BIO151 Final Exam Study Quizlet

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Which of the following statements about the DNA in one of your brain cells is TRUE?

It is the same as the DNA in one of your heart cells

If a cell has completed meiosis I and is just beginning meiosis II, which of the following is an appropriate description of its contents?

It has half the amount of DNA as the cell that began meiosis.

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?

It increases the surface for oxidative phosphorylation.

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

It is lost to the environment.

You have isolated a previously unstudied protein, identified its complete structure in detail, and determined that it catalyzes the breakdown of a large substrate. You notice it has two binding sites. One of these is large, apparently the bonding site for the large substrate; the other is small, possibly a binding site for a regulatory molecule. What do these findings tell you about the mechanism of this protein?

It is probably an enzyme that works through allosteric regulation.

As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy?

It is used to establish and maintain a proton gradient.

When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?

It may be used to form a phosphorylated intermediate.

What is the function of the group of amino acids on the RNA polymerase, called the rudder?

It moves template and non-template strands of DNA through channels inside the enzyme.

What is the function of the nuclear pore complex found in eukaryotes?

It regulates the movement of proteins and RNAs into and out of the nucleus.

Why is glycolysis described as having an investment phase and a payoff phase?

It uses stored ATP and then forms a net increase in ATP.

If you were reading off the sequence of amino acids in the figure to a biologist friend, what should the first three letters be? A) M-N-G B) A-P-A C) It does not matter, since the protein has no polarity or directionality.

M-N-G

Different body cells can respond differently to the same peptide hormones because ________.

a target cell's response is determined by the components of its signal transduction pathways

If a cell were unable to produce histone proteins, which of the following would be a likely effect?

The cell's DNA couldn't be packed into its nucleus.

How does a scientific theory differ from a scientific hypothesis?

Theories are usually an explanation for a more general phenomenon; hypotheses typically address more specific issues

_____ in natural science are based on a LOT of evidence

Theory

Why are lipids and proteins free to move laterally in membranes?

There are only weak hydrophobic interactions in the interior of the membrane.

What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA?

There is no difference.

Researchers pulsed rapidly dividing cultured cells with radioactive thymidine for 30 minutes. The cells were then exposed to a solution containing non-radiolabeled thymidine. Cells were analyzed at 2-hour intervals. At the 2-hour time point, no cells appeared to be in the mitosis (M) phase. Only after 4 hours did some labeled cells appear to be in M phase. This result can be explained in the following way:

There seems to be a gap or a lag in the cell cycle, between the synthesis of DNA and cell division.

The primary difference between enhancers and promoter-proximal elements is that enhancers ________.

are at considerable distances from the promoter; promoter-proximal elements are close to the promoter

In comparison to eukaryotes, prokaryotes ________.

are smaller

A hydrocarbon skeleton is covalently bonded to an amino group at one end and a carboxyl group at the other end. When placed in water this molecule would function ________. A) only as an acid because of the carboxyl group B) only as a base because of the amino group C) as an acid and a base D) as neither an acid nor a base E) It is impossible to determine how it would function, based on the information provided.

as an acid and a base

If an organism is diploid and a certain gene found in the organism has 18 known alleles (variants), then any given organism of that species can/must have which of the following?

at most, 2 alleles for that gene

The microtubule-organizing center found in animal cells is an identifiable structure present during all phases of the cell cycle. Specifically, it is known as the ________.

centrosome

A noncompetitive inhibitor decreases the rate of an enzyme reaction by _____.

changing the shape of the enzyme's active site

Cells are ______.

characteristics of prokaryotic and eukaryotic organisms

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through ________.

gap junctions

Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells?

gap junctions

Which one of the following is NOT a component of each monomer used to make proteins? A) a phosphorus atom, P B) an amino functional group, NH2 C) a side chain, R D) a carboxyl group, COOH

a phosphorus atom, P

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely ________.

a plant cell in the process of cytokinesis

What is responsible for termination of transcription in eukaryotic protein-coding genes?

a polyadenylation, or poly(A), signal

In negative control, a gene is switched off when ________.

a regulatory protein binds to DNA and shuts down transcription

If a molecular biologist deleted a sequence of DNA outside the protein-coding region of a gene and found that this increased the rate of transcription, the deleted sequence likely functions as ________.

a silencer

Which of the following mutations is most likely to cause a phenotypic change?

a single nucleotide deletion in an exon coding for an active site

During elongation, RNA polymerase has three prominent channels, or grooves. These channels provide sites for all of the following EXCEPT ________.

a site for the exit of the diphosphates removed from the nucleotide triphosphates

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What is substance X?

a substrate

Some of the proteins that are to be released or will eventually find their way to the cell membrane need to be modified with addition of polysaccharides (sugars). This type of protein maturation is likely to occur in ______.

the Golgi apparatus

An example of a basal transcription factor is ________.

the TATA-binding protein

Death cap mushrooms produce a substance called alpha-amanitin. Alpha-amanitin efficiently blocks synthesis of mRNA, but not of tRNA or rRNA, in eukaryotic organisms. This is possible because alpha-amanitin efficiently interferes with

the action of RNA polymerase II, but not RNA polymerase I or III

A solution of starch at room temperature does NOT readily decompose to form a solution of simple sugars because ________.

the activation energy barrier for this reaction cannot easily be surmounted at room temperature

What ensures that the correct amino acid is added during translation?

the anticodon of a properly formed aminoacyl tRNA

In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to permit ________.

the attachment of microtubules to kinetochores

According to the induced fit hypothesis of enzyme catalysis, ________.

the binding of the substrate changes the shape of the enzyme's active site

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following?

gaps left at the 5' end of the lagging strand

Although the expression of most genes is tightly regulated, some genes are expressed at roughly constant rates. Which of the following genes would you predict to be constitutively (constantly) expressed?

genes that code for cellular infrastructure

Phospholipids and triglycerides both ________. A) contain serine or some other organic compound B) have three fatty acids C) have a glycerol backbone D) have a phosphate

have a glycerol backbone

Recall Pasteur's experiment on spontaneous generation. If he had just warmed the nutrient-rich brother, rather than boiled it, what would have been the likely outcome of his experiment? Cells would ______.

have appeared in both flasks

Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. For the target organ to respond to a particular hormone, it must ________.

have receptors that recognize and bind the hormone molecule

If you were to observe the activity of methylated DNA (gene promoter or protein coding sequence), you would expect it to ________.

have turned off or slowed down the process of transcription

The greatest expression of the lac operon occurs when lactose levels are ________

high and glucose levels are low

In a nucleosome, the DNA is wrapped around ________.

histones

DNA double helices are soluble in water because of all the following except ________ (This has an important practical application for DNA isolation (extraction): when DNA is in alcohol, it is insoluble white-powder-like material that biologists and chemists call "precipitate")

hydrogen at 2' C

Water has a high specific heat because of the _______.

hydrogen bond formed between the hydrogen of one water molecule and the oxygen of another water molecule

What type of bonding is responsible for maintaining the shape of the tRNA molecule?

hydrogen bonding between bases

The amino acids of the protein keratin are arranged predominantly in an α-helix. This secondary structure is stabilized by ________. A) covalent bonds B) peptide bonds C) ionic bonds D) polar bonds E) hydrogen bonds

hydrogen bonds

Why type of bond must be broken for water to vaporize?

hydrogen bonds

which type of interaction stabilizes the α-helix and the β-pleated sheet structures of proteins? A) hydrophobic interactions B) disulfide bonds C) ionic bonds D) hydrogen bonds E) peptide bonds

hydrogen bonds

What type of interaction is directly responsible for the formation of secondary structure? A) peptide bonds between adjacent amino acids B) peptide bonds between nonadjacent amino acids C) hydrogen bonds between sections of the polypeptide backbone D) hydrogen bonds between side chains of amino acids

hydrogen bonds between sections of the polypeptide backbone

The process of photosynthesis probably originated ________.

in prokaryotes

Homologous pairs of chromosomes align opposite to each other at the equator of a cell during ________.

metaphase I of meiosis

Which structure - function pair is mismatched?

microtubule - muscle contraction

which structure-function is wrong?

microtubule-muscle contraction

Movement of vesicles within the cell depends on what cellular structures?

microtubules and motor proteins

Which of the following levels of gene expression allows the most rapid response to environmental change?

post-translational control

If cells are grown in a medium containing radioactive 35S, which of these molecules will be labeled? A) phospholipids B) nucleic acids C) proteins D) amylose E) proteins and nucleic acids

proteins

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?

proteins

In mitochondria, exergonic redox reactions ________.

provide the energy that establishes the proton gradient

Which of the following did Watson and Crick already know when they were trying to determine the structure of DNA? The number of ________.

purines is always the same as pyrimidines

During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is ________.

retained-in-two-pyruvates

Proteins coded for by nuclear DNA but found within mitochondria move from the cytoplasm into mitochondria using ________.

signal sequences (peptides)

An atom has four electrons in its valence shell. What types of covalent bonds is it capable of forming?

single, double, or triple

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

single-strand DNA binding proteins

Which of the following is the most spontaneous reaction? A reaction that is ______.

slightly exothermic and leads to a huge increase in entropy

The liver is involved in detoxification of many poisons and drugs. Thus, liver cells are likely to have abundant ______.

smooth ER

You need to represent a molecule to best illustrate the relative sizes of the atoms involved and their interrelationships. Which representation would work best?

space-filing model

To act as an effective coolant in a car's radiator, a substance has to have the capacity to absorb a great deal of heat. You have a reference book with tables listing the physical properties of many liquids. In choosing a coolant for your car, which table would you check first?

specific heat

When oxygen is released as a result of photosynthesis, it is a direct by-product of ________.

splitting water molecules

A friend of yours calls to say that his car would not start this morning. He asks for your help. You say that you think the battery must be dead. If so, then jump-starting the car from a good battery will solve the problem. In doing so, you are _____.

stating a hypothesis and using that hypothesis to make a testable prediction.

The receptors for steroid hormones are located inside the cell instead of on the membrane surface like most other signal receptors. This is NOT a problem for steroids because ________.

steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane

In mitochondria, chemiosmosis moves protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis moves protons from the ________.

stroma to the thylakoid space

The ATP made during fermentation is generated by ________.

substrate-level phosphorylation

Catabolic pathways _____.

supply energy, primarily in the form of ATP, for the cell's work

Catabolic pathways ________.

supply energy, primarily in the form of ATP, for the cell's work

A cell with an extensive area of smooth endoplasmic reticulum is specialized to _____.

synthesize large quantities of lipids

Hormones bind to membrane-bound or cytoplasmic proteins called receptor (for that protein). Cells with such receptors can respond to the homone's "signal" and thus are that hormone's ________.

target cell

At which level of protein structure are interactions between the side chains (R-groups) most important? A) primary B) secondary C) tertiary D) quaternary E) primary, secondary, tertiary, and quaternary

tertiary

Refer to the figure. Which level of structure is maintained by the disulfide bond? A) primary B) secondary C) tertiary D) quaternary

tertiary

Some photosynthetic organisms contain chloroplasts that lack photosystem II yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be to ________.

test for liberation of O2 in the light

A controlled experiment is one that ______.

tests experimental and control groups in parallel

Reactions that require CO2 take place in

the Calvin cycle alone

Some bacteria are metabolically active in hot springs because ________.

their enzymes have high optimal temperatures

What feature of single nucleotides provides the energy needed for polymerization when nucleic acids are formed?

their phosphate groups

For a tissue or an organ to function as a unit, ________.

there must be cell—cell communication among the cells within a tissue or organ

The functioning of enhancers is an example of ________.

transcriptional control of gene expression

The first law of thermodynamics states that energy cannot be created or destroyed, but only ______ or transformed

transferred

Once a peptide bond has been formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site, what occurs next?

translocation

Cells require which of the following to form cilia or flagella?

tubulin

Somatic cells of roundworms have four individual chromosomes per cell. How many chromosomes would you expect to find in a gamete from a roundworm?

two

In glycolysis, for each molecule of glucose oxidized to pyruvate ________.

two molecules of ATP are used and four molecules of ATP are produced.

What component of amino acid structure varies among different amino acids? A) the long carbon-hydrogen tails of the molecule B) the presence of a central C atom C) the components of the R-group D) the glycerol molecule that forms the backbone of the amino acid

the components of the R-group

What is a telomere?

the ends of linear chromosomes

Which of the following events takes place in the electron transport chain?

the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle

When biological membranes are frozen and then fractured, they tend to break along the middle of the bilayer. The best explanation for this is that ________. a.the hydrophobic interactions that hold the membrane together are weakest at this point b. hydrophilic interactions between the opposite membrane surfaces are destroyed on freezing c. water that is present in the middle of the bilayer freezes and is easily fractured d. the carbon—carbon bonds of the phospholipid tails are easily broken the integral membrane proteins are not strong enough to hold the bilayer together

the hydrophobic interactions that hold the membrane together are weakest at this point.

The leading and the lagging strands differ in that ________.

the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction

The tertiary structure of a protein is the ________. A) bonding together of several polypeptide chains by weak bonds B) order in which amino acids are joined in a polypeptide chain C) unique three-dimensional shape of the fully folded polypeptide D) organization of a polypeptide chain into an α-helix or β-pleated sheet E) overall protein structure resulting from the aggregation of two or more polypeptide subunits

unique three-dimensional shape of the fully folded polypeptide

The mathematical expression for the change in free energy of a system is ΔG=ΔH − TΔS. Which of the following is (are) correct?

ΔG is the change in free energy.

Which of the following is an example of post-transcriptional control of gene expression?

the removal of introns and alternative splicing of exons

The product of the lacI gene is ________.

the repressor

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that ________.

the rules for base pairing between the third base of a codon and tRNA are flexible

Which of the following is the first event to take place in translation in eukaryotes?

the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation. Surprisingly, this stops mitosis. Specifically, Taxol must affect ________.

the structure of the mitotic spindle

What does it mean to say a system's energy is equal to zero?

the system is at equilibrium

In E. coli, if RNA polymerase apoenzyme is missing ________, then transcription initiation would not occur

sigma

When the atoms involved in a covalent bond have the same electronegativity, what type of bond results?

a nonpolar covalent bond

A mutation that disrupts the ability of an animal cell to add polysaccharide modifications to proteins would most likely cause defects in its ________.

Golgi apparatus and extracellular matrix

During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction?

-20 kcal/mol

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?

Which of the boxes marked 1—4 correspond to plants that will be true-breeding?

1 and 4 only

Albinism is an autosomal (not sex-linked) recessive trait. A man and woman are both of normal pigmentation, but both parents have one parent (grandparent) who is albino (without melanin pigmentation). What is the probability that their first child will be an albino? (calculate probability, and multiply those probabilities)

1/4

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?

100

A solution with a pH of 10 has how many fewer protons in it than a solution with a pH of 7?

1000 times

A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be composed of ________.

120 thymine and 120 adenine molecules

From its atomic number of 15, it is possible to predict that the phosphorus atom has ______.

15 protons and 15 electrons

The diploid number of a roundworm species is 4. Assuming there is no crossover, and random segregation of homologs during meiosis, how many different possible combinations of chromosomes might there be in the offspring?

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2?

16; 16

When Mendel crossed yellow-seeded and green-seeded pea plants, all the offspring were yellow seeded. When he took these F1 yellow-seeded plants and crossed them to green-seeded plants, what genotypic ratio was expected?

1:1

Starting with one molecule of glucose, the energy-containing products of glycolysis are ________.

2 NADH, 2 pyruvate, and 2 ATP

If there are 20 chromatids in a cell which is in the G1 phase, how many centromeres are there?

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is ________

3' UCA 5'

Put the following events of bacterial transcription in chronological order.1. Sigma binds to the promoter region.2. The double helix of DNA is unwound, breaking hydrogen bonds between complementary strands.3. Sigma binds to RNA polymerase.4. Sigma is released.5. Transcription begins.

3, 1, 2, 5, 4

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the α form. Which of the following could amylase break down? A) glycogen, starch, and amylopectin B) glycogen and cellulose C) cellulose and chitin D) starch and chitin E) starch, amylopectin, and cellulose

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?

Depending on the trait being considered, there is dominant and recessive phenotype, or some type of mix where the two homozygotes and heterozygote all have different phenotypes. What types of ratios are likely to occur in crosses dealing with a single gene and 2 or more alleles?

3:1, 1:1, 1:2:1

Which of the following, if missing, would usually prevent translation from starting in eukaryotes?

5' cap or AUG codon

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?

5'-AGCT-3' with 5'-TCGA-3'

If the sequence in the coding strand of DNA for a particular amino acid is 5'AGT3', then the anticodon on the corresponding tRNA would be ________.

5'ACU3'

If one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence ________. Hint: you have to start in reverse because it is antiparallel.

5'TGCAAT3'

All of the following are polysaccharides EXCEPT _____. A) lactose B) glycogen C) chitin D) cellulose E) amylopectin

In tigers, a recessive allele causes a white tiger (absence of fur pigmentation). If one phenotypically normal tiger that is heterozygous is mated to another that is phenotypically white, what percentage of their offspring is expected to be white?

50 percent

When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype?

50 percent

How many oxygen molecules (O2) are required each time a molecule of glucose (C6H12O6) is completely oxidized to carbon dioxide and water via aerobic respiration?

The egg of a fruit fly has 4 individual chromosomes. How many chromosomes are in a somatic cell of a fruit fly?

Upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. How many peptide bonds are present in this protein? A) 101 B) 100 C) 99 D) 98 E) 97

As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy? A) It is used to establish and maintain a proton gradient. B) It excites electrons of the reaction center of photosystem I. C) It is lost as heat. D) It is used to phosphorylate NAD+ to NADPH, the molecule that accepts electrons from photosystem I.

Cell walls are used by many different organisms for protection from their environment and structural support. These cell walls must obviously be insoluble in water; otherwise, they would dissolve the first time an organism got wet. Which of the following carbohydrates would you expect to be most soluble in water? A) starch B) peptidoglycan C) cellulose D) chitin

Compare the molecular formula of a carbohydrate (CH2O)n with that of carbon dioxide (CO2). What does the presence of hydrogen atoms in carbohydrates indicate? A) Carbohydrates are more reduced than carbon dioxide. B) Carbohydrates are more oxidized than carbon dioxide. C) Every carbon atom in a carbohydrate is bonded to four different atoms. D) Carbohydrates contain a carbonyl functional group.

Enzymes that readily break starch apart cannot hydrolyze the glycosidic linkages found in cellulose. Why is this logical? A) The geometry of the bonds is different, and the shapes of enzyme active sites are highly specific. B) Starch is held together by hydrogen bonding, not covalent bonding. C) Cellulose molecules are highly branched, and enzymes are too bulky to fit. D) Starch is held together by peptide bonds, not glycosidic linkages.

For the following question(s), match the labeled component of the cell membrane in the figure with its description. Which component is a protein fiber of the extracellular matrix?

How are the light-dependent and light-independent reactions of photosynthesis related? A) The products of light-dependent reactions are used in light-independent reactions. B) The products of light-independent reactions are used in light-dependent reactions. C) The products of light-independent reactions must be present for light-dependent reactions to take place. D) They are not related.

How do the α and β forms of glucose differ? A) Their ring structures differ in the location of a hydroxyl group. B) Their linear structures differ in the location of a hydroxyl group. C) The α form can be involved in 1,4- and 1,6-glycosidic linkages; the β form can participate only in 1,4 linkages. D) The oxygen atom inside the ring is located in a different position.

Humans can digest starch but not cellulose because _____. A) humans have enzymes that can hydrolyze the α-glycosidic linkages of starch but not the β- glycosidic linkages of cellulose B) humans have enzymes that can hydrolyze the β-glycosidic linkages of starch but not the α- glycosidic linkages of cellulose C) starch monomers are joined by covalent bonds and cellulose monomers are joined by ionic bonds D) the monomer of starch is glucose, while the monomer of cellulose is galactose E) the monomer of starch is fructose, while the monomer of cellulose is glucose

If two molecules of the general type shown in the accompanying figure were linked together, carbon-1 of one molecule to carbon-4 of the other, the single molecule that would result would be _____. A) maltose B) fructose C) glucose D) galactose E) sucrose

Starch and cellulose _____. A) are polymers of glucose B) are cis-trans isomers of each other C) can be digested by humans D) are used for energy storage in plants E) are structural components of the plant cell wall

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the α form. Which of the following could amylase break down? A) starch B) cellulose C) chitin D) starch and chitin only E) starch, cellulose, and chitin

The following question is based on the reaction A + B ↔ C+ D shown in the accompanying figure. Which of the following represents the activation energy needed for the enzyme-catalyzed reverse reaction, C + D → A + B, in the figure?

The molecule shown in the accompanying figure is _____. A) a hexose B) a pentose C) a phosphate D) fructose E) maltose

The proteins of the electron transport chain active in the light-dependent reactions ________. A) are membrane proteins present in the thylakoid B) are free proteins present in the thylakoid lumen C) absorb the same wavelengths of light as their associated chlorophylls D) are considered to be part of the reaction center of photosystem I

What does the term insoluble fiber refer to on food packages? A) cellulose B) polypeptides C) starch D) amylopectin E) chitin

What is the primary function of the Calvin cycle? A) synthesizing simple sugars from carbon dioxide B) splitting water and releasing oxygen C) using ATP to release carbon dioxide D) using NADPH to release carbon dioxide E) transporting RuBP out of the chloroplast

Which of the following are directly associated with photosystem I? A ) receiving electrons from the thylakoid membrane electron transport chain B) extraction of hydrogen electrons from the splitting of water C) passing electrons to the cytochrome complex D) harvesting of light energy by ATP E) generation of molecular oxygen

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle? A) ATP and NADPH B) CO2 and glucose C) ADP, i, and NADP+ D) electrons and H+ E) H2O and O2

Which of the following can vary among monosaccharides? A) the number of carbon atoms B) the presence of a carbonyl group C) the presence of hydroxyl groups D) the presence of sulfur groups

Which of the following is NOT a polymer? A) glucose B) starch C) cellulose D) chitin E) DNA

Which of the following would you expect to have the most free energy per gram? The most free energy per gram would be found in a molecule with _____. A) carbon and hydrogen atoms only B) carbon, hydrogen, and oxygen atoms only C) a variety of atoms that are found in cells D) hydrogen and oxygen atoms only

Which of these best reflects the following relationship: monosaccharide versus polysaccharide? A) glucose versus glycogen B) glucose versus fructose C) 1,4-glycosidic linkage versus 1,6-glycosidic linkage D) α-linkage versus β-linkage

Which polysaccharide is an important component in the structure of many animals and fungi? A) chitin B) cellulose C) amylopectin D) amylose

Which of the following is a large organic molecule that is NOT assembled by polymerization of a few kinds of simple subunits?

A steroid

How does termination of translation take place?

A stop codon is reached

Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?

Golgi-derived vesicles

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same. If you examine side A after three days, you should find ________.

A decrease in the concentration of NaCl and a decrease in the water level

Which of the following observations may have resulted in the hypothesis that a codon is made up of three bases?

A codon of three bases in length, from four different bases, would code for a maximum of sixty-four different amino acids

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?

A gene from an organism can theoretically be expressed by any other organism

Which of the following factors would tend to increase membrane fluidity?

A greater proportion of saturated phospholipids

Which of the following statements is FALSE?

A plant cell continues growing after the secondary cell wall forms but stops growing with the formation of the tertiary cell wall.

Which of the following effects can occur because of the high surface tension of water?

A raft spider can walk across the surface of a small pond

During elongation, which site in the ribosome represents the location where a codon is being read?

A site

Which of the following crosses lipid bilayers the fastest?

A small, nonpolar molecule like oxygen (O2)

Which of the following is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?

A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose

A membrane protein that spans the phospholipid bilayer one or more times is ________.

A transmembrane protein

Which of the following nucleotide triplets best represents a codon?

A triplet in the same reading frame as an upstream AUG

A particular triplet of bases in the template sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is ________.

AAA

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of ________.

ATP, CO2, and ethanol (ethyl alcohol)

Misfolding of polypeptides is a serious problem in cells. Which of the following diseases are associated with an accumulation of misfolded polypeptides? A) Alzheimer's only B) Parkinson's only C) diabetes mellitus only D) Alzheimer's and Parkinson's only E) Alzheimer's, Parkinson's, and diabetes mellitus

Alzheimer's and Parkinson's only

A black guinea pig crossed with an albino guinea pig produced twelve black offspring. When the albino was crossed with a second black animal, six blacks and six albinos were obtained. What is the best explanation for this genetic situation?

Albino is recessive; black is dominant.

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when lactose enters the cell?

Allolactose binds to the repressor protein.

Which of the following is NOT synthesized from a DNA template?

Amino acids

Which of the following is TRUE for this reaction? 3H2 + N2 <----> 2NH3

Ammonia is being formed and decomposed simultaneously

Suppose several genes are grouped together in a bacterial genome and the group results in an assembly line of enzymes. If one of these genes is mutated and that enzyme is no longer active, this gene must be part of __________________

An Operon

What event accompanies energy absorption by chlorophyll (or other pigment molecules of the antenna complex)?

An electron is excited.

Which of the following allows water to move much faster across cell membranes?

Aquaporins

One interesting and surprising finding regarding the regulation of the ara operon is that it is under both positive and negative control. What protein is responsible for the dual action of this operon?

AraC is responsible for both the positive and negative control of the ara operon.

Lipids ________.

Are insoluble in water

Steroids are considered to be lipids because they ________.

Are not soluble in water

Which of these statements is correct?

At sexual maturity, ovaries and testes produce haploid gametes by meiosis.

A glycosidic linkage is analogous to which of the following in proteins? A) an amino group B) a peptide bond C) a disulfide bond D) a β-pleated sheet

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma (what happens across this membrane and what is that used for by cells). This damage will most directly affect the ________. A) flow of electrons from photosystem II to photosystem I B) synthesis of ATP C) absorption of light energy by chlorophyll D) splitting of water E) reduction of NADP+

Dairy cattle were unknown in Thai culture until recently, and 97 percent of Thai people are lactose intolerant as adults. Which explanation for such widespread lactose intolerance is most likely correct? A) Allergies are becoming more common in humans as more chemicals are being encountered during longer lifetimes. B) Evolutionarily, producing an enzyme to break down a sugar that will never be encountered is wasteful. C) The ability to digest sugar in milk is determined by environment, and most humans are not exposed to milk as a food source beyond childhood years. D) There is no good explanation for this situation in humans.

Glucose (C6H12O6) has a single carbonyl group (-C=O) in its linear form. Based on the number of oxygen atoms in glucose, how many hydroxyl groups (-OH) would you expect glucose to have? A) 6 B) 5 C) 3 D) 1

How do carbohydrates contain and/or display information for cells? A) Carbohydrates store information in the nucleus. B) Carbohydrates contain and display information at the cell surface. C) Carbohydrates display information used by mitochondria to bond to substrates and catalyze reactions. D) Carbohydrates have no role in containing or displaying information for cells.

In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and ________. A) sugars are sent to most of the cells of the leaves B) carotenoids and other pigments are still present in the leaves C) the degraded chlorophyll changes into many other colors D) water supply to the leaves has been reduced

P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary? A) It obtains carbon from a sugar molecule, so it must have a stronger attraction for electrons than either oxygen or hydrogen. B) It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has. C) It is the receptor for the most excited electron in either photosystem of photosynthesis. D) It transfers its electrons to reduce NADP+ to NADPH. E) It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system.

The molecular formula for glucose is C6H12O6. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions? A) C18H36O18 B) C18H32O16 C) C6H10O5 D) C18H30O15 E) C3H6O3

What is the correct chromosomal condition at prometaphase (before metaphase) of mitosis?

Which of the following do starch and cellulose have in common? A) the type of glycosidic linkage used B) the size of their monosaccharide subunits C) the amount of hydrogen bonding that occurs between parallel strands D) their main function in plants

Which of the following represents the activation energy required for the enzyme-catalyzed reaction in the figure?

Which of the following sequences correctly represents the flow of electrons during photosynthesis? A) NADPH → O2 → CO2 B) H2O → NADPH → Calvin cycle C) H2O → Calvin cycle → photosystem II D) NADPH → electron transport chain → O2 E) NADPH → chlorophyll → Calvin cycle

Why do plants require sunlight? A) Sunlight helps plants break down their food products so they can extract the energy stored in them. B) Sunlight energy can be used by plants to reduce the carbon atoms in carbon dioxide. C) Sunlight oxidizes carbon dioxide and water to form glucose. D) Sunlight can be used directly by plants to perform a number of physiological processes.

You isolate an organic molecule that contains C, H, O, N, and S. This molecule _____. A) is a disaccharide B) could be a glycoprotein C) is a nucleic acid D) could be cellulose or glycogen

Which of the following linkages would you expect to find at a branch point in glycogen or amylopectin? A) α-1,4-glycosidic linkage B) β-1,4-glycosidic linkage C) α-1,6-glycosidic linkage D) β-1,6-glycosidic linkage

Which of the following is the best explanation for why cholesterol decreases the permeability of biological membranes?

Because cholesterol is amphipathic, it fits in between the phospholipids and blocks diffusion through the membrane.

What is the difference between NAD+ and NADP?

Both function as electron carriers, but NADP has a phosphate group and NAD+ does not.

Albinism is an autosomal (not sex-linked) recessive trait. A man and woman are both of normal pigmentation and have one child out of three who is albino (without melanin pigmentation). What are the genotypes of the albino's parents?

Both parents must be heterozygous.

Chitin is a major component of the _____. A) skeleton of mammals B) hydrostatic skeletons of earthworms C) exoskeleton of insects D) body hairs of mammals E) skeleton in birds

Diffusion _____. A) is very rapid over long distances B) requires an expenditure of energy by the cell C) is a passive process in which molecules move from a region of higher concentration to a region of lower concentration D) is an active process in which molecules move from a region of lower concentration to one of higher concentration E) requires integral proteins in the cell membrane

If you were going to develop a new antibiotic against bacteria, you would probably need to become an expert on which of these carbohydrates? A) glycogen B) chitin C) peptidoglycan D) cellulose E) starch

In the metabolic pathway illustrated below, If all products (A-F) are essential for survival, then a strain mutant for the gene encoding enzyme 2 would be able to grow only if the medium was supplemented with ________

Peptidoglycan forms sheets that stiffen the cell walls of bacteria. How is the formation of sheets possible? A) The polysaccharides in peptidoglycan are highly branched and form a network. B) The glycosidic linkages between monosaccharides in peptidoglycan are extraordinarily strong. C) Individual strands are joined by peptide bonds, a type of covalent bond. D) The polysaccharides in peptidoglycan form helical structures, as in cellulose.

Refer to the associated figure. In the branched metabolic pathway indicated in the figure, if enzyme 4 is defective and the amount of each enzyme is constant, you might expect to see an increase in the amount of which intermediate or product?

The molecular formula for glucose is C6H12O6. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions? A) C60H120O60 B) C6H12O6 C) C60H102O51 D) C60H100O50 E) C60H111O51

What is the difference between an aldose sugar and a ketose sugar? A) the number of carbons B) the position of the hydroxyl groups C) the position of the carbonyl group D) One is a ring form, the other is a linear chain

Which of the following best explains why "carbs" (carbohydrates) are advertised by manufacturers of candy bars and sports drinks as a "quick energy boost"? A) The energy in them can be stored as fat, which has high energy per unit weight. B) The carbons in carbohydrates are rich in energy because they are highly oxidized. C) Carbohydrates are reduced molecules that have high-energy electrons. D) This is an advertising gimmick that has no scientific evidence to support it.

Which of the following structural features is common to cellulose, chitin, and peptidoglycan? A) They are all composed of glucose in either the α or β form. B) They all contain peptide bonds. C) They can all form bonds between polymer chains that create parallel strands. D) They are all composed of highly branched fibers.

Which of the listed statements describes the results of the following reaction?C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

C6H12O6 is oxidized and O2 is reduced.

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?

CO2

Alternative RNA splicing ________.

Can allow the production of proteins of different sizes and functions from a single mRNA

Which of the following statements is representative of the second law of thermodynamics?

Cells require a constant input of energy to maintain their high level of organization.

How do cells use the ATP cycle shown in the figure?

Cells use the cycle to recycle ADP and phosphate.

Bacterial and eukaryotic cells primarily control gene expression at the level of transcription. If instead cells exerted control of gene expression primarily at the post-translational level, what would be different?

Cells would expend significantly more energy.

The statement "DNA → RNA → Proteins" ________

Central Dogma

_______ us the process by which DNA is read to make proteins in ALL cells on Earth.

Central dogma

In what way do the membranes of a eukaryotic cell vary?

Certain proteins are unique to each membrane.

Thylakoids, DNA, and ribosomes are all components found in ______.

Chloroplast

Which of the following statements about cellular metabolism is FALSE?

Citric acid cycle is dependent solely on availability of substrate; otherwise, it is unregulated

Codons are three-base sequences that specify the addition of a single amino acid. How do eukaryotic codons and prokaryotic codons compare?

Codons are a nearly universal language among all organisms.

What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?

ER → Golgi → vesicles that fuse with plasma membrane

You have just sequenced a new protein found in mice and observe that sulfur-containing cysteine residues occur at regular intervals. What is the significance of this finding? A) Cysteine residues are required for the formation of α-helices and β-pleated sheets. B) It will be important to include cysteine in the diet of the mice. C) Cysteine residues are involved in disulfide bridges that help form tertiary structure. D) Cysteine causes bends, or angles, to occur in the tertiary structure of proteins.

Cysteine residues are involved in disulfide bridges that help form tertiary structure.

The glucose molecule has a large quantity of energy in its ________.

C—H bonds

Bacteria, insects, and plants use carbohydrates to build structures. Which of the following is true of structural carbohydrates? A) Different types of pentose monomers form the basis of all carbohydrate-based structures. B) Structural carbohydrates show a high degree of branching. C) All structural carbohydrates are made from the same monomer, α-glucose. D) Structural carbohydrates are long strands, which are chemically linked into a network.

Cellulose is _____. A) a polymer composed of fructose monomers B) a storage polysaccharide for energy in plant cells C) used by plants to make glycogen D) a major structural component of plant cell walls E) a monomer of starch.

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified? A) as a pentose B) as a hexose C) as a monosaccharide D) as a disaccharide E) as a polysaccharide

Photorespiration ________. A) generates oxygen and consumes ATP, carbon dioxide, and sugars B) generates ATP and sugars and consumes oxygen and carbon dioxide C) consumes carbon dioxide and generates ATP, sugars, and oxygen D) generates carbon dioxide and consumes ATP and oxygen

Refer to the paragraph about Kawakubo's group. Kawakubo's group created a glycoprotein with a terminal NAG (i.e., a protein with NAG attached to its end). Their hypothesis is that the terminal NAG, and not the protein component, is responsible for the damage to the cell wall in H. pylori. What would be the most appropriate control for testing this hypothesis? A) Grow H. pylori in a test tube (in vitro) with no glycoprotein. B) Destroy the H. pylori by exposing them to a hypotonic solution. Then add the glycoprotein and observe. C) Expose other species of bacteria to the glycoprotein. D) Grow H. pylori in a test tube with a glycoprotein that has its terminal NAG removed.

The following question is based on the reaction A + B ↔ C + D shown in the accompanying figure. Which of the following in the figure would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?

What is the major structural difference between starch and glycogen? A) the types of monosaccharide subunits in the molecules B) the type of glycosidic linkages in the molecule C) whether glucose is in the α or β form D) the amount of branching that occurs in the molecule

What role, if any, did polysaccharides play in chemical evolution? A) Polysaccharides catalyzed chemical reactions. B) Polysaccharides used complementary pairing between monosaccharides to copy themselves. C) Glycosidic linkages formed spontaneously between monosaccharides. D) Polysaccharides played little, if any, role in chemical evolution.

What wavelength of light in the figure is most effective in driving photosynthesis? A) 625 mm B) 730 mm C) 475 mm D) 420 mm E) 575 mm

Which component is a peripheral protein?

Which of the following categories includes all others in the list? A) monosaccharide B) disaccharide C) starch D) carbohydrate E) polysaccharide

Which of the following molecules contains at least one peptide bond? A) glycogen B) cellulose C) chitin D) peptidoglycan

Which of the following polymers contain nitrogen? A) starch B) glycogen C) cellulose D) chitin E) glucose

Which of the following statements best describes the relationship between photosynthesis and respiration? A) Photosynthesis is catabolic; respiration is anabolic. B) Photosynthesis occurs only in plants; respiration occurs only in animals. C) ATP molecules are produced in photosynthesis but not in aerobic respiration. D) Photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules E) Respiration runs the biochemical pathways of photosynthesis in reverse.

Which process is most directly driven by light energy? A) carbon fixation in the stroma B) creation of a pH gradient by pumping protons across the thylakoid membrane C) reduction of NADP+ molecules D) removal of electrons from chlorophyll molecules E) ATP synthesis

Why are there several structurally different pigments in the reaction centers of photosystems? A) They enable the reaction center to excite electrons to a higher energy level. B) They enable the plant to absorb more photons from light energy, all of which are at the same wavelength. C) Excited electrons must pass through several pigments before they can be transferred to electron acceptors of the electron transport chain. D) This arrangement enables the plant to absorb light energy of a variety of wavelengths.

If you wanted to prevent a regulatory protein from directly changing gene expression, you would have to prevent physical contact between the protein and ________.

DNA

In eukaryotic cells, chromosomes are composed of ________.

DNA and proteins

Two potential devices that eukaryotic cells use to regulate transcription are ________.

DNA methylation and histone modification

Which of the following is the strongest evidence that protein structure and function are correlated? A) Proteins function best at certain temperatures. B) Proteins have four distinct levels of structure and many functions. C) Enzymes tend to be globular in shape. D) Denatured (unfolded) proteins do not function normally.

Denatured (unfolded) proteins do not function normally.

If cells of an individual contain the same set of genes, how do these cells become different from each other during development?

Differences in extracellular signals received by each cell lead to differences in the types of regulatory proteins present in each cell.

Which of the following can occur by the process of meiosis but not mitosis?

Diploid cells form haploid cells.

A molecule with the chemical formula C6H12O6 is probably a _____. A) fatty acid B) polysaccharide C) phospholipid D) nucleic acid E) monosaccharide

A primary function of carbohydrates attached to the glycoproteins and glycolipids of animal cell membranes is to _____. A) facilitate diffusion of molecules down their concentration gradients B) actively transport molecules against their concentration gradients C) maintain the integrity of a fluid mosaic membrane D) maintain membrane fluidity at low temperatures E) mediate cell-cell recognition

The following question is based on the reaction A + B ↔ C+ D shown in the accompanying figure. Which of the following represents the activation energy needed for the noncatalyzed reverse reaction, C + D → A + B, in the figure?

The unlettered circle at the top of the accompanying figure shows a diploid nucleus with four chromosomes that have not yet replicated. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is black, and the other is gray. The circles labeled A to E show various combinations of these chromosomes. What is the correct chromosomal condition for one daughter nucleus at telophase of mitosis (not meiosis)?

Where do the enzymatic reactions of the Calvin cycle take place? A) matrix of the mitochondria B) thylakoid space C) thylakoid membranes D) cytosol around the chloroplast E) stroma of the chloroplast

Which of the events listed below occurs in the light reactions of photosynthesis? A) ATP is phosphorylated to yield ADP. B) NADP is produced. C) Carbon dioxide is incorporated into PGA. D) NADPH is reduced to NADP+. E) Light is absorbed and funneled to reaction-center chlorophyll a.

You have discovered an enzyme that can catalyze two different chemical reactions. Which of the following is most likely to be correct?

Either the enzyme has two distinct active sites or the reactants involved in the two reactions are very similar in size and shape.

Ions diffuse across membranes through specific ion channels down ________.

Electrochemical gradient

______ theory explains how eukaryotes have evolved.

Endosymbiosis

During chemical evolution, which of the following occurred in the molecules involved?

Entropy decreased while potential energy increased

Which of the following is TRUE of enzymes?

Enzymes increase the rate of chemical reaction by lowering activation energy to the substrate.

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?

Estrogen binds to specific receptors inside many kinds of cells, each with different responses.

Which of the following statements is a logical consequence of the second law of thermodynamics?

Every chemical reaction must increase the total entropy of the universe.

Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?

Facilitated diffusion

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA?

A substrate-level phosphorylation occurs in the citric acid cycle when ________.

GDP is phosphorylated to produce GTP

When many genes of an organism are globally regulated, those genes are considered as regulon genes. What is the common theme of such genetic regulation?

Genes of regulons are silenced by a common repressor.

More than 99.99% of our cells have the same ______, yet each cell is a little different from the rest.

Genome

Transport vesicles with newly synthesized proteins bind to one side of the ______ and leave from the opposite side with mature proteins.

Golgi apparatus

______ atoms determine the overall chemical behavior of organic molecules (containing carbon).

H, N, and O

A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?

Which of the following statements is TRUE of histones?

Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together.

Which of the following is most critical for the association between histones and DNA?

Histones are positively charged

Why do histones bind tightly to DNA?

Histones are positively charged, and DNA is negatively charged.

Which of the following happens at the conclusion of meiosis I?

Homologous chromosomes of a pair are separated from each other

In solution, why do hydrolysis reactions occur more readily than condensation reactions? A) Hydrolysis increases entropy and is exergonic. B) Hydrolysis decreases entropy and is endergonic. C) Hydrolysis decreases entropy and is exergonic. D) Hydrolysis increases entropy and is endergonic.

Hydrolysis increases entropy and is exergonic.

Which of the following statements best distinguishes scientific hypotheses from scientific theories?

Hypotheses are usually narrower in scope; theories have broader explanatory power

Which of the following is a TRUE statement about sexual versus asexual reproduction?

In sexual reproduction, individuals transmit half of their nuclear genes to each of their offspring.

You have a planar bilayer with equal amounts of saturated and unsaturated phospholipids. After testing the permeability of this membrane to glucose, you increase the proportion of unsaturated phospholipids in the bilayer. What will happen to the membrane's permeability to glucose?

Increase

In the first step of their experiments, Jacob and Monod treated E. colicells with ultraviolet light or X-rays to ________

Increase the frequency of mutations in all genes

When a membrane is freeze-fractured, the bilayer splits down the middle between the two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane, the bumps seen on the fractured surface of the membrane are ________.

Integral Protein

As scientists were unraveling the mysteries associated with transcription and translation in eukaryotes, they discovered there was not a one-to-one correspondence between the nucleotide sequence of a gene and the base sequence of the mRNA it codes for. They proposed the genes-in-pieces hypothesis. How can the genes-in-pieces hypothesis be explained?

Introns are noncoding segments of DNA that are present in the initial transcript, but are removed by splicing.

Which of the following statement about ionic bonds is correct?

Ionic bonds involve the electrical attraction between charged atoms

Which one of the following is TRUE? A codon ________

Is the basic unit of the genetic code

At about pH 7 in most cells, what happens to the amino R-group on an amino acid? A) It acts as a base and gains a proton, giving it a positive charge. B) It acts as an acid and loses a proton, giving it a negative charge. C) It is reduced and tends to act as an electron donor in redox reactions. D) It remains neutral, like water, and does not have a charge.

It acts as a base and gains a proton, giving it a positive charge

At about pH 7 in most cells, what happens to the carboxyl R-group on an amino acid? A) It acts as a base and gains a proton, giving it a positive charge. B) It acts as an acid and loses a proton, giving it a negative charge. C) It is oxidized and tends to act as an electron acceptor in redox reactions. D) It remains neutral, like water, and does not have a charge.

It acts as an acid and loses a proton, giving it a negative charge.

Why is carbon so important in biology?

It can form a variety of carbon skeletons and host functional groups.

Which of the following is TRUE of carbon?

It can form both polar and nonpolar bonds.

There is a mutation in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. Which of these would characterize such a mutant?

It cannot bind to the inducer.

How do enzymes telomerase meet the challenge of repeating the ends of linear chromosomes?

It catalyzes the lengthening of telomerase.

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.

Which of the following is a characteristic feature of a carrier protein (facilitated diffusion) in a plasma membrane? a. It is a peripheral membrane protein. b. It has no hydrophobic regions. c. It works against diffusion. d. It exhibits a specificity for a particular type of molecule. e. It requires the expenditure of cellular energy to function.

It exhibits specificity for a particular type of molecule.

Gramicidin is an antibiotic that increases the permeability of bacterial cell walls to inorganic ions. What is the most likely mode of action of gramicidin?

It forms a channel in the membrane

How is the structure of kinesin related to its function?

Kinesin has a tail region that binds to vesicles and two heads that can attach to microtubules.

The R-group, or side chain, of the amino acid serine is -CH2-OH. The R-group, or side chain, of the amino acid leucine is -CH2-CH-(CH3)2. Where would you expect to find these amino acids in a globular protein in aqueous solution? A) Serine would be in the interior, and leucine would be on the exterior of the globular protein. B) Leucine would be in the interior, and serine would be on the exterior of the globular protein. C) Serine and leucine would both be in the interior of the globular protein. D) Serine and leucine would both be on the exterior of the globular protein.

Leucine would be in the interior, and serine would be on the exterior of the globular protein.

Who performed classic experiments that supported the semiconservative model of DNA replication?

Meselson and Stahl

Which of the following correctly matches a component of the cytoskeleton to one of its functions?

Microtubules move chromosomes.

If photosynthesizing green algae are provided with CO2 containing heavy oxygen (18O), later analysis will show that all of the following molecules produced by the algae contain 18O EXCEPT ________.

What does it mean when we say the genetic code is redundant?

More than one codon can specify the addition of the same amino acid

Rate of an enzyme-catalyzed reaction as a function of varying reactant concentration, with the concentration of enzyme constant. In the accompanying figure, why does the reaction rate plateau at higher reactant concentrations?

Most enzyme molecules are occupied by substrate at high reactant concentrations.

Which of the following statements about NAD+ is TRUE?

NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.

Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of ________.

NADH

Which electron carrier(s) function in the citric acid cycle?

NADH and FADH2

In addition to ATP, what are the end products of glycolysis?

NADH and pyruvate

The light-independent reactions of plants function to make organic molecules using carbon dioxide as a carbon source. What is the electron source that helps reduce carbon dioxide to sugars and other organic molecules?

NADPH

You have two beakers. One contains pure water, the other contains pure methanol (wood alcohol). The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. You pour crystals of table salt (NaCl) into each beaker. Predict what will happen.

NaCl crystals will dissolve readily in water but will not dissolve in methanol

On a NOIR scale, your course section number is on _______ scale.

Nominal Categorical

A phospholipid is a ________.

Nonpolar lipid molecule that is made amphipathic by the addition of a phosphate

Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties?

One allele was dominant.

Which of the following affects the osmolarity of a solution?

Only I and II

The figure shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?

Other pigments absorb light in addition to chlorophyll a.

In what general way are regulons regulated?

Regulons can be under either positive or negative control.

Some fatty acids and lipids are broken down using oxidation. Such processes are likely to occur in ______.

Peroxisomes

In plants, reduction of NADP+ occurs during

Photosynthesis

What is a major difference between the extracellular matrix (ECM) of a plant cell and the ECM of an animal cell?

Plant ECM is primarily carbohydrate in nature, whereas animal ECM is mainly proteins.

How is plant cell cytokinesis different from animal cell cytokinesis?

Plant cells deposit vesicles containing cell-wall building blocks on the metaphase plate; animal cells form a cleavage furrow.

Suppose that an induced mutation removes most of the 5' end of the 5' UTR of an mRNA. What is most likely to happen?

Removal of the 5' UTR also removes the 5' cap and the mRNA will quickly degrade.

Major difference between Eukaryotic DNA replication and Prokaryotic DNA Replication

Prokaryotic chromosomes have a single origin of replication

Independent assortment of chromosomes occurs during ________.

meiosis I only

_____ is thought to have given rise to LUCA because it has been shown in the lab that random assembly of its building blocks can lead to a self-replication molecule.

RNA

The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called ________.

RNA interference

In the process of transcription, ________

RNA is synthesized

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein (one of the protein components of hemoglobin)?

RNA polymerase II

When 10,000 molecules of ATP are hydrolyzed to ADP and i in a test tube, about half asmuch heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the

Reactant and product concentrations in the test tube are different from those in the cell.

Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs (miRNAs) is still not well understood?

Recent advances in technology and our understanding of how DNA is expressed have made this possible.

What is the difference between a ribonucleotide and a deoxyribonucleotide?

Ribonucleotides have a hydroxyl group on the 2 carbon of their sugar subunit.

Which one of the following statements about RNA processing is TRUE?

Ribozymes may function in RNA splicing

which component is a peripheral protein D which component is cholesterol E which component is a protein fiber of the extracellular matrix A which component is a microfilament (actin filament) of the cytoskeleton C which component is a glycolipid B

SCIENCE

Mammals have a family between 500 and 1000 genes that encode receptor proteins on the surface of odor-receptor neurons. If all mammals have these genes, why do some mammals have a better sense of smell than others do?

Some of the genes may have been mutated and rendered inactive in some species but not in others.

The ribosome-binding sequence on mRNA in prokaryotes is also known as the

Shine—Dalgarno sequence

Side A is hypotonic to side B

______ is primarily involved in the synthesis of lipids, phospholipids, and steriods?

Smooth ER

If you mechanically shook a mixture of phospholipids and water, what would you expect to see when you observe the solution using an electron microscope?

Some lipids will have formed tiny vesicles filled with water.

Where would you most likely find an integral membrane protein?

Spanning the cell membrane, with parts of the protein visible from both the inside and the outside of the cell

Why does ice float in liquid water?

Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water.

How does primary protein structure affect the function of protein enzymes? A) Substrates interact with R-groups at the enzyme's active site. B) Substrates interact with R-groups at the enzyme's external surface. C) Substrates interact with hydrophobic R-groups at any region of the enzyme. D) Substrates permanently bind to R-groups at the enzyme's active site.

Substrates interact with R-groups at the enzyme's active site.

The figure below shows a branched metabolic pathway that synthesizes two related amino acids (D and F). If there is a genetic defect, resulting in a nonfunctional enzyme (3), how could you ensure that adequate amounts of the amino acid F are synthesized?

Supplement with intermediate E

Telomere shortening puts a limit on the number of times a cell can divide. Research has shown that telomerase can extend the lifespan of cultured human cells. How might adding telomerase affect cellular aging?

Telomerase eliminates telomere shortening and retards aging.

Scientists have found that polypeptides which are normally synthesized in the endoplasmic reticulum are about 20 amino acids longer when they are synthesized by ribosomes not attached to the endoplasmic reticulum. What is a possible explanation for the greater length of these polypeptides?

The 20 amino acids serve as a signal (peptide) sequence that directs the forming polypeptides to the endoplasmic reticulum, where they are cleaved off during processing.

How does the simple primary and secondary structure of DNA hold the information needed to code for the many features of multicellular organisms?

The base sequence of DNA carries the information needed to code for proteins

In the Morse code, a series of dots and dashes code for letters of the alphabet. (If you do not know Morse code, it is OK - just imagine a language with the above rules.) How is this analogous to the genetic code?

The bases of DNA code for the more complex amino acid sequence of the proteins in cells

To attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur?

The binding of the first two molecules must cause a 3-D change that opens another active site on the enzyme.

The binding of the two molecules must cause a 3-D change in the enzyme.

Which of the following is TRUE when comparing an uncatalyzed reaction to the same reaction with a catalyst?

The catalyzed reaction will have the same ∆G.

Myosin is a motor protein involved in animal cell cytokinesis. It binds to ATP or ADP, causing the myosin to move with respect to actin. What is the effect of the interaction between myosin and actin?

The cleavage furrow deepens.

Which of the following is an exception to the central dogma?

The discovery of RNA viruses that synthesize DNA using reverse transcriptase

According to the table, which enzyme is defective in the strain with the arg2 mutation?

The enzyme that converts ornithine to citrulline

Which of the following mechanism is (are) used to coordinate the expression of multiple, related genes in eukaryotic cells?

The genes share a single common enhancer, which allows appropriate activators to turn on their transcription at the same time

All three domains (Bacteria, Archaea, and Eukarya) follow the same genetic code. Therefore, which of the following statements would most likely be correct?

The genetic code evolved before the different domains diverged

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?

The light reactions provide ATP and NADPH to the Calvin cycle, and the Calvin cycle returns ADP, i, and NADP+ to the light reactions.

A couple has a child with Down syndrome. The mother is 39 years old at the time of delivery. Which of the following is the most probable cause of the child's condition?

The mother most likely underwent nondisjunction during gamete production.

Imagine that you have isolated a yeast mutant that contains a constitutively (constantly) active histone deacetylase. What phenotype do you predict for this mutant?

The mutant will show low levels of gene expression.

Why are hydrocarbons insoluble in water?

The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.

You have just discovered an organism that lives in extremely cold environments. Which of the following would you predict to be TRUE about the phospholipids in its membranes, compared to phospholipids in the membranes of organisms that live in warmer environments?

The membrane phospholipids of cold-adapted organisms will have more unsaturated hydrocarbon tails

Why might adding inorganic phosphate to a reaction mixture where glycolysis is rapidly proceeding help sustain the metabolic pathway?

The metabolic intermediates of glycolysis are phosphorylated.

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed its 5' cap and poly-A tail. Which of the following would you expect her to find?

The molecule is digested by enzymes because it is not protected at the 5' end.

There should be a strong positive correlation between the rate of protein synthesis and ________.

The number of ribosomes

For living organisms, which of the following is an important consequence of the first law of thermodynamics?

The organism ultimately must obtain all of the necessary energy for life from its environment.

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

The pH of the matrix increases.

The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. Which, if any, relationship would you expect to find?

The pH within the thylakoid is less than that of the stroma.

A patient was involved in a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids, distilled water—equal to the volume of blood lost—is added to the blood directly via one of his veins. What will be the most probable result of this transfusion?

The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells

Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together (reverse of polymerization). What would happen to DNA molecules treated with these enzymes?

The phosphodiester linkages of the polynucleotide backbone would be broken.

What does it mean to say that a signal is transduced?

The physical form of the signal changes from one form to another.

How are the light-dependent and light-independent reactions of photosynthesis related?

The products of light-dependent reactions are used in light-independent reactions.

Which of the following correctly describes a reaction that has reached chemical equilibrium?

The rate of the forward reaction is equal to the rate of the reverse reaction

If you were to add one of the eight citric acid cycle intermediates to the culture medium of yeast growing in the laboratory, what do you think would happen to the rates of ATP and carbon dioxide production?

The rates of ATP production and carbon dioxide production would both increase.

Which of the following is TRUE for all exergonic reactions?

The reaction proceeds with a net release of free energy.

Which of the following is directly related to a single amino acid?

The three-base sequence of mRNA

The energy of electron transport serves to move (translocate) protons to the outer mitochondrial compartment. How does this help the mitochondrion produce ATP?

The translocation of protons sets up the electrochemical gradient that drives ATP synthesis in the mitochondria.

How are RNA hairpin turns related to transcriptional termination in E. coli?

The turns are formed from complementary base pairing and cause separation of the RNA transcript and RNA polymerase.

Acetylcholine is a neurotransmitter that binds to receptors on skeletal muscle cells. The receptor—signal complex brings about a series of events that result in contraction of skeletal muscle. Venom from black widow spiders causes an explosive release of acetylcholine. What would that do to its victims?

The victim's muscles would be unable to relax.

Ions diffuse across membranes through specific ion channels down _________.

Their electrochemical gradient

Steroid hormones are large communication molecules that are modified cholesterol molecules. How do you think they enter a cell? (remember this for Ch8)

Their lipid nature probably allows them to diffuse through the plasma membrane.

Franklin and Wilkins analyzed DNA by bombarding DNA crystals with X-rays. Their analysis yielded two numbers that sparked interest, 3.4 nm and 0.34 nm. What is the significance of these numbers?

These numbers demonstrate there are 10 rungs, or steps, on the DNA "ladder" for every turn of the helix.

Aquaporins are proteins that control the passage of water molecules across a cell membrane. The protein forms a pore, or opening, in the membrane. You isolate what you think are two different molecules of aquaporin and determine that one of the proteins has a larger pore diameter than the second. Which of the following do you conclude? A) These two forms of aquaporin will have identical sequences of amino acids. B) These two forms of aquaporin will have different sequences of amino acids. C) You will have to sequence the proteins to compare their primary structure, because it should have no effect on pore diameter. D) These two forms of aquaporin have identical primary structure but differ in their tertiary structure.

These two forms of aquaporin will have different sequences of amino acids.

Histone acetyl transferases exert their effect on gene activity by ________.

neutralizing positive charges on the lysines of histones

Which aspect of phospholipids is most important to the formation of bilayers?

They are amphipathic

Eukaryotic cells manufacture cytoskeletal proteins, which help to maintain cell shapes and functions. What would you predict about these proteins?

They are manufactured on free ribosomes in the cytoplasm.

Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?

They protect against oxidative damage from excessive light energy.

Why are fermentation reactions important for cells?

They regenerate NAD+ so that glycolysis can continue to operate.

Which of the following statements is TRUE about protein synthesis in prokaryotes?

Translation can begin while transcription is still in progress

The constituents of the electron transport chain have similar capabilities, with the exception of ubiquinone (coenzyme Q). What is different about ubiquinone?

Ubiquinone is not a protein, is lipid soluble, and can move through the inner mitochondrial membrane.

HIV, the causative agent of AIDS, is a retrovirus. A retrovirus ________

Uses reverse transcriptase to make DNA from RNA

Beadle and Tatum discovered that metabolic pathways are studied most effectively using which of the following techniques?

Using single gene mutations resulting in nonfunctional enzymes specific to a metabolic pathway

Which of the following descriptions best fits the class of molecules known as nucleotides?

a nitrogenous base, a phosphate group, and a sugar

Of the following, which is the most current description of a gene?

a DNA sequence that is expressed to form a functional product: either RNA or polypeptide

You want to engineer a eukaryotic gene into a bacterial colony and have it expressed. What must be included in addition to the coding exons of the gene?

a bacterial promoter sequence

zinc, and essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. the zinc most likely functions as

a cofactor necessary for enzyme activity

When nucleotides polymerize to form a nucleic acid ________.

a covalent bond forms between the sugar of one nucleotide and the phosphate of a second

The DNA of telomeres has been highly conserved throughout the evolution of eukaryotes. This most likely reflects ________.

a critical function of telomeres

Which of the following is most likely to have a small protein called ubiquitin attached to it?

a cyclin protein, which usually acts in G1, in a cell that is in G2

The partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. What is this attraction called?

a hydrogen bond

Not all intercellular signals require transduction. Which one of the following signals would be processed without transduction?

a lipid-soluble signal

Pemphigus vulgaris is an autoimmune disorder in humans in which antibodies are produced against the cadherins of desmosomes. The blistering of the skin and mucous membranes characteristic of this disorder is probably a consequence of ________.

a loss in cell—cell adhesion

Which of the following is NOT found in a prokaryote?

a mitochondrion

Which of the following is an example of potential rather than kinetic energy?

a molecule of glucose

Cilia and flagella bend because of ________.

a motor protein called dynein

Which of the following crosses lipid bilayers the slowest? a. a sodium ion b. a small, polar molecule like water c. a large, polar molecule like glucose d. a small, nonpolar molecule like oxygen (O2)

a. a sodium ion

Based on the accompanying figure (inside is to the left), which of these experimental treatments would increase the rate of sucrose transport into the cell? a. decreasing extracellular pH b. decreasing cytoplasmic pH c. adding a substance that makes the membrane more permeable to hydrogen ions d. decreasing extracellular sucrose concentration e. adding an inhibitor that blocks the regeneration of ATP

a. decreasing extracellular pH

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they ________.

amplify the original signal many times

Under what circumstances does membrane transport require energy? a. whenever a solute is moved against its electrochemical gradient b. whenever an ion moves through a phospholipid bilayer membrane c. wherever large molecules are moved within a cell d. whenever oxygen moves through a phospholipid bilayer membrane

a. whenever a solute is moved against its electrochemical gradient

Spherocytosis is a human blood disorder associated with a defective cytoskeletal protein in the red blood cells (RBCs). What do you suspect is the consequence of such a defect?

abnormally shaped RBCs

The oxygen consumed during cellular respiration is involved directly in which process or event?

accepting electrons at the end of the electron transport chain

The primary role of oxygen in cellular respiration is to ________.

act as an acceptor for electrons and protons

All of the following proteins (or portion thereof) may be found in the extracellular matrix of animal cells EXCEPT ________.

actin

Which cytoskeletal proteins are important constituents of the contractile structures that form the cleavage furrows involved in animal cell cytokinesis?

actin

Protein kinase is an enzyme that ________.

activates or inactivates other proteins by adding a phosphate group to them

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's ________.

activation energy

Mutations in the DNA may lead to _______ that increases fitness and lays the foundation for natural selection to 'select' a particular trait that is inheritable.

adaptation

Actin filaments have polarity. This means that the two ends can be identified due to structural differences. The plus end is the end to which subunits are added more rapidly, or the end of polymerization. Which of the following would enable you to identify the plus end of actin filaments?

adding radiolabeled actin subunits to a mixture of actin filaments in which conditions are favorable for polymerization

Plasmodesmata are cell—cell junctions that are found between ________.

adjacent plant cells

Even though plants cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in ________.

all cells all the time

Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in ________

all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

Recall the experiment on ant navigation. To run a controlled experiment, what parameters were held constant for the test group of 75 ants?

all variables except leg length

Altering patterns of gene expression in prokaryotes would most likely serve an organism's survival by ________.

allowing an organism to adjust to changes in environmental conditions

You determine the amino acid sequence of a protein and find it contains a long sequence of methionine, followed by a long sequence of proline, followed by a long sequence of valine. Using these data you predict the sequence of this protein's secondary structure will be ________. A) beta sheets, then a region of no secondary structure, then beta sheets B) alpha-helices, then a region of no secondary structure, then alpha helices C) beta sheets, then a region of no secondary structure, then alpha-helices D) alpha-helices, then a region of no secondary structure, then beta sheets

alpha-helices, then a region of no secondary structure, then beta sheets

Normal hemoglobin is a tetramer, consisting of two molecules of β hemoglobin and two molecules of α hemoglobin. In sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. Based on this information alone, we can conclude that sickle-cell hemoglobin exhibits ________. A) only altered primary structure B) only altered secondary structure C) only altered tertiary structure D) only altered quaternary structure E) altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered

altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered

Which of the following allows more than one type of protein to be produced from one gene?

alternative forms of RNA splicing

Changing a single amino acid in a protein consisting of 325 amino acids would ________. A) alter the primary structure of the protein but not its tertiary structure or function B) cause the tertiary structure of the protein to unfold C) always alter the biological activity or function of the protein D) always alter the secondary structure of the protein and disrupt its biological activity E) always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein, and sometimes affect its biological activity

always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein, and sometimes affect its biological activity

An E. coli cell without a functional lacI gene is expected to ________.

always produce β-galactosidase

A ribozyme is ________.

an RNA with catalytic activity

Which kind of metabolic poison would most directly interfere with glycolysis?

an agent that closely mimics the structure of glucose but is not metabolized

an allosteric inhibitor.

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons (a spontaneous reaction within the system) across the membrane down their electrochemical gradient, is an example of ________.

an endergonic reaction coupled to an exergonic reaction

All of the following are part of a prokaryotic cell EXCEPT _____.

an endoplasmic reticulum

During which phase of mitosis do the two sister chromatids become independent chromosomes?

anaphase

In meiosis, homologous chromosomes are separated during ________.

anaphase I

Centromeres split and sister chromatids migrate to opposite poles in ________ of meiosis.

anaphase II

Spontaneous generation ______.

apparently occurred at least once- when life on Earth began

Under what condition is the AraC protein an activator? The AraC protein is an activator when it is bound to _______.

arabinose

Which of the following is TRUE of osmosis? a. Osmosis only takes place in red blood cells. b. In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration. c. Osmosis is an energy-demanding or "active" process. d. In osmosis, solutes move across a membrane from areas of lower water concentration to areas of higher water concentration.

b. In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

What is the most important factor in explaining why osmosis occurs spontaneously? a. It leads to an increase in entropy. b. It leads to a decrease in entropy. c. The process is endothermic. d. The process is exothermic.

b. It leads to a increase in entropy.

What is/are the variable structure(s) of a nucleotide?

base and sugar

Steroid hormones bind to receptors inside the cell and alter their conformation. The hormone—receptor complex is then transported into the nucleus, where it can directly affect gene expression. To get from the location where the receptor binds the hormone to its site of action, the hormone—receptor complex must ________.

be transported through the nuclear pore complex

A mutation in yeast makes it unable to convert pyruvate to ethanol. How will this mutation affect these yeast cells? The mutant yeast cells will ________.

be unable to grow anaerobically

Ribosomes can attach to prokaryotic messenger RNA ________.

before transcription is complete

There are two conserved regions in the promoter sequences of bacterial genes. These two regions (−10 box and the −35 box) of the promoter ________.

bind the sigma subunit that is associated with RNA polymerase

In eukaryotes, general transcription factors ________ .

bind to other proteins or to the TATA box

Which of the following processes is central to the initiation of transcription in bacteria?

binding of sigma to the promoter region

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the ________.

binding of the tRNA anticodon to the mRNA codon

The lock-and-key analogy for enzymes applies to the specificity of enzymes ________.

binding to their substrate

If you guys had any other questions i missed the password to edit is :

bio151

Chlorophylls absorb most light in which colors of the visible range?

blue and red

How might a change of one amino acid at a site, distant from the active site of an enzyme, alter an enzyme's substrate specificity?

by changing the shape of an enzyme

Which of the following is a difference between chlorophyll a and chlorophyll b? A) Chlorophyll a contains magnesium in its ring structure, whereas chlorophyll b contains iron. B) Chlorophyll a absorbs yellow light, and chlorophyll b absorbs green. C) Chlorophyll a and b absorb light energy at slightly different wavelengths. D) Chlorophyll a is a pigment, and chlorophyll b is the enzyme that transfers excited electrons from chlorophyll a to electron carriers of the thylakoid membrane.

Which aspect of phospholipids is most important to the formation of bilayers? a. Their polar heads can interact with water. b. The length of their hydrocarbon tails can be altered to modulate membrane fluidity. c. They are amphipathic. d. Their hydrocarbon tails can consist of fatty acids or isoprene subunits.

c. They are amphipathic.

c. facilitated diffusion

What region of a steroid is hydrophilic? a. the methyl (—CH3) groups b. the ring structures c. the terminal hydroxyl group d. the long hydrocarbon chain

c. the terminal hydroxyl group

Consider this pathway: epinephrine → G-protein-coupled receptor → G-protein → adenylyl cyclase → cAMP. The second messenger in this pathway is ________.

cAMP

A system at chemical equilibrium ________.

can do no work

Imagine that you have set up a genetic screen to identify E. colimutants that cannot metabolize the amino acid tryptophan for energy. Beginning with a master plate containing many colonies, you prepare replica plates on medium with glucose or tryptophan as the only energy source. You would look for colonies that ________.

can grow only on the plates with glucose

______ atoms give organic molecules their overall shape.

carbon

Amino acids are acids because they always possess which functional group? A) amino B) carbonyl C) carboxyl D) phosphate E) hydroxyl

carboxyl

Which of the functional groups below acts most like an acid in water?

carboxyl

which two functional groups are always found in amino acids? A) ketone and methyl groups B) carbonyl and amino groups C) carboxyl and amino groups D) amino and sulfhydryl groups E) hydroxyl and carboxyl groups

carboxyl and amino groups

Homologous chromosomes ________.

carry information for the same traits

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

catabolism (catabolic pathways)

Proteins in biological systems ________. A) store genetic information B) link with other proteins to form bilayers in cell membranes C) form high-energy intermediates such as ATP D) catalyze reactions

catalyze reactions

One characteristic of life and living systems is that they are able to adapt. In general, cells interact with other cells and their environment through the action of their ________.

cell surface proteins

In the cells of some organisms, mitosis occurs without cytokinesis. This results in ________.

cells with more than one nucleus

The first chemicals that provided potential energy on Earth may have been formaldehyde and hydrogen cyanide. While these were produced by sunlight-driven reactions, they also occurred around deep-sea vents. If the first organisms on Earth evolved around these vents, the first life on Earth was _____.

chemosynthetic, obtaining energy from chemicals

Inside an active mitochondrion, most electrons follow which pathway?

citric acid cycle → NADH → electron transport chain → oxygen

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?

cleavage furrow formation and cytokinesis

Which of the following would you NOT find in a plant cell?

collagen

HIV is the virus that causes AIDS. In the mid-1990s, researchers discovered an enzyme in HIV called protease. Once the enzyme's structure was known, researchers began looking for drugs that would fit into the active site and block it. If this strategy for stopping HIV infections were successful, it would be an example of what phenomenon?

competitive inhibition

What is the structural feature that allows DNA to replicate in anti-parallel manner?

complementary pairing of the nitrogenous bases

The anticodon of a particular tRNA molecule is ________.

complementary to the corresponding mRNA codon

Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures?

components of cytoskeleton

Which of the following occurs in prokaryotes but not in eukaryotes?

concurrent transcription and translation

Which of the following involves a decrease in entropy?

condensation reactions

In telophase I, each chromosome ________.

consists of two sister chromatids joined by a centromere

Anabolic pathways ________.

consume energy to build up polymers from monomers

Which method is utilized by eukaryotes to control their gene expression that is NOT used in bacteria?

control of both RNA splicing and chromatin remodeling

A carbon atom is most likely to form what kind of bond(s) with other atoms?

covalent

Kinetochore microtubules assist in the process of splitting centromeres by ________.

creating tension by pulling toward opposite poles

The bulldog ant has a diploid number of two chromosomes. Therefore, following meiosis, each daughter cell will have a single chromosome. Diversity in this species may be generated by mutations and ________.

crossing over and independent assortment

The accumulation of free oxygen in Earth's atmosphere began with the origin of ________.

cyanobacteria using photosystem II

Identify the location of the disulfide bond in the figure, located at the bottom of the third transmembrane segment. What is the name of the amino acids that are forming this bond? A) cytosine B) aspartic acid C) cysteine D) glycine

cysteine

Mitosis separates chromosomes. Cytoplasm is divided between two daughter cells by ________.

cytokinesis

What is the location of the C-terminus of the protein in the figure? A) extracellular B) cytoplasm C) embedded within the membrane D) nucleus

cytoplasm

Which of the following is characteristic of a steroid hormone action?

cytoplasmic receptor binding

Which of the following are pyrimidine nitrogenous bases?

cytosine and uracil

Which of the following includes all of the pyrimidines found in RNA and DNA?

cytosine, uracil, and thymine

Integrins are integral membrane proteins. They are often attached to ________.

cytoskeletal proteins and proteins in the extracellular matrix

Which of the following in the figure would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?

For a protein to be an integral membrane protein, it would have to be ________. a. hydrophilic b. hydrophobic c. exposed on only one surface of the membrane d. amphipathic, with at least one hydrophobic region e. completely covered with phospholipids

d. amphipathic, with at least one hydrophobic region

Celery stalks (and chopped lettuce for salad) that are immersed in freshwater for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. From this we can deduce that the freshwater ________. a. is isotonic and the salt solution is hypertonic to the cells of the celery stalks b. is hypertonic and the salt solution is hypotonic to the cells of the celery stalks c. is hypotonic and the salt solution is hypertonic to the cells of the celery stalks d. and the salt solution are both hypotonic to the cells of the celery stalks e. and the salt solution are both hypertonic to the cells of the celery stalks

d. and the salt solution are both hypotonic to the cells of the celery stalks

Cooking oil and gasoline (a hydrocarbon) are NOT amphipathic molecules because they ________. a. do not have a nonpolar region b. have hydrophobic and hydrophilic regions c. are highly reduced molecules d. do not have a polar or charged region

d. do not have a polar or charged region

Which of the following increases the strength of the hydrophobic interactions in lipid bilayers and thus makes them less permeable to polar molecules? a. removing cholesterol b. the presence of double bonds c. increasing temperature d. increasing length of the hydrocarbon chains

d. increasing length of the hydrocarbon chains

The membranes of winter wheat are able to remain fluid when it is extremely cold by ________. a. using active transport b. decreasing the number of hydrophobic proteins in the membrane c. increasing the percentage of cholesterol molecules in the membrane d. increasing the percentage of unsaturated phospholipids in the membrane e. cotransport of glucose and hydrogen

d. increasing the percentage of unsaturated phospholipids in the membrane

Which of the following types of molecules are the major structural components of the cell membrane? a. phospholipids and cellulose b. proteins and cellulose c. glycoproteins and cholesterol d. phospholipids and proteins e. nucleic acids and proteins

d. phospholipids and proteins

DNA contains the template needed to copy itself, but it has no catalytic activity in cells. What catalyzes the formation of phosphodiester bonds between adjacent nucleotides in the DNA polymer being formed?

deoxyribonucleotide triphosphates

here are 20 different amino acids. What makes one amino acid different from another? A) different side chains (R-groups) attached to a carboxyl carbon B) different side chains (R-groups) attached to the amino groups C) different side chains (R-groups) attached to an α carbon D) different structural and optical isomers E) different asymmetric carbons

different side chains (R-groups) attached to an α carbon

Several of the different globin genes are expressed in humans but at different times in development. What mechanism could allow for this?

differential gene regulation over time

The activation of receptor tyrosine kinases is characterized by ________.

dimerization and phosphorylation

Fatty acids usually have an even number of carbons in their structures. They are catabolized by a process called beta-oxidation. The end products of the metabolic pathway are acetyl groups of acetyl-CoA molecules. These acetyl groups ________.

directly enter the citric acid cycle

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to ________.

disruption of mitotic spindle formation

What type of covalent bond between amino acid side chains (R-groups) functions in maintaining a polypeptide's specific three-dimensional shape? A) ionic bond B) hydrophobic interaction C) van der Waals interaction D) disulfide bond E) hydrogen bond

disulfide bond

Lysosomes that lack mannose-6-phosphate receptors _____.

don't receive enzyme shipments from the Golgi

Which of the following best describes DNA's secondary structure?

double antiparallel helical strands

Which of the following processes includes all others? a. transport of an ion down its electrochemical gradient b. osmosis c. diffusion of a solute across a membrane d. facilitated diffusion e. passive transport

e. passive transport

Which of the following is a correct statement about the atoms in ammonia (NH3)?

each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge

Van der Waals interactions may result when ________. A) hybrid orbitals overlap B) electrons are not symmetrically distributed in a molecule C) molecules held by ionic bonds react with water D) two polar covalent bonds react E) a hydrogen atom loses an electron

electrons are not symmetrically distributed in a molecule

An ionic bond is one in which ______.

electrons are removed from one atom and transferred to another atom so that the two atoms become oppositely charged

The presence of cholesterol in the plasma membranes of some animal cells ________.

enables the membranes to stay fluid when cell temperature drops

A chemical reaction that has a positive ΔG is best described as _____.

endergonic

A chemical reaction that has a positive ΔG is best described as ________.

endergonic

The evolution of eukaryotic cells most likely involved ______.

endosymbiosis of an aerobic bacterium in a larger, phagocytic host cell

Second law of Thermodynamics states that ______ always increases in an isolated system.

entropy chaos

Whenever energy is transformed, there is always an increase in the ________.

entropy of the universe

DNA methylation and histone acetylation are examples of ______

epigenetic phenomena

The chemiosmotic process in chloroplasts involves the ________.

establishment of a proton gradient across the thylakoid membrane

Which of the following is a major difference between prokaryotic cells an eukaryotic cells?

eukaryotic cells have more intracellular organelles than prokaryotes

Gene expression can be altered more easily at the level of post-transcriptional processing in eukaryotes than in prokaryotes because ________.

eukaryotic exons may be spliced in alternative patterns

Forms of the Ras protein found in tumors usually cause which of the following?

excessive cell division

The difference in lipid and protein composition between the membranes of the endomembrane system is largely determined by

function of the golgi apparatus in sorting and directing membrane components

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase II is transcription of ________.

protein-coding genes

Muscle cells differ from nerve cells mainly because they ________.

express different genes

The predominant mechanism driving cellular differentiation is the difference in gene ________.

expression

If the cell whose nuclear material is shown in the accompanying figure continues toward completion of mitosis, which of the following events would occur next?

formation of telophase nuclei

A peptide bond ________. A) forms between the functional R-groups of different amino acids B) forms between the central carbon and the amino R-group of a single amino acid C) forms the primary structure of proteins D) does not play a role in maintaining the tertiary structure of proteins

forms the primary structure of proteins

How many electrons are involved in a double covalent bond?

four

What makes sexually reproduced offspring genetically different from their parents?

genetic recombination during meiosis

What carbon source(s) can yeast cells metabolize under anaerobic conditions to make ATP?

glucose

Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy?

glucose

Which metabolic pathway is common to both cellular respiration and fermentation?

glycolysis

Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?

glycolysis

Which of the following occurs in the cytosol of a eukaryotic cell?

glycolysis and fermentation

Amoebae move by crawling over a surface (cell crawling), which involves ________.

growth of actin filaments to form bulges in the plasma membrane

Which of the following are purine nitrogenous bases?

guanine and adenine

Which of the following is a property of liquid water? Liquid water ______.

has a heat of vaporization that is higher than that for most other substances

Biological evolution of life on Earth, from simple prokaryote-like cells to large, multicellular eukaryotic organisms, _____.

has occurred in accordance with the laws of thermodynamics

Which of the following involves an increase in entropy? A) hydrolysis B) reactions that join monomers C) polymerization D) chemical evolution

hydrolysis

Suppose you discovered a new amino acid. Its R-group contains only hydrogen and carbon atoms. Predict the behavior of this amino acid. A) It is hydrophobic. B) It is hydrophilic. C) Relative to the amino acids found in organisms, its interactions with water will be intermediate. D) Relative to the amino acids found in organisms, its interactions with water will be very high.

hydrophobic

celery stalks that are immersed in freshwater for several hours become stiff and hard. Similar stalks left in a salt solution become limp and soft. From this we can deduce that the cells of the celery stalk.

hypertonic to fresh water but hypotonic to the salt solution

A good experimental design has all of the following except _______.

implemented by an expert

Where are proteins produced other than on ribosomes free in the cytosol or ribosomes attached to the ER?

in mitochondria

Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly acquires mutations with amino acid changes that make them resistant to these competitive inhibitors. Where in the reverse transcriptase enzyme would such amino acid changes most likely occur in drug-resistant viruses?

in or near the active site

Which of the following is true of osmosis?

in osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration

Scientists isolate cells in various phases of the cell cycle. They find a group of cells that have 1.5x times more DNA than G1 phase cells. The cells of this group are ________.

in the S phase of the cell cycle

C6H12O6 (glucose) + 6 O2 → 6 CO2 + 6 H2O Where is most of the water in this reaction produced?

in the electron transport chain

Where would you expect to find tight junctions?

in the epithelium of an animal's stomach

In a normal cellular protein, where would you expect to find a hydrophobic amino acid like valine? A) in the interior of the folded protein, away from water B) on the exterior surface of the protein, interacting with water C) in the transmembrane portion interacting with lipid fatty-acid chains D) in the interior of the folded protein, away from water, or in a transmembrane portion interacting with lipid fatty-acid chains E) anywhere in the protein, with equal probability

in the interior of the folded protein, away from water, or in a transmembrane portion interacting with lipid fatty-acid chains

A controlled experiment ______.

includes at least two groups, one of which does not receive the experimental treatment.

In comparing DNA replication with RNA transcription in the same eukaryotic cell, only DNA replication ________.

incorporates the entire template molecule in the product

In the first step of their experiments, Jacob and Monod treated E. coli cells with ultraviolet light or X-rays to ________.

increase the frequency of mutations in all genes

Enzymes ________.

increase the rate of a reaction by lowering the activation energy barrier

Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?

inducer

Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer binds to the operator?

inducer

Regulatory transcription factors ________.

influence the assembly of the basal transcription complex

Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount of ATP in a cell would be expected to ________.

inhibit the enzyme and thus slow down the rates of glycolysis and the citric acid cycle.

Signals from the extracellular matrix to the cytoskeleton may be transmitted by ________.

integrins

The extracellular matrix is thought to participate in the regulation of animal cell behavior by communicating information from the outside to the inside of the cell via which of the following?

integrins

Histogram graph is the best choice when you are reporting observational data that can be measured on a _______ scale.

interval

Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because ________.

intracellular receptors are present only in target cells

A G-protein receptor with GTP bound to it ________.

is in its active state

The active site of an enzyme is the region that ________.

is involved in the catalytic reaction of the enzyme

What can you infer about a high molecular weight protein that cannot be transported into the nucleus?

it lacks a nucleus localization signal (NLS)

why is ATP an important molecule in metabolism?

it provides energy coupling between exergonic and endergonic reactions

Consider the following reaction at equilibrium: CO2 + H2O <-> H2CO3. What would be the effect of adding additional H2CO3?

it would drive the equilibrium dynamics to the left

When does the synaptonemal complex disappear?

late prophase of meiosis I

In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common?

length, centromere position, staining pattern, and traits coded for by their genes

The molecule that functions as the reducing agent in a redox or oxidation—reduction reaction ________.

loses electrons and loses potential energy

Glycolysis is active when cellular energy levels are ________; the regulatory enzyme, phosphofructokinase, is ________ by ATP.

low; inhibited

Asbestos is a material that was once used extensively in construction. One risk from working in a building that contains asbestos is the development of asbestosis caused by the inhalation of asbestos fibers. Cells will phagocytize asbestos but are not able to degrade it. As a result, asbestos fibers accumulate in ________.

lysosomes

According to the central dogma, what molecule should go in the blank?DNA → ________ → Proteins

mRNA

Codons are part of the molecular structure of ________

mRNA

Which of the following macromolecules leaves the nucleus of a eukaryotic cell through pores in the nuclear membrane?

mRNA

Translation requires ________.

mRNA, tRNA, and rRNA

Translation directly involves ________.

mRNA, tRNA, ribosomes, and GTP

Cloning of plants from cuttings demonstrates that ________.

mature plant cells retain the full genetic information needed to carry out the developmental processes to produce a new individual plant

Side chains of amino acids ________. A) are all nonpolar B) are nonpolar if they contain N or S C) are all polar D) may be polar or nonpolar

may be polar or nonpolar

Crossing over normally takes place during which of the following processes?

meiosis I

What are prions? A) mobile segments of DNA B) tiny circular molecules of RNA that can infect plants C) viral DNA that attaches itself to the host genome and causes disease D) misfolded versions of normal protein that can cause disease E) viruses that invade bacteria

misfolded versions of normal protein that can cause disease

A biologist ground up some plant leaf cells and then separated organelles into different tubes (by centrifuging the mixture and fractionating [separating] the mixture). One tube could produce ATP in the dark, suggesting that it is likely to contain ______.

mitochondria

Cyanide binds with at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide will be found within the _______.

mitochondria

When yeast cells are transferred from anaerobic to aerobic growth conditions, which of these organelles become much more numerous?

mitochondria

Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?

mitochondrial intermembrane space

During cellular respiration, acetyl CoA accumulates in which location?

mitochondrial matrix

Which structure is common to plant and animal cells?

mitochondrion

Asexual reproduction occurs during ________.

mitosis

Sister chromatids separate from each other during

mitosis and meiosis II

Evolution is descent with ______.

modification change

What kind of molecules serve as electron acceptors in cellular respiration?

molecules with low potential energy

Turner syndrome is characterized by the presence of only one X chromosome in an affected female. Which of the following accurately describes Turner syndrome?

monosomy

Researchers tried to explain how vesicular transport occurs in cells by attempting to assemble the transport components. They set up microtubular tracks along which vesicles could be transported, and they added vesicles and ATP (because they knew the transport process requires energy). Yet, when they put everything together, there was no movement or transport of vesicles. What were they missing?

motor proteins

Refer to the figure associated with this question. The mRNA is smaller than the length of the DNA that codes for it because ________.

post-transcriptional modification removes the introns

what is true of the cytoskeleton?

movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other.

______meter is 10^-9 of a meter, and 10^-6 of a millimeter (the smallest hatch-mark or a regular ruler)/.

nano

A solution contains 0.0000001 (10^-7) moles of hydroxyl ions [OH-] per liter. Which of the following best describes this solution?

neutral

Which component of the complex described enters the exit tunnel in the large subunit of the ribosome?

newly formed polypeptide

A cell in late anaphase of mitosis will have ________.

no chromosomes in the center of the cell

At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. Many people were surprised that the number of protein-coding sequences was much smaller than they had expected. Which of the following could account for much of the DNA that is NOT coding for proteins?

non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function

What is the most common source of the extra chromosome 21 in an individual with Down syndrome?

nondisjunction in the mother

Bonds between two atoms that are equally electronegative are _____.

nonpolar covalent bonds

The first gap in the cell cycle (G1) corresponds to ________.

normal growth and cell functionB) the phase in which DNA is being replicated

If cells are grown in a medium containing radioactive 32P-labeled phosphate, which of these molecules will be labeled?

nucleic acids

Nucleic acids are polymers made up of which of the following monomers?

nucleotides

Why is each element unique with respect to its chemical properties? Each element has a distinctive _____.

number of protons

When does DNA replication take place regarding meiosis? DNA replication ________.

occurs before meiosis I begins

In eukaryotes, the normal or default state is that genes are turned _______

off through their association in nucleosomes

In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?

on the inside surface of the vesicle

Which is the smallest unit containing the entire human genome (all genes)?

one male somatic cell

Semiconservative replication uses _____ as a template.

one strand of the DNA molecule

Plants photosynthesize ________.

only in the light but respire in light and dark

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase I is transcription of ________.

only rRNA-coding genes

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase III is transcription of ________.

only tRNA-coding genes

Stanley Miller's 1953 experiments with heating of simple molecules and applying electric current supported the hypothesis that ______.

organic molecules can be synthesized under conditions that may have existed on early Earth

Activator proteins in eukaryotes usually have a domain that binds to DNA and other activation domains that often bind to ________.

other regulatory proteins

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

oxidation of pyruvate to acetyl CoA and the citric acid cycle

Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide and water?

oxidative phosphorylation (chemiosmosis)

In its mechanism, photophosphorylation is most similar to ________.

oxidative phosphorylation in cellular respiration

When a glucose molecule loses a hydrogen atom as the result of an oxidation—reduction reaction, the molecule becomes ________.

oxidized

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is ________.

oxygen

What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10^-12 M?

pH 2

The product of the lacI gene functions most like a car's ________.

parking brake

Osteocytes are bone cells. Collagen fibers and calcium salts are found in abundance between and among the osteocytes. The collagen and calcium salts are ________.

part of the extracellular matrix

Within a double-stranded DNA molecule, adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine. This arrangement ________.

permits complementary base pairing

Like many molecules, nucleotides have asymmetry. This gives nucleic acids a specific direction for polymerization. The 3' carbon of a nucleotide has a hydroxyl group, while the 5' carbon is covalently bonded to _____.

phosphate group

Some viruses consist only of a protein coat surrounding a nucleic acid core. If you wanted to radioactively label the nucleic acids separately from the protein, you would use radioactive ________. (Which atom is in nucleotides but not proteins?)

phosphorus

In plants, reduction of NADP+ occurs during ________.

photosynthesis

The arabinose operon (ara) provides a particularly interesting example of ________ in that when arabinose is present in the environment, the operon is transcribed.

positive control

Water is an excellent solvent for polar molecules and ions. What part of the solute will interact with oxygen atoms of water?

positively charged

Pasteur's experiment showed that all life comes from ______.

preexisting cells cells life

Pasteur's experiments proved that ______.

preexisting cells present in the air can grow in sterilized nutrient broth

A cell with a lot of free ribosomes and few attached to rough endoplasmic reticulum is most likely

primarily producing proteins in the cytosol

A cell with a predominance of free ribosomes is most likely ______.

primarily producing proteins in the cytosol

When polymerization of a protein is complete, but a protein is still completely linear, what is the highest level of structure in the protein? A) primary B) secondary C) tertiary D) quaternary

primary

You disrupt all hydrogen bonds in a protein. What level of structure will be preserved? A) primary structure B) secondary structure C) tertiary structure D) quaternary structure

primary

The structural level of a protein LEAST affected by a disruption in hydrogen bonding is the ________. A) primary level B) secondary level C) tertiary level D) quaternary level E) All structural levels are equally affected by a disruption in hydrogen bonding.

primary level

You are studying a protein that is shaped like a doughnut. The shape is a function of which level(s) of protein structure? A) primary only B) secondary only C) tertiary only D) secondary and tertiary only E) primary, secondary, and tertiary

primary, secondary, and tertiary

A scientific theory has two components: a pattern based on observations and a ______ to explain that pattern.

process

At which phase are the two centrosomes beginning to move apart in animal cells?

prophase

One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this?

receptor tyrosine kinases

How do chromatin-remodeling complexes recognize the genes they should act on? Chromatin-remodeling complexes ________.

recognize specific transcription factors bound to regulatory sequences of DNA

Why are polymerization reactions endergonic? Polymerization reactions ________. A) reduce entropy B) release heat, making the reactant monomers move faster C) release energy D) are at equilibrium

reduce entropy

The bonding of two amino acid molecules to form a larger molecule requires the ________. A) release of a water molecule B) release of a carbon dioxide molecule C) addition of a carbon dioxide molecule D) addition of a water molecule E) addition of a water molecule and a carbon dioxide molecule

release of a water molecule

Which of the following does NOT occur during mitosis?

replication of the DNA

Which of the following is a protein produced by a regulatory gene?

repressor

In general, a signal transmitted via phosphorylation of a series of proteins ________.

results in a conformational change to each protein

Which of the following is present in all prokaryotic cells?

ribosome

A gap junction is a channel that connects adjacent cells. Which one of the following cannot pass through a gap junction?

ribosomes

What molecules in the spliceosome catalyze the intron removal reactions?

ribozymes

Which level of protein structure do the α-helix and the β-pleated sheet represent? A) primary B) secondary C) tertiary D) quaternary E) primary, secondary, tertiary, and quaternary

secondary

DNA is synthesized through a process known as ________.

semiconservative replication

a primary objective of cell fractionation (including differential centrifiguration) is to ___

separate the major organelles

The mitotic spindle is a microtubular structure that is involved in ________.

separation of sister chromatids

The reason for differences in the sets of proteins expressed in a nerve and a pancreatic cell of the same individual is that nerve and pancreatic cells contain different ________.

sets of regulatory proteins

In eukaryotic cells, transcription cannot begin until ________.

several transcription factors have bound to the promoter

Which of these provide evidence of the common ancestry of all life?

shared genetic sequences

Movement of the chromosomes during anaphase would be most affected by a drug that prevents ________.

shortening of microtubules

In a bacterium, we will find DNA in _____.

the nucleoid

Knowing the atomic mass of an element allows inferences about which of the following?

the number of protons plus neutrons in the element

Two plants are crossed, resulting in offsprings with a 3:1 ratio for a particular trait. 75% expressed the dominant trait and remainder were recessive. This ratio suggests that ________.

the parents were both heterozygous for the particular trait

Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription?

the phosphate bonds in the nucleotide triphosphates that serve as substrates

Motor proteins require energy in the form of ATP. ATP hydrolysis results in a conformational change that allows the protein to move along microtubular tracks (pathways). What structural component of the motor protein contains the ATP binding site and, therefore, changes shape to enable movement?

the portion of the molecule that binds to the microtubular track along which the vesicle is being transported

Cell differentiation always involves ________.

the production of tissue-specific proteins, such as muscle actin

If the DNA sequence was substantially altered from one of the following, which would prevent the binding of the TATA-binding protein (TBP)?

the promoter

An enzyme has a total of four active sites. When you denature the molecule and study its composition, you find that each active site occurs on a different polypeptide. Which of the following hypotheses does this observation support? A) The enzyme is subject to regulation. B) The enzyme requires a cofactor to function normally. C) The protein's structure is affected by temperature and pH. D) the protein has a quaternary structure

the protein has a quaternary structure

Independent assortment of chromosomes is a result of ________.

the random way each pair of homologous chromosomes lines up at the metaphase plate during meiosis I

Which of the following always tend to make chemical reactions spontaneous?

the reactants are more ordered than the product

What is the function of DNA polymerase III?

to add nucleotides to the 3' end of a growing DNA strand

What is the major adaptive advantage of cellular respiration?

to produce adenosine triphosphate (ATP)

Enthalpy (H) is the ________.

total energy in biological systems

Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that ________.

traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1 generation

In all living species, DNA is the genetic material that codes for proteins (robots). In order for this, the DNA has to be ______ into messenger RNA (mRNA).

transcribed

A series of hydrophobic side chains will congregate together as a protein folds in an aqueous solution and be stabilized by ________. A) disulfide bonds B) van der Waals interactions C) hydrogen bonds D) quaternary structure bonds

van der Waals interactions

The electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come?

water

An important group of peripheral membrane proteins are enzymes such as the phospholipases that cleave the head groups of phospholipids. What properties must these enzymes exhibit?

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