

 

Short answer: Define allele.
Correct answer: An allele is one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Explanation: Different alleles can produce variation in traits.

 

Fill in: A cross between individuals that are heterozygous for a single trait is called a __________ cross.
Correct answer: monohybrid
Explanation: A monohybrid cross examines inheritance of one gene with two alleles.

 

True or False: Incomplete dominance results in a heterozygote with a phenotype intermediate between the two homozygotes.
Correct answer: True.
Explanation: The heterozygous phenotype shows partial expression of both alleles.

 

Multiple choice: Which molecule carries amino acids to the ribosome during translation?
A) Messenger RNA
B) Transfer RNA
C) Ribosomal RNA
D) Small nuclear RNA
Correct answer: B) Transfer RNA
Explanation: Transfer RNA has anticodons that pair with codons and deliver specific amino acids.

 

Short answer: What is a promoter region in a gene?
Correct answer: A promoter is a DNA sequence where RNA polymerase and transcription factors bind to initiate transcription.
Explanation: It regulates when and where transcription begins.

 

Fill in: The plasma membrane is described by the __________ mosaic model.
Correct answer: fluid
Explanation: The model describes a dynamic membrane with proteins moving within a fluid lipid bilayer.

 

True or False: Primary protein structure is determined by the sequence of amino acids.
Correct answer: True.
Explanation: The order of amino acids dictates higher-level folding and function.

 

Multiple choice: Which kingdom includes organisms that are multicellular, photosynthetic, and have cell walls made of cellulose?
A) Animalia
B) Plantae
C) Fungi
D) Protista
Correct answer: B) Plantae
Explanation: Plants are multicellular photoautotrophs with cellulose-rich cell walls.

 

Short answer: Define homeostasis with one example.
Correct answer: Homeostasis is the regulation of internal conditions within narrow limits; for example, maintaining human body temperature near 37 degrees Celsius.
Explanation: Negative feedback mechanisms help maintain internal stability.

 

Fill in: In ecological terms, the living components of an ecosystem are called the __________ factors.
Correct answer: biotic
Explanation: Biotic factors include producers, consumers, and decomposers.

 

True or False: Energy transfer between trophic levels is typically very efficient, with more than half of the energy passed on.
Correct answer: False.
Explanation: Only about ten percent of energy is transferred to the next trophic level on average.

 

Multiple choice: Which level of biological organization includes all organisms of the same species in a given area?
A) Community
B) Ecosystem
C) Population
D) Biosphere
Correct answer: C) Population
Explanation: A population is a group of individuals of the same species in one area.

 

Short answer: Describe the role of chlorophyll in photosynthesis.
Correct answer: Chlorophyll absorbs light energy, primarily in the blue and red wavelengths, and initiates the conversion of light energy into chemical energy.
Explanation: Excited electrons in chlorophyll drive the photosynthetic reactions.

 

Fill in: The enzyme that links deoxyribonucleotides to synthesize a new strand during DNA replication is __________.
Correct answer: DNA polymerase
Explanation: DNA polymerase catalyzes the formation of phosphodiester bonds in the new strand.

 

True or False: The anticodon is a three-base sequence on messenger RNA that pairs with a codon on transfer RNA.
Correct answer: False.
Explanation: The anticodon is on transfer RNA and pairs with a codon on messenger RNA.

 

Multiple choice: Which bond stabilizes the secondary structure of proteins such as alpha helices?
A) Ionic bonds between side chains
B) Hydrogen bonds between backbone groups
C) Disulfide bonds between cysteine residues
D) Covalent bonds between peptide backbones
Correct answer: B) Hydrogen bonds between backbone groups
Explanation: Regular hydrogen bonding between the carbonyl and amide groups stabilizes helices and sheets.

 

Short answer: What is genetic drift?
Correct answer: Genetic drift is a change in allele frequencies in a population due to random sampling effects, especially in small populations.
Explanation: It is a nonselective mechanism of evolution.

 

Fill in: The phylogenetic tree represents hypotheses about the __________ relationships among species.
Correct answer: evolutionary
Explanation: Branching patterns suggest common ancestry and divergence.

 

True or False: Natural selection acts on individuals, but evolution is a change observed in populations over time.
Correct answer: True.
Explanation: Individuals do not evolve; allele frequencies in populations change across generations.

 

Multiple choice: Which organelle modifies, sorts, and packages proteins for secretion or delivery to other organelles?
A) Smooth endoplasmic reticulum
B) Rough endoplasmic reticulum
C) Golgi apparatus
D) Peroxisome
Correct answer: C) Golgi apparatus
Explanation: The Golgi apparatus processes and traffics proteins and lipids.

 

Short answer: Define symbiosis and give one type.
Correct answer: Symbiosis is a close, long-term interaction between different species; for example, mutualism where both partners benefit.
Explanation: Other types include commensalism and parasitism.

 

Fill in: The nitrogen cycle converts atmospheric nitrogen into forms usable by living organisms through __________ fixation.
Correct answer: nitrogen
Explanation: Nitrogen-fixing microbes convert nitrogen gas into ammonia or related compounds.

 

True or False: All viruses are considered living because they have genetic material and reproduce independently.
Correct answer: False.
Explanation: Viruses require host cells to replicate and do not carry out metabolism on their own.

 

Multiple choice: Which statement about meiosis is correct?
A) It produces diploid somatic cells
B) It consists of one round of division
C) It produces four haploid cells
D) It duplicates chromosomes twice
Correct answer: C) It produces four haploid cells
Explanation: Two divisions follow one replication, generating four haploid gametes.

 

Short answer: What is a transcription factor?
Correct answer: A transcription factor is a protein that binds specific DNA sequences to regulate the initiation and rate of transcription.
Explanation: It can act as an activator or a repressor of gene expression.

 

Fill in: The semiconservative model of DNA replication means each daughter molecule has one __________ strand and one __________ strand.
Correct answer: old; new
Explanation: Each new DNA double helix contains one parental and one newly synthesized strand.

 

True or False: A species is typically defined as a group of organisms that can interbreed and produce fertile offspring.
Correct answer: True.
Explanation: This is the biological species concept, widely used for many animals and plants.

 

Multiple choice: In plants, the opening and closing of stomata are primarily regulated to balance:
A) Mineral uptake and root growth
B) Water loss and carbon dioxide intake
C) Nitrogen fixation and photosynthesis
D) Protein synthesis and respiration
Correct answer: B) Water loss and carbon dioxide intake
Explanation: Guard cells adjust pore size to control gas exchange and water conservation.

 

Short answer: Define an operon in prokaryotes.
Correct answer: An operon is a cluster of genes under control of a single promoter and operator that are transcribed together into one messenger RNA.
Explanation: It allows coordinated regulation of related genes.

 

Fill in: The small, circular DNA molecules in bacteria that often carry nonessential genes are called __________.
Correct answer: plasmids
Explanation: Plasmids can confer advantages such as antibiotic resistance.

 

True or False: All enzymes function best at the same optimal temperature and pH.
Correct answer: False.
Explanation: Enzymes have different optimal conditions based on their structure and environment.

 

Multiple choice: Which of the following is a density-dependent factor that can limit population growth?
A) Natural disaster
B) Seasonal drought
C) Disease transmission
D) Volcanic eruption
Correct answer: C) Disease transmission
Explanation: Density-dependent factors intensify as population density increases.

 

Short answer: What is a keystone species?
Correct answer: A keystone species is one that has a disproportionately large effect on community structure and function relative to its abundance.
Explanation: Removing it causes major changes in community composition.

 

Fill in: Primary succession occurs on surfaces where no __________ exists, such as newly formed volcanic rock.
Correct answer: soil
Explanation: Soil must first develop through weathering and colonization by pioneer species.

 

True or False: Commensalism is an interaction in which both species benefit.
Correct answer: False.
Explanation: In commensalism, one benefits and the other is neither helped nor harmed.

 

Multiple choice: Which level of protein structure involves interactions between distinct polypeptide chains?
A) Primary
B) Secondary
C) Tertiary
D) Quaternary
Correct answer: D) Quaternary
Explanation: Quaternary structure describes how multiple polypeptides assemble into a functional protein.

 

Short answer: Define apoptosis.
Correct answer: Apoptosis is a regulated process of programmed cell death that removes unwanted or damaged cells without causing inflammation.
Explanation: It is essential for development and tissue homeostasis.

 

Fill in: In a food web, organisms that feed on primary producers are called __________ consumers.
Correct answer: primary
Explanation: Primary consumers are herbivores that eat producers.

 

True or False: A hypothesis must be testable and falsifiable to be considered scientific.
Correct answer: True.
Explanation: Scientific hypotheses must generate predictions that can be supported or refuted by evidence.

 

Multiple choice: Which process best explains how a new species can arise when a population is physically separated by a geographic barrier?
A) Artificial selection
B) Allopatric speciation
C) Gene flow
D) Stabilizing selection
Correct answer: B) Allopatric speciation
Explanation: Physical isolation allows divergence through mutation, drift, and selection.

 

Short answer: What is the function of lysosomes in animal cells?
Correct answer: Lysosomes contain hydrolytic enzymes that digest macromolecules, damaged organelles, and pathogens.
Explanation: They are central to intracellular digestion and recycling.

 

Fill in: In transcription, the enzyme that synthesizes RNA from a DNA template is called __________ polymerase.
Correct answer: RNA
Explanation: RNA polymerase reads the DNA template to produce RNA.

 

True or False: The leading strand during DNA replication is synthesized continuously in the same direction as the fork movement.
Correct answer: True.
Explanation: The leading strand follows the replication fork, while the lagging strand is synthesized in fragments.

 

Multiple choice: Which ecological term describes the role and position of a species in an ecosystem, including its resource use and interactions?
A) Habitat
B) Niche
C) Territory
D) Range
Correct answer: B) Niche
Explanation: A niche includes how a species obtains resources and interacts with other species.

 

Short answer: Define endosymbiosis theory in one or two sentences.
Correct answer: The endosymbiosis theory proposes that mitochondria and chloroplasts originated as free-living prokaryotes that were engulfed by ancestral eukaryotic cells and formed a mutualistic relationship.
Explanation: Evidence includes double membranes, their own circular DNA, and ribosomes similar to bacteria.

 

Fill in: During translation, peptide bonds are formed between __________ acids to build a polypeptide chain.
Correct answer: amino
Explanation: The ribosome catalyzes peptide bond formation between amino acids.

 

True or False: A dominant allele is always the most common allele in a population.
Correct answer: False.
Explanation: Dominance relates to expression in heterozygotes, not frequency in populations.

 

Multiple choice: Which statement correctly describes a plasmodesma in plants?
A) A protein channel for diffusion of ions only
B) A lipid channel that transports lipids between cells
C) A cytoplasmic channel through cell walls connecting adjacent plant cells
D) A structure that only transports deoxyribonucleic acid
Correct answer: C) A cytoplasmic channel through cell walls connecting adjacent plant cells
Explanation: Plasmodesmata connect cytoplasm of neighboring cells for transport and signaling.

 

Short answer: What is alternative splicing?
Correct answer: Alternative splicing is the process by which different combinations of exons are joined to produce multiple messenger RNA variants from a single gene.
Explanation: It increases protein diversity without increasing gene number.

 

Fill in: The part of the brain responsible for coordinating voluntary movement and balance is the __________.
Correct answer: cerebellum
Explanation: The cerebellum integrates sensory input to fine-tune motor activity.

 

True or False: In plants, xylem primarily transports sugars, while phloem transports water and minerals.
Correct answer: False.
Explanation: Xylem mainly transports water and minerals; phloem transports sugars and other organic molecules.

 

Multiple choice: Which molecule is the primary structural component of plant cell walls?
A) Chitin
B) Cellulose
C) Glycogen
D) Peptidoglycan
Correct answer: B) Cellulose
Explanation: Cellulose fibers provide rigidity and strength to plant cell walls.

 

Short answer: Define gene expression.
Correct answer: Gene expression is the process by which the information in a gene is used to synthesize a functional product, typically a protein or functional RNA.
Explanation: It involves transcription and, for protein-coding genes, translation.

 

Fill in: The three domains of life are Bacteria, Archaea, and __________.
Correct answer: Eukarya
Explanation: This classification reflects major differences in cell structure and genetics.

 

True or False: The secondary structure of deoxyribonucleic acid is a double helix with antiparallel strands.
Correct answer: True.
Explanation: The two strands run in opposite directions and are held together by hydrogen bonds between bases.

 

Multiple choice: Which factor is the most direct energy source for most ecosystems on Earth?
A) Heat from Earth’s core
B) Sunlight captured by primary producers
C) Chemical energy from deep-sea vents for all ecosystems
D) Wind energy
Correct answer: B) Sunlight captured by primary producers
Explanation: Photosynthetic organisms convert light energy into chemical energy at the base of most food webs.

 

Short answer: What is a cladogram and what does it show?
Correct answer: A cladogram is a branching diagram that depicts hypothesized evolutionary relationships among taxa based on shared derived characters.
Explanation: It shows patterns of common ancestry and divergence.

 

Fill in: The portion of a gene that codes for amino acid sequence and remains in the mature messenger RNA after splicing is an __________.
Correct answer: exon
Explanation: Exons are expressed sequences that are retained in the final transcript.

 

True or False: Water has a high specific heat capacity, which helps moderate Earth’s climate.
Correct answer: True.
Explanation: Water absorbs and releases large amounts of heat with small temperature changes.

 

Multiple choice: Which statement best describes signal transduction in cells?
A) The direct transport of proteins across membranes without receptors
B) The conversion of an external signal into a specific cellular response through a series of molecular events
C) The replication of DNA in response to nutrient availability
D) The export of messenger RNA from the nucleus
Correct answer: B) The conversion of an external signal into a specific cellular response through a series of molecular events
Explanation: Receptors detect signals and trigger intracellular pathways that change cell behavior.

 

Short answer: Define carrying capacity in population ecology.
Correct answer: Carrying capacity is the maximum population size that an environment can sustain indefinitely given the available resources and conditions.
Explanation: It can change with resource availability and environmental factors.

 

Fill in: A symbiotic relationship where both species benefit is called __________.
Correct answer: mutualism
Explanation: Both partners gain advantages such as nutrients or protection.

 

True or False: Restriction enzymes cut deoxyribonucleic acid at specific sequences and are used in molecular cloning.
Correct answer: True.
Explanation: They recognize short palindromic sequences and create predictable fragments.

 

Multiple choice: Which process produces complementary deoxyribonucleic acid from a messenger RNA template?
A) Transcription
B) Reverse transcription
C) Replication
D) Translation
Correct answer: B) Reverse transcription
Explanation: Reverse transcriptase synthesizes complementary DNA from RNA.

 

Short answer: What is the role of transfer RNA synthetase enzymes?
Correct answer: Transfer RNA synthetase enzymes attach the correct amino acid to its corresponding transfer RNA, ensuring accurate translation.
Explanation: Each enzyme recognizes a specific amino acid and its matching transfer RNA.

 

Fill in: In plants, the primary growth in length of roots and shoots originates from regions called __________.
Correct answer: apical meristems
Explanation: Apical meristems contain dividing cells that enable elongation.

 

True or False: A phylogeny that requires the fewest evolutionary changes is preferred under the principle of parsimony.
Correct answer: True.
Explanation: Parsimony favors simpler explanations consistent with observed data.

 

Multiple choice: Which biomolecule primarily stores and transmits genetic information?
A) Carbohydrates
B) Lipids
C) Proteins
D) Nucleic acids
Correct answer: D) Nucleic acids
Explanation: Deoxyribonucleic acid and ribonucleic acid store and transmit genetic information.

 

Short answer: Define epigenetics in one or two sentences.
Correct answer: Epigenetics refers to heritable changes in gene function that do not involve changes to the DNA sequence, often through DNA methylation or histone modification.
Explanation: These changes can alter gene expression and can be influenced by environment.

 

Fill in: The Calvin cycle in photosynthesis uses carbon dioxide to build sugars in the __________ of the chloroplast.
Correct answer: stroma
Explanation: The stroma contains enzymes for carbon fixation and sugar synthesis.

 

True or False: In animals, the primary function of the large intestine is absorption of most nutrients.
Correct answer: False.
Explanation: The large intestine mainly absorbs water and electrolytes and compacts waste.

 

Multiple choice: Which cellular junction forms a seal that prevents leakage between epithelial cells?
A) Desmosome
B) Gap junction
C) Tight junction
D) Plasmodesma
Correct answer: C) Tight junction
Explanation: Tight junctions prevent passage of materials between cells by sealing their membranes.

 

Short answer: What is a prion?
Correct answer: A prion is a misfolded protein that can induce normal proteins to misfold, leading to protein aggregation without nucleic acids.
Explanation: Prions are infectious proteins that propagate by altering protein conformation.

 

Fill in: The process by which organisms with heritable traits better suited to the environment tend to survive and produce more offspring is called __________ selection.
Correct answer: natural
Explanation: Natural selection drives adaptation by favoring traits that increase fitness.

 

True or False: In coevolution, evolutionary changes in one species can drive changes in another interacting species.
Correct answer: True.
Explanation: Interactions such as predator–prey or mutualism can cause reciprocal evolutionary change.

 

Multiple choice: Which statement correctly describes a nucleotide?
A) It is composed of a fatty acid and glycerol
B) It is composed of a sugar, a phosphate group, and a nitrogenous base
C) It is composed of amino acids linked by peptide bonds
D) It is composed of monosaccharides linked by glycosidic bonds
Correct answer: B) It is composed of a sugar, a phosphate group, and a nitrogenous base
Explanation: Nucleotides are the monomers of nucleic acids.

 

Short answer: Define codominance with an example.
Correct answer: Codominance is when both alleles in a heterozygote are fully expressed in the phenotype, such as the AB blood type in humans.
Explanation: Both alleles contribute to the phenotype without blending.

 

Fill in: The type of bond that links amino acids in a protein is called a __________ bond.
Correct answer: peptide
Explanation: Peptide bonds form between the carboxyl and amino groups of adjacent amino acids.

 

True or False: The light reactions of photosynthesis occur in the stroma of the chloroplast.
Correct answer: False.
Explanation: Light reactions occur in the thylakoid membranes; the Calvin cycle occurs in the stroma.

 

Multiple choice: Which process allows water to move up a plant against gravity through the xylem?
A) Active transport of water molecules
B) Cohesion–tension mechanism due to transpiration
C) Root pressure alone
D) Diffusion of water vapor through stomata only
Correct answer: B) Cohesion–tension mechanism due to transpiration
Explanation: Evaporation from leaves pulls water up, with cohesion and adhesion aiding movement.

 

Short answer: What is the main function of the smooth endoplasmic reticulum in many cells?
Correct answer: The smooth endoplasmic reticulum synthesizes lipids, metabolizes some molecules, and stores calcium ions in muscle cells.
Explanation: It lacks ribosomes and is involved in lipid-related processes and calcium storage.

 

Fill in: The scientific name of a species uses binomial nomenclature, which includes the __________ name followed by the __________ name.
Correct answer: genus; species
Explanation: The two-part name uniquely identifies a species.

 

True or False: Gene flow tends to reduce genetic differences between populations.
Correct answer: True.
Explanation: Movement of alleles among populations makes them more genetically similar.

 

Multiple choice: Which term describes a group of genes that are located close together on the same chromosome and tend to be inherited together?
A) Linked genes
B) Codominant genes
C) Polygenic genes
D) Epistatic genes
Correct answer: A) Linked genes
Explanation: Physical proximity reduces recombination between these genes.

 

Short answer: Define primary producer in an ecosystem.
Correct answer: A primary producer is an organism that synthesizes organic compounds from inorganic sources, typically using sunlight or chemical energy.
Explanation: They form the base of the food web by producing biomass.

 

Fill in: The membrane potential of a neuron at rest is typically __________ millivolts, negative inside relative to outside.
Correct answer: about −70
Explanation: Ion gradients and selective permeability create a negative resting potential.

 

True or False: All traits are controlled by a single gene with two alleles.
Correct answer: False.
Explanation: Many traits are polygenic and influenced by multiple genes and the environment.

 

Multiple choice: Which experimental approach separates molecules by size using a porous gel matrix and an electric field?
A) Centrifugation
B) Chromatography
C) Gel electrophoresis
D) Mass spectrometry
Correct answer: C) Gel electrophoresis
Explanation: Molecules migrate through a gel, with smaller molecules moving farther in a given time.

 

Short answer: What is horizontal gene transfer in prokaryotes?
Correct answer: Horizontal gene transfer is the movement of genetic material between organisms other than by descent, such as transformation, transduction, or conjugation.
Explanation: It contributes to rapid genetic change and adaptation.

 

Fill in: In animal development, a ball of cells formed after cleavage is called a __________.
Correct answer: blastula
Explanation: The blastula is a hollow sphere of cells that precedes gastrulation.

 

True or False: The Hardy–Weinberg principle describes conditions under which allele frequencies remain constant in a population.
Correct answer: True.
Explanation: It provides a null model of no evolution when specific assumptions are met.

 

Multiple choice: Which organelle contains catalase and is involved in detoxifying hydrogen peroxide?
A) Lysosome
B) Peroxisome
C) Mitochondrion
D) Nucleus
Correct answer: B) Peroxisome
Explanation: Peroxisomes convert hydrogen peroxide to water and oxygen and perform other oxidation reactions.

 

Short answer: Define community in ecology.
Correct answer: A community is all the populations of different species that live and interact in the same area at the same time.
Explanation: Communities focus on species interactions and diversity.

 

Fill in: A trait that increases an organism’s ability to survive and reproduce in a particular environment is an __________.
Correct answer: adaptation
Explanation: Adaptations enhance fitness under specific conditions.

 

True or False: Microtubules are composed primarily of actin monomers.
Correct answer: False.
Explanation: Microtubules are made of tubulin dimers; microfilaments are made of actin.

 

Multiple choice: Which organ system is primarily responsible for long-distance chemical signaling in animals using hormones?
A) Nervous system
B) Endocrine system
C) Immune system
D) Muscular system
Correct answer: B) Endocrine system
Explanation: The endocrine system secretes hormones into the bloodstream to regulate body processes.

 

Short answer: What is the function of the sodium–potassium pump in animal cells?
Correct answer: It uses energy from adenosine triphosphate to move sodium ions out of the cell and potassium ions into the cell against their gradients, helping maintain membrane potential.
Explanation: The pump is an active transport protein that sustains ion gradients.

 

Fill in: In gene regulation of bacteria, a small molecule that binds a repressor and inactivates it to allow transcription is called an __________.
Correct answer: inducer
Explanation: Inducers relieve repression, enabling gene expression in inducible operons.

 

True or False: The primary role of messenger RNA is to carry amino acids to the ribosome.
Correct answer: False.
Explanation: Transfer RNA carries amino acids; messenger RNA carries the coding information from DNA.

 

Multiple choice: Which process creates recombinant deoxyribonucleic acid molecules by joining sequences from different sources?
A) Cloning by binary fission
B) Recombinant DNA technology using ligase
C) Natural selection
D) Genetic drift
Correct answer: B) Recombinant DNA technology using ligase
Explanation: DNA ligase joins DNA fragments to form recombinant molecules.

 

Short answer: Define trophic cascade.
Correct answer: A trophic cascade is an ecological process where changes at one trophic level, often predators, cause indirect effects across lower trophic levels and alter ecosystem structure.
Explanation: Removing or adding top consumers can reshape communities.

 

Fill in: The type of population growth where growth rate decreases as the population approaches carrying capacity is called __________ growth.
Correct answer: logistic
Explanation: Logistic growth produces an S-shaped curve with a stable maximum.

 

True or False: Water potential determines the direction of water movement in plants, moving from higher water potential to lower water potential.
Correct answer: True.
Explanation: Differences in solute concentration and pressure drive water movement.

 

Multiple choice: Which statement best defines a gene pool?
A) The sum of all genes within an individual
B) The set of all alleles in a population
C) The number of species in a community
D) The combination of genes in a single chromosome
Correct answer: B) The set of all alleles in a population
Explanation: The gene pool includes all genetic variation available to a population.

 

Short answer: What is the function of chaperone proteins?
Correct answer: Chaperone proteins assist in the proper folding of other proteins and help refold or degrade misfolded proteins.
Explanation: They reduce aggregation and promote correct conformation.

 

Fill in: In plants, the movement of sugars from sources to sinks through phloem is called __________.
Correct answer: translocation
Explanation: Pressure-driven flow moves sugars from areas of production to areas of use or storage.

True or False: In animals, antibodies are part of the innate immune response.
Correct answer: False.
Explanation: Antibodies are part of the adaptive immune response produced by B lymphocytes.