Biology final

Aerobic organisms use ____ as the final electron acceptor in electron transport phosphorylation.

02

The snapdragon plant exhibits incomplete dominance for flower color. RR plants produce red flowers; rr plants produce white flowers; Rr plants produce pink flowers. If two pink-flowered snapdragons are crossed, the phenotypes of their offspring will likely occur in what ratio?

1 red: 2 pink: 1 white

The pH of black coffee is about 5, while the pH of lemon juice is about 2. A change of one unit on the pH scale corresponds to a tenfold change in the amount of hydrogen ions. Lemon juice is therefore approximately ____ times more acidic than black coffee.

1,000

The first fossilized eukaryotes date to about how many years ago?

1.8 billion

An atom of sodium has an atomic number of 11 and a mass number of 23. How many neutrons does it have?

12

For each six atoms of carbon derived from CO2 fixed in the light-independent reactions, how many molecules of PGAL (phosphoglyceraldehyde) are produced?

12

Refer to the accompanying figure. What percentage of the 14C in a fossil still remains after three half-lives?

12.5

An experimenter surveyed one-half acre of a desert preserve and found three cactus wren nests. Assuming that the habitat is fairly uniform, how many nests would he expect to be in the entire 200-acre preserve?

1200

If a diploid organism has a genome consisting of 4 chromosomes, it can produce ____ different combinations of chromosomes through meiosis (disregarding crossing over).

16

A duplicated chromosome has ____ chromatid(s).

2

How many ATP molecules (net yield) are produced per molecule of glucose during glycolysis?

2

Magnesium has 12 protons. How many electrons are in its third energy level?

2

Molecular oxygen is composed of two oxygen atoms that share four electrons. How many covalent bonds exist between the two oxygen atoms?

2

​How many rounds of the citric acid cycle does it take to harvest the energy from one molecule of glucose?

2

The human genome has approximately ____ protein-coding genes.

20,000

The DNA molecule is made up of ____ strand(s) and most RNA molecules are made up of ____ strand(s)

2;1

The DNA molecule is made up of ____ strand(s) and most RNA molecules are made up of ____ strand(s).

2;1

​For each molecule of CO2 that enters the Calvin-Benson cycle, ____ NADPH molecules are reduced and ____ molecules of ATP are split into ADP and Pi.

2;2

A fluorine atom (atomic number 9) has _____ electrons in the first energy level, _____ electrons in the second energy level, and _____ electrons in the third energy level.

2;7;0

Which molecule(s) shown in the reaction below represent the product(s)? 2H2 + O2 = 2H2O

2H2O only

A codon consists of ____ nucleotide bases.

3

Arrange the following steps into the order that correctly represents the sequence for the evolution of cells: ​ 1. organic polymers 2. DNA-based cells 3. inorganic molecules 4. organic monomers 5. protocells

3, 4, 1, 5, 2

Dogs have a diploid chromosome number of 78. How many chromosomes do their gametes have?

39

A carbon atom has how many electron vacancies?

4

In fruit flies, red eyes (R) are dominant to sepia eyes (r), and the presence of wings (A) is dominant to wingless (a) flies. If two flies heterozygous for each trait are crossed (RrAa × RrAa), how many different phenotypes would be produced in the offspring?

4

All species on Earth today are descended from a cell that lived as early as ____ years ago.

4 billion

Meiosis typically results in the production of ____ cell(s).

4 haploid

In a population that is in Hardy-Weinberg equilibrium, the frequency of the homozygous dominant genotype is 0.49. The percentage of the population that is heterozygous is ____.

42

​DNA sequencing gives a readout of 5' AATCGGTTG 3' based on the color-labeled nucleotides detected after gel electrophoresis. What is the sequence of the template strand?

5' CAACCGATT 3'

Approximately ____ percent of a sexual reproducer's genes is passed on to each offspring.​

50

The chance that the maternal or the paternal version of any chromosome will end up in a particular nucleus is _____.

50%

How many carbon atoms are depicted in the model in the accompanying figure 3.2B?

6

Of the six carbons in a molecule of glucose, how many are converted to CO2 during aerobic respiration?

6

How many codons constitute the genetic code?

64

There are a total of ____ codons that specify a total of ____ naturally occurring amino acids.

64;20

What is the pH of a solution in which the number of H+ ions equals the number of OH- ions?

7

According to the atomic shell model, the second shell can hold up to ____ electrons.

8

If a parent cell of a certain organism has 16 chromosomes and undergoes meiosis, the resulting cells will have ____ chromosomes.

8

If shape and color of radishes are both due to genes with incompletely dominant alleles, crossing two dihybrid heterozygotes will produce how many different phenotypes?

9

About ____ percent of an individual's genes are the same as in the general population.

99

About _____percent of your DNA is exactly the same as everyone else's

99

The ratio of phenotypes among the offspring of a dihybrid cross is _____.

9:3:3:1

Someone with type AB blood could have which combination of alleles?

A and B

Which molecule(s) in the accompanying figure is/are found in plants?

A and B

Which generalization is a component of the cell theory?

A cell is the smallest unit of life.

What process occurs during cytokinesis in plant cells?

A cell plate forms in the middle of the cell.

What process occurs during cytokinesis in animal cells?

A contractile ring pinches the cytoplasm in two.

What is the basic structure of a fatty acid?

A hydrophobic hydrocarbon "tail" with a hydrophilic carboxyl group "head"

Mitochondria arose from an endosymbiotic relationship between a eukaryotic cell and an aerobic bacterium. Which statement supports this theory?

A mitochondrion has its own DNA in the form of a single circular chromosome, like bacteria.

Which molecule(s) in the accompanying figure is/are indigestible by humans?

A only

How is a protocell similar to a cell?

A protocell can replicate itself.

An example of a homozygous genotype is ____.

AA and aa

​People with type _____ blood are universal recipients.

AB

Light-independent photosynthetic reactions generate _____.

ADP, NADP+, and sugars

In the accompanying figure, letter F represents ____, a product of light-dependent reactions in both the cyclic and noncyclic reactions.

ATP

The nucleotide that serves as an energy carrier in cells is ____.

ATP

Which molecule is produced by the light-dependent reactions of the cyclic pathway?

ATP

What role(s) do ATP and NADPH from the light-dependent reactions play in the conversion of PGA to PGAL in the Calvin-Benson cycle?

ATP donates a phosphate group and NADPH donates electrons and hydrogen.

Which function do mitochondria perform?

ATP generation

What are the products of the light-dependent reactions of photosynthesis?

ATP, NADPH and O2

Motor proteins, fueled by ____, move cellular cargo along tracks of ____.

ATP; microtubules and microfilaments

In most species, the codon _____ signals the start of translation.

AUG

The normal start codon for protein synthesis is ____.

AUG

Which genotype(s) produce(s) a dominant phenotype?

Aa and AA

Why do the cells of photosynthetic organisms contain accessory pigments?

Accessory pigments optimize the amount of energy that can be harvested in specific environments.

ATP contains ____.

Adenine

During transcription, uracil pairs with ____.

Adenine

The Ti plasmid from which plant pathogen is used to transfer genes into plants?

Agrobacterium tumefaciens

Who is credited with being the codiscoverer of the theory of natural selection?

Alfred Wallace

In Engelmann's 1882 experiment, why did bacteria cluster in areas of red or blue wavelengths of light?

Algae photosynthesized most efficiently at those wavelengths, producing needed oxygen.

The allele E4 of the APOE gene is associated with an increased risk of developing _____.

Alzheimer's disease

Homologous chromosomes separate during ____.

Anaphase I

Life probably originated during which geologic time?

Archaean

What is a key feature of autotrophs?

Autotrophs harvest energy directly from the environment.

In the eukaryotic cell depicted in Figure 9.10, what letter identifies the functioning ribosome

B

In the eukaryotic cell depicted in Figure 9.10, what letter identifies the functioning ribosome?

B

In cocker spaniels, black coat color (B) is dominant over red (b), and solid color (S) is dominant over spotted (s). If a red spotted male was crossed with a black solid female and all the offspring from several crosses were only black and solid, the genotype of the female would be ____.

BB SS

The first major split in evolution separated ____.

Bacteria and Archaea

What newly discovered ability may help to explain the success of bdelloids despite their rejection of intraspecies sexual reproduction?

Bdelloids import genetic material from other organisms.

Once an endosymbiotic relationship was established between a bacteria and a eukaryotic cell, what effect did it have on their genomes?

Both genomes evolved so that eventually the host and the bacteria became incapable of living independently.

Which type(s) of plants have adapted to hot, dry conditions by minimizing photorespiration?

C4 and CAM

If the metabolic pathway in the accompanying figure is regulated by feedback inhibition, ____ inhibits the activity of ____.​

C; enzyme 1

Methane (CH4) is a natural gas that is often used as a fuel. When it burns in the presence of oxygen, carbon dioxide and water are produced. Replace the "X" in the following reaction of methane combustion to balance the equation. CH4 + 2O2 → CO2 + XH2O

CH4 + 2O2 → CO2 + 2H2O

Which gas is released into the environment when organic material is burned?

CO2

The smallest unit of life that can survive and reproduce on its own is a(n) ____.

Cell

Why do cells make many copies of an mRNA molecule?

Cells have a high RNA turnover.

If a cell's DNA is damaged, the products of ____ genes interact to delay or stop the cell cycle.

Checkpoint

If the earliest self-replicating genetic systems were RNA-based, then what is one reason all organisms have a genome of DNA?

Compared to a double-stranded DNA molecule, single-stranded RNA breaks apart more easily. Hide Feedback

Susan, a mother with type B blood, has a child with type O blood. She claims that Craig, who has type A blood, is the father. He claims that he cannot possibly be the father. Further blood tests ordered by the judge reveal that Craig has genotype AA. What can we predict about the judge's ruling?

Craig is right and will not be ordered to pay child support.

Which naturalist proposed that many species that once existed are now extinct?

Cuvier

According to the accompanying diagram, where are hydrogen ions sequestered?

D

A scientist randomly divided a group of 100 lab rats into two groups of 50. One group was fed regular rat chow while the other was fed the same amount of rat chow with added DDT. Both groups were housed in the same room with the same environmental conditions. At the end of the experiment, rats were weighed and the mean difference calculated. Refer to the accompanying narrative. Which variable(s) were manipulated by the scientist?

DDT only

Which statement best describes the process of gene expression?

DNA is transcribed into RNA, which can be translated into protein

A collection of cells that host different fragments of foreign DNA, often representing an organism's entire genome, is known as a _____.

DNA library

During the production of recombinant DNA, ____ seals the gaps between hybridized DNA fragments.

DNA ligase

Which enzyme is used to copy cDNA into a second strand of DNA?

DNA polymearse

The enzyme used in the polymerase chain reaction (PCR) is ____.

DNA polymerase

Most DNA replication errors occur because _____.

DNA polymerases work very fast

The S stage of the interphase is characterized by _____.

DNA synthesis

In the experiments by Avery, MacLeod, and McCarty, R cells were unable to be transformed by extracts from S cells treated with _____.

DNA-degrading enzymes

The template for transcription is ____ and the template for translation is ____.

DNA; mRNA

In the F2 generation of a cross of DD RR with dd rr, the most common genotype would be ____.

Dd Rr

What prevents the first reactions of glycolysis from running in reverse, thereby building and metabolizing glucose at the same time?

Due to the energy input required for glycolysis to proceed, the reverse reaction would require too much energy to run spontaneously.

In the eukaryotic cell depicted in Figure 9.10, what letter identifies the newly constructed polypeptide?

E

According to the accompanying diagram, the electron transfer chains of the light-dependent reactions are located in which plant structure(s)?

E only

According to the accompanying figure, how does temperature affect the activities of E. coli and T. aquaticus polymerases?

E. coli polymerase functions optimally at higher temperatures than T. aquaticus polymerase.

Which situation is most probable at a metaphase I alignment?

Each side has a mixture of maternal and paternal chromosomes.

The biosphere is _____.

Earth's largest ecosystem

Suppose that it takes three pounds of feed to generate one pound of chicken meat. What happens to the other two pounds of feed?

Energy is both lost in substances that are indigestible, and as heat.

What is the first step of DNA replication?

Enzymes unwind and separate the two strands of DNA.

On a per carbon basis, why are fats a richer source of energy than carbohydrates?

Fatty acid tails contain no oxygen atoms; therefore, more reactions are required for complete oxidation.

Suppose the Pinocchio frog, which was discovered in the remote Foja Mountains in New Guinea, is determined to be a new species based on the biological species concept. Why might the criteria of this concept not be applicable to these frogs?

Geographical barriers may prevent Pinocchio frogs from interbreeding with other frog populations.

Substances targeted for export from the cell are modified and packaged in the ____.

Golgi bodies

Darwin was influenced by a concept that is attributable to Charles Lyell. Which concept is this?

Gradual geologic forces formed Earth's current landscape.

Which process describes the ability of living organisms to maintain an internal environment within a tolerable range?

Homeostasis

Which is the correct format for the scientific name of modern humans?

Homo sapiens

What is one of the very important differences between mitosis and meiosis?

Homologous chromosomes pair up and exchange genetic material only in meiosis.

During light-dependent reactions, ____ accumulates inside the thylakoid compartment.

Hydrogen ions

The transport of ____ across the thylakoid membrane powers ATP production.

Hydrogen ions

How do hydrogen ions facilitate the formation of ATP during electron transfer phosphorylation?

Hydrogen ions flow through ATP synthases to drive electron transfer phosphorylation.

Which condition(s) increase the rate of diffusion through a semipermeable membrane? I. steep concentration gradients II. high temperatures III. large molecules

I and II

Chromosomes are present as attached sister chromatids in which stages? ​ I. metaphase II. telophase III. prophase IV. anaphase

I and III

What is the correct operational sequence of the processes of aerobic respiration? I. glycolysis II. electron transfer III. citric acid cycle IV. acetyl-CoA formation

I → IV → III → I

Why does the ΔF508 allele associated with cystic fibrosis likely persist in the human population despite the fact that it is so harmful?

Individuals heterozygous for ΔF508 are more resistant to certain infections.

Sodium (Na) atoms often lose the single electron that is in their outermost shell. How does losing the electron affect sodium's charge?

It becomes positively charged.

Consider a purple-flowered pea plant with one allele that specifies purple flowers (P) and another allele that specifies white flowers (p). What can we conclude about this pea plant?

It is heterozygous for the gene that encodes flower color; the genotype is Pp and the phenotype is purple flowers.

Which naturalist believed that environmental pressures caused the development of heritable changes in an individual's body?​

Lamarck

Archaea have molecules with reactive side chains in their plasma membrane, so the tails of archaeal phospholipids form covalent bonds with one another. As a result, the plasma membrane is ____.

Less fluid

Why is it difficult to devise a concise definition of "life?"

Living and nonliving things consist of the same basic components.

What evidence supports the hypothesis that the molecular machinery of mitosis remodeled into meiosis?

Many of the same molecules of mitosis are involved in meiosis.

Compare mitosis and meiosis. Which statement is accurate?

Meiosis II resembles mitosis

According to _____, two alleles at any locus are distributed into separate gametes during meiosis.

Mendel's law of segregation

Who demonstrated the possibility of producing organic compounds from gases and water if the mixture is exposed to sparks from an electrode?

Miller and Urey

Why is pH stability important in biological systems?

Most biological molecules function only in narrow pH ranges.

Why is pH stability important for homeostasis?

Most biological molecules function optimally only within a narrow pH range.

Glycolysis depends on a continuous supply of ____.

NAD+

The final steps of both alcoholic and lactate fermentation regenerate ____.

NAD+

Which cofactor is reduced during both glycolysis and the citric acid cycle?

NAD+

During alcoholic fermentation, electrons and hydrogen ions are transferred from NADH to acetaldehyde, forming ____.

NAD+ and ethanol

In the metabolic pathway of ethanol breakdown, as shown in the accompanying figure, ____.​

NAD+ is a coenzyme for both the ADH and ALDH enzymes

Which function does not directly involve the instructions coded in an organism's DNA?

Need for nutrients

The ultimate electron acceptor in aerobic respiration is ____.

O2

Which property is shared by the processes of replication and transcription?

One strand of nucleic acid serves as a template for synthesis of another.

During which epoch did the first major extinction occur?

Ordovician

During which era did the first land plants, fishes, and reef-forming corals appear?

Paleozoic

Which structure makes each amino acid unique, in effect defining the amino acid?

R group

Before DNA, ____ likely served as the genetic material.

RNA

Protein synthesis on the primordial Earth may have been catalyzed by ____ before the evolution of enzymes.

RNA

Transcription is catalyzed by the enzyme ____.

RNA polymerase

Which step occurs first during transcription?

RNA polymerase attaches to the promoter site.

Why is measuring radioisotopes an ideal method for estimating the age of rock layers?

Radioactive decay is only influenced by time.

During enzyme-catalyzed reactions, the substrate is also known as the ____.

Reactant

Chromosomes are duplicated during the ____ phase of the cell cycle.

S

Imagine you have paid for a genetic test from a company that can report your probability of developing Alzheimer's disease based on the presence of a certain allele. This test would be examining your ____ profile.

SNPs

How does sexual reproduction differ from asexual reproduction?

Sexual reproduction involves the mixing of genetic material.

How did Rosalind Franklin contribute to the discovery of the structure of DNA?

She made the first clear x-ray diffraction image of DNA as it occurs in cells.

Why does the evaporation of sweat effectively cool the body?

Since evaporation requires energy to overcome cohesion, heat energy is removed from the body surface.

How do strong acids behave in water?

Strong acids ionize completely in water.

The base of each nucleotide on one strand of DNA pairs with a suitable partner base on the complementary strand. The correct pairing of adenine in a DNA structure is A to _____.

T

The chromosomes have arrived at opposite poles by the beginning of ____.

Telophase

What popular belief of the time did Lyell's theory of uniformity challenge?

The Earth is only 6,000 years old

How do cells harness the energy stored in sugars?

The carbon backbones of sugars are broken down to release energy to make ATP

Why can't humans digest cellulose?

The crosslinked chains of glucose monomers form long, tough fibers.

​How does the cyclic pathway of light-dependent reactions differ from noncyclic reactions?

The cyclic pathway evolved before the noncyclic pathway and does not produce oxygen.

What occurs when glucose molecules are broken apart during cellular respiration?

The energy released is used in ATP synthesis.

How did the emergence of abundant levels of oxygen in Earth's atmosphere first affect life?

The formation of free radicals caused many cells to die out.

Which statement describes the arrangement or properties of electrons in an atom?

The innermost orbital holds two electrons.

During the initiation of translation, the small ribosomal subunit binds mRNA, and then the initiator tRNA base-pairs with mRNA. Which step happens next?

The large ribosomal subunit joins the small subunit.

Why do new combinations of traits occur in the offspring of sexual reproducers?

The offspring inherit new combinations of alleles.

Given the constraints on cell size, how can eukaryotic cells be so much larger than prokaryotic cells?

The presence of membrane-bound organelles effectively increases the area across which substances can pass.

Short hair (L) is dominant to long hair (l). Suppose a short-haired animal of unknown genotype is crossed with a long-haired animal and they produce one long-haired and one short-haired offspring. What do these results indicate?

The short-haired animal was heterozygous

How does the structure of RNA differ from the structure of DNA?

The sugar in an RNA nucleotide is a ribose.

Why do different photosynthetic species have different combination of pigments?

The wavelengths of light that reach the environment differ from habitat to habitat.

Refer to the accompanying figure. Suppose only 10 test subjects had been used in this study and 4 out of 5 participants (80 percent) who ate chips with Olestra® reported intestinal cramps. Given the difference between this result and the actual experimental results of 15.8 percent, what might be the most likely reason for these different results?

There is a sampling error due to a small sample size.

Which statement best describes the movement of sucrose in this system?

There is no net movement of sucrose

The polymerase used in PCR was isolated from ____, which typically lives in ____.

Thermus aquaticus; hydrothermal vents

Twelve PGAL molecules form when six carbon dioxide molecules are attached to six RuBP molecules. Only two of these PGAL molecules are needed to form a 6-carbon sugar. What is the fate of the 10 remaining PGAL molecules?

They are converted to RuBP molecules

Which characteristic(s) do bacteria and archaea have in common?

They have a nucleoid but no nucleus.

If the DNA triplets were ATG and CGT, the mRNA codons would be ____.

UAC and GCA

Which feature of water allows sheets of ice to form on the surface of lakes, thereby insulating the water below and protecting aquatic organisms during winter?

Water is less dense when solid.

Why does ice float on water?

Water molecules are spaced farther apart in ice than in liquid water.

In the accompanying figure, side A contains a 3% sucrose solution and side B contains a 10% sucrose solution. The membrane separating the two sides is permeable to water but impermeable to sucrose. ​Which statement best describes the movement of water in this system?

Water moves in both directions, but net movement is from side A to side B.

By 4.3 billion years ago, what event led to the formation of protocells?

Water pooled in seas.

Two solutions of different solute concentrations are separated by a selectively permeable membrane. How does this affect osmosis?

Water will flow from the hypotonic solution to the hypertonic solution.

A scientist randomly divided a group of 100 lab rats into two groups of 50. One group was fed regular rat chow while the other was fed the same amount of rat chow with added DDT. Both groups were housed in the same room with the same environmental conditions. At the end of the experiment, rats were weighed and the mean difference calculated. Refer to the accompanying narrative. Which dependent variable was measured?

Weight

Which concept is a principle of natural selection?

When resources are limited, individuals of a population compete for them.

According to the accompanying diagram, which letter indicates the chloroplast membrane?

a

In the eukaryotic cell depicted in Figure 9.10, where does transcription occur?

a

A collection of cells containing different fragments of foreign DNA, often representing an organism's entire genome, is called ____.

a DNA library

What commonly serves as a DNA cloning vector?

a bacterial plasmid

A molecule is ____.

a combination of two or more atoms

In the Hardy-Weinberg equation, the term q2 refers to the frequency of ____.

a homozygous recessive genotype at a given locus

A population that has ____ cannot be in Hardy-Weinberg equilibrium.

a low survival rate

Most scientists believe that the dinosaurs went extinct due to ____.

a meteorite impact

The presence of iridium in the K-Pg boundary layer is evidence of ____.

a meteorite impact

A tumor suppressor gene may become an oncogene if _____.

a mutation ruins its product's function

Mitosis ends when ____.​

a new nuclear envelope forms around each cluster of chromosomes

In transcription, ____ is used as a template for the construction of a single new RNA molecule.

a segment of one strand of double-stranded DNA

Transcription produces _____.

a single strand of RNA

The eighteenth-century naturalist Carolus Linnaeus is known for developing ____.

a system for naming and classifying organisms

The first event in photosynthesis is the ____.

absorption of a photon by a photosystem

When more protein is consumed than the body needs to build molecules, amino acids are broken down. The carbon-containing fragments are converted to pyruvate, which enters aerobic respiration at the _____ stage, or to acetyl-CoA which enters aerobic respiration at the _____ stage.

acetyl-CoA formation; citric acid cycle

The citric acid cycle starts as one carbon atom is transferred from _____ to _____ to form citrate.

acetyl-CoA; oxaloacetate

When fats are broken down as energy sources, the fatty acids are converted to ____ and enter ____.

acetyl-CoA; the citric acid cycle

When dissolved in water, a(n) _____ donates H+, while a(n) _____accepts H+.

acid; base

Substances that are ____ give up hydrogen ions when they dissolve in water.

acidic

Enzymes increase the rate of a given reaction by lowering ____ energy.

activation

What is occurring when a transport protein uses energy to pump a solute across a cell membrane against its concentration gradient?

active transport

In any population, some individuals have forms of traits that make them better suited to their environment than others. This is referred to as a(n) ____ trait.

adaptive

The acquisition of a key evolutionary innovation by a species gives evidence for the concept of ____.

adaptive radiation

Which evolutionary process left the Hawaiian honeycreepers vulnerable to extinction following the arrival of Europeans in 1778?

adaptive radiations

While in the Galapagos Islands, Darwin noticed that finches had developed unique traits that suited them to their particular island habitat. This is an example of a(n) ____.

adaptive trait

During transcription, uracil pairs with ____.

adenine

According to the endosymbiont hypothesis, _____ entered and replicated inside a host cell, leading to the formation of mitochondria.

aerobic bacteria

Mitochondria most resemble ____.

aerobic bacteria

A rise in oxygen in Earth's air and seas put organisms that engaged in ____ at a selective advantage.

aerobic respiration

An −OH group is characteristic of ____ and functions to ____.

alcohols and sugars; increase solubility in water

During the metaphase stage of mitosis, _____.

all chromosomes align midway between spindle poles

According to the cell theory, ____.

all living organisms are made up of one or more cells

If tall (D) is dominant to dwarf (d) in plants and two homozygous varieties DD and dd are crossed, then what kind of offspring will be produced?

all tall

Homologous chromosomes may differ from each other in terms of ____.

alleles

Mendel's law of independent assortment states that _____.

alleles at one gene locus on homologous chromosomes tend to be distributed into gametes independently of alleles at other loci

Crossing over mixes up ____.

alleles on homologous chromosomes

When the Great Wall of China was built, it separated plant species on either side of the wall, which has led to genetic diversity. If new plant species arise as a result of this separation, which type of speciation would have occurred?

allopatric

The enzyme aspartate transcarbamoylase (ATCase) catalyzes the first step in the pyrimidine synthesis pathway. When cytosine and uracil nucleotides are present in excess, they bind to sites outside of the active site to inhibit ATCase. This scenario illustrates ____.

allosteric regulation and feedback inhibition

The nuclear pores in the nuclear envelope _____.

allow proteins to enter the nucleus and RNA to leave

A polypeptide chain is composed of ____.

amino acids

Experiments like those first performed by Miller and Urey demonstrated that ____.

amino acids and other organic compounds could form in conditions that mimicked the earth's early atmosphere

Ribosomes can catalyze formation of peptide bonds. This supports the hypothesis that ____.

an RNA world preceded DNA-based genomes

Each tRNA has two attachment sites: ____.

an anticodon and an amino acid binding site

In order for glycolysis to proceed ____.

an input of energy from ATP is required

What is formed when an atom loses or gains an electron?

an ion

The surfaces of an insect wing, a bat wing, and a bird wing provide examples of _____ structures.

analogous

The wings of a bird and the wings of a butterfly are ____ and show morphological ____.

analogous; convergence

The sister chromatids detach from one another and become visibly separated chromosomes during ____.

anaphase

The stage of meiosis that makes descendant cells haploid is ____.

anaphase 1

Sister chromatids are separated during ____ of meiosis.

anaphase 2

Homologous structures share ____.​

ancestry

The first aerobic organisms could live in the presence of oxygen without harm due to the presence of ____.

antoxidants

While related species do share similar genomes, it is the diversity in genes that makes them phenotypically different. How do most genes change and lead to species diversity?

any type of mutation

Which organism arose first?

archaea

In the accompanying figure, the reactions at letter B ____.​

are dependent on light

Two atoms that are joined by an ionic bond _____.

are held together by mutual attraction of opposite charges

An atom of which element is the least reactive?

argon (atomic number 18)

​Humans are solely responsible for ____ selection in certain species.

artificial

In allopatric speciation, species usually form ____.

as a result of a barrier to gene flow

The second law of thermodynamics states that ___

as energy disperses, entropy increases

Mitosis is an example of ____ reproduction.

asexual

When a C3 plant closes stomata during the day, rubisco _____.

attaches O2, instead of CO2, to RuBP

A hydrogen bond is a(n) ____.

attraction between a covalently bonded hydrogen atom and another atom taking part in a separate polar covalent bond

According to the accompanying diagram, in which plant cell structure do the light-independent reactions occur?

b

About 2.5 billion years ago, increased oxygen created a new selective pressure. Oxygen was toxic to many species that had evolved in its absence because it _____.

b. led to the formation of free radicals

Which genetically modified organisms currently make the majority of human insulin for medical purposes?

bacteria

Which organisms lack nuclei?

bacteria

Most genetic engineering involves _____.

bacteria and yeast

Two or more alleles of a gene are circulating at relatively high frequency in a population's gene pool. What term describes this state?

balanced polymorphisms

A single nucleotide polymorphism (SNP) is a(n) _____ carried by a measurable percentage of a population.

base-pair substitution

Sickle cell anemia has been traced to a(n) ____ mutation.

base-pair substitution

Which type of mutation causes sickle-cell anemia?

base-pair substitution

Which structure is an example of an extracellular matrix in animals?

basement membrane

A female from one species does not recognize the mating patterns of a male from another species. What type of reproductive isolation is occurring?

behavioral

Which type of distribution curve indicates a trait varies continuously?

bell curve

​Which molecule(s), derived from cholesterol, plays an important role in the digestion of fats?

bile

The analogy of a key fitting into a lock is descriptive of the ____. binding of substrate to the enzyme's active site

binding of substrate to the enzyme's active site

Allosteric regulation controls reaction rate by ____.

binding regulatory molecules at a site other than the active site

A community of microorganisms living within a shared mass of secreted slime is known as a(n) ____.

biofilm

Many species of bacteria live bound together by a glue-like substance that, among other things, makes up the plaque on human teeth. This is an example of a ____.

biofilm

Which fuel type is generated from renewable sources of energy?

biofuels

Which term refers to the study of the patterns in the distribution of plants and animals around the world?

biogeography

A naturalist is studying morphological patterns that are shared between species in two temperate rainforests that are located on different continents. This is an example of which field of study?

biogeopraphy

What are the molecular reactants for photosynthesis in plants?

both CO2 and H2O

Which domain(s) is/are made up of organisms without nuclei?

both archaea and bacteria

In bacteria and archaea, translation can begin before transcription is complete because ____.

both processes occur in the cytoplasm

During the late 1890s, hunting caused the population size of northern elephant seals to dwindle to about 20 individuals. Although hunting restrictions have since allowed the population to recover, genetic diversity among its members has been greatly reduced, demonstrating _____.

bottleneck

Cellular pH is kept near a value of seven due to the action of ____ that can ____.

buffers; alternately donate and accept H+

The primary characteristics of cystic fibrosis include ____.

buildup of mucus in the passageways and ducts throughout the body

Which food item is an example of a saturated fat?

butter

Because it does not contain introns, researchers prefer to use ____ when working with human genes.

cDNA

Tumor suppressor genes ____.

can become oncogenes when mutated

An oncogene is any gene that _____.

can transform a normal cell into a tumor cell

Which organic molecules can be oxidized by aerobic respiration to yield ATP?

carbohydrates, fats, and proteins

Four of the five items listed below are associated with light-dependent reactions. Select the exception.

carbon fixation

Which part of a fatty acid is hydrophilic?

carboxyl group head

An atom with the same number of electrons and protons _____.

carries no charge

The process by which an enzyme allows a reaction to run much faster than it would on its own is known as ____.

catalyis

Four of the five features below are exclusive to the domain Eukarya. Select the exception.

cell wall

Humans are unable to digest ____.

cellulose

Fluid-filled sacs that may store amino acids, sugars, toxins, and ions in plant cells are called ____.

central vacuoles

Sister chromatids attach to one another at a constricted region called the ____

centromere

The mitotic spindle attaches to chromosomes at the _____.

centromere

What structure may have acted as a boundary for a cell-like environment before protocells formed?

chambers in rocks

Which structure is large enough to be visualized with a light microscope?

chloroplast

In plant and some protist cells, photosynthesis takes place in ____.

chloroplasts

Plastids that are specialized for photosynthesis are known as _____.

chloroplasts

Pigments, other than chlorophylls, are synthesized and stored in ____.

chromoplast

During the telophase stage of mitosis, _____.

chromosomes arrive at opposite spindle poles and loosen up

During the prophase stage of mitosis, _____.

chromosomes condense and attach to the spindle

Short hair-like structures that protrude from the plasma membrane of some eukaryotic cells are called ____.

cilia

A method called ____ uses diagrams to group species based on their shared characteristics.

cladistics

ATP acts as a(n) ____ in many metabolic pathways.

coenzyme

Some enzymes require inorganic or organic molecules for proper function. These molecules are known as ____.

coenzymes and cofactors

The 30-cm floral tube of the flower Angraecum and the 35-cm proboscis of its hawk moth pollinator are the result of ____.

coevolution

Hydrogen bonds in water collectively exert a continuous pull on its individual molecules; therefore, water molecules resist separating from each other. This property is called ____.

cohesion

Which term describes the collection of all populations living in the same area?

community

The study of body plans and structures among groups of organisms is called ____.

comparative morphology

Probes for cloned genes of interest are ____.

complementary nucleotide sequences labeled with a tracer

The genetic code is comprised of the ____.

complete set of 64 mRNA codons

Which features are characteristic of all living organisms?

composed of cells; requires energy and nutrients; must maintain homeostasis; contains DNA as the hereditary material

Monomers are arranged and linked to form polymers by _____ reactions.

condensation

The border across which genes can flow between two populations is called the ____.

contact zone

A bell-shaped curve of phenotypic variation is a representation of ____.

continuous variation

In animal cells, the cytoplasm divides by formation of a ____, while in plant cells, cytoplasmic division occurs by formation of a ____.

contractile ring; cell plate

In the experiment to determine whether Olestra® was linked to stomach cramps, scientists gave some people potato chips containing Olestra® while others were given regular chips. The group fed the regular potato chips served as the _____.

control group

The ATP/ADP cycle _____.

couples endergonic (ADP + Pi → ATP) and exergonic (ATP → ADP + Pi) reactions

In nucleic acids, the sugar of one nucleotide is bound to the phosphate of the adjacent nucleotide by _____ bonds.

covalent

Carbon's importance to life arises from its ability to form four _____ with other atoms.

covalent bonds

New combinations of alleles for the offspring of sexual reproducers are produced by _____.

crossing over and random sorting of chromosomes

The first O2 producing organisms were probably ____.

cyanobacteria

At present, the oldest widely accepted eukaryote microfossils resemble _____.

cysts from marine protists

The distribution of cytoplasm to daughter cells is accomplished during ____.

cytokenisis

Cytoplasmic division is called _____.

cytokinesis

Radiometric dating of the most ancient fossils involves ____.

dating volcanic rocks above and below the fossil-containing layer of sedimentary rock

What may have been a site for the synthesis of organic molecules on the early Earth with its source of hot water and metal ions from rocks?

deep sea hydrothermal vents

Grass growing in a field is eaten by a deer. Later on, the deer dies and its body is decomposed, in part, by bacteria. In this scenario, which organism(s) are consumers?

deer and bacteria

Which nucleotides are used in DNA sequencing reactions?

deoxynucleotides and dideoxynucleotides

A novel trait present in a clade but not in the clade's ancestors is known as a(n) _____.

derived trait

The "natural" use of restriction enzymes by bacteria is to ____.

destroy viral DNA

Which term describes the transformation of one cell into a multicellular adult?

development

Which type of molecular movement is a passive process?

diffusion

Antibiotic resistant strains of bacteria are a modern health concern. Namely, the overuse of antibiotics has promoted the survival of bacteria with alleles that allow resistance. This is an example of ____ selection.

directional

The rise of pesticide-resistant insects in agricultural fields is a prime example of ____ selection.

directional

Warfarin, a compound that interferes with blood clotting, became a popular rat poison in the 1950s. However, by the 1980s, 10 percent of the urban rat population had a mutation that rendered them resistant to warfarin. The favored survival of these mutant rats illustrates the concept of _____.

directional selection

If R is dominant to r, the offspring of the cross of RR with rr will ____.

display the same phenotype as the RR parent

Black-bellied seedcrackers (a type of finch) mainly feed on two types of sedge seeds: hard seeds or soft seeds. Because of this, the bill of a typical black-bellied seedcracker is either 12 millimeters wide, or 15 millimeters wide; bill sizes in between this range are rare. The favored survival of birds with 12 or 15 millimeter bills illustrates the concept of _____.

disruptive selection

Sodium chloride is hydrophilic because it _____.

dissolves easily in water

Change in forelimbs from the ancestor stem reptile to modern vertebrates is an example of morphological _____.

divergence

Four of the five answers listed below are characteristics of living organisms. Select the exception.

diversity

Which is the most diverse and inclusive taxon?

domain

Which type of chemical bond joins the oxygen (atomic number 8) and carbon (atomic number 6) atoms in carbon dioxide (CO2)?

double covalent

To visualize objects smaller than those that can be resolved by a light microscope, a(n) ____ microscope is used.

electron

A(n) ____ is an organized series of reaction steps in which membrane-bound arrays of enzymes and other molecules give up and accept electrons in turn.

electron transfer chain

The highest yield of ATP molecules comes from _____.

electron transfer phosphorylation

Which pathway generates the most ATP?

electron transport chain

The measure of an atom's ability to pull electrons away from another atom is called ____.

electronegativity

A chemical bond is an attractive force that arises between two atoms when their _____ interact.

electrons

For an atom to be electrically neutral, it must have the same number of ____.

electrons and protons only

What happens when a photosystem absorbs energy?

electrons are ejected

Which subatomic particles are arranged in various energy levels or orbitals?

electrons only

The laboratory technique used to separate the DNA fragments produced by automated DNA sequencing is ____.

electrophoresis

The study of early life stages has revealed the conservation of the genes responsible for ____.

embryonic development

Lipids and proteins are synthesized in the ____.

endomembrane system

is always decreasing because some of the energy in every transfer disperses as heat

energy can be neither created nor destroyed

The absence of free oxygen on early Earth _____.

ensured early organic molecules were not broken down by oxidation

Suppose that researchers find a difference in methylation patterns of one gene between two individuals. What may have influenced this difference?

environment

Organic molecules that increase the rate of chemical reactions, such as condensation and hydrolysis, without being changed in the process are known as ____.

enzymes

Consider fur color in dogs, which depends on pigments called melanins. The product of one gene (TYRP1) helps make the brown melanin; a different gene (MC1R) affects which type of melanin is produced. Therefore, both genes, TYRP1 and MC1R, contribute to the fur color. This process is known as _____.

epistasis

In Labrador retrievers, dogs with alleles E and B have black fur. Those with an E and two recessive b alleles have brown fur. Dogs homozygous for the recessive e allele have yellow fur. This is an example of _____.

epistasis

Coat color in one breed of mice is controlled by incompletely dominant alleles so that yellow and white are homozygous, whereas cream is heterozygous. The cross of two cream individuals will produce ____.

equal numbers of white and yellow mice, with twice as many creams as the other two colors individually

Alcoholic fermentation by yeast produces ____.

ethanol and CO2 `

The products of alcoholic fermentation are _____, while the products of lactate fermentation are _____.

ethanol and CO2; lactate

The majority of plants are classified as _____.

eukaryotic producers

Chloroplasts ____.

evolved from cyanobacteria

When protein molecules are used as energy sources, the amino groups of the amino acids are ____ and the carbon backbones enter ____.

excreted as ammonia (NH3); the citric acid cycle

The protein-coding regions of DNA molecules are the ____.

exons only

A testable explanation for a natural phenomenon is a(n) _____.

experiment

The process of carbon fixation involves _____.

extracting carbon atoms from an inorganic source and incorporating them into an organic molecule

A glucose transporter changes shape when it binds to a molecule of glucose. The shape change moves glucose down its concentration gradient to the opposite side of the membrane, where it detaches from the transport protein. What does this illustrate?

facilitated diffusion

A passive process that requires a protein for the movement of a solute across a membrane is known as ____.

facilitated diffusion

Although the concentration of amino acids is typically higher outside the cell than inside, these molecules are too large to pass easily across the plasma membrane; therefore, they enter cells via transport proteins. This is an example of _____.

facilitated diffusion

What is one characteristic of a malignant neoplasm?

failure to anchor properly in tissues

Individuals that are better suited to their environment are likely to have more offspring and pass their genetic material onto future generations. This is referred to as ____.

fitness

Each DNA nucleotide contains a ____.

five-carbon sugar, three phosphate groups, and a nitrogen-containing base

Cells use monosaccharides _____.

for cellular fuel

Due to their instability, free radicals ____.

forcibly donate or remove electrons from other molecules

If free phospholipids were swirled into water, they would ____.

form a lipid bilayer sheets or bubbles, with the hydrophobic tails facing each other

Water is an excellent solvent because of its ability to _____.

form hydrogen bonds

The end result of meiosis is the formation of _____.

four haploid nuclei

The primitive Earth's atmosphere contained very little to no ____.

free oxygen

During aerobic respiration, ____ is/are formed and detoxified by antioxidant molecules in the cell's cytoplasm.

free radicals

Atoms with unpaired electrons, known as ____, are dangerous because they ____.

free radicals; damage biological molecules

The specific chemical properties and behaviors of a given biological molecule derive from its _____.

functional groups

The CFTR gene encodes a protein that ____.

functions as a receptor that alerts the body to the presence of bacteria and moves chloride ions out of epithelial cells

What is the correct order of the three stages of interphase?

g1, s, g2

Which cell type contains only one set of chromosomes?

gamate

In intervals of interphase, G stands for _____.

gap

It is now easier than ever for humans to travel to and live in other parts of the world. Because of this, populations from different parts of the world that were once isolated from each other are now much more likely to interact and breed. This leads to increased ____.

gene flow

Mendel's dihybrid crosses, but not his monohybrid crosses, showed that ____.

gene pairs are sorted into gametes independently of other gene pairs

What term describes all alleles of all the genes in a population?

gene pool

A cancer patient's cells are removed and a new gene is introduced into the cells during growth in cell culture. The cells are then reintroduced into the patient and the inserted gene directs the destruction of the cancer cells. This is an example of ____.

gene therapy

The only cure for a genetic disorder is _____.

gene therapy

What treatment involves the transfer of a normal gene into cells of an individual with the intent to correct a genetic defect or treat a disease?

gene therapy

A linkage group is composed of all ____.

genes on a chromosome

An organism's complete set of genetic material is its ____.

genome

CRISPR is a _____.

genome editing technique

The study of whole-genome structure and function is called ____.

genomics

The taxonomic classification system designates a species by _____.

genus name and specific epithet

Allopatric speciation requires ____.

geographic isolation

The chronology of Earth's history is known as the _____.

geologic time scale

Mutations in BRCA1 and BRCA2 ____.

give rise to neoplasms in the breast

Triglycerides contain ____.

glycerol and fatty acids

In humans, liver and muscle cells require a lot of energy; therefore, these cells contain an abundance of ____.

glycogen

When blood glucose levels decrease (for example, between meals), which energy reserves are tapped first?

glycogen

Pyruvate is the end product of ____.

glycolysis

On his voyage, Darwin observed similarities between fossils of the extinct armored glyptodonts and modern armadillos. This observation led him to reason that ____.

glyptodons were ancient relatives of armadillos

Which term refers to an increase in number, size, or volume in the cells of an organism?

growth

The 5' cap of an mRNA molecule is composed of ____ bases.

guanine

When O2 accepts electrons in aerobic respiration, it is converted to ____.

h2o

Meiosis ____ the parental chromosome number.

halves

Each of the cells formed after meiosis I are ____.

haploid

Gametes are _____.

haploid

Which characteristic is common to all living systems?

has the capacity for growth

C4 and CAM plants _____.

have carbon-fixing adaptations for hot, dry environments

Mitochondria ____.

have their own DNA and ribosomes and divide independently of the cell

As energy is transferred among organisms, some escapes from the environment as ____ energy.

heat

Most of the E. coli strains that reside in the human digestive tract ____.

help with digestion, produce vitamins, and prevent the growth of pathogens

An enzyme found inside a human cell ____.

helps bring reactants to the transition state

Mendel's work with pea plants led him to conclude that _____.

hereditary information passes from one generation to the next in discrete units

In eukaryotes, a DNA molecule wraps at regular intervals around proteins called ____.

histones

About 12 to 24 hours after the last meal, a person's blood sugar level normally varies from 60 to 90 mg per 100 ml of blood, although it may rise to 130 mg per 100 ml after meals high in carbohydrates. Yet, the blood sugar level is maintained within a fairly narrow range, despite uneven intake of sugar. This is possible due to the process of ____.

homeostasis

The process of crossing over occurs between _____.

homologous chromosomes

During anaphase I, _____ separate; during anaphase II, _____ separate.

homologous chromosomes; sister chromatids

If all the offspring of a testcross are alike and resemble the organism being tested, then that parent is ____.

homozygous dominant

Locations where molten rock ruptures a tectonic plate are called ____.

hot spots

Thomas Malthus proposed that ____.

humans reproduce beyond the capacity of their environment to sustain them

A heterozygous individual may also be considered _____.

hybrid

The spontaneous establishment of base pairing between two nucleic acid strands is called _____.

hybridization

According to the pH scale, which substance is the most acidic?

hydrochloric acid, pH=1

During electron transfer phosphorylation, ____ ions accumulate in the intermembrane space of the mitochondria.

hydrogen

The modified nucleotides used in DNA sequencing have a(n) ____ instead of a hydroxyl group on the 3' carbon.

hydrogen

The pH value is a measure of _____ ions in solution.

hydrogen

Which type of bond contributes to a protein's secondary structure?

hydrogen

Which type of bonds account for cohesion of water molecules?

hydrogen

An organic molecule is primarily composed of ____.

hydrogen and carbon

The technique of DNA sequencing depends on modified nucleotides that have a(n) _____.

hydrogen atom instead of a hydroxyl group on the 3′ carbon

Which chemical interaction(s) is/are the weakest?

hydrogen bonds only

The flow of electrons through the electron transfer chain generates a(n) ____ gradient that drives ____ by ____.

hydrogen ion; ATP synthesis; electron transfer phosphorylation

The breakdown of large molecules by the enzymatic addition of water occurs during a(n) ____ reaction.

hydrolysis

Phospholipid fatty acid tails spontaneously cluster together away from the aqueous cellular interior and exterior environment due to their ____ nature.

hydrophobic

Cell membranes contain transmembrane proteins, which span the lipid bilayer with portions of the protein protruding into the aqueous external and internal cellular environments. The protein regions that span the membrane are ____, while the regions that extend from the membrane are ____.

hydrophobic; hydrophilic

As part of the scientific method, a scientist proposes and tests _____.

hypotheses

A scientific theory is a _____.

hypothesis that has not been disproven after many years of testing

In the accompanying figure, side A contains a 3% sucrose solution and side B contains a 10% sucrose solution. The membrane separating the two sides is permeable to water but impermeable to sucrose. ​Side A is ____ to side B.

hypotonic

A cell placed in a(n) ____ solution will ____.

hypotonic; swell

Asexually produced daughter cells are ____

identical to each other and to the mother cell

Mechanisms that adjust phenotype in response to external cues are_____.

important for adaptation

Asexual reproduction is/was evolutionarily advantageous ____.

in favorable, unchanging environments

Energy flows ____ in an ecosystem

in one direction

​When examining the fossil record, organisms most closely related to living species will be found ____.

in the topmost layers

In radishes, red is dominant (RR), white is recessive (rr), and purple color results in heterozygotes (Rr). This is an example of ____.

incomplete dominance

The rate of an enzymatic reaction typically _____.

increases with temperature until the enzyme becomes denatured

A car uses the energy stored in the organic molecules of gasoline to propel the vehicle forward. However, not all the energy contained in the fuel molecules is used for propulsion; instead, some is lost as heat. In this scenario, entropy is ____, illustrating the ____ law of thermodynamics.

increasing; second

According to the law of _____, during meiosis, alleles at one gene locus on homologous chromosomes tend to be distributed into gametes independently of alleles at other loci.

independent assortment

A scientist is investigating the results of varying temperature on the growth rate of a bacterial culture. In this experiment, temperature is the _____.

independent variable

In the experiment with peacock butterflies, researchers noticed that the butterflies folded their wings and made hisses and clicks in the presence of bird predators. They therefore hypothesized that these behaviors helped the butterflies escape predation. Next, they predicted that removal of the spots on the butterfly's wings and/or removal of the ability of the butterfly to hiss and click will result in a greater risk of predation. To arrive at the hypothesis, the researchers used ____, while developing the prediction used ____.

inductive reasoning; deductive reasoning

Pleiotropic genes ____.

influence more than one aspect of phenotype

Eukaryotic nuclei arose through ____.

infoldings of the cell's plasma membrane

The transmission of DNA to offspring is known as ____.​

inheritance

Chromosomal DNA is duplicated in ____.

interphase

Which phase of the cell cycle lasts the longest?

interphase

Intervening, untranslated nucleotide sequences are called ____.

introns

Most eukaryotic genes contain intervening sequences called _____.

introns

Which component is missing in a post-transcriptionally modified mRNA molecule?

introns

Researchers often start with mature mRNA when cloning eukaryotic cDNA because _____.

introns are removed during post-transcriptional processing

The process of crossing over ____.

involves breakages and exchanges being made between homologous chromosomes

Substrate level phosphorylation ____.

involves the direct transfer of a phosphate group from a substrate

Which chemical interactions is/are classified as true chemical bonds?

ionic and covalent bonds

A salt will dissolve in water to form ____.

ions

We know that Earth's early atmosphere contained little or no oxygen gas, because the oldest existing rocks show no evidence of _____.

iron oxidation

Metabolism may have begun when ____ within rocks donated electrons to dissolved carbon monoxide (CO), forming organic compounds.

iron sulfide

The process of phagocytosis _____.

is a form of receptor-mediated endocytosis

The total amount of energy available for doing work in the universe _____.

is always decreasing because some of the energy in every transfer disperses as heat

On an SNP chip, a yellow dot indicates that the individual ____.

is heterozygous for the SNP

An enzyme ____.

is not altered during the course of a reaction

Hawaiian honeycreepers illustrate the diversity that often flourishes due to ____.

isolation throughout archipelagos

The red blood cells shown in the top micrograph of the accompanying figure are immersed in a(n) ____ solution.

isotonic

Why do we perceive chlorophyll a as the color green?

it reflects green light

Critical thinking is the process of ____.

judging the quality of information before accepting it

Which features characterize all prokaryotes?

lacks nuclei

When intense exercise depletes oxygen in muscle cells faster than it can be replenished, these cells will produce ____ by ____.

lactate; lactate fermentation

The combination of glucose and galactose forms ____, the principle sugar found in milk.

lactose

In a cyclic metabolic pathway, the ____.

last step regenerates the reactant for the first step in the pathway

A consistent natural phenomenon that cannot be described by a complete scientific explanation is known as a ____.

law of nature

During endergonic reactions, reactants with ____ free energy are converted to molecules with ____ free energy; therefore, they require a net input of energy in order to proceed.

less;more

Gene therapy is a promising therapeutic tool; however, some unwanted side effects can occur. What did some patients being treated for SCID-X1 develop after gene therapy?

leukemia

A person with one copy of a mutated CFTR gene will ____.

likely be healthy

Most vegetable oils are ____.

liquid at room temperature and unsaturated

​Astrobiologists believe ____ is an essential component for life throughout our universe.

liquid water

Sexually reproducing populations of New Zealand mudsnails are more competitive than asexual reproducers in ____ environments.​

low-phosphate

What serves as the template for the production of cDNA?

mRNA

Anticodons pair with ____.

mRNA codons

During the G2 phase of the cell cycle, most of the cell's activity is directed toward ____.

making the proteins that drive mitosis

During the 1800s, Georges Cuvier, an expert in zoology and paleontology, proposed that _____.

many species that had once existed were now extinct

An allele is dominant if it _____.

masks its paired recessive allele

Hox genes are examples of highly conserved _____ genes.

master

Sometimes, plant species that grow in the same area cannot interbreed because their physical shape has become specialized for different types of pollinators. What type of reproductive isolation is occurring?

mechanical

Which process is a nuclear division mechanism that halves the chromosome number and is a necessary part of gamete formation and sexual reproduction?

meiosis

Which type of RNA is correctly matched with its function?

messenger RNA (mRNA) → contains the protein-building sequence

Which type of RNA carries the protein-building message?

messenger rna

The activities by which cells acquire and process energy are collectively called ____.

metabolism

The chromosomes are aligned midway between the spindle poles during ____.

metaphase

A child more strongly resembles the maternal grandmother than the maternal grandfather. One explanation could be due to random chromosome alignment during which stage of the mother's gamete formation?

metaphase 1

The first amino acid in most proteins is ____.

methionine

Stress-induced depression causes _____.

methylation-based silencing of a nerve growth factor gene

Fibers known as ____ contain the protein actin and help to strengthen and change the shapes of eukaryotic cells.

microfilaments

In pseudopods, elongating ____ cause lobes of cytoplasm to bulge outward, while ____ help to drag the plasma membrane along.

microfilaments; motor proteins

The mitotic spindle is made of ____.

microtubules

Which cytoskeletal element separates the cell's duplicated DNA molecules during eukaryotic cell division?

microtubules

Which organelle converts the energy stored in sugars to ATP by aerobic respiration?

mitochodrion

Electron flow through the electron transport chain drives the flow of hydrogen ions from the ____ to the ____.

mitochondrial matrix; mitochondrial intermembrane space

Four of the five items listed below participate in photosynthesis. Select the exception.

mitochondrion

The citric acid cycle takes place in the ____.

mitochondrion

One function of the Golgi body is to _____.

modify proteins

A checkpoint protein that functions during S stage would likely ____.

monitors the cell's chromosomes for damage during DNA replication

A cross between two individuals identically hybrid for one gene is called a ____ cross.

monohybrid

A group that contains an ancestor in which a derived trait evolved, plus all of its descendants, is called a ____.

monophyletic group

What are the building blocks of carbohydrates?

monosaccharides

Studies show that crocodiles are more closely related to birds and dinosaurs than they are to other reptiles. Based on this evidence, crocodile DNA is _____.

more similar to bird DNA than to that of other reptiles

The main evolutionary advantage of sexual over asexual reproduction is that sexual reproduction produces _____.

more variation among offspring

Possible evolutionary relationships, when determined solely by the study of comparative morphology, may be incorrect due to ____.

morphological convergence

Through ____, a body part of an ancestor is modified differently in different lines of descent.

morphological divergence

The ABO gene is an example of a(n) ____.

multiple allele system

In asexual reproduction, new combinations of genes arise by ____.

mutation

New alleles are created through the process of _____.

mutation

Which ongoing processes drive microevolution?

mutation, natural selection, and genetic drift

Parapatric speciation would be expected to occur most often ____.

near a common border between two populations

The prevalence of iron-sulfide cofactors in organisms supports the hypothesis that life arose _____.

near geothermal vents

An atom of which element possesses electrons in only the first and second energy levels? (The number in parentheses indicates the number of electrons in an atom of that element.)

neon (10)

Most changes in DNA sequence are ____.

neutral

Mutations that neither harm nor help an organism are called ____.

neutral

The mass number of an atom is determined by the number of ____.

neutrons and protons

The nucleus of an atom contains ____.

neutrons and protons

Carbon has several isotopes including 12C and 14C. These isotopes differ in the number of ____.

neutrons only

Which light-dependent photosynthetic pathway generates ATP, NADPH, and O2?

noncyclic pathway

If short hair (L) is dominant to long hair (l), then what fraction of the offspring produced by a cross of Ll × ll will be homozygous dominant?

none

Which structure consists of two lipid bilayers folded together as a single membrane?

nuclear envelope

Proteins embedded in the nuclear envelope that selectively allow substances to cross into and out of the nucleus form ____.

nuclear pores

Which type of DNA mutation is the primary cause of skin cancer?

nucleotide dimer

A dense, irregularly shaped region within the nucleus in which subunits of ribosomes are synthesized is called the ____.

nucleous

Any gene that can transform a normal cell into a tumor cell is called a(n) ____.

oncogene

The accompanying figure illustrates the ____ biological systems.

one-way flow of energy through

Cyanobacteria are the most likely ancestors of chloroplasts because

only cyanobacteria use an oxygen-producing pathway for photosynthesis

DNA synthesis proceeds _____.

only in the 5′ to 3′ direction

Which genotype(s) can produce type O blood?

oo

The fossil record is incomplete because ____.

organisms tend to decay before becoming fossilized

Which compound is associated with aerobic respiration pathways, but not anaerobic pathways?

oxaloacetate

The last intermediate produced in the citric acid cycle is ____, which is also a substrate for the first reaction in this pathway, making the citric acid cycle a(n) ____ metabolic pathway.

oxaloacetate; cyclic

The removal of electrons from a compound is known as ____.

oxidation

Before photosynthesis evolved, ____ was a very small component of Earth's early atmosphere.

oxygen

Life probably never would have emerged if the ancient atmosphere had been the same as the present one, because ____ interferes with the assembly of simple organic compounds.

oxygen

The large land mass that contained all the continents 240 million years ago was called ____.

pangea

The accompanying figure shows the formation of a(n) ____ bond between two ____ during a ____ reaction.

peptide; amino acids; condensation

White blood cells use ____ to remove foreign particles from the blood.

phagocytosis

Which lipids make up most of the cell membrane?

phospholipids

Glucose enters a cell via a glucose transporter. What prevents glucose molecules from moving back through the transporter and leaving the cell?

phosphorylation

Discrete packages of light energy are called ____.

photons

The process by which producers use light energy to make sugars from carbon dioxide and water is known as _____.

photosynthesis

Which process or element was present first?

photosynthesis

Carbon dioxide, water, sugar, and oxygen cycle through the world via ____ (energy capture) and ____ (energy release).

photosynthesis; aerobic respiration

Stromatolites were formed by ____.

photosynthetic bacteria

In the cyclic pathway of the light-dependent reactions, electrons ejected from photosystem I enter the electron transport system before returning to ____.

photosystem I

The electrons that are accepted by NADP+ to form NADPH during the noncyclic pathways of the light-dependent reactions are emitted by ____.

photosystem I

The cyclic pathway of light-dependent reactions uses ____ to absorb light energy and emit electrons.​

photosystem I only

Which organisms are multicellular eukaryotes, the majority of which are photosynthetic producers?

plants

Which structures are common to all cells?

plasma membrane, cytoplasm, and DNA

The cytoplasm of adjoining cells is connected via _____ in plant cells and _____ in animal cells.

plasmodesmata; gap junctions

What is the general term for double-membrane organelles that function in photosynthesis, storage, or pigmentation in plant and algal cells?

plastids

According to the theory of ____, molten rock emanates from the edge of a plate on the Earth's crust, pushing rock on the other side into a trench.

plate tectonics

A(n) _____ gene influences multiple traits.

pleiotropic

A gene that produces multiple effects is called a(n) ____.

pleiotropic gene

Marfan syndrome is a genetic disorder that arises from the mutation in a single gene. This gene, however, has multiple effects in the body. It affects tissue composition of the heart, skin, blood vessels, tendons, and other parts of the body. This gene is an example of a(n) ____.

pleiotropic gene

Water molecules consist of one oxygen atom covalently bonded to two hydrogen atoms. In these covalent bonds, the electrons are pulled toward the oxygen side of the covalent bond, making one side of the molecule slightly negative and the other side of the molecule slightly positive. This characteristic of water is called ____.

polarity

Which biotechnology tool allows many copies of a specific section of DNA to be made very rapidly?

polymerase chain reaction

Biological molecules are composed of building blocks that are linked together to form ____.

polymers

Allopatric and sympatric speciation both occur in the absence of ____.

polyploidy

When many ribosomes simultaneously translate the same mRNA molecule, the structure is called a ____.

polysome

All of the coyotes (Canis latrans) living in the Mojave Desert constitute a(n) ____.

population

Removal of introns, addition of a poly-A tail, and addition of a 5' cap are all events that occur during ____.

post-transcriptional modification

The energy in chemical bonds is a type of _____ energy.

potential

According to research studies performed on mice, what is the effect of knocking out the enzyme telomerase?

premature aging

Pressure that a fluid exerts against its container is called ____.

pressure gradient

The sequence of amino acids represents the ____ structure of proteins.

primary

The hemoglobin protein, responsible for carrying oxygen in red blood cells, is composed of four polypeptide chains: two alpha-globin and two beta-globin. Sickle cell anemia is characterized by a mutation that causes a change in one amino acid in the beta-chain. This change substitutes a hydrophobic amino acid side chain for the normal polar side chain; therefore, these mutant chains stick to other hemoglobin molecules instead of being attracted to water molecules in the cellular environment. As a result, many hemoglobin molecules clump together, forming large fibers and sickle-shaped red blood cells that are unable to deliver needed oxygen to the body's tissues. The sickle cell mutation affects which level(s) of hemoglobin structure?

primary plus abnormal protein aggregation

In a polymerase chain reaction, the DNA _____ determine which portion of the DNA template is amplified.

primers

Fossils found in the lowest geological strata are generally the most ____.

primitive

Abnormally folded proteins that cause normal proteins to midfold are called ____.

prions

Autotrophic organisms are _____.

producers that obtain carbon from inorganic molecules

The first organisms were most probably ____.

prokaryotic

The mitotic spindle becomes visible during ____.

prophase

The nuclear envelope begins to break up in early ____.

prophase

Crossing over occurs in ____.

prophase 1

During _____ of meiosis, homologous chromosomes condense, pair up, and swap segments.

prophase 1

The function of telomeres is to _____.

protect DNA coding sequences from degradation

Researchers have transferred the gene encoding the Bacillus thuringiensis (Bt) protein into plants to _____.

protect crops from insect larvae

The formation of the ozone layer facilitated the movement of life from sea to land by _____.

protecting organisms from UV radiation

Different cell membranes can have different functions depending on the____.

proteins that are anchored to the membrane

Most archaeal cell walls consist of ____, while most bacterial cell walls consist of ____, a polymer of peptides and polysaccharides.

proteins; peptidoglycan

An epidermal growth factor (EGF) stimulates a cell to enter mitosis by binding to a receptor on the cell's plasma membrane. The EGF receptor is a product of a ____ gene.

proto-onco

Normal checkpoint genes encoding proteins that promote mitosis are called ____.

proto-oncogenes

Which subatomic particles are found within an atom's nucleus?

protons and neutrons

Telomeres ____.

provide a buffer against the loss of coding DNA

The flow of hydrogen ions out of the thylakoid compartment ____.

provides energy to produce ATP molecules

After glycolysis is complete, _____ the mitochondrion and _____ is formed.

pyruvate enters; acetyl-CoA

In order to reduce bias and subjectivity, scientists perform experiments that yield ____ results.

quantitative

The association of four subunit peptides in a fully functional molecule of hemoglobin is an example of ____ protein structure.

quaternary

The _____ components of a ribosome cause peptide bonds to form between amino acids

rRNA

Which type of RNA shows enzymatic activity by catalyzing peptide bond formation between amino acids?

rRNA

The process by which a nucleus of an atom breaks up and emits subatomic particles and/or energy is known as ____.

radioactive decay

Genetic equilibrium requires ____.

random mating

The continuous variation of a trait refers to the _____.

range of small differences in a trait

In response to low blood glucose levels, the pancreas produces the hormone glucagon. Glucagon functions by binding to molecules on the surface of liver cells, causing changes in cellular activity that lead to the release of glucose into the blood. The proteins to which glucagon binds are ____.​

recepetor proteins

Which membrane protein is responsible for binding hormones that can trigger changes in the cell's activity?

receptor

Which plasma membrane protein triggers a change in cell activity after binding to a specific signal?

receptor protein

The earliest species known to reproduce sexually was a(n) ____.

red algea

The oldest fossil of a multicellular organism that can be assigned to a modern group is a filamentous _____.

red algea

Chlorophyll a absorbs which color(s) of light?

red, violet, and orange

NAD+ and NADH are coenzymes that carry electrons during glycolysis according to the accompanying reaction. In the accompanying figure, NAD+ is ____ to form NADH and NADH is then ____ to form NAD+.

reduced; oxidized

What provides the cell a margin of safety in the event a mutation occurs in a protein-coding region?

redundancy of the genetic code

A biofilm allows the participating cells to ____.

remain in a favorable location without being swept away

Hydrophobic molecules are ____ water.

repelled by

When nineteenth century scientists compared desert plants, differences in their ____ indicated that these plants could not be as closely related as might otherwise be thought.

reproductive parts

Cytokinesis in plant cells ____.

requires vesicles to cluster at the future plane of division

What benefit does the bacterial gene encoding the Bt protein confer on genetically modified plants?

resistance to insects

Discovery of _____ allowed researchers to cut chromosomal DNA into manageable chunks and to combine DNA fragments from different organisms.

restriction enzymes

Enzymes used to cut DNA molecules in recombinant DNA research are ____.

restriction enzymes

Sexual reproduction ____.

results in new combinations of genetic traits

In animals, large glycogen molecules are broken down into glucose monomers to provide energy during times of low blood sugar levels, such as between meals. This reaction _____.

results in products with less free energy than the reactants

The poison ricin inactivates which of the following cellular organelles?

ribosomes

Which structure is the primary site for the production of polypeptide chains?

ribosomes

The enzyme rubisco fixes carbon by attaching CO2 to ____.

ribulose bisphosphate (RuBP)

Hot spots are places where plumes of molten rock _____.

rupture a tectonic plate

Suppose that in an experiment, data obtained from a subset of samples differ from the results obtained from the entire experimental group. This could be explained by ____.

sampling error

Which type of micrograph gives the most detailed image of the surface of a cell?

scanning electron micrograph

A hypothesis that has been repeatedly and rigorously tested and supported is known as a _____.

scientific theory

The accompanying figure shows the misfolding of the PrPC protein that occurs in variant Creutzfeldt-Jakob disease (vCJD). The misfolding affects the ____ structure of the normal protein.

secondary

The folding of a polypeptide into helices and sheets is an example of _____ protein structure.

secondary

With sexual selection, adaptive forms of a trait are those that give individuals an advantage in _____.

securing mates

What step occurred first in the evolution of life?

self-assembly of organic monomers

DNA is heated at the beginning of each PCR cycle to ____.

separate double-stranded DNA

Electrophoresis _____.

separates DNA fragments by their length

Males are often more colorful, larger, and more aggressive than females. What is the term for these types of differences between the sexes?

sexual dimorphism

Which reproductive strategy would allow the most rapid adaptation to a changing environment?

sexual reproduction

The three birds in the accompanying figure look similar because of their ____.

shared ancestry only

Which group of animals is an example of morphological convergence?

sharks, penguins, and porpoises

A common DNA profiling method is _____.

short tandem repeat analysis

DNA profiling is based on the slight differences that occur in ____ in the human genome.

short tandem repeats

The introduction of a premature stop codon would lead to a(n) _____.

shortened polypeptide chain

In gel electrophoresis, the ____ the DNA fragment, the faster it moves through the gel.

shorter

Of all the different codons that exist, three of them do not encode a particular amino acid. Their role is to ____.

signal translation to stop

Which type of bond is formed whenever atoms share one pair of electrons?

single covalent

A base-pair substitution carried by a measurable percentage of a population is called a ____.

single-nucleotide polymorphism

Copies of chromosomes linked together at their centromeres at the beginning of meiosis are called ____ chromatids.

sister

Following DNA replication, a single chromosome and its copy are attached at the centromere, forming ____ chromatids.

sister

During meiosis II, ____.

sister chromatids separate

During the anaphase stage of mitosis, _____.

sister chromatids separate and move toward opposite spindle poles

Four of the five answers below are traits that are signatures of a eukaryotic cell fossil. Select the exception

small cell wall diameter

Phospholipids that are destined for cell membranes are synthesized in the ____.

smooth endoplasmic reticulum

Wilting of a plant occurs when ____.

soil water becomes hypertonic

Complete reproductive isolation is evidence that what has occurred?

speciation

Restriction enzyme cut ____.

specific DNA nucleotide sequences

​The oldest multicellular eukaryote, a(n) ____, can be found in the Proterozoic fossil record.

sponge

Four of the five answers represent likely mechanisms contributing to how life's first building blocks formed. Select the exception.

spontaneous combustion

In a certain bird species, clutch size (the number of eggs laid by a female in one breeding season) ranges from four to eight, and the most frequent clutch size is six. This phenomenon is an example of ____ selection.

stabilizing

Sociable weavers (a bird) forage in the open for seeds. Birds that are inefficient at foraging cannot survive periods of low food (starvation) because they have too low body weight. Birds that forage too often are fatter and more easily captured by predators. In this case, _____ favors birds with intermediate weight and foraging behaviors.

stabilizing selection

Plants store excess carbohydrates in the form of ____.

starch

Plants store their sugars in the form of _____.

starch

A result that is very unlikely to have occurred by chance alone is said to be _____.

statistically significant

Which species would be considered more primitive based upon the structure of their limbs?

stem reptiles

Many restriction enzymes leave single-stranded tails called ____ ends on DNA fragments.

sticky

Evidence of early cellular life comes from fossil _____.

stromatolites

Each intact ribosome consists of a large and a small subunit made of rRNA and ____.

structural proteins

The transfer of a phosphate group (Pi) from an intermediate in the glycolysis pathway to ADP is an example of harvesting energy by ____.

substrate-level phosphorylation

The only type of speciation observed to occur within a single generation is ____ speciation.

sympatric

The G2 stage of the interphase is characterized by _____.

synthesis of proteins needed for division

Which molecule has an anticodon and binds to the protein-synthesizing machinery?

tRNA

Regions of noncoding DNA that occur at the ends of eukaryotic chromosomes are called ____.

telomeres

The nuclear envelope reforms during ____.

telophase

The rate of diffusion through a semipermeable membrane is slowest when ____.

temperatures are low

At which structural level does a protein become a working molecule?

tertiary

Crossovers are least likely to separate genes _____.

that are close in proximity

The primary reason for hybrid sterility is ____.

that hybrids cannot produce viable gametes

The sharp reduction of the gene pool and the numbers of a population through a severe epidemic is an example of ____.

the bottleneck effect

In the nineteenth century, most people believed that ____.

the characteristics of parents were blended in the offspring

DNA fragments from different organisms can be combined because ____.

the chemical structure of DNA is the same in all organisms

If meiosis did not occur in sexually reproducing organisms, ____.

the chromosome number would double in each generation

During which phase(s) of aerobic respiration is ATP produced directly by substrate-level phosphorylation?

the citric acid cycle and glycolysis

Disruptive selection favors ____.

the extremes at both ends of a range of variation

Four of the five answers listed below are proposed steps leading to the first cells. Select the exception.

the formation of a cell wall

Which occurrence is an example of allopatric speciation?

the genetic divergence of plants on either side of The Great Wall of China

Naturalists were puzzled when they observed body parts with no apparent function. This observation led them to question which traditional theory?

the great chain of being

Microevolution within a population is least likely to be influenced by ____.

the law of dominance

A locus is ____.

the location of a gene on a chromosome

Nearly all eukaryotic cells have mitochondria, but the number varies by the type of cell and by the organism. In general, cells that have the highest demand for energy tend to have ____.

the most mitochondria

Refer to the accompanying figure. What was the independent variable in this experiment?

the presence of Olestra® in the potato chips

Refer to the accompanying figure. What was the dependent variable in this experiment?

the presence of intestinal cramps

Precambrian life was restricted to the sea because _____.

the seawater helped screen out ultraviolet radiation

A cell is _____.

the smallest unit of life

The ultimate source of energy for living organisms is ____.

the sun

Science is _____.

the systematic study of the observable world

If two genes are on the same chromosome, ____.

they are in the same linkage group

Light-dependent photosynthetic reactions take place in the _____.

thylakoid membrane

Light-dependent reactions in plants occur in the ____.

thylakoid membrane

In a DNA-RNA hybrid molecule, the RNA nucleotide adenine pairs with the DNA nucleotide _____.

thymine

Which nitrogenous base is present in DNA but not RNA?

thymine

Which type of junction prevents fluid leakage between cells?

tight junction

Radioactive decay is influenced solely by ____.

time

​While the same genes direct development in all vertebrate lineages, the ____ is partially responsible for variations in the adult forms of vertebrates.

timing of developmental steps

Why is pyruvate reduced to lactate during fermentation?

to regenerate NAD+ from NADH

Why are cells stained prior to viewing with a light microscope?

to visualize transparent internal cellular structures

Suppose that a dinosaur's footprints were preserved, but that its body was not fossilized upon its death. Evidence of the existence of this organism is provided by which type of fossil?

trace

Membrane ____ proteins move specific substances across the membrane, typically by forming a channel

transport

In an experiment, the experimental group is _____.

treated exactly the same as the control group, except for one independent variable

The ____ molecule in the accompanying figure contains ____.

triglyceride; two unsaturated and one saturated fatty acid

What is the most abundant and richest source of energy in vertebrate bodies?

triglycerides​

To clone an adult, the DNA of a somatic cell must be reprogrammed so the parts that trigger embryonic development are ____.

turned back on

Mitosis followed by cytoplasmic division produces ____.

two cells with the same number and types of chromosomes as the parent

Glycolysis converts glucose to ____, with a net yield of ____ ATP and ____ NADH.

two pyruvate molecules; 2; 2

Human cells are considered diploid because they have _____.

two sets of chromosomes

An experimental result that is statistically significant is _____.

unlikely to occur by chance alone

A promoter is found ____ of the gene it controls.

upstream

​A promoter is found ____ of the gene it controls.

upstream

Researchers clone a fragment of DNA by inserting it into a ____.

vector

The wavelength of visible light with the highest energy is ____.

violet

All of these substances assist enzymes during the catalysis of biochemical reactions. Which one is a cofactor (that is, not a coenzyme)?

vitamin B7 (biotin)

Electrons lost by chlorophyll are replaced by electrons donated from ____.

water

The metabolic reactions that occur in all cells require a certain molecule, also believed to be present very early on Earth. What is this molecule?

water

The oxygen released during photosynthesis originates from ____.

water

Plant cuticles, which reduce water loss, are primarily made of ____.

waxes

What substances do plants secrete onto their exposed surfaces to restrict water loss and keep out parasites and other pests?

waxes

Organic molecules ____.

were present on Earth before the appearance of cells

Hardy-Weinberg equilibrium is most likely to be maintained ____.

when there is no gene flow among different populations

Sexual reproduction probably originated _____.

with mutations that affected processes of mitosis

The first cell of a new individual is known as a(n) _____.

zygote

Which cell is diploid?

zygote

​Most major groups of animals had appeared on Earth by the ____ period.

​Cambrian

The order of information flow in gene expression is ____.

​DNA to RNA to protein

The Precambrian began with an Earth that was too hot for life and had no oxygen during the ____ eon.

​Hadean

When hydrogen ions accumulate in the mitochondrial intermembrane space, what prevents them from moving back into the mitochondrial matrix without flowing through ATP synthase?

​Hydrogen ions cannot cross the lipid bilayer of the mitochondrial m

Which statement correctly describes chromosome segregation during meiosis?

​Maternal and paternal chromosomes segregate randomly.

Why is photorespiration an inefficient way to produce sugars?

​Photorespiration only occurs during the night, when the light-dependent reactions are inactive

The molecule in the accompanying figure is ____, the building block of ____.

​a nucleotide; RNA

The molecule in the accompanying figure is ____ derived from ____.

​a steroid; cholesterol

A cell membrane that is selectively permeable ____.

​allows only certain molecules to cross

​A(n) ____ forms from the movement of a tectonic plate over a hot spot.

​archipelago

During times of high sugar production, some PGAL molecules that remain in the chloroplast ____.

​are assembled into starch molecules

Alcoholic fermentation is used to produce ____.

​beer, wine, and bread

​What is the role of DNA?

​carrier of biological information

When nonionic solids dissolve in water, they

​do not dissociate into atoms

Astrobiologists study Earth's ____ to find clues about possible extraterrestrial life.​

​extreme habitats

Alleles of a gene ____.

​have slightly different DNA sequences

​In eukaryotes, transcription occurs in the ____; in prokaryotes, transcription occurs in the ____.

​nucleus; cytoplasm

Genes are found ____.​

​on both strands of a DNA molecule

​During aerobic respiration, glucose becomes ____ and coenzymes become ____.

​oxidized; reduced

​Burning fossil fuels results in a net increase in the amount of CO2 released into the atmosphere because ____.

​photosynthetic organisms cannot recapture all of the CO2 emitted by the burning of fossil fuels

Under intense sunlight, ____.

​the noncyclic pathway stalls and the cyclic pathway provides extra ATP