AP Biology MC Review

(A) Glysolysis(B) Krebs cycle (citric acid cycle)(C) Calvin cycle (light-independent reactions of photosynthesis)(D) Light-dependent reactions of photosynthesis(E) Chemiosmosis Process in which sugar is oxidized to pyruvic acid A B C D E

A

if 30%30% of the nucleotides in a single-stranded RNARNA molecule are adenine, then what percent are expected to be thymine? A 0%0% B 20%20% C 30%30% D 70%

A 0%

Assume that genes A and B are not linked. If the probability of allele A in a gamete is 1/2 and the probability of allele B in a gamete is 1/2, then the probability that both A and B are in the same gamete is A 1/2 x 1/2 B 1/2 + 1/2 C (1/2) / (1/2) D square root of 1/2 E |1/2 — 1/2|

A 1/2 x 1/2

Muscle contraction depends on ATPATP hydrolysis. During periods of intense exercise, muscle cells rely on the ATPATP supplied by three metabolic pathways: glycolysis, mitochondrial respiration, and the phosphagen system. Figure 1 shows the rates at which the three metabolic pathways produce ATPATP following the start of an intense period of exercise. Figure 1. ATPATP production by three metabolic pathways following the start of an intense period of exercise Which of the following correctly uses the data to justify the claim that the phosphagen system is an immediate, short-term source of ATPATP for muscle cells? A ATPATP production by the phosphagen system increases and decreases rapidly following the start of the exercise period. B ATPATP production by the phosphagen system increases gradually and continuously throughout the entire exercise period. C The ATPATP produced by the phosphagen system contains more energy per molecule than does the ATPATP produced by the other pathways. D ATPATP hydrolysis in muscle cells occurs immediately after the start of the exercise period but stops before the end of the exercise period.

A ATP production by the phosphagen system increase sand decerases raplidly following the start of the exercise period

A researcher is conducting an experiment in which cells in different phases of the cell cycle are fused together. The researcher then records what happens to the nuclei of the resulting cell (Table 1). TABLE 1. COMBINATIONS OF CELLS THAT WERE FUSED AND THE PHASE OF NUCLEI IN THE RESULTING CELL Phase of Cell 11Phase of Cell 22Phase of Nuclei in Resulting CellSS phaseG1G1 phaseTwo SS-phase nucleiSS phaseG2G2 phaseOne SS-phase nucleus and one G2G2-phase nucleusG1G1 phaseG2G2 phase One G1G1-phase nucleus and one G2G2-phase nucleus InterphaseMM phaseTwo MM-phase nuclei Which of the following research questions is best addressed by the experiment? A How do chemical messengers affect a cell's transition between the phases of the cell cycle? B How does the number of chromosomes affect when a cell transitions to the next phase of the cell cycle? C How does the amount of genetic information change throughout the cell cycle? D How does the checkpoint at G2G2 serve to prevent the transmission of mutations?

A How do chemical messengers affect a cell's transition between the phases of the cell cycle?

According to the data, the mice at 10o C demonstrated greater oxygen consumption per gram of tissue than did the mice at 25o C. This is most likely explained by which of the following statements? A The mice at 10o C had a higher rate of ATP production than the mice at 25o C. B The mice at 10o C had a lower metabolic rate than the mice at 25o C. C The mice at 25o C weighed less than the mice at 10o C. D The mice at 25o C were more active than the mice at 10o C.

A The mice at 10o C had a higher rate of ATP production than the mice at 25o C.

Pyruvate kinase, a key enzyme in the glycolysis pathway, is inhibited by the amino acid alanine. The ability of alanine to inhibit the enzyme is not affected by increasing the concentration of substrate. Which of the following best explains the mechanism by which alanine inhibits pyruvate kinase activity? A Alanine binds to an allosteric site of the enzyme, changing the shape of the enzyme's active site. B Alanine increases the enzyme-substrate binding until the enzyme becomes saturated. C Alanine is a competitive inhibitor that reversibly binds to the active site of the enzyme. D Alanine binds to the substrate, preventing the substrate from being able to bind to the active site of the enzyme.

A alanine binds to an allosteric site of the enzyme, changing the shape of the enzyme's active site

A common test for liver function involves sprinkling sulfur powder onto a sample of urine (mostly water with dissolved bodily waste). Sulfur powder sprinkled on a sample from an individual with impaired liver function will sink because the urine contains a high level of bile salts, while the sulfur powder sprinkled on normal urine samples will float. Which of the following best explains why bile salts cause the sulfur powder to sink? A Bile salts decrease the surface tension of the urine sample. B Bile salts increase the water potential of the urine. C Bile salts increase the density of the urine sample. D Bile salts decrease the strength of the covalent bonds within a water molecule.

A bile salts decrease the surface tension of the urine sample

Glycogen synthetase kinase 3 beta is a protein kinase that has been implicated in many types of cancer. Depending on the cell type, the gene for glycogen synthetase kinase 3 beta (GSK3β)(GSK3β) can act either as an oncogene or as a tumor suppressor. Which of the following best predicts how GSK3βGSK3β mutations can lead to the development of cancer? A Cells with inactive GSK3βGSK3β fail to trigger apoptosis. B Cells with inactive GSK3βGSK3β fail to proceed past the G2/MG2/M checkpoint. C Cells with overactive GSK3βGSK3β are more likely to repair DNADNA damage. D Cells with overactive GSK3βGSK3β have longer cell cycles.

A cells with inactive GSK 3 beta fail to trigger apoptosis

The reactions of glycolysis occur in the A cytosol B nucleus C matrix of the mitochondrion D membranes of the mitochondrion E stroma of the chloroplast

A cytosol

Which of the following best describes the role of mitosis in the cell cycle? A Distributing replicated chromosomes to daughter nuclei B Dividing the cytoplasm to form four gametes C Producing organelles and replicating chromosomes D Exchanging genetic material between homologous chromosomes

A distributing replicated chromsomes to daughter nuclei

DNA replication occurs A during the S phase of the cell cycle B as the nuclear envelope breaks down in early mitosis C during mitosis but not during meiosis D in animal cells but not in plant cells E only in cells destined to become gametes

A during the S phase of the cell cycle

When a substance moves across the plasma membrane along a concentration gradient at a rate faster than would be expected by simple diffusion alone but without the expenditure of metabolic energy, the process is best described as A facilitated diffusion B osmosis C active transport D pinocytosis E the work of an ion pump

A factilitated diffusion

Which of the following best explains why a cell's plasma membrane is composed of two layers of phospholipids rather than just a single layer? A Having two oppositely oriented layers of phospholipids allows only the hydrophilic heads to interact with water inside and outside of the cell. B Having two oppositely oriented layers of phospholipids allows the hydrophilic heads to repel water both inside and outside of the cells. C Having two identically oriented layers of phospholipids gives cells more protection from the exterior environment than just a single layer would. D Having two identically oriented layers of phospholipids allows for the production of vacuoles while still maintaining a protective barrier.

A having two oppositely oriented layers of phospholipids allows only the hydrophili head sto interact with water inside and outside of the cell

Which of the following best predicts the effect of not having ATPATP available to supply energy to this process? A H+H+ ions will stop moving through the protein. B H+H+ ions will move in the other direction through the protein. C H+H+ ions will continue to move through the protein in the original direction but at a slower rate. D H+H+ ions will begin to move through the phospholipid portion of the membrane in the original direction.

A hydrgoen ions will stop moving through the protein

In sweet pea plants, purple flower color is dominant over red flower color and long pollen grain shape is dominant over round pollen grain shape. Two sweet pea plants that are heterozygous for both flower color and pollen grain shape are crossed with one another. A geneticist is surprised to observe that there are far fewer round, purple offspring and long, red offspring than were predicted by the 9:3:3:19:3:3:1 expected phenotypic ratio. Which of the following statements provides the most reasonable prediction to account for the deviation from the expected results? A In sweet pea plants, the gene for flower color and the gene for pollen grain shape are genetically linked. B In sweet pea plants, the genes for flower color and for pollen grain shape both exhibit codominance. C Several mutations occurred spontaneously producing a deviation from the expected phenotypic ratios of the offspring. D The genes for flower color and pollen grain shape are inherited independently because of the law of independent assortment.

A in sweet pea plants, the gene for flower color and the gene for pollen grain shape are genetically linked

Which of the following statements is true regarding the movement of substances across cell membranes? A Ions are unable to move through the phospholipid bilayer because the nonpolar tail regions of the phospholipids are hydrophobic. B Ions are able to move through the phospholipid bilayer because the polar head regions of the phospholipids are charged. C Water is able to move through the phospholipid bilayer because the nonpolar tail regions of the phospholipids are charged. D Water is unable to move through the phospholipid bilayer because the polar head regions of the phospholipids are charged.

A ions are unable to move through the phospholipid bilayer because the nonpolar tail regoins of the phospholiipds are hydrophobic

Within the cell, many chemical reactions that, by themselves, require energy input (have a positive free-energy change) can occur because the reactions A may be coupled to the hydrolysis of ATP B take place very slowly C take place when the cells are at unusually high temperatures D are catalyzed by enzymes E are aided by various metal ions that act as catalysts

A may be coupled to the hydrolysis of ATP

A respirometer is a container used to measure the amount of oxygen consumed by an organism. A respirometer was used to determine how environmental temperature affects the uptake of oxygen in one 300-gram rat and one 50-gram mouse. The results of this experiment are shown on the graph below. Which of the following hypotheses is best supported by the results of this experiment? A Metabolic rate per gram of tissue is higher in smaller mammals. B Metabolic rate per gram of tissue is not related to body mass. C Mice produce less CO2 per gram of tissue than do rats. D Rats consume more food per gram of tissue than do mice.

A metabolic rate per gram at tissue is higher in smaller mammals

Which of the following occurs in all species of living organisms and may lead to an increase in genetic variation? A Mutations in the genome B Crossing-over in meiosis C Random assortment of chromosomes D Alternative splicing of mRNA

A mutations in the genome

Oxygen consumption can be used as a measure of metabolic rate because oxygen is A necessary for ATP synthesis by oxidative phosphorylation B necessary to replenish glycogen levels C necessary for fermentation to take place D required by all living organisms E required to break down the ethanol that is produced in muscles

A necessary for ATP syntheiss by oxidative-phosphorylation

Most cells that have become transformed into cancer cells have which of the following characteristics when compared to normal, healthy cells? A Shorter cell cycle B More carefully regulated rates of cell division C Lower rates of mitosis D Higher rates of protein translation E Identical DNA

A short cell cycle

A student claims that the YY chromosome contains the sex-determining region gene, known as the SRYSRY gene, which causes male fetuses to develop testes. Which of the following provides correct information about cell signaling that supports the claim? A The SRYSRY gene produces a protein that binds to specific regions of DNADNA in certain tissues, which affects the development of these tissues. B The SRYSRY gene produces a protein that deletes portions of the XX chromosome in males so that male characteristics can develop. C The SRYSRY gene produces an RNARNA segment that is exported from specific cells and targets the developing gonads. D The SRYSRY gene is found only in tissues of the developing gonads.

A the SRY gene produces a protein that binds to specific regions of DNA in certain tissues, which affects the development of these tissues

A team of biologists develop a new drug, and one team member hypothesizes that the drug is incapable of freely passing across the plasma membrane and requires the help of membrane proteins to enter cells. Alternatively, another biologist on the team hypothesizes that the drug can diffuse passively across the plasma membrane like O2O2 and CO2CO2 can. Which of the following, if true about the drug, best supports the alternative hypothesis that the new drug will exhibit simple diffusion across plasma membranes? A The drug is a small nonpolar molecule. B The drug is a small charged molecule. C The drug is a large polar molecule. D The drug is a large charged molecule.

A the drug is a small nonpolar molecule

A researcher designs an experiment to investigate the effect of environmental temperature on the function of an enzyme. For each trial included in the experiment, the researcher will add the enzyme and its substrate to an aqueous buffer solution and then measure the amount of product formed over 20 minutes. Which of the following must remain the same for all trials of this experiment? A The initial concentration of the substrate B The final concentration of the product C The three-dimensional structure of the enzyme D The temperature of the aqueous buffer solution

A the initial concentration of the substrate

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells Which of the following outcomes will most likely result from the irreversible binding of GDPGDP to the G protein? A The intracellular concentration of glycogen will increase. B The intracellular concentration of activated protein kinase A will increase. C The intracellular concentration of cyclic AMPAMP will increase. D The intracellular concentration of glucose-1-phosphate will increase.

A the intracellular concentraiton of glycogen will increase

Two nutrient solutions are maintained at the same pH. Actively respiring mitochondria are isolated and placed into each of the two solutions. Oxygen gas is bubbled into one solution. The other solution is depleted of available oxygen. Which of the following best explains why ATP production is greater in the tube with oxygen than in the tube without oxygen? A The rate of proton pumping across the inner mitochondrial membrane is lower in the sample without oxygen. B Electron transport is reduced in the absence of a plasma membrane. C In the absence of oxygen, oxidative phosphorylation produces more ATP than does fermentation. D In the presence of oxygen, glycolysis produces more ATP than in the absence of oxygen.

A the rate of proton pupmping across the inner mitochondrial membrane is lower in the sample wihtout oxygen

Insulin is a hormone produced by some pancreatic cells. Scientists have isolated the DNADNA sequence that codes for human insulin production. Which of the following best predicts the effect of inserting this gene into the DNADNA of a bacterial cell? A The recombinant bacterium will produce human insulin using its own transcription and translation machinery. B The recombinant bacterium will not transcribe the human insulin gene because this gene is not normally found in the bacterial genome. C The recombinant bacterium will transcribe the gene but will be unable to translate the mRNAmRNA. D The recombinant bacterium will die because it has been exposed to foreign DNADNA.

A the recombinant bacterium will produce human insulin using its own transcription and translation machinery

(A) Glysolysis(B) Krebs cycle (citric acid cycle)(C) Calvin cycle (light-independent reactions of photosynthesis)(D) Light-dependent reactions of photosynthesis(E) Chemiosmosis Process in which CO2, is released as a by-product of oxidation-reduction reactions A B C D E

B

Assume that the alleles referred to all assort independently.(A) 0(B) 1/16(C) 1/4(D) 1/2(E) 3/4 Probability that the genotype ccdd will be produced by the parents CcDd x CcDd A 0 B 1/16 C 1/4 D 1/2 E 3/4

B 1/16

A couple has 5 children, all sons. If the woman gives birth to a sixth child, what is the probability that the sixth child will be a son? A 5/6 B 1/2 C 1/5 D 1/6 E 1/64

B 1/2

in sheep, eye color is controlled by a single gene with two alleles. When a homozygous brown-eyed sheep is crossed with a homozygous green-eyed sheep, blue-eyed offspring are produced. If the blue-eyed sheep are mated with each other, what percent of their offspring will most likely have brown eyes? A 0% B 25% C 50% D 75% E 100%

B 25%

A researcher claims that the synthesis of ATPATP from ADPADP and inorganic phosphate (Pi)(Pi) is essential to cellular function. Which of the following statements best helps justify the researcher's claim? A ADPADP is a small molecule that some cells release into their environment as a way of communicating with other cells. B ATPATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy. C Inorganic phosphate (Pi)(Pi) is a substance that cells typically acquire from their environment. D ATPATP synthase is a mitochondrial enzyme that catalyzes the conversion of ADPADP and PiPi to ATPATP.

B ATp hydrolyss is an energy-releasing reaction that is often coupled with reactions that requrie an input of energy

This group of questions refers to molecules of the following substances. (A) Cytochrome(B) FADH2(C) NAD+(D) NADP+(E) Oxygen (O2) Coenzyme that transfers electrons from the Krebs cycle to the mitochondrial electron-transport chain at a lower energy level than that of electrons entering at the beginning of the chain A Cytochrome B FADH2 C NAD+ D NADP+ E Oxygen (O2)

B FADH2

A researcher measured the temperature at which two different samples of double-stranded DNADNA denature (separate into single strands). Sample 11 denatured at a significantly lower temperature than sample 22 did. Based on the data, the researcher claims that the DNADNA in sample 22 is composed of a higher percentage of guanine and cytosine than the DNADNA in sample 11 is. Which of the following best supports the researcher's claim? A The bonds between guanine and cytosine are covalent bonds, which require more energy to disrupt than those between adenine and thymine. B Guanine-cytosine pairs denature at a higher temperature because they have more hydrogen bonds between them than adenine-thymine pairs do. C Adenine-thymine pairs require less energy to separate because adenine and thymine are both single-ring bases. D Guanine-cytosine pairs require more energy to separate because one is a purine and one is a pyrimidine.

B Guanine-cytosine pairs denature at a higher temperature because they have more hydrogen bonds between them than adenine-thymine pairs do.

Ultraviolet (UVUV) radiation can damage DNADNA by breaking weak bonds. Which of the following best explains how this occurs? A UVUV radiation disrupts the double helix structure by breaking the covalent bonds between the nitrogenous base pairs. B UVUV radiation disrupts the double helix structure by breaking the hydrogen bonds between the nitrogenous base pairs. C UVUV radiation is able to break DNADNA strands in two by breaking covalent bonds between the sugar-phosphate backbone molecules. D UVUV radiation is able to break DNADNA strands in two by breaking hydrogen bonds between the sugar-phosphate backbone molecules.

B UV radiation disrupts the double helix structure by breaking the hydrogen bonds bewteen the nitrogenous base pairs

Which of the following is evidence that eukaryotes and prokaryotes share a common ancestor? A All eukaryotes and prokaryotes contain linear DNADNA. B All eukaryotes and prokaryotes contain ribosomes. C All eukaryotes and prokaryotes use organic molecules as an energy source. D All eukaryotes and prokaryotes are capable of mitosis.

B all eukaryoties and prokaryotes contain ribosomes

Amylase is an enzyme that converts carbohydrate polymers into monomers. Glycogen synthase is one of the enzymes involved in converting carbohydrate monomers into polymers. Which of the following best explains the reactions of these enzymes? A Amylase aids in the removal of a water molecule to break covalent bonds whereas glycogen synthase aids in the addition of a water molecule to form covalent bonds. B Amylase aids in the addition of a water molecule to break covalent bonds whereas glycogen synthase aids in the removal of a water molecule to form covalent bonds. C Amylase aids in the addition of a water molecule to form covalent bonds whereas glycogen synthase aids in the removal of a water molecule to break covalent bonds. D Amylase aids in the removal of a water molecule to form covalent bonds whereas glycogen synthase aids in the addition of a water molecule to break covalent bonds.

B amylase aids in the addition of a water molecule to break covalent bonds wheras glycogen synthase aids in the removal of a water moecule to form covalent bonds

Simple diffusion and facilitated diffusion are related in that both A require protein carriers B depend on a concentration gradient C occur via contractions of cytoskeletal elements attached to membrane proteins D are endergonic processes and thus require the hydrolysis of ATP E occur in eukaryotic cells but not in prokaryotic cells

B depend on a concentration gradient

A tissue culture of vertebrate muscle was provided with a constant excess supply of glucose under anaerobic conditions starting at time zero and the amounts of pyruvic acid and ATP produced were measured. The solid line in the graph above represents the pyruvic acid produced in moles per liter per minute. ATP levels were also found to be highest at points A and C, lowest at B and D. A second culture was set up under the same conditions, except that substance X was added, and the results are indicated by the dotted line. Which of the following is most likely to result if oxygen is added to the tissue culture? A Lactic acid formation will increase. B For each glucose molecule consumed, more ATP will be formed. C The levels of ATP produced will decrease. D Ethyl alcohol will be produced. E No change in the production of pyruvic acid will be observed.

B for each glucose molecule consumed, more ATP will be formed

Which metabolic process is common to both aerobic cellular respiration and alcoholic fermentation? A Krebs cycle B Glycolysis C Electron transport chain D Conversion of pyruvic acid to acetyl CoA E Production of a proton gradient

B glycolysis

Plant cell walls are composed of cellulose, while fungal cell walls are composed of chitin. A group of scientists hypothesize that this difference means the cell wall has largely different functions in plant cells and fungal cells. Alternatively, another group of scientists hypothesize that despite their biochemical differences, plant and fungal cell walls serve similar functions. Which of the following observations would best support the alternative hypothesis described above? A Plant cell walls are found just outside the plasma membrane, while fungal cell walls are found just beneath the plasma membrane. B In both plant cells and fungal cells, the cell wall surrounds the outside of the cell membrane. C Some plant cells have secondary cell walls that confer additional rigidity, while fungal cells do not. D Photosynthesis occurs in plant cells, but it does not occur in fungal cells.

B in both plant cells and fungal cells, the cell wall surrounds the outside of the cell membrane

Which of the following best explains how the extensive folding of the inner mitochondrial membrane benefits a eukaryotic cell? A It enlarges the volume of the matrix, which allows for more enzymatic reactions. B It increases the area available for proteins involved in energy transfer. C It allows for greater area for the diffusion of water into and out of the mitochondria. D It provides better insulation for reactions in the matrix from conditions outside the mitochondria.

B it increaes the area available for proteins involved in energy transfer

Which of the following is true of mitosis? A It is also known as cytokinesis. B It maintains the same chromosome number in the daughter cells as in the parent cell. C It is the last phase of interphase. D It regulates the transfer of genetic information from one daughter cell to another. E It moves homologous chromosomes to opposite poles.

B it maintains the same chromosome number in the daughter cells as in the parent cell

The enzyme peroxidase is found in many organisms. It catalyzes the breakdown of hydrogen peroxide into water and oxygen gas. The rate of peroxidase activity at different pHpH values was assessed by students in the lab. The students' results are shown in graph 1. Graph 1. Effect of pHpH on peroxidase activity If the experiment is repeated at pHpH 11, the observed activity level of the enzyme will most likely be A the same as the level at pHpH 7 B lower than the level at pHpH 9 C greater than the level at pHpH 9 D between the levels observed at pHpH 5 and pHpH 7.

B lower than the level at pH 9

A researcher examining a root tip observes a plant cell with condensed sister chromatids, kinetochores with attached microtubules, and individual chromosomes that are aligned at the equatorial plate of the cell. Which of the following best describes what the next process will be in the cell? A Homologous chromosomes (each with two sister chromatids) will move toward opposite poles of the cell. B Paired chromatids will separate, and the new daughter chromosomes will move toward opposite poles of the cell. C The nuclear envelope will break down, and the spindle will begin to form. D The chromatin will decondense, and the daughter cell will enter interphase.

B paired chormatids will separate, and the new daughter chromosomes will move toward opposite poles of the cell

Which of the following statements best explains the processes of passive and active transport? A Passive transport is the net movement of substances down a concentration gradient that requires metabolic energy. Active transport is the movement of substances up a concentration gradient that does not require energy. B Passive transport is the net movement of substances down a concentration gradient that does not require metabolic energy. Active transport is the movement of substances up a concentration gradient that requires energy. C Passive transport is the net movement of substances up a concentration gradient that requires metabolic energy. Active transport is the movement of substances down a concentration gradient that does not require metabolic energy. D Passive transport is the net movement of substances up a concentration gradient that does not require metabolic energy. Active transport is the movement of substances down a concentration gradient that requires energy.

B passive transport is the net movement of substances down a concentration gradietn that does not require metabolic energy. Active transport is the movement of substances up a concentration gradient that requires energy.

Which of the following components of the cell membrane is responsible for active transport? A Phospholipid B Protein C Lipid D Phosphate E Cholesterol

B protein

During respiration, most ATP is formed as a direct result of the net movement of A potassium against a concentration gradient B protons down a concentration gradient C electrons against a concentration gradient D electrons through a channel E sodium ions into the cell

B protons down a concetnration gradient

Which of the following can be used to determine the rate of enzyme-catalyzed reactions? A Rate of disappearance of the enzyme B Rate of disappearance of the substrate C Rate of disappearance of the product D Change in volume of the solution E Increase in activation energy

B rate of disappearance of the substrate

During mitosis, which of the following normally occurs? A Homologous chromosomes pair. B Replicated chromosomes line up on the equatorial plate. C Tetrads form. D Unreplicated chromosomes become oriented in the center of the cell. E Maternal and paternal chromatids pair.

B replicated chromosomes ilne up on the equatorial plate

The salinity of a small inland lake has recently started to increase. Researchers are planning to study the lake over several decades to investigate how freshwater organisms survive significant changes in their natural habitat. Which of the following physiological mechanisms will the researchers most likely observe among the surviving organisms in the lake? A Prokaryotic organisms will use various mechanisms to counteract swelling of cells as a result of increased water uptake. B Single-celled organisms will use various mechanisms to counteract the increased flow of water from cells to the environment. C Eukaryotic organisms will use various mechanisms to counteract the diffusion of positively charged ions across the cell membrane. D Multicellular organisms will use various mechanisms to counteract the loss of cell adhesion as a result of calcium deficiencies.

B single-celled organisms will use various mechanisms to counteract the increased flow of water from cells to the environment

A student analyzed a viral genome and found that the genome had the following nucleotide composition. • 28% adenine • 20% thymine • 35% cytosine • 17% guanine Which of the following best describes the structure of the viral genome? A Double-stranded DNA B Single-stranded DNA C Double-stranded RNA D Single-stranded RNA

B single-stranded DNA

Cholesterol is an important component of animal cell membranes. Cholesterol molecules are often delivered to body cells by the blood, which transports the molecules in the form of cholesterol-protein complexes. The complexes must be moved into the body cells before the cholesterol molecules can be incorporated into the phospholipid bilayers of cell membranes. Based on the information presented, which of the following is the most likely explanation for a buildup of cholesterol molecules in the blood of an animal? A The animal's body cells are defective in exocytosis. B The animal's body cells are defective in endocytosis. C The animal's body cells are defective in cholesterol synthesis. D The animal's body cells are defective in phospholipid synthesis.

B the animal's body cells are defective in endocytosis

DNADNA and RNARNA are nucleic acids that can store biological information based on the sequence of their nucleotide monomers. Figure 1 shows a short segment of each of the two types of nucleic acids. Which of the following best describes a structural difference between DNADNA and RNARNA? A DNADNA contains four types of nitrogenous bases, whereas RNARNA contains only two types of nitrogenous bases. B The backbone of DNADNA contains deoxyribose, whereas the backbone of RNARNA contains ribose. C A DNADNA molecule is composed of two parallel strands with the same 5′5′ to 3′3′ directionality, whereas an RNARNA molecule is composed of only one 5′5′ to 3′3′ strand. D Phosphate groups provide rigidity to DNADNA, but RNARNA is flexible and contains no phosphate groups.

B the backbone of DNA contains deoxyribose, wheras the backbone of RNA contains ribose

Researchers compared similar proteins from related organisms in different habitats. They found that the proteins from organisms living in harsh environments had a greater number of cysteine amino acids than did proteins from organisms not living in harsh environments. The structure of cysteine is shown. Bonds can form between the sulfur atom of different cysteine amino acids (S-SS-S bonds). Figure 1. Chemical structure of cysteine Which of the following best describes the effect of a greater number of cysteine amino acids on the stability of the proteins? A The change has no effect on the stability of the protein because only one type of amino acid is involved. B The change leads to increased protein stability because of an increased number of S-SS-S bonds in the tertiary structure of the proteins. C The change leads to decreased protein stability because of an increased number of S-SS-S bonds in the tertiary structure of the proteins. D The change leads to increased protein stability only when the added cysteine amino acids are next to other cysteine amino acids in the primary structure.

B the change leads to increased protein stability because of an increased number of S-S bonds in the tertiary structure of the proteins

Glucocorticoids are steroid hormones that control cellular responses through several different signaling pathways. One of the signaling pathways involves the glucocorticoid receptor, an intracellular protein that is activated by binding to a glucocorticoid molecule. A simplified model of the glucocorticoid receptor signaling pathway is represented in Figure 1. Figure 1. A simplified model of the glucocorticoid receptor signaling pathway Which of the following statements best predicts the effect of a mutation that results in a loss of the glucocorticoid receptor's ligand binding function? A The transduction of the glucocorticoid signal across the plasma membrane will be blocked. B The glucocorticoid receptor will remain associated with the accessory proteins. C The rate of diffusion of glucocorticoid molecules into the cell will increase. D The concentration of glucocorticoid receptors inside the nucleus will increase.

B the glucorticoid receptor will remain associated with the accessory proteins

Which of the following organelles modifies and packages for secretion the materials produced by the ribosomes? A The chloroplast B The Golgi apparatus C The nucleus D The nucleolus E The mitochondrion

B the golgi apparatus

Humans produce sweat as a cooling mechanism to maintain a stable internal temperature. Which of the following best explains how the properties of water contribute to this physiological process? A The high specific heat capacity of water allows the body to absorb a large amount of excess heat energy. B The high heat of vaporization of water allows the body to remove excess heat through a phase change of water from liquid to gas. C The high surface tension of water contributes to the physical process by which water leaves the body. D The high melting temperature of water allows the body to remove excess heat through a phase change of water from solid to liquid.

B the high heat of vaporization of water allows the body to remove excess heat through a phase change of water form liquid to gas

Which of the following best describes how amino acids affect the tertiary structure of a protein? A The number of amino acids determines the tertiary structure of the protein. B The interactions of the different RR-groups with other RR-groups and with their environment determine the tertiary structure of the protein. C The RR-group of the last amino acid that is added to a growing polypeptide chain determines the next amino acid that is added to the chain. D The sequence of the amino acids in the polypeptide chain determines the protein's primary structure but has no effect on its tertiary structure.

B the interactions of the different R gorups with other R groups and with their environemnt determine the teritary structure of the protein

A cell's membrane potential is maintained by the movement of ions into and out of the cell. A model showing the influence of membrane proteins on the movement of sodium (Na+Na+) and potassium (K+K+) ions across the plasma membrane is presented in Figure 1. Figure 1. Section of a cell's plasma membrane, showing ion concentrations and membrane proteins Based on the model presented in Figure 1, which of the following outcomes will most likely result from a loss of protein XX function? A The membrane potential will be disrupted by an increase in Na+Na+ concentration inside the cell. B The membrane potential will be disrupted by an increase in K+K+ concentration inside the cell. C The membrane potential will be maintained by the Na+−K+Na+⁢−⁢K+ pump moving more K+K+ ions into the cell. D The membrane potential will be maintained by the diffusion of Na+Na+ ions into the cell.

B the membrane potentioal will be distrupted by an incerase in potassium ion concentration inside the cell

Figure 1 shows a model of a signal transduction cascade, initiated by the binding of a ligand to the transmembrane receptor protein AA. Figure 1. Model of signal transduction cascade incorporating protein AA A DNADNA mutation changes the shape of the extracellular domain of transmembrane receptor protein AA produced by the cell. Which of the following predictions is the most likely consequence of the mutation? A Production of activated molecule 1 will stop, but production of activated molecules 2 and 3 will continue. B The molecule that normally binds to protein AA will no longer attach, deactivating the cellular response. C The molecule that normally binds to protein AA will not enter the cell, thus no cellular response will occur. D Since protein AA is embedded in the membrane, the mutation will be silent and not affect the cellular response.

B the molecule that normally binds to protein A will no longer attach, deactivitating the cellular response

The following questions refer to an experiment in which a dialysis-tubing bag is filled with a mixture of 3% starch and 3% glucose and placed in a beaker of distilled water, as shown below. After 3 hours, glucose can be detected in the water outside the dialysis-tubing bag, but starch cannot. From the initial conditions and results described, which of the following is a logical conclusion? A The initial concentration of glucose in the bag is higher than the initial concentration of starch in the bag. B The pores of the bag are larger than the glucose molecules but smaller than the starch molecules. C The bag is not selectively permeable. D A net movement of water into the beaker has occurred. E The molarity of the solution in the bag and the molarity of the solution in the surrounding beaker are the same.

B the pores of the bag are larger than the glucose molecules but smaller than the starch molecules

The primary function of the kidney is to exchange molecules across a membrane between the blood and the urine. One type of kidney cell has a basic rectangular shape, except for a single surface, which is lined with tiny, finger-like projections that extend into the surrounding extracellular space. Which of the following best explains the advantage these projections provide the cell? A The projections increase the volume of the cell without affecting the surface area, which increases the metabolic needs of the cell. B The projections increase the surface area-to-volume ratio of the cell, which allows for more efficient nutrient exchange with the environment. C The projections increase the speed at which an individual molecule can move, resulting in faster nutrient exchange with the environment. D The projections increase the selectivity of the membrane because the small size of the projections limits the number of transport proteins that can be embedded in the membrane.

B the projections increase the surface area-to-volume ratio of the cell, which allows for more efficient nutrient exchange with the environment

The coagulation cascade controls blood clot formation in response to blood vessel injury. Thrombin is an enzyme that plays a key role in regulating the coagulation cascade. A simplified model of thrombin's role in regulating the coagulation cascade is represented in Figure 1. Figure 1. A simplified model of thrombin's role in regulating the coagulation cascade Argatroban is a competitive inhibitor of thrombin. Which of the following effects on the coagulation cascade is most likely to result from inhibiting thrombin activity with argatroban? A The activation of clotting factors will be blocked. B The rate of fibrin formation will decrease. C Thrombin will be converted to prothrombin. D The rate of blood clot formation will increase.

B the rate of fibrin formation will decrease

Which of the following best describes the structures of carbohydrates? A They only occur as disaccharides. B They occur as monomers, chains of monomers, and branched structures. C They only occur as long and branched structures. D They occur as chains of monomers that hydrogen bond with complementary chains of monomers.

B they occur as monomers, chains of monomoers, and branched structures

Which statement best describes the effect on water transport across the cell membrane if the aquaporin in the figure ceases to function? A Water molecules will no longer be able to move across the cell membrane. B Water molecules will still be able to move across the cell membrane but at a slower rate. C Water molecules will only be able to enter the cell by active transport. D Water molecules will move across the cell membrane at a faster rate without the aquaporin regulating their flow.

B water molecules will still be bale to move across the cell membrane but at a slower rate

The endosymbiont theory proposes a model for the evolution of mitochondria. According to the model, an ancestral eukaryote engulfed a small, free-living prokaryotic organism. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host. Which of the following observations best supports the model? A Prokaryotes and eukaryotes acquire nutrients from the surrounding environment. B Organelles such as mitochondria and the endoplasmic reticulum have membranes composed of phospholipids. C Mitochondria and some prokaryotes share similar metabolic reactions that produce ATPATP. D Eukaryotes evolved after prokaryotes and have more complex structures.

C Mitochondria and some prokaryotes share similar metabolic reactions that produce ATPATP.

Which of the following statements best helps explain the reaction specificity of an enzyme? A The free energy of the reactants is greater than the free energy of the products. B The equilibrium constant of the reaction is much greater than 1. C The shape and charge of the substrates are compatible with the active site of the enzyme. D The concentration of the enzyme inside living cells is greater than the concentration of substrate.

C The shape and charge of the substrates are compatible with the active site of the enzyme.

Assume that the alleles referred to all assort independently.(A) 0(B) 1/16(C) 1/4(D) 1/2(E) 3/4 Probability that the genotype TTSs will be produced by the parents TTSs x TtSS A 0 B 1/16 C 1/4 D 1/2 E 3/4

C 1/4

If 2n = 48 for a particular cell, then the chromosome number in each cell after meiosis would be A 96 B 48 C 24 D 12

C 24

The events listed below generally take place during meiosis. I. Synapsis occurs.II. Crossing-over is completed.III. Condensation of chromosomes begins.IV. Separation of homologous chromosomes begins. Which of the following is the correct sequence of these events? A I, II, III, IV B II, I, III, IV C III, I, II, IV D III, IV, II, I E IV, II, III, I

C III, I, II, IV

This group of questions refers to molecules of the following substances. (A) Cytochrome(B) FADH2(C) NAD+(D) NADP+(E) Oxygen (O2) An intermediate electron acceptor for oxidations that occur in both glycolysis and in Krebs cycle reactions A Cytochrome B FADH2 C NAD+ D NADP+

C NAD+

Cancer can result from a variety of different mutational events. Which of the following is LEAST likely to result in the initiation of a cancerous tumor? A A receptor mutation results in activation of a cell-division pathway in the absence of the appropriate ligand. B A mutation results in the loss of the ability to produce a tumor-suppressor protein. C A defect in a cell-cycle checkpoint prevents a cell from entering the S phase. D At the anaphase checkpoint, separation of chromatids occurs without all centromeres being attached to kinetochore microtubules from both poles.

C a defect in a cell-cycle chekcpoint prevents a cell from entering the S phase

In most vertebrates, the sperm cell normally contributes which of the following to the new organism? A Many mitochondria B Significant amounts of RNA C A haploid complement of chromosomes D Most of the cytoplasm of the zygote E Two sex chromosomes

C a halpoind complement of chromosomes

Which of the following describes a mutation that would lead to an increase in the frequency of nondisjunction? A A mutation affecting checkpoint 11 proteins that forces cells to enter G0G0 B A mutation affecting checkpoint 22 proteins that allows cells to divide with DNADNA damage C A mutation affecting checkpoint 33 proteins that prevents attachment of spindle fibers D A mutation affecting checkpoint 22 proteins that prevents duplication of the chromosomes

C a mutation affecting checkpoint 3 proetins that prevents attachment of spindble fibers

A section of a cell's plasma membrane, showing a channel protein and a concentration gradient across the membrane An investigator wants to understand whether a newly found membrane protein is involved in membrane transport of a certain particle. Which investigation will help determine whether the new membrane protein is a channel protein involved in membrane transport? A Add small nonpolar molecules to the extracellular space and measure the direction of particle movement of the molecules. B Measure the rate of extracellular fluid movement into the intracellular space. C Add more of the proteins to the plasma membrane and measure the rate of the particle movement. D Remove ATPATP from the intracellular space and measure the rate of the particle movement into the intracellular space.

C add more of the proteins to the plasma membrane and measure the rate of the particle movement

An investigator wants to understand whether a newly found membrane protein is involved in membrane transport of a certain particle. Which investigation will help determine whether the new membrane protein is a channel protein involved in membrane transport? A Add small nonpolar molecules to the extracellular space and measure the direction of particle movement of the molecules. B Measure the rate of extracellular fluid movement into the intracellular space. C Add more of the proteins to the plasma membrane and measure the rate of the particle movement. D Remove ATPATP from the intracellular space and measure the rate of the particle movement into the intracellular space.

C add more of the proteins to the plasma membrane and measure the rate of the particle movement

An African violet grower observes that genetically identical African violet plants growing near the walls of the greenhouse have white flowers, that plants growing farther away from the walls have pale blue flowers, and that plants growing nearest the center of the greenhouse have dark blue flowers. Which of the following best explains the differences in flower color of the African violets in the greenhouse? A Warmer temperatures result in genotypic alterations, which result in flower color differences. B The plants along the walls of the greenhouse are homozygous recessive and therefore have white flowers. C An enzyme responsible for flower color does not fold correctly in cooler temperatures, and the greenhouse is warmest in the center. D More light is available along the walls of the greenhouse, so the flowers need less pigment to absorb sunlight for photosynthesis.

C an enzyme responsible for flower color doe snot fold correctly in cooler temperatures, and the greenhouse is warmest in the center

A researcher claims that only a portion of the light energy captured by green plants is available for growth and repair. Which of the following observations best helps justify the researcher's claim? A Light-capturing pigment molecules in green plants absorb red, blue, and violet light but reflect green light. B The energy of a photon of light is proportional to its frequency and inversely proportional to its wavelength. C As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat. D Captured energy is stored in the molecular bonds of organic molecules, including simple sugars and starch.

C as light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat

Which two cellular organelles in eukaryotes have both electron transport systems and chemiosmotic mechanisms? A Ribosomes and endoplasmic reticulum B Chloroplasts and endoplasmic reticulum C Chloroplasts and mitochondria D Mitochondria and nuclei E Nuclei and Golgi apparatus

C chloroplasts and mitchondria

if chemical signals in the cytoplasm control the progression of a cell to the M phase of the cell cycle, then fusion of a cell in G1 with a cell in early M phase would most likely result in the A replication of chromosomes only in the G1 cell B exiting of both cells from the cell cycle and into the G0 phase C condensation of chromatin in preparation of nuclear division in both cells D transfer of organelles from the G1 cell to the cell in the M phase

C condensation of chromatid in preparation of nuclaer division in both cells

Which of the following is responsible for the cohesive property of water? A Hydrogen bonds between the oxygen atoms of two adjacent water molecules B Covalent bonds between the hydrogen atoms of two adjacent water molecules C Hydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule D Covalent bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule E Hydrogen bonds between water molecules and other types of molecules

C hydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule

Researchers performed an experiment to determine the effect of certain genetic mutations on mitosis in tropical fruit fly embryos. They determined the percentage of cells in each of four phases of mitosis as shown in Figure 1. Figure 1. Percent of cells in phases of mitosis Which of the following patterns is shown by the data? A Mutant 1 cells are more similar to mutant 3 cells than to wild-type cells. B In wild-type cells, the percent of cells in anaphase is twice the amount of those in telophase C In mutant 3 cells, more time is spent in prophase/prometaphase than in the later stages of mitosis. D The percent of mutant 2 cells in anaphase is higher than that of mutant 1 cells.

C in mutant 3 cells, more time is spent in prophase/prometaphase than in the later stages of mitosis

The transport of a substance across a plasma membrane of a specific organelle requires energy. The rate at which the transport takes place also depends on temperature. A scientist isolated the specific organelle and then used the following treatments to determine the conditions that will result in the maximal transport. All treatments contained the extracted organelle and were maintained at 25°C25°C. The data from this experiment indicate that maximal rate of transport of protein XX at 25°C25°C occurs at an ATPATP concentration of 1.0μm/mL1.0μm/mL. Figure 1. The four ATPATP concentrations used in the experiment Which procedure should be done next to gather data needed to meet the scientist's objective? A Incubate samples with the same four ATPATP concentrations at 30°C30°C. B Incubate samples containing 5.0μm/mL5.0μm/mL of ATPATP at four temperatures other than 25°C25°C. C Incubate samples containing 1.0μm/mL1.0μm/mL of ATPATP at four temperatures other than 25°C25°C. D Incubate samples containing 1.0μm/mL1.0μm/mL of ATPATP at 25°C25°C and determine the rate of transport for four other proteins.

C incubate samples containing 1.0 micrometers/mL of ATP at four temperatures other than 25 degrees celsius

Which of the following statements best describes the role of adenylyl cyclase in the epinephrine signaling pathway? A It converts a polymer to its monomer subunits. B It moves substances across the plasma membrane. C It accelerates the production of a second messenger. D It transfers phosphate groups from ATPATP to protein substrates.

C it accelerates the production of a second messanger

In a certain signal transduction pathway, the binding of an extracellular molecule to a cell-surface protein results in a rapid increase in the concentration of cyclic AMPAMP inside the cell. The cyclic AMPAMP binds to and activates cytosolic enzymes that then activate other enzymes in the cell. Which of the following statements best describes the role of cyclic AMPAMP in the signal transduction pathway? A It acts as a signaling molecule that passes the signal from the cell to other cells. B It acts as a receptor that carries the signal from outside the cell to inside the cell. C It acts as a second messenger that helps relay and amplify the signal within the cell. D It acts as a channel protein that transmits the signal across the cell's nuclear membrane.

C it acts as a second messenger that helps relay and amplify the signal within the cell

ATP serves as a common energy source for organisms because A it is the smallest energy molecule B it stores the least energy of any energy source C its energy can be easily transferred to do cellular work D it is extremely stable and can be stored in the cell for long periods of time E traces of it have been found in fossils of ancient organisms dating back to the beginning of life on Earth

C its energy can be easily transferred to do cellular work

The amino acid in Figure 1 is found in a region of a polypeptide that folds away from water. Which part of the amino acid most likely contributes to the hydrophobic behavior of this region of the polypeptide? A Amine (NH2NH2) group B Carboxyl (COOHCOOH) group C Methyl (CH3CH3) group D Hydrogen (HH) atom

C methyl (CH3) group

This group of questions refers to the following groups of biological compounds. (A) Proteins(B) Carbohydrates(C) Nucleic acids(D) Lipids(E) Steroids Used to carry the genetic code A Proteins B Carbohydrates C Nucleic acids D Lipids E Steroids

C nucleic acids

The molecular structures of linoleic acid and palmitic acid, two naturally occurring substances, are shown in the figure. Based on the molecular structures shown in the figure, which molecule is likely to be solid at room temperature? A Linoleic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together. B Linoleic acid, because the presence of carbon-carbon double bonds prevents the molecules from packing closely together. C Palmitic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together. D Palmitic acid, because the presence of carbon-carbon double bonds prevents the molecules from packing closely together.

C palmitic acid, because the absence of carbon-carbon double bonds allwos the molecules to pack closely together

If ATP breakdown (hydrolysis) is inhibited, which of the following types of movement across cell membranes is also inhibited? A Movement of oxygen into a cell B Movement of water through aquaporins C Passage of a solute against its concentration gradient D Facilitated diffusion of a permeable substance

C passage of a solute against its concentration gradient

Cyclic AMPAMP phosphodiesterase is an enzyme that catalyzes the conversion of cyclic AMPAMP to a different molecule. Which of the following best predicts the effect of inhibiting cyclic AMPAMP phosphodiesterase in a muscle cell stimulated by epinephrine? A The concentration of cyclic AMPAMP will decrease because adenylyl cyclase will no longer be activated. B The G protein will diffuse out of the cell because it will no longer bind to the plasma membrane. C Phosphorylase kinase will remain active because protein kinase A will no longer be deactivated. D Glycolysis will stop because epinephrine signaling will no longer stimulate glycogen breakdown.

C phosphorylase kinase will reamin active because protein kinase A will no longer be deactivated

Prokaryotic and eukaryotic cells generally have which of the following features in common? A A membrane-bound nucleus B A cell wall made of cellulose C Ribosomes D Flagella or cilia that contain microtubules E Linear chromosomes made of DNA and protein

C ribosomes

Which of the following best describes the hydrolysis of carbohydrates? A The removal of a water molecule breaks a covalent bond between sugar monomers. B The removal of a water molecule forms a covalent bond between sugar monomers. C The addition of a water molecule breaks a covalent bond between sugar monomers. D The addition of a water molecule forms a covalent bond between sugar monomers.

C the addition of a water molecule breaks a covalent bond between sugar monomers

Which of the following provides evidence to best support the researchers' claim? A The organelle has a phospholipid membrane. B The organelle has protein in the membrane. C The organelle has a double membrane. D The organelle has an internal aqueous environment that is similar to the cytosol of the larger cell.

C the organelle has a double membrane

Which of the following statements best helps explain the reaction specificity of an enzyme? A The free energy of the reactants is greater than the free energy of the products. B The equilibrium constant of the reaction is much greater than 1. C The shape and charge of the substrates are compatible with the active site of the enzyme. D The concentration of the enzyme inside living cells is greater than the concentration of substrate.

C the shape and charge of the substrates are compatible with the active site of the enzyme

Researchers studying cell cycle regulation in budding yeast have observed that a mutation in the CDC15 gene causes cell cycle arrest in telophase when the yeast cells are incubated at an elevated temperature. Which of the following statements best predicts the effect of the cell cycle arrest on proliferating yeast cells? A The yeast cells will transition out of G0G0 but will fail to complete the G1G1 phase. B The yeast cells will initiate mitosis but will fail to complete the G2G2 phase. C The yeast cells will replicate their chromosomes but will fail to complete cytokinesis. D The yeast cells will replicate their organelles but will fail to complete the S phase.

C the yeast cells will replicate their chromosomes but wil lfail to complete cytokinesis

Which of the following best describes the cells that result from the process of meiosis in mammals? A They are diploid. B They can be used to repair injuries. C They are genetically different from the parent cell. D They are genetically identical to all the other cells in the body. E They are identical to each other.

C they are genetically different from the parent cell

Both mitosis and meiosis begin with a parent cell that is diploid. Which of the following best describes how mitosis and meiosis result in daughter cells with different numbers of chromosomes? A In mitosis, the chromosomes consist of a single chromatid, which is passed to two haploid daughter cells. In meiosis, the chromosomes consist of two chromatids during the first round of division and one chromatid during the second round of division, resulting in two haploid daughter cells. B In mitosis, synapsis of homologous chromosomes results in four haploid daughter cells after one division. In meiosis, synapsis of homologous chromosomes occurs during the second division and results in four diploid daughter cells. C Mitosis produces one identical daughter cell after one round of division. Meiosis has two rounds of division and doubles the number of chromosomes in the second round of division, producing four diploid cells. D Mitosis produces two identical diploid daughter cells after one round of division. Meiosis produces four haploid daughter cells after two rounds of division.

D Mitosis produces two identical diploid daughter cells after one round of division. Meiosis produces four haploid daughter cells after two rounds of division

The manner in which several different ions and molecules move through a cell membrane is shown in the diagram above. For each ion or molecule, the relative concentration on each side of the membrane is indicated. Which of the following accurately describes one of the movements taking place? A Glucose is transported into the cell by active transport. B Na+ is transported into the cell by active transport. C The movement of glucose through the membrane requires ATP hydrolysis. D Na+ transport out of the cell requires ATP hydrolysis.

D Na+ transport out of the cell requires ATP hydrolysis.

Which of the following statements best supports the claim that certain organelles within eukaryotic cells evolved from free-living prokaryotic cells? A The cytoplasm of both eukaryotes and prokaryotes is surrounded by a plasma membrane. B Eukaryotes and prokaryotes both contain ribosomes, but the ribosomes of eukaryotes are more complex in structure than those of prokaryotes. C Eukaryotes exchange segments of internal membranes between the endoplasmic reticulum and Golgi apparatus, but prokaryotes have no such internal membranes. D Some organelles contain their own DNADNA that is more similar to prokaryotic DNADNA in structure and function than to the eukaryotic DNADNA found in the cell's nucleus.

D Some organelles contain their own DNADNA that is more similar to prokaryotic DNADNA in structure and function than to the eukaryotic DNADNA found in the cell's nucleus.

Saccharomyces cerevisiae is a diploid yeast species that can reproduce either sexually or asexually. An experiment was performed to induce mitotically dividing S. cerevisiae cells in G2G2 to undergo meiosis. Which of the following best describes the steps these cells will follow to form gametes? A The first division will result in crossing over between homologous chromosomes, and the second division will reduce the original number of chromosomes by half in the daughter cells. B The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will result in each daughter cell having one-fourth of the original number of chromosomes. C The first division will move single chromatids to each daughter cell, and the second division will double the number of chromosomes in each daughter cell. D The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will move single chromatids to each daughter cell.

D The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will move single chromatids to each daughter cell.

What is the expected percent change in the DNADNA content of a typical eukaryotic cell as it progresses through the cell cycle from the start of the G1G1 phase to the end of the G2G2 phase? A −100%−100% B −50%−50% C +50%+50% D +100%

D +100%

A cell is treated with a drug that prevents the formation of new lysosomes. The cell continues to transcribe the genes that code for the hydrolytic enzymes that are normally found in lysosomes and continues to translate the mRNA for those proteins on membrane-bound ribosomes. The hydrolytic enzymes are most likely to accumulate in which of the following cellular structures? A Nucleus B Mitochondrion C Smooth endoplasmic reticulum D Golgi complex

D Golgi complex

In a mesophyll cell of a leaf, the synthesis of ATP occurs in which of the following? I. RibosomesII. MitochondriaIII. Chloroplasts A I only B II only C III only D II and III only

D II and III only

In peas the trait for tall plants is dominant (T) and the trait for short plants is recessive (t). The trait for yellow seed color is dominant (Y) and the trait for green seed color is recessive (y). A cross between two plants results in 296 tall yellow plants and 104 tall green plants. Which of the following are most likely to be the genotypes of the parents? A TTYY x TTYY B TTyy x TTYy C TtYy x TtYy D TtYy x TTYy E TtYY x Ttyy

D TtYy x TTYy

Aquaporins are channel proteins that facilitate the transport of water across the cell membrane. One group of researchers hypothesizes that without functional aquaporins, no water will be able to enter the cell. A different group proposes an alternative hypothesis, stating that even with nonfunctional aquaporins, a small amount of water will still cross the cell membrane. An experiment is set up in which plant cells with mutated (nonfunctional) aquaporins and plant cells with normally functioning aquaporins are both placed in distilled water. Which of the following data would support the alternative hypothesis? A Cells with functional aquaporins exhibit low turgor pressure and are hypertonic. B Cells with functional aquaporins exhibit high turgor pressure and are hypotonic. C Cells with mutated aquaporins exhibit an absence of turgor pressure and are completely plasmolyzed. D Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.

D cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic

Alcohol dehydrogenase (ADHADH) is an enzyme that aids in the decomposition of ethyl alcohol (C2H5OH)(C2H5OH) into nontoxic substances. Methyl alcohol acts as a competitive inhibitor of ethyl alcohol by competing for the same active site on ADHADH. When attached to ADHADH, methyl alcohol is converted to formaldehyde, which is toxic in the body. Which of the following statements best predicts the effect of increasing the concentration of substrate (ethyl alcohol), while keeping the concentration of the inhibitor (methyl alcohol) constant? A There will be an increase in formaldehyde because ADHADH activity increases. B Competitive inhibition will be terminated because ethyl alcohol will bind to methyl alcohol and decrease ADHADH activity. C The peptide bonds in the active site of the enzyme will be denatured, inhibiting the enzyme. D Competitive inhibition will decrease because the proportion of the active sites occupied by substrate will increase.

D competetive inhibition will decerase the proportion of the active sites occupied by substrate will increase

According to the chemiosmotic theory (chemiosmotic coupling), the energy required to move protons from the mitochondrial matrix to the intermembrane space against a concentration gradient comes most directly from A photons of red or blue light B the hydrolysis of ATP C the breakdown of high-energy fatty acids inthe mitochondrial matrix D electrons flowing along the electron transportchain E substrate-level phosphorylation

D electrons flowing along the electron transport chain

The enzyme hexokinase catalyzes the conversion of glucose to glucose-6-phosphate, which is an important step in glycolysis. The reaction involves the transfer of a phosphate group from ATPATP to glucose. Either a glucose molecule or a water molecule can fit in the active site of hexokinase. The presence of a water molecule in hexokinase's active site would result in the hydrolysis of ATPATP to ADPADP instead of the conversion of glucose to glucose-6-phosphate. Which of the following statements best helps explain the reaction specificity of hexokinase? A Both glucose and water are polar molecules that form favorable interactions with charged and polar amino acid side chains in hexokinase's active site. B Both glucose and water have oxygen atoms that can form covalent bonds with the phosphorus atoms of phosphate groups. C Glucose is an energy-rich organic molecule that can be broken down by glycolysis to produce ATPATP, whereas water is an inorganic molecule. D Glucose has the right shape and charge to cause hexokinase to undergo a structural change needed for catalysis, whereas water does not.

D glucose has the right shape and charge to cuase hexokinase to udnergo a structural change needd for catalysis, wheras water does not

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells A researcher claims that the epinephrine signaling pathway controls a catabolic process in muscle cells. Which of the following statements best helps justify the researcher's claim? A Epinephrine is a signaling molecule that binds to a transmembrane protein. B The G protein in the epinephrine signaling pathway consists of three different subunits. C Phosphorylase kinase catalyzes the hydrolysis of ATPATP. D Glycogen phosphorylase catalyzes the conversion of glycogen to glucose-1-phosphate.

D glycogen phosphorylase catalyzes the conversion of glycogen to glucose-1 phosphate

Figure 1 is a diagram of water molecules at the air-water interface at the surface of a pond. Figure 1. Alignment of water molecules at air-water interface Based on Figure 1, which of the following best describes how the properties of water at an air-water interface enable an insect to walk on the water's surface? A Covalent bonds between water molecules and the air above provide cohesion, which causes tiny bubbles to form under the feet of the insect. B Ionic bonds between molecules at the surface of the water provide an electric charge, which attracts the feet of the insect, keeping it on the surface. C Polar covalent bonds between molecules at the surface of the water provide adhesion, which supports the weight of the insect. D Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the water surface to deform but not break under the insect.

D hydrogen bonds between molecules at hte surface of the water provide surface tension, which allows the water surface to deform but not break under the insect

Of the following, which additional investigation can be used to determine when the cells are in an isotonic solution? A Decreasing the salinity of the environment a little at a time until the ATPATP usage reaches a maximum B Decreasing the salinity of the environment a little at a time until ATPATP usage reaches a minimum C Increasing the salinity of the environment a little at a time until ATPATP usage reaches a maximum D Increasing the salinity of the environment a little at a time until the ATPATP usage reaches a minimum

D increasing the saliinity of the environment a little at a time until the ATP usage reaches a minimum

Water is constantly diffusing into the cytosol of freshwater single-celled organisms. In order to maintain the proper solute concentrations in the cytosol, contractile vacuoles pump out the excess water. An experimenter placed single-celled organisms into various saline concentrations and recorded the ATPATP used by the contractile vacuole. The data are shown in the graph. Of the following, which additional investigation can be used to determine when the cells are in an isotonic solution? A Decreasing the salinity of the environment a little at a time until the ATPATP usage reaches a maximum B Decreasing the salinity of the environment a little at a time until ATPATP usage reaches a minimum C Increasing the salinity of the environment a little at a time until ATPATP usage reaches a maximum D Increasing the salinity of the environment a little at a time until the ATPATP usage reaches a minimum

D increasing the salinity of the environment a little at a time until the ATP usage reaches a minimum

Which of the following is most directly responsible for water's unique properties? A It contains oxygen atoms. B It contains hydrogen atoms. C It is an ionic compound. D It forms hydrogen bonds. E It is nonpolar.

D it forms hydrogen bonds

The CFTRCFTR protein is made up of 1,4801,480 amino acids linked together in a chain. Some humans produce a version of the CFTRCFTR protein in which phenylalanine (an amino acid) has been deleted from position 508 of the amino acid chain. Which of the following best predicts how the amino acid deletion will affect the structure of the CFTRCFTR protein? A It will have no observable effect on the structure of the CFTRCFTR protein. B It will affect the primary structure of the CFTRCFTR protein, but the other levels of protein structure will not be affected. C It will affect the secondary and tertiary structures of the CFTRCFTR protein, but the primary structure will not be affected. D It will affect the primary, secondary, and tertiary structures of the CFTRCFTR protein.

D it will affect the primary, secondary, and teritary structures of the CFTR protein

Ethylene causes fruits to ripen. In a signaling pathway, receptors activate transcription factors, which ultimately leads to ripening. Which of the following best supports the claim that ethylene initiates the signal transduction pathway that leads to ripening of fruit? A Ethylene is a simple gaseous molecule, which makes it easily detected by receptors. B Fruit will ripen in closed containers without exposure to air. C Ethylene synthesis is under both positive and negative feedback regulation. D Loss-of-function mutations in ethylene receptors result in changes to the ripening process.

D loss-of-function mutations in ethylene receptors reslut in changes to the ripening process

Which of the following best describes how the amount of DNADNA in the cell changes during MM phase? A The amount of DNADNA doubles as the DNADNA is replicated. B The amount of DNADNA slightly increases as a result of new organelle synthesis. C The amount of DNADNA does not change while the cell grows. D The amount of DNADNA is halved as the cell divides into two daughter cells.

D the amount of DNA is hlaved as the cell idvides into two daughter cells

Individuals with an inherited autosomal recessive disorder called primary ciliary dyskinesia (PCD) often have severe respiratory problems due to defective cilia. Males with PCD are often sterile because they produce sperm with defective flagella. Which of the following most likely explains the effect of the recessive allele? A The mitochondria are defective and do not produce sufficient protein to synthesize microtubules in the cilia and flagella. B The plasma membrane of the alveoli is not permeable to carbon dioxide during respiration because it is too hydrophobic. C The Golgi bodies secrete an enzyme that destroys the proteins in the flagella and cilia. D The cells do not produce functional motor proteins in flagella and cilia.

D the cells do not produce functional motor proteins in flagella and cilia

When hydrogen ions are pumped out of the mitochondrial matrix, across the inner mitochondrial membrane, and into the space between the inner and outer membranes, the result is A damage to the mitochondrion B the reduction of NAD C the restoration of the Na-K balance across the membrane D the creation of a proton gradient E the lowering of pH in the mitochondrial matrix

D the creation of a proton gradient

Cancer cells behave differently than normal body cells. For example, they ignore signals that tell them to stop dividing. Which of the following conditions will most likely cause a normal body cell to become a cancer cell? A The environment already contains cancer cells. B The environment has an abundance of nutrients. C The environment lacks signals that would otherwise tell the cell to stop dividing. D The environment contains mutagens that induce mutations that affect cell-cycle regulator proteins.

D the environment contains mutagens that induce mutations that affect cell-cycle regulator proetins

A human kidney filters about 200 liters of blood each day. Approximately two liters of liquid and nutrient waste are excreted as urine. The remaining fluid and dissolved substances are reabsorbed and continue to circulate throughout the body. Antidiuretic hormone (ADH) is secreted in response to reduced plasma volume. ADH targets the collecting ducts in the kidney, stimulating the insertion of aquaporins into their plasma membranes and an increased reabsorption of water. If ADH secretion is inhibited, which of the following would initially result? A The number of aquaporins would increase in response to the inhibition of ADH. B The person would decrease oral water intake to compensate for the inhibition of ADH. C Blood filtration would increase to compensate for the lack of aquaporins. D The person would produce greater amounts of dilute urine.

D the person would produce greater amounts of dilute urine

A) Glysolysis(B) Krebs cycle (citric acid cycle)(C) Calvin cycle (light-independent reactions of photosynthesis)(D) Light-dependent reactions of photosynthesis(E) Chemiosmosis Process found in both photosynthesis and cellular respiration A B C D E

E

Which of the following statements about mitochondrial chemiosmosis is NOT true? A A proton gradient is established across the inner membrane of the mitochondrion. B The potential energy released from the mitochondrial proton gradient is used to produce ATP. C The mitochondrial proton gradient provides energy for muscle contraction. D Proteins embedded in the inner mitochondrial membrane play an important role in ATP synthesis. E Heat energy is required to establish the electron transport chain.

E heat energy is requried to establish the electron transport chain

The organelle that is a major producer of ATP and is found in both heterotrophs and autotrophs is the A chloroplast B nucleus C ribosome D Golgi apparatus E mitochondrion

E mitochondrion

In humans, red-green color blindness is a sex-linked recessive trait. If a man and a woman produce a color-blind son, which of the following must be true? A The father is color-blind. B Both parents carry the allele for color blindness. C Neither parent carries the allele for color blindness. D The father carries the allele for color blindness. E The mother carries the allele for color blindness.

E the mother carries the allele for color blindness

Which of the following best describes the functionof the coenzymes NAD+ and FAD in eukaryoticcellular respiration? A They participate in hydrolysis reactions byaccepting protons from water molecules. B They participate directly in thephosphorylation of ADP to ATP. C They serve as final electron acceptors in theelectron transport chain. D They aid vitamins such as niacin in the breakdownof glucose. E They accept electrons during oxidation-reductionreactions.

E they accept electrons during oxidaiton-reduction reactions

The synthesis of protein or carbohydrate polymers always produces which of the following as a byproduct? A ATP B Oxygen C Carbon dioxide D Urea E Water

E water

A researcher proposes a model of an enzyme-catalyzed reaction in which a reactant is converted to a product. The model is based on the idea that the reactant passes through a transition state within the enzyme-substrate complex before the reactant is converted to the product. Which of the following statements best helps explain how the enzyme speeds up the reaction? A The enzyme's active site binds to and stabilizes the reactant, which decreases the free-energy change of the reaction. B The enzyme's active site binds to and stabilizes the transition state, which decreases the activation energy of the reaction. C The enzyme's active site binds to and stabilizes the product, which increases the amount of energy released by the reaction. D The enzyme's active site binds to and stabilizes both the reactant and the product at the same time, which increases the reaction's equilibrium constant.

The enzyme's active site binds to and stabilizes the transition state, which decreasese the activation energy of the reaction

Contains hydrolytic enzymes associated with the intracellular digestion of macromolecules A Centriole B Lysosome C Nucleolus D Peroxisome E Ribosome

b lysosome

Several members of a family are found to involuntarily sneeze when exposed to bright lights, such as sunlight. Following analysis of the condition in the family, a doctor predicts that the symptoms have an underlying genetic basis. A pedigree of the family is shown in Figure 1. Figure 1. Pedigree showing family members with and without symptoms For this condition, which of the following modes of inheritance is most consistent with the observations? A Autosomal dominant B Autosomal recessive C X-linked dominant D X-linked recessive

A autosomal dominant

Testosterone is a small steroid hormone that is important in cell signaling. Which of the following indicates where testosterone enters a cell and why it is able to cross at that point? A 1, because testosterone is nonpolar and can diffuse through the membrane. B 2, because testosterone covalently binds to a surface protein and transports into the cell. C 3, because testosterone dissolves in water and flows through the channel. D 4, because testosterone is filtered out of the extracellular fluid and taken into the cell by endocytosis.

A because testerterone is nonpolar and can diffuse through the membrane

A magnesium sulfate solution taken orally can cause a net movement of water into the large intestine, which results from water molecules diffusing through aquaporins embedded in the cells of the intestinal lining. By which of the following mechanisms do the water molecules most likely move into the large intestine? A By passive transport from an area of low osmolarity to an area of high osmolarity B By passive transport from an area of high osmolarity to an area of low osmolarity C By active transport from an area of low osmolarity to an area of high osmolarity D By active transport from an area of high osmolarity to an area of low osmolarity

A by passive transport from an area of low osmolarity to an area of high osmolarity

Aldosterone (a steroid hormone) is a small, nonpolar, hydrophobic molecule that enters a target cell by moving across the plasma membrane, down a concentration gradient. Based on the information presented, how does aldosterone most likely enter target cells? A By simple diffusion B By facilitated diffusion C By active transport D By endocytosis

A by simply diffusion

All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum. Which of the following best describes a process that occurs within the Golgi complex? A Enzymatic modification of newly synthesized integral membrane proteins B Synthesis of cytosolic proteins based on the nucleotide sequences of mRNAsmRNAs C Degradation of proteins by hydrolytic enzymes contained within the complex D Synthesis of various types of lipids

A enzyumatic modiciation of newly synthesized integral membrae proteins

Researchers performed a dihybrid cross with coffee bean plants to investigate whether the inheritance of two traits (height and stem circumference) follows Mendel's law of independent assortment. The data for the F2F2 generation are presented in Table 1. Table 1. Data for the F2F2 generation PhenotypeObservedExpectedDwarf with small stem circumference191172Dwarf with large stem circumference2657Tall with small stem circumference3957Tall with large stem circumference4919TOTAL305305 Which of the following is closest to the calculated chi-square (χ2)(χ2) value for the data presented in Table 1? A 8.35 B 72.01 C 98.00 D 2,546.00

B 72.01

The epidermal growth factor receptor EGFREGFR is a cell surface receptor. When a growth factor binds to EGFREGFR, the receptor is activated. The activated EGFREGFR triggers a signal transduction pathway, which leads to increased frequency of cell division. Which of the following best predicts the effect of a mutation that causes EGFREGFR to be active in the absence of a growth factor? A Increased apoptosis will lead to abnormal growth of the tissue. B Increased cell division will lead to the formation of a tumor. C Cells will exit the cell cycle, entering a non-dividing G0G0 phase. D Fewer cells will be in any of the stages of mitosis.

B increased cell division will lead to the formation of a tumor

For sexually reproducing diploid parent cells, which of the following statements best explains the production of haploid cells that occurs in meiosis but not in mitosis? A Separation of chromatids occurs once, and there is one round of cell division in meiosis. B Separation of chromatids occurs twice, and there are two rounds of cell division in mitosis. C Separation of chromatids occurs once, and there are two rounds of cell division in meiosis. D Separation of chromatids occurs twice, and there is one round of cell division in mitosis.

C separation of chromatids occurs once, and there are two rounds of clel division in meiosis

Some cells, such as intestinal cells, exchange a lot of material with their surroundings. The surface-to-volume ratio of these cells affects the efficiency of material exchange. The table provides measurements of four different eukaryotic cells. Cell1234Total surface area (μm2)(μm2)406080100Total volume (μm3)(μm3)20103020 Based on the data, which cell is likely to be most effective in the exchange of materials? A Cell 11 B Cell 22 C Cell 33 D Cell 4

b Cell 2

Researchers propose a model to explain variation in phytoplankton cell sizes in a marine environment. They base their model on the idea that smaller cells absorb nutrients more efficiently. The researchers predict that the mean diameter of phytoplankton cells will change by 50 micrometers for every 5-kilometer increase in distance from the shore because of a gradual decrease in nutrient availability. To test their model, the researchers determine that the phytoplankton cells found closest to shore have a mean diameter of 900 micrometers. Based on the model, what will be the mean diameter of the phytoplankton cells that are found 25 kilometers from shore? A 650 micrometers B 875 micrometers C 925 micrometers D 1150 micrometers

A 650 micrometers

Researchers investigated the effect of urea on the three-dimensional structure of a certain enzyme. The researchers dissolved the enzyme in an aqueous buffer solution and added urea to the solution. The enzyme did not appear to have a secondary or tertiary structure. The researchers carefully removed the urea from the solution and determined that the enzyme had the original secondary and tertiary structure again. Based on the results of the experiment, which of the following statements best predicts the effect of urea on the enzyme's function? A Function will be disrupted by adding the urea and regained by removing the urea. B Function will be disrupted by adding the urea, but it will not be regained by removing the urea. C Function will be gained by adding the urea and disrupted by removing the urea. D Function will be unaffected by the addition and removal of the urea.

A Function will be disrupted by adding the urea and regained by removing the urea

Researchers have discovered details about apoptosis (programmed cell death) by studying embryologic development of a nematode worm, Caenorhabditis elegans. Apoptosis is a normal developmental process in C. elegans. They found several genes involved in apoptosis, including ced−9ced−9 and ced−3ced−3 . The ced−3ced−3 gene was found to promote cell death, and ced−9ced−9 to inhibit it. The ced−9ced−9 gene serves as a regulator that prevents apoptosis in the absence of a signal promoting apoptosis. Which of the following statements best justifies the claim that changes in the expression of ced−9ced−9 in C. elegans can affect regulation of apoptosis in the cell? A An experiment showed that a mutation in the ced−9ced−9 gene led to excessive cell death in C. elegans. B An experiment showed that the ced−9ced−9 gene normally produces a protein that promotes excessive cell death in C. elegans. C A mutation in ced−3ced−3 will cause ced−9ced−9 to be incorrectly transcribed. D Apoptosis is dependent on a signal from the ced−9ced−9 gene in C. elegans.

A an experiment showed that a mutation in the ced-9 gene led to excessive cell death in C. elegans

Of the two cells represented in the figure, which would likely be more efficient at exchanging substances with the surrounding environment? A Cell A, because it has the larger surface-area-to-volume ratio. B Cell A, because it has the smaller surface-area-to-volume ratio. C Cell B, because it has the larger surface-area-to-volume ratio. D Cell B, because it has the smaller surface-area-to-volume ratio.

A cell A, because it has the larger surface area-to-volume ratio

During a fight-or-flight response, epinephrine is released into the body's circulatory system and transported throughout the body. Some cells exhibit a response to the epinephrine while other cells do not. Which of the following justifies the claim that differences in components of cell signaling pathways explain the different responses to epinephrine? A Cell signaling depends on the ability to detect a signal molecule. Not all cells have receptors for epinephrine. Only cells with such receptors are capable of responding. B Cell signaling depends on the transduction of a received signal by the nervous system. Not all cells are close enough to a synapse to receive the signal and respond. C Cell signaling depends on the signal being able to diffuse through the cell membrane. Epinephrine is incapable of diffusing through some plasma membranes because of the membrane's phospholipid composition. D Cell signaling requires reception, transduction, and response. All cells can receive epinephrine, all cells respond with a pathway, but only select cells have the proper coding in their DNADNA to respond.

A cell signaling depends on the ability to detect a signal molecule. not all cells have receptors for epinephrine. only cells with such receptors are capable of responding.

An antigen can induce an immune response in a host organism. Antigens are targeted by antibodies that are produced by the organism's immune system in response to contact with the antigen. Antibodies are specific to antigens. Many different cell types are involved in immune responses. Which of the following best describes the role of cell-to-cell communication during a response to an invasion of antigens? A Chemicals that are secreted from antigen-presenting cells then activate helper T cells. B A macrophage cell engulfs a pathogen in the blood. C Antigens attaching to receptors on memory B cells stimulate the memory B cells to become plasma cells. D Antigen-presenting cells engulf antigens at the first exposure.

A chemicals that are secreted from antigen-presenting cells then activiate helper T cells

Catalase is an enzyme found in yeast cells that facilitates the chemical breakdown of hydrogen peroxide to water and oxygen gas. An experiment was conducted to determine the effect of pHpH on catalase function. Five buffer solutions of varying pHpH (2, 4, 6, 8, and 10) were prepared and added to separate test tubes. Hydrogen peroxide (H2O2)(H2O2) was added to each test tube. Yeast was added, and the reactions were timed. After 1 minute the amount of oxygen gas released was determined by measuring the foam layer produced in each test tube. Figure 1 illustrates the experimental setup. Figure 1. Illustration of experimental procedure A set of five additional test tubes were prepared and used as controls. Which of the following best describes the contents expected to be contained in one of the five control test tubes? A pHpH 4 buffer solution and hydrogen peroxide only B All five pHpH buffer solutions combined and hydrogen peroxide only C Water, hydrogen peroxide, and yeast D Water and yeast only

A pH 4 buffer solution and hydrogen peroxide only

Intravenous (IV)(IV) therapy is used for fluid replacement in instances of dehydration in humans and other animals. One type of IVIV fluid is essentially a saltwater solution. To determine the best concentration for therapy in people, a team of students is researching the effects of solutions of different salt concentrations on red blood cells. The following observations were made from three different red blood cell samples viewed under a microscope. 0.3%0.3% Saline (Cells swell) 0.9%0.9% Saline (Cells unchanged) 1.5%1.5% Saline (Cells shrink) The team wants to extend the research project. What should the team of students do next to obtain data that are more conclusive? A Repeat the process with other salt concentrations. B Develop a model to explain why the cells react differently to different salt concentrations. C Repeat the process using red blood cells from other animals. D Develop an experimental procedure that uses a stain that makes the organelles of red blood cells more visible.

A repeat the process with other salt concentrations

Acetylcholinesterase (AChE)(AChE) is a protein that catalyzes the conversion of acetylcholine to acetate and choline. When the concentration of AChEAChE in an aqueous solution is held constant, the rate of the reaction catalyzed by AChEAChE increases with increasing concentrations of substrate. At low concentrations of acetylcholine, a small increase in the substrate concentration results in a large increase in the reaction rate. At high concentrations of acetylcholine, however, a large increase in the substrate concentration results in only a small increase in the reaction rate. Which of the following statements correctly explains the observed effect of the acetylcholine concentration on the rate of the enzyme-catalyzed reaction? A The active site of AChEAChE is specific for acetylcholine, and only one substrate molecule can occupy the active site at a time. B AChEAChE begins converting product into substrate as the acetylcholine concentration changes from low to high. C The AChEAChE protein becomes denatured as the acetylcholine concentration changes from low to high. D The substrate specificity of AChEAChE changes as the acetylcholine concentration changes from low to high.

A the active site of AChE is specific for acetylcholine, and only one substrate molecule can occupy the active site at a time

Researchers hypothesized that red eye color in Japanese koi, a type of fish, is due to a mutation. To study the inheritance of red eye color in koi, the researchers conducted breeding experiments over several generations. The results are summarized in Figure 1. Figure 1. Inheritance of eye color in Japanese koi Based on the data in Figure 1, which of the following is the best prediction of the mode of inheritance of red eyes in Japanese koi? A The allele for red eyes is inherited in an autosomal dominant pattern. B The allele for red eyes is inherited in an autosomal recessive pattern. C The allele for red eyes is inherited in an XX-linked recessive pattern. D The allele for red eyes is inherited in an XX-linked dominant pattern.

A the allele fro red eyes is inherited in an autosomal dominant pattern

Muscle cells have high ATPATP demands. Which of the following is a scientific claim about how the structure of the mitochondria in muscle cells should be different than it is in other cells because of the high energy demands of mitochondria? A The inner membrane of the mitochondria in muscle cells should have more folds to increase the surface area, allowing more ATPATP to be synthesized. B The inner membrane of the mitochondria in muscle cells should be more permeable to large enzymes, allowing the same reactions to occur in both compartments of the mitochondria. C The outer membrane of the mitochondria in muscle cells should be thicker, allowing more rapid diffusion of molecules into the mitochondria. D The outer membrane of the mitochondria of muscle cells should have more folds, increasing the surface area for faster diffusion of molecules from the cytoplasm.

A the inner membrane of the mitochondria in muscle cells should have more folds to increase the surface area, allowing more ATP to be synthesized

Fibroblast growth factor receptors (FGFRs)(FGFRs) are transmembrane proteins that regulate cellular processes such as cell proliferation and differentiation. The extracellular domains of FGFRFGFR proteins bind specifically to signaling molecules called fibroblast growth factors. The intracellular domains of FGFRFGFR proteins function as protein kinases, enzymes that transfer phosphate groups from ATPATP to protein substrates. FGFRFGFR activation occurs when binding by fibroblast growth factors causes FGFRFGFR proteins in the plasma membrane to become closely associated with each other. The association of two FGFRFGFR proteins stimulates protein kinase activity, which triggers the activation of intracellular signaling pathways. A simplified model of FGFRFGFR activation is represented in Figure 1. Figure 1. A simplified model of FGFRFGFR activation Which of the following changes in the FGFRFGFR signaling pathway is most likely to result in uncontrolled cell proliferation? A The irreversible association of FGFRFGFR proteins B The loss of the FGFRFGFR protein kinase function C A decrease in the intracellular concentration of ATPATP D A decrease in the extracellular concentrations of fibroblast growth factors

A the irreversible association of FGFR proteins

Lysosomes digest food particles brought into a cell by endocytosis. After a vesicle containing food particles fuses with a lysosome, H+H+ ions are transported into the lysosome from the cytosol. This significantly lowers the pHpH of the lysosome relative to the cytosol and activates the enzymes that digest the particles. Which of the following best predicts what will happen to the lysosomal enzymes if the proteins that transport H+H+ ions from the cytosol into the lysosome are damaged? A The lysosomal enzymes will not become active, since there will be no active transport of H+H+ ions. B The lysosomal enzymes will not become active, since H+H+ ions will diffuse out of the lysosome. C The lysosomal enzymes will become active, since facilitated diffusion will move H+H+ ions into the lysosome. D The lysosomal enzymes will become active, since passive diffusion will move H+H+ ions into the lysosome.

A the lysosomal enzymes will not become active, since there will be no active transport of hydrogen ions

Stomata are pores on the surfaces of the leaves and stems of plants that regulate gas exchange between the plants and the atmosphere. Researchers found that the stomata density on the leaves of a species of plant change as the concentration of CO2CO2 in the atmosphere changes. When grown at 350 ppmppm CO2CO2 the plant has an average density of 300 stomata per mm2mm2, but when grown at 400 ppmppm CO2CO2 the plant has an average density of 250 stomata per mm2mm2. Which of the following best describes how the ratio of the density of stomata (stomata per mm2mm2) per CO2CO2 concentration (ppmppm CO2CO2) changes as the CO2CO2 concentration increases? A The ratio decreases from 0.860.86 to 0.630.63, because fewer stomata are needed at higher CO2CO2 concentrations. B The ratio decreases from 1.61.6 to 1.21.2, because fewer stomata are needed at higher CO2CO2 concentrations. C The ratio increases from 0.630.63 to 0.860.86, because more stomata are needed at higher CO2CO2 concentrations. D The ratio increases from 1.21.2 to 1.61.6, because more stomata are needed at higher CO2CO2 concentrations.

A the ratio decreases from 0.86 to 0.63, because fewer stomat are needed at higher O2 concentrations

Adjacent plant cells have narrow channels called plasmodesmata that pass through the cell walls of the connected cells and allow a cytoplasmic connection between the cells. Which of the following statements best describes a primary function of plasmodesmata? A They allow the movement of molecules from one cell to another, enabling communication between cells. B They prevent the cell membrane from pulling away from the cell wall during periods of drought. C They eliminate the need to produce signaling molecules and eliminate the need for cells to have receptors for signaling molecules. D They increase the surface area available for attachment of ribosomes and thus increase protein synthesis.

A they allow the movement of molecules form one cell to another, enabling communication between cells

A student is using dialysis bags to model the effects of changing solute concentrations on cells. The student places one dialysis bag that contains 25 mL25 mL of distilled water into each of two beakers that are filled with 200 mL200 mL of distilled water. (Figure 1). The membrane of each dialysis bag membrane contains pores that allow small solutes such as monoatomic ions to pass through but are too small for anything larger to pass. After 30 minutes, 5 mL5 mL of a concentrated solution of albumin (a medium-sized, water-soluble protein) is added to one of the two beakers. Nothing is added to the other beaker. After two more hours at room temperature, the mass of each bag is determined. There is no change in the mass of the dialysis bag in the beaker to which no albumin was added. Which of the graphs below best represents the predicted change in mass over time of the dialysis bag in the beaker to which albumin was added? A line stays constant before and after albumin is added B line goes down after albumin is added C line goes up until albumin is added and then it will go down D line is constant until albumin is added, and then it will raise

B line goes down after albumin is added

Students carry out a genetics experiment to investigate the inheritance pattern of the white-eye trait in fruit flies. In the experiment, the students cross a red-eyed female with a white-eyed male to produce an F1F1 generation. The students observe that all the flies in the F1F1 generation have red eyes. The students then allow the F1F1 flies to mate and produce an F2F2 generation. The students will use the F2F2 data to perform a chi-square goodness-of-fit test based on a null hypothesis of autosomal recessive inheritance. The observed and expected values for the chi-square goodness-of-fit test are shown in Table 1. Table 1. The observed and expected values for a chi-square goodness-of-fit test PhenotypeObservedExpectedRed-eyed female497375Red-eyed male254375White-eyed female0125White-eyed male249125 The students plan to use a significance level of p=0.01p=0.01. Which of the following is the most appropriate critical value for the students to use in their chi-square goodness-of-fit test? A 7.82 B 11.34 C 13.28 D 326.7

B 11.34

Four trials measuring recombination frequency between gene RR and gene LL were conducted, and the results are shown in Table 1. Table 1. Recombination frequency Trial 1Trial 2Trial 3Trial 4Frequency of recombination24%33%26%29% The mean map distance between gene RR and gene LL is closest to which of the following? A 0.28 map units B 28 map units C 0.14 map units D 14 map units

B 28 map units

R. C. Punnett conducted experiments on the inheritance of traits in the sweet pea, Lathyrus odoratus. In one experiment, he crossed two different true-breeding sweet pea plant strains, one with erect petals and long pollen, and the other with hooded petals and round pollen. All the offspring (F1F1 generation) had erect petals and long pollen (Figure 1). Figure 1. Sweet pea plant cross Next, Punnett allowed the F1F1 generation to self-fertilize and recorded the phenotypes of their offspring. The data are shown in Table 1. Table 1. F2F2 results of F1F1 self-fertilization cross Phenotype of F2F2Number of OffspringErect petals, long pollen765Erect petals, round pollen62Hooded petals, long pollen71Hooded petals, round pollen220Total1,118 How many degrees of freedom should be used when looking up the critical value for a chi-square analysis of the ratios of phenotypes observed among the F2F2 offspring versus the expected phenotypic ratio assuming independent assortment? A 2 B 3 C 4 D 5

B 3

Sex chromosomes determine the phenotype of sex in humans. Embryos containing XXXX chromosomes develop into females, and embryos containing XYXY chromosomes develop into males. The sex chromosomes separate during meiosis, going to different gamete cells. A woman is heterozygous for the XX-linked recessive trait of hemophilia AA. Her sex chromosomes can be designated as XHXhXHXh. During meiosis the chromosomes separate as shown in Figure 1. Figure 1. Transmission pattern for sex chromosomes of a woman heterozygous for hemophilia AA into gametes If the woman and a man with normal clotting function have children, what is the probability of their children exhibiting hemophilia AA? A 50 percent for daughters, 0 percent for sons B 50 percent for sons, 0 percent for daughters C 50 percent for all children D 0 percent for all children

B 50% for sons, 0% for daughters

The figure shows a representation of a protein embedded in a cell membrane. The numbers indicate different structural regions of the protein. Based on the figure, which of the following statements best describes the relationship between regions 1 and 2 of the protein? A Region 1 is hydrophilic because it interacts with the interior of the membrane, whereas region 2 is hydrophobic because it interacts with an aqueous environment. B Region 1 is hydrophilic because it interacts with an aqueous environment, whereas region 2 is hydrophobic because it interacts with the interior of the membrane. C Region 1 is hydrophobic because it interacts with the interior of the membrane, whereas region 2 is hydrophilic because it interacts with an aqueous environment. D Region 1 is hydrophobic because it interacts with an aqueous environment, whereas region 2 is hydrophilic because it interacts with the interior of the membrane.

B Region 1 is hydrophilic because it interacts with an aqueious environment, whereas region 2 is hydrophobic because it interacts with the interior of the membrane

A study was conducted to understand the factors controlling the rate at which molecules or ions travel across cell membranes. An artificial membrane was created that was composed of a phospholipid bilayer only. The speed at which various substances crossed this membrane was measured. Some substances can pass through an actual cell membrane much faster than they passed through the artificial membrane in this study. Which of the following statements best explains this finding? A Actual cell membranes have a much thicker phospholipid bilayer than the artificial membrane does. B Actual cell membranes have a variety of proteins embedded in the membrane that are absent in the artificial membrane. C Hydrophobic substances spend more time between the two layers of phospholipid in the artificial membrane than they do between the layers in an actual membrane. D Hydrophilic substances spend more time attached to the polar region of the phospholipids in the artificial membrane than they do attached to the polar region of the phospholipids in an actual membrane.

B actual cell membranes have a variety of proteins embedded in the membrane that are absent in the artificial membrane

A researcher claims that a certain herbicide suppresses plant growth by inhibiting chloroplast function. To test the claim, the researcher treats isolated chloroplasts with increasing concentrations of the herbicide. The data from the experiment are presented in Table 1. Table 1. The effect of an herbicide on the function of isolated chloroplasts Herbicide Concentration (μg/L)(μg/L)pHpH Difference across Thylakoid MembraneATPATP Production003.53.5Very high222.52.5Moderate880.50.5Very low323200Very low Which of the following statements best clarifies how the data support the researcher's claim? A The thylakoid membrane is more permeable to carbon dioxide than to polar molecules. B ATPATP synthase activity depends on a proton gradient across the thylakoid membrane. C Some enzymes embedded in the thylakoid membrane catalyze the hydrolysis of ATPATP. D Carbon fixation in the Calvin-Benson cycle takes place in the stroma of chloroplasts.

B atp synthase activity depends on a proton gradient across the thylakoid membrane

Which of the following claims is scientifically accurate and consistent with an observation that a decrease in lysosome production within a cell leads to a decline in mitochondrial activity? A A lack of lysosomes will cause a decrease in the synthesis of enzymes necessary for cellular respiration. B Fewer lysosomes will be available to break down macromolecules to provide the necessary nutrients for cellular respiration. C Fewer lysosomes will be available to store materials required for the functioning of the mitochondria. D Lysosomes will not be available to modify proteins so that they are targeted to the mitochondria.

B fewer lysosomes will be available to break down macromolecules to provide the necessary nutrients for celular respiration

Signal transduction may result in changes in gene expression and cell function, which may alter phenotype in an embryo. An example is the expression of the SRYSRY gene, which triggers the male sexual development pathway in mammals. This gene is found on the Y chromosome. Which statement provides the evidence to justify the claim that signal transduction may result in an altered phenotype? A If the SRYSRY gene is absent or nonfunctional, the embryo will exhibit male sexual development. B If the SRYSRY gene is absent or nonfunctional, the embryo will exhibit female sexual development. C An embryo with a male sex chromosome will always exhibit male sexual development. D An embryo with two male sex chromosomes will always exhibit male sexual development.

B if the SRY gene is absent or nonfunctional, the embryo wil exhibit female sexual development

A person's blood glucose level fluctuates during the day, as represented in Figure 1. Two hormones, insulin and glucagon, are directly involved in regulating the blood glucose level to maintain a healthy level. Insulin acts to lower the blood glucose level, and glucagon acts to increase the blood glucose level. Figure 1. Blood glucose fluctuations of an individual Which of the following best predicts what will happen to the blood glucose level if the person has another meal at 5 p.m.? A Immediately after the meal, the blood glucose level will decrease because of the increase in glucagon levels. B Immediately after the meal, the blood glucose level will increase, and then insulin will be secreted to counter the increase. C Several hours after the meal, the blood glucose level will increase sharply because of an increase in the amount of glucagon secreted. D The blood glucose level will not change after the 5 p.m. meal because the person has already consumed two meals and the blood glucose level has been adjusted to a steady-state level.

B immediately after the meal, the blood glucose level will incerase, and then insuline will be secreted to counter the increase

in an experiment, researchers compared the growth of two different plants, plant XX and plant YY. The researchers maintained the plants under nearly identical conditions and observed that plant XX grew faster than plant YY. The researchers also observed that the inner mitochondrial membranes of plant XX had more folds than did those of plant YY. Which of the following conclusions about increasing the number of folds in the inner mitochondrial membrane is best supported by the results of the experiment? A It increases the efficiency of photosynthesis, which results in faster cell growth. B It increases the surface area available for ATPATP production, which results in faster cell growth. C It increases the amount of space available for storing cellular wastes, which results in faster cell growth. D It increases the rate of protein transport to the plasma membrane, which results in faster cell growth.

B it increases the surface area available for ATP production, which results in faster cell growth

Metformin is a drug used to treat type 2 diabetes by decreasing glucose production in the liver. AMPAMP-activated protein kinase (AMPK)(AMPK) is a major cellular regulator of glucose metabolism. Metformin activates AMPKAMPK in liver cells but cannot cross the plasma membrane. By blocking AMPKAMPK with an inhibitor, researchers found that AMPKAMPK activation is required for metformin to produce an inhibitory effect on glucose production by liver cells. Which of the following best describes the component that metformin represents in a signal transduction pathway that regulates glucose production in the liver? A It is a secondary messenger that amplifies a signal through a cascade reaction. B It is a ligand that activates the signal transduction pathway of the activation of AMPKAMPK. C It is an allosteric regulator that binds to a crucial section of the DNADNA that makes the enzymes needed for glucose uptake. D It is a competitive inhibitor that binds to glucose and prevents it from entering the cell.

B it is a ligan that activates the signal transduction pathway of the activaiton of AMPK

In an experiment, researchers provided a radiolabeled amino acid to living plant cells. After one hour, the researchers determined the amount of the radiolabeled amino acid that was in each of several subcellular compartments. The results of the experiment are represented in the table. RELATIVE AMOUNTS OF RADIOLABELED AMINO ACID NucleusMitochondriaEndoplasmic ReticulumCytosol2.12.71.91 Which of the following conclusions about the radiolabeled amino acid is best supported by the results of the experiment? A It was mostly incorporated into nucleic acids that store the biological information. B It was mostly incorporated into proteins that regulate and manage metabolic reactions. C It was mostly incorporated into lipids that help separate cells from their surrounding environment. D It was mostly incorporated into carbohydrates that form protective structures outside the cells.

B it was mostly incorporated into proteins that regulate and manage metabolic reactions

When a mustard plant seedling is transferred to an environment with higher levels of carbon dioxide, the new leaves have a lower stomata-to-surface-area ratio than do the seedling's original leaves. Which of the following best explains how the leaves from the same plant can have different stomatal densities when exposed to an elevated carbon dioxide level? A Increased photosynthesis leads to larger leaves that need more stomata for photosynthesis, leading to an increase in stomatal density. B Leaf growth is promoted through increased photosynthesis, but the genetically regulated rate of stomatal production is not altered, leading to a decrease in stomatal density. C Leaf growth is inhibited by decreased photosynthesis, and the genetically regulated rate of stomatal production remains the same, leading to an increase in stomatal density. D Leaf growth is inhibited by decreased photosynthesis, and the genetically regulated rate of stomatal production remains the same, leading to a decrease in stomatal density.

B leaf growth is promoted through increased photosynthesis, but the genetically regulated rate of stomatal production is not alterned, leading to a decreaes in stomatal density

Phosphofructokinase (PFK)(PFK) is a key enzyme in glycolysis. ATPATP is one of the two substrates for the reaction catalyzed by PFKPFK. ATPATP is also an allosteric regulator of PFKPFK. Figure 1 shows the enzyme-substrate interactions of PFKPFK. Figure 1. The enzyme-substrate interactions of PFKPFK A researcher found a mutation that resulted in the PFKPFK enzyme being unable to bind ATPATP to the allosteric site. Which of the following best predicts the effect of the mutation? A The activity of the enzyme will not be affected because the active site is not involved in substrate binding at the allosteric site. B Negative feedback regulation does not occur, so the enzyme will be active when glycolysis is not needed. C Positive feedback does not occur, and the activity of the enzyme will decrease when glycolysis is needed. D The activity of the enzyme will fluctuate independent of the ATPATP concentration.

B negative feedback regulation does not occur, so the enzyme will be active when glycolysis is not needed

Glycolysis is a metabolic pathway that converts glucose into pyruvate and is observed in each of the three domains. The hexokinase family of enzymes is required during glycolysis to phosphorylate six-carbon sugars. Researchers designed a general hexokinase inhibitor that is effective in the neurons of rats. Which of the following best predicts the effect of adding this inhibitor to a culture of plant cells? A Plant cells will be unaffected by the inhibitor as they do not perform glycolysis. B Plant cells will be unable to perform glycolysis due to the inhibitor and will die. C Plant cells will be unable to perform photosynthesis due to the inhibitor and will die. D Plant cells will still be able to perform glycolysis since plant hexokinase is not structurally similar to animal hexokinase.

B plant cells will be unable to perform glycolysis due to the inhibitor and will die

The relative amounts of DNADNA present in the nucleus of a cell at four different stages of the life cycle are shown in Figure 1. Figure 1. Relative amounts of DNADNA present in the nucleus of a cell Based on Figure 1, which of the following statements correctly links a stage of the cell cycle with the event occurring at that stage? A Stage II represents the G2G2 phase of the cell cycle. B Synthesis of sufficient DNADNA for two daughter cells occurs in stage IIII. C Stage IIIIII includes mitosis. D The replication of genetic material occurs in stage IVIV.

B synthesis of sufficient DNA for 2 daughter cels occurs in stage II

Some membrane proteins help maintain the concentrations of ions inside a cell by transporting the ions across the cell's plasma membrane. Other membrane proteins form pores in the plasma membrane through which the ions can diffuse. A model showing the influence of membrane proteins on the movement of sodium (Na+Na+) and potassium (K+K+) ions across a plasma membrane is presented in Figure 1. Figure 1. Section of a cell's plasma membrane, showing ion concentrations and membrane proteins Based on the model presented in Figure 1, which of the following changes will most likely result from a depletion of available ATPATP stores inside the cell? A The Na+Na+ concentration outside the cell will increase. B The Na+Na+concentration inside the cell will increase. C The K+K+ concentration inside the cell will increase. D The K+K+ concentration outside the cell will decrease.

B the Na+ concentration inside the cell will increase

A scientist is studying the various prokaryotic and eukaryotic species found floating in a sample of water taken from a marine ecosystem. Which cellular component will be found in the widest range of organisms in the sample? A The chloroplast, since all organisms need a source of energy. B The ribosome, since all organisms need to synthesize proteins. C The mitochondrion, since all organisms need to break down glucose. D The cell wall, since all marine organisms need them for support.

B the ribosome, since all organisms need to synthesize proteins

The insulin receptor is a transmembrane protein that plays a role in the regulation of glucose homeostasis. The receptor's extracellular domain binds specifically to the peptide hormone insulin. The receptor's intracellular domain interacts with cellular factors. The binding of insulin to the receptor stimulates a signal transduction pathway that results in the subcellular translocation of GLUT4GLUT4, a glucose transport protein that is stored in vesicles inside the cell. A simplified model of the insulin receptor-signaling pathway is shown in Figure 1. Figure 1. A simplified model of the insulin receptor-signaling pathway Which of the following statements best predicts the effect of a loss of function of the insulin receptor's intracellular domain? A The stimulation of the signal transduction pathway will increase. B The storage of GLUT4GLUT4 in vesicles inside the cell will increase. C The number of GLUT4GLUT4 molecules in the plasma membrane will increase. D The concentration of glucose inside the cell will increase.

B the storage of GLUT4 in vesicles inside the cell will increase

Which statement best predicts why a cell's progression through the cell cycle might be halted at the G1G1/SS checkpoint? A Spindle fibers have not correctly attached to chromosomes. B There are not enough nucleotides available to construct new DNADNA. C Damage occurred to DNADNA when it was being copied in G1G1. D Proteins necessary for MM phase of the cell cycle have not been produced.

B there are not enough nucleotides available to contruct new DNA

Organelles such as mitochondria and the endoplasmic reticulum have membranes that compartmentalize reactions and other metabolic processes. To function properly, the organelles must move substances across their membranes. Which of the following statements describes a feature shared by mitochondria and the endoplasmic reticulum that increases the efficiency of their basic functions? A They have rigid, nonfluid membranes. B They have highly folded membranes. C They have membranes composed of many carbohydrates. D They have double membranes, with one membrane enclosed within the other.

B they have highly folded membranes

Beetroot cells contain a family of dark red pigments called betalains. The selectively permeable nature of the beetroot cells keeps the internal environment of the cell separate from the external environment of the cell. Researchers are interested in determining whether the selective permeability of beetroot cells is due to the cell membrane or if it is due to the cell wall. Exposure to cellulase is known to damage the structure of the cell wall. An experiment is set up in which beetroot cells are placed in an aqueous solution with cellulase and in one without cellulase. Which of the following results best refutes the alternative hypothesis that selective permeability is a consequence of the cell wall? A When beetroot cells are placed in a solution with cellulase, the solution turns dark red. B When beetroot cells are placed in a solution with cellulase, the solution remains clear. C When beetroot cells are placed in a solution, it turns dark red with or without cellulase present. D Since plant cells contain cell membranes, not cell walls, the alternate hypothesis cannot be tested.

B when beetroot cells are placed in a solution with cellulase, the solution remains clear

Which of the following best explains how the sweet pea plants in the parental generation produce F1F1 offspring with 14 chromosomes? A Meiosis II and IIII lead to the formation of cells with 14 chromosomes. When two cells combine during fertilization, extra chromosomes are randomly broken down, leading to offspring with 14 chromosomes. B Meiosis II and IIII lead to the formation of cells with 14 chromosomes. When two cells combine during fertilization, extra chromosomes with recessive traits are broken down, leading to offspring with 14 chromosomes. C Meiosis II and IIII lead to the formation of cells with 7 chromosomes. During meiosis II, homologous chromosomes separate. During meiosis IIII, sister chromatids separate. Two cells combine during fertilization to produce offspring with 14 chromosomes. D Meiosis II and IIII lead to the formation of cells with 7 chromosomes. During meiosis II, sister chromatids separate. During meiosis IIII, homologous chromosomes separate. Two cells combine during fertilization to produce offspring with 14 chromosomes.

C Meiosis II and IIII lead to the formation of cells with 7 chromosomes. During meiosis II, homologous chromosomes separate. During meiosis IIII, sister chromatids separate. Two cells combine during fertilization to produce offspring with 14 chromosomes.

Which of the following statements best predicts the effect of increasing the permeability of the mitochondrial membranes to large molecules? A ATPATP production will increase because of an increase in the rate at which proteins diffuse out of mitochondria. B ATPATP production will increase because of an increase in the mixing of mitochondrial and cytosolic substances. C ATPATP production will decrease because of an increase in the occurrence of uncontrolled chemical reactions. D ATPATP production will decrease because of an increase in the surface area of the mitochondrial membranes.

C ATP production will decrease because of an increaes int he occurence of unctonrolled chemical reactions

Which of the following steps in a signaling pathway typically occurs first once a chemical messenger reaches a target cell? A Specific genes are activated. B A second messenger molecule is produced. C A ligand binds to a receptor. D Specific proteins are synthesized.

C a ligand binds to a receptor

Huntington's disease has been traced to the number of CAGCAG repeats in the HTTHTT gene, which is located on chromosome 4. The phenotypic influence of individual alleles with different numbers of repeats is shown in Table 1. Table 1: Effect of CAGCAG repeat number on Huntington's disease expression CAGCAG RepeatsExpression<27<27No symptoms27-35No symptoms but increased risk for offspring36-39May develop symptoms in old age>40>40Will express symptoms from an early age Which of the following is most likely the immediate cause of the first appearance of Huntington's disease in a person? A A point mutation occurs in the HTTHTT gene. B The first appearance of the CAGCAG repeat occurs in the HTTHTT gene. C An allele with more than 39 CAGCAG repeats was inherited by the affected person. D The person inherited two alleles that each contained 20 CAGCAG repeats.

C an allele with more than 39 CAG repreats was inherited by the affected person

The cell membrane is selectively permeable due to its structure. Thus, the internal environment of the cell is distinct from the external environment of the cell. One biologist hypothesizes that small nonpolar molecules readily pass through the membrane. Another biologist alternatively hypothesizes that these types of molecules require channel and transport proteins that are embedded in the membrane in order to move across the membrane. Which of the following data would best refute this alternative hypothesis? A Ethanol is found in the cytosol of cells when they are briefly exposed to a ten percent ethanol solution. B Cells become oxygen deficient when membrane protein activity is blocked. C CO2CO2 and N2N2 movement in and out of cells is unaffected when membrane protein activity is blocked. D Sodium ions cannot move across the cell membrane when membrane protein activity is blocked.

C co2 and n2 movement in and out of cells is unaffected when membrnae protein activity is blocked

Notch is a receptor protein displayed on the surface of certain cells in developing fruit fly embryos. Notch's ligand is a membrane-bound protein called Delta that is displayed on the surface of adjacent cells. When Notch is activated by its ligand, the intracellular tail of the Notch protein becomes separated from the rest of the protein. This allows the intracellular tail to move to the cell's nucleus and alter the expression of specific genes. Which of the following statements best explains Delta's role in regulating cell communication through the Notch signaling pathway? A Delta transmits a chemical signal to all the cells of a developing embryo. B Delta allows the cells of a developing embryo to communicate without making direct contact. C Delta restricts cell communication to short distances within a developing embryo. D Delta determines which cells in a developing embryo express the gene that encodes the Notch protein.

C delta restricts cell communication to short distances within a developing embryo

Some viral infections can lead to the rupture of the lysosome membrane. Which prediction of the effect of this disruption of cellular compartmentalization is most likely correct? A Enzymes will be released that will specifically target the virus. B Cellular osmotic concentrations will change, preventing viral entry into the cell. C Hydrolytic enzymes will be released, which will cause cell death. D Intracellular digestion of organic materials will increase, which will increase the energy available to the cell for fighting the virus.

C hydrolytic enzymes will be released, which will cause cell death

Researchers investigate the transport of a certain protein into cells by endocytosis. In an experiment, the researchers incubate the cells in the presence of the protein and measure the amount of the protein that is absorbed into the cells over a five-minute period. Based on their observations, what should the researchers do to further clarify how the availability of the protein outside the cells affects the rate of endocytosis of the protein? A Incubate the cells in the absence of the protein. B Incubate the cells in the presence of several different proteins. C Incubate the cells in the presence of several different concentrations of the protein. D Incubate the cells in the presence of the protein for several different lengths of time.

C incubate the cells in the presence of several different concentrations of the protein

Aminolevulinate dehydratase (ALADALAD) is an enzyme that relies on zinc as a coenzyme. A zinc ion binds to the ALADALAD active site, where it forms favorable interactions with the side chains of three amino acids. Researchers have found that substituting a lead ion for a zinc ion in the ALADALAD active site causes inhibition of ALADALAD. Which of the following statements best helps explain how the lead ion causes inhibition of ALADALAD? A It changes the shape and charge of the substrate so that it becomes more compatible with ALADALAD's active site. B It changes the amino acid sequence of the ALADALAD protein so that the enzyme catalyzes a different reaction. C It changes the three-dimensional structure of the active site so that ALADALAD is no longer compatible with its substrate. D It changes the enzyme-substrate complex so that the transition state is more stable and the reaction proceeds at a faster rate.

C it changes the 3d structure of the active site so that ALAD is no longer compatible with its substrate

The tadpoles of Mexican spadefoot toads are known to exhibit phenotypic plasticity depending on food availability. Tadpole mouthparts can vary significantly, prompting researchers to categorize them as either omnivore-morph or carnivore-morph. Carnivore-morph tadpoles are larger and have mouthparts that are better suited for predation. Remarkably, carnivore-morph tadpoles can change into omnivore-morph tadpoles when the food supply changes. Which of the following best describes an advantage of the phenotypic plasticity displayed by the tadpoles? A It allows the tadpoles to change their genome in response to environmental pressures. B It enables the tadpoles to develop into a distinct species of toads. C It gives the tadpoles increased versatility with respect to diet. D It allows the tadpoles to delay metamorphosis until there is maximal food available for the adults.

C it gives the tadpoles increased versatility with respect to diet

Researchers investigated the influence of environmental pHpH on the activity of peroxidase, an enzyme that catalyzes the conversion of hydrogen peroxide to water and oxygen gas. In an experiment, the researchers added a hydrogen peroxide solution containing guaiacol to several identical test tubes and adjusted the solution in each test tube to a different pHpH. The researchers included the guaiacol because it caused the solutions to change color as the reactions proceeded, which the researchers relied on for measuring reaction rates. Finally, the researchers added the same amount of peroxidase to each test tube and measured the rate of each reaction at 23°C23°C. The results of the experiment are represented in Figure 1. One of the researchers proposes using oxygen gas production to measure reaction rates. Which of the following statements best justifies the use of the proposed modification as a way of creating an appropriate control for the investigation? A The experiment can be repeated without hydrogen peroxide, which will help eliminate an uncontrolled variable. B The experiment can be repeated without peroxidase, which will introduce a second independent variable. C The experiment can be repeated without guaiacol, which will reveal the effect of guaiacol on the reaction rates. D The experiment can be repeated without water, which will reveal whether the reaction can occur inside a living cell.

C the experiment can be repeated without guaiacol, which wil reveal the effect of guaiacol on the reaction rates

Researchers have proposed a model of the process by which a newly synthesized protein is transported to the plasma membrane and secreted into the extracellular space. The model is represented in Figure 1. Figure 1. A model of the intracellular transport of a newly synthesized secreted protein Based on the model, the newly synthesized protein is transported directly from the endoplasmic reticulum to which of the following? A The nucleus B The plasma membrane C The Golgi complex D The extracellular space

C the golgi complex

A hydrophilic peptide hormone is produced in the anterior pituitary gland located at the base of the brain. The hormone targets specific cells in many parts of the body. Which of the following best explains a possible mechanism that would enable the hormone to efficiently reach all of the target cells in the body? A The hormone interacts with the nerves at the base of the brain and directs signals to the target cells through the nervous system. B The hormone diffuses into target cells adjacent to the anterior pituitary gland, where the hormone is degraded. C The hormone is released into the bloodstream where it can be transported to all cells with the correct receptors. D The hormone moves through cytoplasmic connections between cells until it has reached all cells with the correct intracellular binding sites.

C the hormone is released into the bloodstream where it can be transported to all cells with the correct receptors

Gaucher disease is an inherited disorder in which cells of the body are unable to break down a particular type of lipid, resulting in a buildup of the lipid in some tissues and organs. Based on the information provided, Gaucher disease results most directly from a defect in the function of which of the following organelles? A The smooth endoplasmic reticulum B The nucleus C The lysosome D The mitochondrion

C the lysosome

Vertebrate immune responses involve communication over short and long distances. Which of the following statements best helps explain how cell surface proteins, such as MHCMHC proteins and T cell receptors, mediate cell communication over short distances? A The proteins receive electrical signals from nerve cells. B The proteins leave the cell and travel in the bloodstream to other cells. C The proteins interact directly with proteins on the surfaces of other cells. D The proteins bind to molecules secreted by cells located in other parts of the body.

C the proteins interact directly with protiens on the surfaces of other cells

Hereditary spherocytosis (HS)(HS) is a disorder of red blood cells that causes the cells to be smaller and spherical instead of having the usual flattened, biconcave shape. The average diameter of normal red blood cells is 7.2μm7.2μm, and the average diameter of red blood cells in a person with HSHS was found to be 6.7μm6.7μm. The normal red blood cell has an average surface area of 136μm2136μm2 and an average volume of 91μm391μm3. Which of the following provides an accurate calculation of the surface area to volume ratio of an HSHS red blood cell, as well as a prediction of its effect on the efficient transferring of oxygen compared to a normal red blood cell? A The ratio is 0.450.45, and the cells are more efficient at transferring oxygen. B The ratio is 1.121.12, and the cells are less efficient at transferring oxygen. C The ratio is 0.890.89, and the cells are less efficient at transferring oxygen. D The ratio is 141141, and the cells are more efficient at transferring oxygen.

C the ratio is 0.89, and the cells are less efficient at transferring oxygen

Which of the following transport mechanisms will be affected most directly by a temporary shortage of ATPATP molecules inside the cell? A The movement of water molecules through aquaporins B The diffusion of oxygen molecules across the plasma membrane C The transport of glucose molecules against a concentration gradient D The facilitated diffusion of Ca2+Ca2+ ions into the cell

C the transport of glucose molecules against a concentration gradient

Researchers tracked the amount of DNADNA (measured in picograms) over time beginning with a single cell and continuing through several rounds of cell division. The researchers observed threadlike chromosomes prior to cell division. The threadlike chromosomes disappeared from view shortly after each division. The amount of DNADNA in picograms per cell over several rounds of cell division is shown in Figure 1. Figure 1. Amount of DNADNA in picograms per cell over several rounds of cell division Which of the following statements is consistent with the data in Figure 1? A The cells have a haploid chromosome number of 3. B The cells have a diploid chromosome number of 6. C There is a change from 3 to 6 picograms of DNADNA because DNADNA is replicated before each round of cell division. D There is a change from 6 to 3 picograms of DNADNA after each cell division because the chromosomes lengthen following cell division.

C there is a change from 3 to 6 pinograms of DNA because DNA is replicated before each round of cell division

The tumor suppressor protein p53p53 binds to DNA and activates target genes, which results in the synthesis of p21p21, CD95CD95, and other proteins. The p21p21 protein promotes cell-cycle arrest, whereas the CD95CD95 protein promotes apoptosis. Which of the following will most likely result from a loss of p53p53 function? A Rapid cell growth without cell division B Immediate activation of apoptosis pathways C Uncontrolled cell proliferation D Increased expression of p53p53 target genes

C uncontrolled cell proliferation

A researcher proposes a model to explain how enzyme-substrate interactions determine enzyme specificity. The model is based on the idea that substrate molecules form favorable interactions with the amino acid side chains in an enzyme's active site. Based on the model, which of the following statements best explains an enzyme's specificity for a particular substrate molecule? A A hydrophilic molecule interacts with nonpolar side chains in the enzyme's active site. B A hydrophobic molecule interacts with polar side chains in the enzyme's active site. C A molecule with positive charges interacts with positively charged side chains in the enzyme's active site. D A molecule with negative charges interacts with positively charged side chains in the enzyme's active site.

D a molecule iwth negative charges interacts with positively charged side chains in the enzyme's active site

GG proteins are a family of receptor proteins that are involved in transmitting signals from outside a cell to inside a cell. When a signaling molecule binds to a GG protein, the GG protein is activated. The GG protein then activates an enzyme that produces a second messenger called cAMPcAMP. Which of the following describes a critical role of cAMPcAMP during the transduction stage of a GG protein signal transduction pathway? A cAMPcAMP carries the signal to the nucleus of the cell and results in new sequences of nucleotides being added to the cell's DNADNA. B cAMPcAMP binds the extracellular signal molecule and carries it to the intracellular target specified by the signal. C cAMPcAMP modifies a specific monomer so that it can be added to an elongating structural macromolecule. D cAMPcAMP results in the activation of an enzyme that amplifies the signal by acting on many substrate molecules.

D cAMP results in the activation of an enzyme that amplifies the signal by acting on many substrate molecules

Researchers have proposed a model of chloroplast evolution. According to the model, chloroplasts evolved from a small prokaryotic organism that was engulfed by an ancestral eukaryote. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host. Which of the following observations best supports the model? A Chloroplasts are separated from other subcellular compartments by semipermeable membranes. B Prokaryotic and eukaryotic organisms both acquire nutrients from the surrounding environment. C Eukaryotes evolved after prokaryotes and have more complex structures. D Chloroplasts and some prokaryotes share similar photosynthetic reactions.

D chloroplasts and some prokaryotes share similar photosynthetic

A researcher claims that the initial rise of oxygen in Earth's early atmosphere, which occurred approximately 2.3 billion years ago, resulted from the metabolic activity of prokaryotic organisms. The claim is based on an interpretation of the geochemical and fossil evidence represented in Figure 1. Figure 1. Selected events in geologic time based on geochemical and fossil evidence Which of the following types of evidence will best support the researcher's claim? A Evidence that some of the earliest eukaryotes used oxygen to produce ATPATP by cellular respiration B Evidence that the earliest plants produced oxygen as a by-product of photosynthesis C Evidence that some of the earliest organisms carried out photosynthesis without producing oxygen D Evidence that the cyanobacteria produced oxygen as a by-product of photosynthesis

D evidence that the cyanobacteria produced oxygen as a by-product of photosynthesis

Blood clots are formed by a positive feedback loop. Two pathways exist, the extrinsic and intrinsic pathways, which converge during clot formation. There are many clotting factors involved, most of which are proteins. Vitamin KK is required for the formation of the active form of several of the clotting factors, including Factor XX. A simplified model of the blood clotting process is shown in Figure 1. Figure 1. Simplified model of clotting cascade Warfarin is a drug used to treat certain blood clots. Warfarin blocks the formation of the active form of vitamin KK-dependent clotting factors. Based on the model, which of the following best predicts the effects of warfarin on a patient? A Fibrinogen will form fibrin, but the clot will not form because Factor XIIIXIII will not be synthesized. B The intrinsic pathway will take over because the clotting factors are part of that pathway. C Thrombin will be converted to prothrombin because Factor XX will reverse the reaction. D Factor XX will not be activated, which will prevent thrombin from forming.

D factor X will not be activated, which will prevent thrombin from forming

Which of the following best explains a distinction between metaphase II and metaphase IIII? A The nuclear membrane breaks down during metaphase II but not during metaphase IIII. B Chromosomes align at the equator of the cell during metaphase IIII but not during metaphase II. C The meiotic spindle is needed during metaphase II but not during metaphase IIII. D Homologous pairs of chromosomes are aligned during metaphase II, but individual chromosomes are aligned during metaphase IIII.

D homologous pairs of chromsoomes are aligned during metaphase I, but individual chromosomes are aligned during metaphase II

In anaphase II of meiosis, cohesion between the centromeres of sister chromatids is maintained while homologous chromosomes migrate to opposite poles of the cell along the meiotic spindle as represented in Figure 1. Figure 1. Migration of homologous chromosomes during anaphase II of meiosis A compound that prevents the separation of the homologous chromosomes in anaphase II is being studied. Which of the following questions can be best answered during this study? A Will the cells produced at the end of meiosis still be genetically identical to each other in the presence of this compound? B Will the long-term development of the individual be affected by this meiotic error? C When do the centrosomes start to move apart during meiosis II as compared to meiosis IIII? D Is there a pattern to the movement of homologous chromosomes in the presence of this compound?

D is there a pattern to the movement of homologous chromosomes in the presence of this compound?

Euglenids are single-cell eukaryotes that live in aquatic environments. The chloroplasts found inside euglenids are enveloped by three membranes, as represented in Figure 1. The inner membrane of euglenid chloroplasts resembles the thylakoid membrane. Figure 1. Simplified diagram of a euglenid, showing the structure of the chloroplast envelope Which of the following claims about the origin of the euglenid chloroplast is best supported by the three-membrane structure of the envelope? A It originated from the spontaneous assembly of organic molecules into a lipid bilayer inside a free-living prokaryote. B It originated from the fusion of the plasma membranes of two different free-living photosynthetic prokaryotes. C It originated from the incorporation of a photosynthetic prokaryote into a eukaryotic cell by a single endosymbiotic event. D It originated from the incorporation of a photosynthetic prokaryote into a eukaryotic cell by two endosymbiotic events.

D it originate from the incroporation of a photosynthetic prokaryote into a eukaryotic cell by two endosymbiotic events

Which of the following observations best supports the claim that mitochondria evolved from once-free-living prokaryotic cells by the process of endocytosis? A Mitochondria produce ATPATP. B Mitochondria contain proteins. C Mitochondria exchange substances with the cytosol. D Mitochondria are surrounded by a double membrane.

D mitochondria are surrounded by a double membrane

Changing the shape or morphology of the mitochondrial inner membrane can change the efficiency of mitochondrial function. Which of the following outcomes will most likely result from a change in the shape of the mitochondrial inner membrane from a highly folded surface to a smooth, flat surface? A Mitochondria will become more efficient because the inner mitochondrial membrane will become more permeable to ions. B Mitochondria will become more efficient because the total volume of the mitochondria will increase. C Mitochondria will become less efficient because the inner mitochondrial membrane will become less permeable to large molecules. D Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease.

D mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease

Researchers grew seedlings of corn, Zea mays, in loose and compact sand. The researchers measured the amount of time required for the cells in the growing root tips of the seedlings to double in number. The mean cell doubling times for the two groups of seedlings are shown in Figure 1. Figure 1. Mean cell doubling times for the growing root tips of Zea mays seedlings planted in loose or compact sand Based on the sample means, which of the following conclusions about the cells in the growing root tips of Zea mays seedlings is best supported by the results of the experiment? A The cells of the root tips grow to larger sizes when the seedlings are planted in compact sand than when the seedlings are planted in loose sand. B The average rate of mitotic cell division is greater for the root tips growing in loose sand than for the root tips growing in compact sand. C The average cell cycle time is greater for the root tips growing in compact sand than for the root tips growing in loose sand. D More cells are produced per unit of time in the root tips growing in compact sand than in the root tips growing in loose sand.

D more cells are produced per unit of time in the root tips growing in compact sand than in the root tips growing in loose sand

Researchers investigated the influence of environmental pHpH on the activity of peroxidase, an enzyme that catalyzes the conversion of hydrogen peroxide to water and oxygen gas. In an experiment, the researchers added a hydrogen peroxide solution containing guaiacol to several identical test tubes and adjusted the solution in each test tube to a different pHpH. The researchers included the guaiacol because it caused the solutions to change color as the reactions proceeded, which the researchers relied on for measuring reaction rates. Finally, the researchers added the same amount of peroxidase to each test tube and measured the rate of each reaction at 23°C23°C. The results of the experiment are represented in Figure 1. Which of the following actions will provide a negative control for the investigation? A Repeating the experiment at 25°C25°C B Repeating the experiment using twice the amount of hydrogen peroxide C Repeating the experiment using twice the amount of peroxidase D Repeating the experiment using heat-denatured peroxidase

D repeating the experiment using heat-denatured peroxidase

Cells contain smaller components called organelles that are necessary for a cell's survival. Organelle functions have often been compared to components of larger systems. Which of the following functional differences between the rough and smooth endoplasmic reticulum (ER)(ER) is explained by the structural differences between them? A Rough ERER breaks down toxic substances, and smooth ERER only transports them out of the cell. B Rough ERER can synthesize and package lipids for export, and smooth ERER cannot. C Rough ERER can produce ATPATP, and smooth ERER cannot. D Rough ERER can synthesize and package proteins for export, and smooth ERER cannot.

D rough ER can syntehsize and package proteins for export, and smooth ER cannot

A cell culture commonly used in research was selected to study the effect of a specific virus on the timing of cell cycle phases. Two separate cultures were started, one untreated and one inoculated with the virus. Both cultures were incubated under identical conditions. After a period of time, 200 cells from each culture were observed and classified as shown in Table 1. Table 1. Number of normal and infected cells found in three phases of the cell cycle Phase of Cell CycleUntreated Cells (n=200n=200)Virus-Infected Cells (n=200n=200)G0G019610Interphase240Mitosis2150 Which of the following most accurately describes an observation and an effect of the viral infection indicated by the data in Table 1? A Normal cells spend 98 percent of their time cycling in and out of interphase. The virus reduces this to 5 percent of the time. B Twenty percent of the virus-infected cells are in interphase. These cells are no longer part of the cell cycle. C Forty percent of the virus-infected cells are in interphase. These cells are preparing for replication of genetic material. D Seventy-five percent of the virus-infected cells are found in mitosis. The virus stimulates frequent cell division.

D seventy-five percent of the virus-infected cells are found in mitosis. the virus stimulates frequent cell division

n flowering plants, plasmodesmata are narrow channels through cell walls that connect the cytoplasms of adjacent cells. An explanation of how plant cells communicate across cell walls will most likely refer to the diffusion through plasmodesmata of which of the following? A Membrane-bound organelles B Condensed, duplicated chromosomes C Branched polysaccharides D Small, water-soluble molecules

D small, water-soluble molecules

A researcher claims that genetic variation provides organisms with the ability to survive and reproduce in different environments. To support the claim, the researcher makes the following observation: bacteria that contain plasmids (small DNADNA molecules) are resistant to a wider range of antibiotics than are bacteria that contain no plasmids. Which of the following statements best establishes a connection between the observation and the researcher's claim? A Some antibiotics inhibit the synthesis of bacterial cell walls. B Some antibiotics inhibit protein synthesis in bacteria cells. C Some plasmids cannot exist in a bacterial cell with certain other plasmids. D Some plasmids contain antibiotic resistance genes.

D some plasmids contain antibiotic resistance genes

Phycobiliproteins are a complex of accessory pigments and proteins found in cyanobacteria but not in green algae. A researcher claims that the phycobiliprotein pigments in cyanobacteria allow the cyanobacteria to survive in certain aquatic niches better than green algae can. Which of the following statements best justifies the researcher's claim? A The additional pigments allow the cyanobacteria to store light energy so that it can be used at night to continue photosynthesis. B The additional pigments block light and prevent it from reaching photosynthetic organisms at greater depths, so no photosynthetic organisms can live below the surface waters containing cyanobacteria. C The additional pigments require energy and cellular resources to produce, so they can be used as an energy source during times of insufficient light. D The additional pigments absorb light at wavelengths that green algae cannot absorb; this may allow cyanobacteria to capture more light energy for photosynthesis than green algae can in certain areas.

D the additional pigments absorb light at wavelengths that green algae cannot absorb; this may allow cyanobacteria to capture more light energy for photosynthesis that green algae can in certain areas

A spherical bacterial cell has a radius of 3μm3μm. The human egg cell has a radius of 100μm100μm. Which statement correctly indicates the cell that is able to more efficiently exchange materials with the external environment and provides a correct explanation? A The egg cell, because it has the smallest surface-to-volume ratio. B The egg cell, because it has the largest surface-to-volume ratio. C The bacterial cell, because it has the smallest surface-to-volume ratio. D The bacterial cell, because it has the largest surface-to-volume ratio.

D the bacterial cell, because it has the largest surface-to-volume ratio

A group of mutations, known as MT-ND1MT-ND1, have been identified in mitochondrial DNADNA. These mutations are associated with a number of debilitating diseases stemming from the production of nonfunctional proteins in the mitochondria. Which of the following cellular deficiencies would most likely be related to these MT-ND1MT-ND1 mutations? A The cell is unable to synthesize most proteins required for normal cell functions. B The cell is unable to break down toxic materials and would accumulate large volumes of these materials. C The cell is able to synthesize proteins, but the proteins would not fold properly and would not contain the correct molecular tags for export from the cell. D The cell is unable to complete reactions related to electron transport and ATPATP production.

D the cell is unable to complete reacitons related to electron transport and ATP production

Himalayan rabbits are a breed of rabbits with highly variable fur color. If genetically similar rabbits are raised in environments that have different temperature conditions, the rabbits can have different color patterns. Which of the following statements best explains how the fur color can be different in Himalayan rabbits raised under different temperature conditions? A The genotype does not contribute to coat color in Himalayan rabbits. B The phenotype determines the genotype of coat color in Himalayan rabbits. C Different environments cause specific mutations in the genes controlling pigment production. D The environment determines how the genotype is expressed.

D the environment determines how the genotype is expressed

A certain type of specialized cell contains an unusually large amount of rough endoplasmic reticulum (ER)(ER). Which of the following functions is this cell type most likely specialized to perform? A The production and secretion of steroids B The destruction of toxic materials produced in other cells of the organism C The synthesis of polysaccharides for energy storage D The production and secretion of proteins

D the production and secretion of proteins

The beta-2 adrenergic receptor is a membrane-bound protein that regulates several cellular processes, including the synthesis and breakdown of glycogen. The receptor binds specifically to the hormone epinephrine. The binding of epinephrine to the beta-2 adrenergic receptor triggers a signal transduction cascade that controls glycogen synthesis and breakdown in the cell. A simplified model of the signal transduction cascade is represented in Figure 1. Figure 1. A simplified model of the signal transduction cascade triggered by epinephrine binding to the beta-2 adrenergic receptor Which of the following outcomes will most likely result from the inactivation of the beta-2 adrenergic receptor? A The cellular concentration of cyclic AMPAMP will increase. B The enzymatic activity of protein kinase A will increase. C The activation of glycogen phosphorylase will increase. D The rate of glycogen synthesis in the cell will increase.

D the rate of glycogen synthesis in the cell will incerase

A researcher claims that the incorporation of carbon dioxide into organic molecules during photosynthesis does not violate the second law of thermodynamics. Which of the following statements best helps justify the researcher's claim? A Organisms contain enzymes that lower the activation energies of specific chemical reactions. B An ecosystem is formed by the interaction of a community of organisms with their surrounding environment. C Photosynthetic organisms use the organic molecules produced during photosynthesis for growth and repair. D The total system that includes photosynthetic organisms and the Sun becomes less ordered over time.

D the total system that includes photosynthetic organisms and the sun becomes less ordered over time

Researchers conducted an experiment to investigate the effects of a valinomycin treatment on skeletal muscle cells. Valinomycin is a naturally occurring substance that can be used as a drug. The results of the experiment are presented in the table. Relative Rates of ATPATP ProductionTime after TreatmentUntreated CellsValinomycin-Treated Cells5 minutes1.00.310 minutes7.72.7 Which of the following claims about the effects of the valinomycin treatment is best supported by the data presented in the table? A The valinomycin treatment caused an increase in the activity of the rough endoplasmic reticulum. B The valinomycin treatment caused an increase in the activity of the Golgi complex. C The valinomycin treatment caused a decrease in the activity of the lysosome. D The valinomycin treatment caused a decrease in the activity of the mitochondria.

D the valinomycin treatement caused a decreaes in the activity of the mitochondria

Certain bacteria can use both ethyl alcohol and acetate as sources of nutrients. In an experiment where both nutrients are available to a bacterial population, the following results were obtained and graphed. What additional procedure would best help determine whether these movements are due to active transport or to passive transport? A Repeat the original experiment, but at three different temperatures. Compare the transport rates among the three temperatures. B Repeat the original experiment, but add a substance known to block movement of molecules across aquaporins. Compare the rates on the two graphs. C Use two additional treatments, one containing only ethyl alcohol and one containing only acetate. Compare the graphs of these two treatments with the original graph. D Use two additional treatments, one containing only ethyl alcohol and one containing only acetate. Include a substance known to block ATPATP use by the plasma membrane. Compare the graphs of these two treatments to the original graph.

D use 2 additional treatments, one containing only ethyl alcohol and one containing only acetate. include a substance known to block atp use by the plasma membrane. comapte the graphs of these 2 treatements to the original graph

Which of the following questions would be most useful to researchers trying to determine the role of meiosis in the F2F2 phenotypic frequencies? A What is the molecular mechanism underlying the dominance of erect petals and long pollen? B Which phenotypes give pea plants the highest level of fitness: erect or hooded petals and long or round pollen? C How do the phases of meiosis differ between sweet pea plants and other organisms? D What is the recombination frequency between the genes for petal shape and pollen shape?

D what is the recombination frequency between the genes for petal shape and pollen shape?

A model of crossing over during gamete formation is shown in Figure 1. Figure 1. Model of crossing over during meiosis Based on Figure 1, which of the following questions could best be addressed? A Does synapsis of homologous chromosomes in the parent cell contribute to an increase in genetic diversity in the daughter cells? B Do sister chromatids separate and form diploid daughter cells? C Do chromatids from nonhomologous chromosomes rearrange to produce identical daughter cells? D Does synapsis of homologous chromosomes produce daughter cells that are identical to the parent cell?

Does synapsis of homologus chromosomes in the parent cell contribute to an increase in genetic diversity in the daughter cells?

Brown fat is a type of fat tissue found in hibernating mammals. Inside the mitochondria of these fat tissue cells, these mammals have an uncoupling protein embedded in the inner mitochondrial membrane. This uncoupling protein allows hydrogen ions to leak from the intermembrane space back into the mitochondrial matrix. Figure 1 shows details of the processes in the inner mitochondrial membrane. Figure 1. Processes in the inner mitochondrial membrane Which of the following statements provides reasoning that supports the claim that brown fatty tissue keeps an animal warm? A The uncoupling protein in this tissue increases the production of ATPATP and causes more body heat to be produced to warm the animal. B The uncoupling protein in this tissue reduces the proton gradient across the membrane and thus produces heat to warm the animal without ATPATP production. C The uncoupling protein in this tissue causes an increase in the proton gradient, which causes more ATPATP to be produced that helps to warm the animal. D The uncoupling protein in this tissue reduces the production of ATPATP and creates an increase in the proton gradient that allows more heat energy to be produced to warm the animal.

The uncoupling protein in this tissue reduces the proton gradient across the membrane and thus produces heat to warm the animal without ATP production

Two competing hypotheses exist regarding the cell membrane structure. One hypothesis states that membrane structure is static and membrane components throughout the bilayer are rigidly bound. Alternatively, the other hypothesis states that cell membranes are a fluid mosaic in which membrane components may drift within the bilayer around the surface of the cell. An experiment is set up in which membrane proteins of two different cells are fluorescently labeled with two different colors and then fused as shown in Figure 1. Figure 1. Model of initiation of cell fusion experiment Which of the following results, one hour after membrane fusion, best supports the alternative hypothesis that the cell membrane is a fluid mosaic?

a cell whose membrane is a mix of dark and light spots

Cholesterol is a naturally occurring substance that helps regulate the fluidity of a cell's plasma membrane. A cholesterol molecule can be represented as having a polar head and a nonpolar region, as shown in the figure. Which of the following models shows how cholesterol molecules most likely interact with the phospholipid bilayer of a cell's plasma membrane?

a membrane with the nonpolar parts of cholesterol embedded in the membrane and the polar part facing the polar heads of the phospholipids

a researcher claims that budding yeast are able to survive in different environments because they produce enzymes that allow them to use different molecules as sources of matter and energy. Which of the following statements best helps justify the researcher's claim by providing a relevant example? A Yeast cells produce protein kinases, which are enzymes that catalyze the transfer of phosphate groups from ATPATP to protein substrates. B Yeast cells produce DNADNA polymerases, which are enzymes that catalyze the conversion of free nucleotides into strands of DNADNA. C Yeast cells produce invertase, which is an enzyme that catalyzes the conversion of the disaccharide sucrose into glucose and fructose. D Yeast cells produce catalase, which is an enzyme that catalyzes the conversion of hydrogen peroxide into water and oxygen gas.

c yeast cells produce invertase, which is an enzyme that catalyzes the conversion of the disaccharide sucrose into glucose and fructose

In corn plants, purple kernel color is dominant to yellow kernel color, and smooth kernels are dominant to wrinkled kernels. Researchers carried out a genetics experiment to investigate whether the genes controlling kernel color and kernel texture segregate independently. In their experiment, the researchers crossed two corn plants that were each heterozygous for both kernel color and kernel texture. The results of the experiment are presented in Table 1. Table 1. Results of a genetic cross between two heterozygous corn plants Offspring PhenotypeObservedExpectedPurple, smooth kernels918900Purple, wrinkled kernels281300Yellow, smooth kernels314300Yellow, wrinkled kernels87100 Using a significance level of p=0.05p=0.05, which of the following statements best completes a chi-square goodness-of-fit test for a model of independent assortment? A The calculated chi-square value is 0.66, and the critical value is 0.05. The null hypothesis can be rejected. B The calculated chi-square value is 0.66, and the critical value is 3.84. The null hypothesis cannot be rejected. C The calculated chi-square value is 3.91, and the critical value is 5.99. The null hypothesis can be rejected. D The calculated chi-square value is 3.91, and the critical value is 7.82. The null hypothesis cannot be rejected.

the calculated chi-square value is 3.91, and the critical value is 7.82. the null hypothesis cannot be rejected

The figure shows a process by which a cell might absorb food from its surrounding environment and break it down for use as a source of energy and matter. The process involves lysosomes, which are membrane-bound organelles that contain hydrolytic enzymes. Activation of the hydrolytic enzymes requires an acidic pHpH, and lysosomes maintain an internal acidic pHpH by using ion pumps. Which of the following outcomes will most likely result from a loss of ion pump function in the cell's lysosomes? A The internal pHpH of the lysosomes will decrease, which will prevent the activation of hydrolytic enzymes and interfere with the intracellular digestion of food. B The internal pHpH of the lysosomes will increase, which will prevent the activation of hydrolytic enzymes and interfere with the intracellular digestion of food. C The internal pHpH of the lysosomes will decrease, which will activate hydrolytic enzymes and enhance the intracellular digestion of food. D The internal pHpH of the lysosomes will increase, which will activate hydrolytic enzymes and enhance the intracellular digestion of food.

the internal pH of hte lysosomes will increase, which will prevent hte activation of hydrolytic enzymes and interfere with the intracellular digestion of food