They have a higher resolution than electron microscopes.

They can only be used with stained, dead cells.

They can be used to view living cells in real time.

They use beams of electrons instead of light.

Circular DNA

70S ribosomes

A cell wall

Membrane-bound organelles such as mitochondria

The last universal common ancestor of all living organisms.

The first eukaryotic cell with a nucleus.

The last unicellular cyanobacterium to exist.

The oldest known fossilized animal.

High levels of free oxygen in the atmosphere

Frequent volcanic activity and lightning providing energy

Constant low temperatures near 0 °C

An extensive ozone layer blocking ultraviolet radiation

It allows larger genomes with no change in metabolism.

It eliminates the need for membranes.

It creates specialized microenvironments that optimize specific reactions.

It prevents any movement of substances within the cell.

It can divide and differentiate into specialized cell types.

It cannot divide and is fully specialized.

It always contains more chromosomes than other cells.

A single xylem vessel element supports the entire plant.

Each chloroplast performs photosynthesis independently.

Water transport from roots to leaves arises from the combined action of many xylem cells.

A single gene encoding a structural protein.

Halving the chromosome number in gametes

Producing genetic variation in offspring

Producing ATP rapidly in muscle cells

Producing genetically identical nuclei for growth and repair

G1 phase

S phase

G2 phase

M phase

A. Chromosomes align along the equatorial plane of the cell.

B. Sister chromatids separate and move to opposite poles.

C. The nuclear envelope reforms around chromosomes.

D. DNA is replicated.

The separation of sister chromatids.

The division of cytoplasm to form two daughter cells.

The condensation of chromatin into chromosomes.

The replication of DNA.

Repairing damaged DNA by excision

Transporting vesicles along microtubules

Regulating progression through cell cycle checkpoints

Attaching spindle fibers to centromeres

They always undergo apoptosis when DNA is damaged.

They divide only when growth factors are absent.

They remain for long periods in the G0 phase.

They divide uncontrollably due to disrupted cell cycle regulation.

Hydrophobic tails face the aqueous environments.

Hydrophilic heads form the hydrophobic core.

Hydrophobic tails face inward, away from water.

The molecules are arranged randomly.

Phospholipids are fixed in place while proteins do not move.

Integral proteins are embedded in a dynamic lipid bilayer and can move laterally.

The membrane is a rigid structure without flexibility.

Only lipids can move within the membrane, not proteins.

Increasing unsaturated fatty acids decreases membrane fluidity.

Increasing cholesterol at high temperatures increases fluidity.

Increasing unsaturated fatty acids increases membrane fluidity.

Unsaturated fatty acids have no effect on fluidity.

Hydrolyzing ATP to pump ions

Forming a hydrophilic pore that allows specific solutes to diffuse down their gradient

Binding signaling molecules outside the cell

Catalyzing reactions on the membrane surface

Movement of molecules from a region of high concentration to low concentration without energy or proteins

Movement of water through a selectively permeable membrane

Movement of molecules against a concentration gradient using ATP

Movement of large molecules through a channel protein

Facilitated diffusion requires ATP and carrier proteins.

Facilitated diffusion moves solutes against a concentration gradient.

Facilitated diffusion occurs only in gases.

Facilitated diffusion uses membrane proteins to allow diffusion down a concentration gradient.

Movement of substances down a concentration gradient without energy input

Movement of substances against a concentration gradient using ATP

Movement of only water molecules across the membrane

Movement of ions through channels without any protein involvement

As cell size increases, surface area to volume ratio decreases, limiting efficient exchange with the environment.

Smaller cells have more DNA.

Large cells have faster diffusion rates.

Smaller cells cannot maintain homeostasis.

Its ability to dissolve ionic compounds

Its low specific heat capacity

Its tendency to stick to other water molecules (cohesion)

Its low surface tension

Water molecules are non-polar.

Water forms hydrogen bonds with polar solutes and surrounds ions.

Water cannot dissolve ionic compounds.

Water does not interact with charged molecules.

The concentration of solute in a solution

The pressure exerted by the cell wall

The tendency of water to move from one region to another (water moves from higher to lower water potential)

The pH of a solution

It loses water and plasmolyzes.

It gains water until it becomes turgid, limited by the cell wall.

It bursts, like an animal cell.

No net water movement occurs.

Become turgid.

Show no change in volume.

Lose water and shrivel.

Gain water and burst.

A polymer is broken down by inserting water.

Two monomers join and water is produced as a by-product.

A molecule is oxidized to release energy.

ATP is hydrolyzed to ADP and Pi.

Glucose

Fructose

Sucrose

Cellulose

Long-term storage of energy in adipose tissue

Short-term storage of glucose in liver and muscle cells

Structural support in cell walls

Building the phospholipid bilayer

A glycerol, two fatty acids, and a phosphate group

A glycerol and three fatty acids

A glycerol and three amino acids

Three glycerol molecules and one fatty acid

The linear sequence of amino acids in a polypeptide

The α-helices and β-pleated sheets in a polypeptide

The overall three-dimensional shape of a polypeptide

The association of multiple polypeptide chains

Primary

Secondary

Tertiary

Quaternary

Hydrolysis of the protein into amino acids

A change in the three-dimensional structure due to disruption of bonds, often irreversible

An increase in the number of peptide bonds

The joining of multiple polypeptides into a complex

RNA that carries amino acids to the ribosome

A protein that acts as a biological catalyst

Any molecule that provides energy to a cell

A lipid that stores chemical energy

They are consumed in the reactions they catalyze.

Their active sites bind many unrelated molecules equally well.

Their active sites have specific shapes and chemical properties complementary to the substrate.

They increase the activation energy of the reaction.

The rate decreases steadily.

The rate increases due to more frequent successful collisions between enzyme and substrate.

The enzyme immediately denatures.

The rate remains constant.

Binds to the active site and can be overcome by increasing substrate concentration.

Binds to an allosteric site and cannot be displaced by more substrate.

Permanently inactivates the enzyme by covalent bonding.

Increases the maximum rate (Vmax) of the reaction.

Glucose

ATP

Oxygen

Carbon dioxide

Conversion of pyruvate to CO₂

Oxidation of NADH to NAD⁺

Production of large amounts of ATP in mitochondria

Splitting of glucose into two pyruvate molecules with a small yield of ATP and NADH

It is the substrate of glycolysis.

It donates electrons to the electron transport chain.

It acts as the final electron acceptor in the electron transport chain, forming water.

It is converted to glucose in the Krebs cycle.

Cytosol

Intermembrane space

Mitochondrial matrix

Thylakoid space

Movement of electrons along the electron transport chain

Movement of H⁺ down its electrochemical gradient through ATP synthase to generate ATP

Diffusion of CO₂ across the inner membrane

Transport of pyruvate into the matrix

Reduced to lactate so that NAD⁺ is regenerated and glycolysis can continue

Oxidized completely to CO₂ in the cytosol

Mitochondrial matrix

Stroma

Thylakoid membranes

Cytosol

To fix carbon dioxide into carbohydrates

To absorb light energy and transfer it to reaction centers

To act as the final electron acceptor

To pump protons into the stroma

Glucose and water

NADPH and ATP

Carbon dioxide and water

Electrons, protons (H+), and oxygen gas

Splitting of water in the light-dependent reactions (photosystem II)

Fixation of CO2 in the Calvin cycle

Reduction of NADP+ in the stroma

Regeneration of RuBP

It donates electrons to the reaction center.

It acts as a structural component of the thylakoid membrane.

It is reduced to NADPH in the light reactions and carries reducing power to the Calvin cycle.

It is the primary pigment that absorbs blue light.

Oxygen and NADPH

Carbon dioxide, ATP, and NADPH

Carbon dioxide and oxygen

ATP and oxygen

Carbon dioxide concentration

Temperature of the enzymes

Chlorophyll concentration

Light intensity

The action spectrum measures light absorbed; the absorption spectrum measures oxygen production.

They are unrelated; absorption does not affect photosynthesis.

Peaks in the action spectrum correspond to wavelengths most strongly absorbed by photosynthetic pigments.

The absorption spectrum measures CO₂ uptake at different temperatures.

DNA contains ribose, while RNA contains deoxyribose.

DNA is usually double-stranded, while many RNA molecules are single-stranded.

DNA contains uracil, while RNA contains thymine.

DNA is only found in the cytoplasm, while RNA is only found in the nucleus.

Sugar–phosphate backbones on the inside with bases on the outside

Parallel strands running in the same 5'→3' direction

Sugar–phosphate backbones on the outside, with complementary bases paired by hydrogen bonds on the inside

Two identical strands held together by ionic bonds

Transformation of non-virulent bacteria into virulent forms when mixed with DNA from virulent bacteria

The presence of sulfur in many proteins

The equal amounts of adenine and thymine in DNA

The presence of phosphorous in cell membranes

Only one strand is replicated each cycle.

The original DNA molecule is completely conserved and a new double-stranded copy is made.

Each new DNA molecule consists of two newly synthesized strands.

Each new DNA molecule has one original (parental) strand and one newly synthesized strand.

Each new DNA molecule has two newly synthesized strands.

Each new DNA molecule has two original (parental) strands.

Each new DNA molecule is identical to the parental DNA without any new strands.

Unwinding the double helix

Joining Okazaki fragments together

Adding nucleotides to form a new strand complementary to the template

Removing RNA primers

Synthesizing RNA primers on the template strand

Unwinding the DNA double helix by breaking hydrogen bonds

Ligating gaps between nucleotides

Proofreading newly synthesized DNA

The lagging strand is synthesized discontinuously as Okazaki fragments.

The lagging strand is synthesized only before the leading strand.

The lagging strand is synthesized in the 3'→5' direction.

The lagging strand does not require primers.

To separate DNA fragments by size

To join together DNA fragments from different sources

To introduce random mutations into DNA

To amplify a specific DNA sequence in vitro

A complete set of chromosomes in a cell

A sequence of amino acids in a polypeptide

A specific sequence of DNA that encodes a functional product (polypeptide or RNA)

A complex of DNA and histone proteins

A. A region of DNA that codes for one protein

B. DNA wrapped around an octamer of histone proteins

C. A double-stranded RNA molecule

D. A single DNA strand with no associated proteins

Nucleus

Cytosol

Mitochondrial matrix

To unwind the DNA and ligate fragments

To attach amino acids to tRNA molecules

To add nucleotides to a growing DNA strand

To synthesize an RNA molecule using a DNA template

Introns are removed and exons are joined together to form mature mRNA.

Exons are removed and introns are joined together.

Splicing occurs in prokaryotes only.

Splicing changes the DNA sequence permanently.

Deleting a gene from the genome

Changing the sequence of bases in DNA

Adding methyl groups to cytosine bases in DNA to alter transcription

Replacing one amino acid in a polypeptide with another

They directly change the base sequence of DNA in all cells.

They can modify epigenetic tags (such as DNA methylation), altering how genes are expressed without changing DNA sequence.

They increase the number of chromosomes in a cell.

They permanently remove introns from DNA.

Only in the nucleus

In the nucleolus

In the chloroplasts only

On ribosomes in the cytoplasm or on the rough endoplasmic reticulum

To carry genetic information from DNA to the ribosome

To deliver specific amino acids to the ribosome and pair its anticodon with codons on mRNA

To form the large subunit of the ribosome

To catalyze peptide bond formation using rRNA

No change in the protein if the codon still specifies the same amino acid

A change in a single amino acid in the polypeptide

Both A and B

Growth and tissue repair

Halving the chromosome number to produce haploid gametes

Producing genetically identical daughter cells

DNA replication without cell division

Crossing over between sister chromatids

Random fertilization of gametes

Replication of DNA in S phase

Random orientation of homologous chromosome pairs along the equator in metaphase I

Fusion of two haploid gametes forms a diploid zygote.

Fusion of diploid gametes forms a haploid zygote.

Gametes are always diploid cells.

Zygotes always contain half the chromosomes of somatic cells.

Genotype describes appearance; phenotype describes alleles.

Genotype and phenotype are identical.

Genotype is the combination of alleles; phenotype is the observable characteristics.

Genotype is influenced only by the environment.

1:1

1:2

2:1

3:1

The trait appears equally in males and females.

The trait appears more frequently in males than females.

The trait never skips generations.

Affected males cannot pass the allele to their daughters.

Red and white snapdragons producing pink flowers

A tall plant and a short plant producing all medium-height plants

The human ABO blood group where IA and IB alleles are both fully expressed in individuals with type AB blood

A gene that has more than two alleles in the population

A. A dominant trait

B. A recessive trait

C. A sex-linked trait only

D. A mitochondrial trait only

Assort completely independently

Never recombine

Be inherited together more frequently than expected, producing more parental than recombinant types

Show equal frequencies of all recombinant gametes

Calculate recombination frequency from map distance

Determine the exact genotypes of parents from offspring

Measure mutation rate directly

Assess whether differences between observed and expected results are likely due to chance

Random changes in allele frequencies from one generation to the next

Changes in an individual's phenotype in response to the environment

Differential survival and reproduction of individuals with heritable traits that are better suited to the environment

The inheritance of acquired characteristics

Random fusion of gametes

Increased mutation rate in germ cells

A predator that preferentially eats brightly colored individuals in a population

Changes in body size due to exercise

Mutation and recombination of alleles during meiosis

Seasonal changes in phenotype only

Loss of body parts during an organism’s lifetime

A. Directional selection favors extreme phenotypes at both ends, while stabilizing selection favors extremes.

B. Directional selection reduces genetic variation, while stabilizing selection increases it.

C. Stabilizing selection shifts the mean phenotype, while directional selection favors the mean.

D. Directional selection favors one extreme phenotype, while stabilizing selection favors intermediate phenotypes.

A population migrates without changing genetically.

One ancestral species rapidly gives rise to many species adapted to different niches.

Gene flow between populations increases.

A population experiences stabilizing selection.

A group of organisms with identical DNA sequences

A group of organisms that share similar appearance

A group of organisms that can interbreed and produce fertile offspring

A group of organisms living in the same habitat

Hybrid offspring are sterile.

Hybrid offspring die before reaching sexual maturity.

Two species breed at different times of year.

Offspring have reduced fitness in the environment.

A group of species that share similar habitats

A group consisting of a common ancestor and all its descendants

A group of organisms with analogous structures

A group of organisms that look similar but are not related

Analogous structures because they are used for movement in different environments

Analogous structures because they have similar functions but different structures

Homologous structures because they have similar functions and arose independently

Mutations occur only in response to environmental changes.

Mutations accumulate at a relatively constant rate, so differences in DNA or protein sequences can estimate time since divergence.

Mutations only occur in non-coding regions of DNA.

All genes evolve at the same rate.

All organisms living in a particular area

All species interacting in a community

A group of individuals of the same species living in the same area

All ecosystems on Earth

The number of species that can live in the area

The maximum number of offspring produced by one individual

The number of predators in a food web

The maximum population size that can be sustained long-term by available resources

Only the temperature range it can tolerate

The habitat, resource use, and interactions with other species

Only the type of food it eats

The number of individuals in its population

The position of an organism in a food chain based on how it obtains energy

The number of individuals in a population

The total energy stored in an ecosystem

The rate of photosynthesis in producers

Because no energy is lost as heat

Because producers do not use any energy for respiration

Because much energy is lost as heat, and not all biomass is eaten or assimilated

Cellular respiration by animals

Burning fossil fuels in power plants

Formation of limestone from marine organisms’ shells accumulating on the seabed

Volcanic eruptions releasing CO₂

Transport of sugars from leaves to roots

Transport of water and mineral ions from roots to shoots

Storage of starch in roots

Production of pollen grains