AP BIO

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. Enzyme modification of newly synthesized integral membrane proteins.

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.

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.

Which of the following describes the most likely location of cholesterol in an animal cell?

A. Embedded in the plasma membrane.

Which of the following best describes the role of water in photosynthesis?

B. Water molecules donate electrons to the electron transport chains.

The maximum production rate of acetyl-CoA under condition 1 is closest to which of the following?

A. 1 micromole/sec

The figures can best assist in answering which of the following questions?

A. Do electron transport chains create a gradient so that ATP synthase can generate ATP molecules?

Which of the following best describes the process by which the bacteria are breaking down the glucose to produce lactic acid?

A. The bacteria are breaking down sugars in the absence of oxygen.

According to the data, which of the following best explains the results of the experiment?

A. The pH of the treatment culture was lower than the pH of the control because the chemical increased the bacterial metabolic rate.

Which of the following outcomes will most likely result from a loss of iron pump function in the cell's lysosomes?

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

In addition to the pigments commonly associated with photosynthesis, a certain photosynthetic species contains two additional pigment types. Which of the following best supports the claim that this species is better adapted to environmental changes than other photosynthetic species are?

D. The additional pigments allow the species containing them to harvest energy from wavelengths of light that the other photosynthetic species cannot use.

Which of the following is an accurate description of the process shown in figure 1?

D. The formation of a covalent peptide bond in a dehydration synthesis reaction.

If 30% of the nucleotides in a single-stranded RNA molecule are adenine, then what percent are expected to be thymine?

A. 0%

Which of the following is the strongest evidence supporting the endosymbiont hypothesis?

A. Mitochondria have their own DNA and divide independently of the cell.

A typical bag of fertilizer contains high levels of nitrogen, phosphorus, and potassium but trace amounts of magnesium and calcium. Which of the following best matches the fertilizer component with the molecule in which it will be incorporated by organisms in the area?

A. Nitrogen will be incorporated into nucleic acids.

Carbon dioxide most likely enters a cell through which of the following processes?

A. Simple diffusion through the membrane

In an experiment, the efficiency of oxygen exchange across the plasma membrane is being assessed in four artificial red blood cells. The table above lists some properties of those artificial cells. Other conditions being equal, which artificial cell is predicted to be the most efficient in exchanging oxygen with the environment by diffusion?

A. The cuboidal cell

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.

Muscle cells have high ATP 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 ATP to be synthesized.

Which of the following best explains how the phospholipid bilayer of a transport vesicle contributes to cellular functions?

A. The phospholipid bilayer allows the vesicle to fuse with the Golgi apparatus and the plasma membrane, allowing the exocytosis of proteins.

The illustration above is a model of a typical beet root cell. Based on the experimental results, which of the following best represents the effect of acetone on the permeability of cellular membranes?

B.

A researcher claims that the synthesis of ATP from ADP and inorganic phosphate (Pi) is essential to cellular function. Which of the following statements best helps justify the researcher's claim?

B. ATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy.

Which of the following is evidence that eukaryotes and prokaryotes share a common ancestor?

B. All eukaryotes and prokaryotes contain ribosomes.

A scientist claims that Elysia chlorotica, a species of sea slug, is capable of photosynthesis.

B. Elysia chlorotica grows when exposed to light in the absence of other food sources

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?

B. Fewer lysosomes will be available to break down macromolecules to provide the necessary nutrients for cellular respiration.

Plant cell wall 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?

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

Which of the following questions will best direct an investigation of the mechanism of ATP synthase?

B. Is the phosphorylation of ADP by ATP synthase dependent on the formation of a protein gradient?

Developers have approved of a project that will permanently reduce the primary producers' biomass by 50 percent and remove all rabbits and deer.

B. The biomass of coyotes will be dramatically reduced.

Paramecia are unicellular protists that have contractile vacuoles to remove excess intracellular water. In an experimental investigation, paramecia were placed in salt solutions of increasing osmolarity. The rate at which the contractile vacuole contracted to pump out excess water was determined and plotted against osmolarity of the solutions, as shown in the graph. Which of the following is the correct explanation for the data?

B. The contraction rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases.

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?

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

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?

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.

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?

B. They have highly folded membranes.

Ultraviolet (UV) radiation can damage DNA by breaking weak bonds. Which of the following best explains how this occurs?

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

Which statement best describes the effect on water transport across the cell membrane if the aquaporin in the figure ceases to function?

B. Water molecules will still be able to move across the cell membrane but at a slower rate.

Which of the following was the dependent variable in the researcher's experiment?

B. pH

Which of the following describes a metabolic consequence of a shortage of oxygen in muscle cells?

C. A buildup of lactic acid in the muscle tissue due to fermention.

Which of the following best describes the formation of the bond shown in figure 1?

C. A covalent bond is formed between a carbon atom and a nitrogen atom along with the formation of H2O.

A researcher claims that only a portion of the light energy captured by green plants is available for repair. Which of the following observations best helps justify the researcher's claim?

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

Newborn babies and hibernating animals contain a large amount of brown adipose (fat) tissue (BAT). Certain proteins in the BAT cells increase the permeability of the inner mitochondrial membrane to protons, disrupting the proton gradient. Which of the following best predicts the effect of disrupting the proton gradient in BAT?

C. Electron transport and oxidative phosphorylation will be decoupled, generating more heat but less ATP.

Which of the following statements best predicts the effect of increased cottonwood growth on the food web?

C. Increased cottonwood growth will provide more resources for cicadas, resulting in an increase in the kestrel population.

Which of the following statements best justifies the inclusion of test tube V as a control in the experiment?

C. It will show the color change that occurs in the absence of enzyme activity.

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?

C. Methyl (CH3) group

In chloroplasts, ATP is synthesized from ADP plus inorganic phosphate (Pi) in a reaction catalyzed by ATP synthase molecules that are embedded in the thylakoid membrane. Which of the following statements provides evidence to support the claim that no ATP will be synthesized in the absence of a proton gradient across the thylakoid membrane?

C. No ATP is synthesized when channel proteins that allow the free passage of protons are inserted into the thylakoid membrane.

Based on the molecular structures shown in the figure, which molecule is likely to be solid at room temperature?

C. Palmitic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together.

Which of the following best describes a feature shown in the diagram that is unique to archaea and bacteria?

C. The organism does not have a nuclear membrane surrounding its genetic material.

Which of the following statements best helps explain the reaction specificity of an enzyme?

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

In an experiment, cells were isolated from an aquatic plant and suspended in pond water, a sucrose sugar solution, or distilled water. All of the cells were then viewed under a microscope. Compared with the cell in the pond water, the cell in the sugar solution appeared shriveled, and the cell in the distilled water appeared inflated. The results of the experiment are represented in Figure 1. Which of the following statements best explains the observations represented in Figure 1?

C. There was a net movement of water out of the cell suspended in the sugar solution and a net movement of water into the cell suspended in the distilled water.

Based on the data in Table 1, which of the following is the earliest time point at which there is a statistical difference in average pH between the control and treatment groups?

D. 35 minutes

Pyruvate dehydrogenase deficiency is a genetic disease most commonly linked to a mutation in the subunit of the _mitochondrial enzyme that causes the enzyme to cease functioning. As a result of the mutation, affected individuals build up dangerous amounts of lactic acid. Which of the following best explains the buildup of lactic acid in individuals with the mutation?

D. Cells undergo fermentation because pyruvate cannot be metabolized to proceed into the Krebs cycle.

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.

D. Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.

Of the following, which additional investigation can be used to determine when the cells are in an isotonic solution?

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

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?

D. Mitochondria will become more efficient because the surface area of the inner mitochondrial membranes will decrease.

Which of the following best describes the cellular location where pyruvate dehydrogenase is most likely active?

D. The mitochondrial matrix

The diagram shows how water can adhere to the xylem in the stems of plants, which contributes to water movement in the plant. Which of the following best explains how water is able to move upward from the roots of a plant, through its xylem in the stem, and out to the leaves?

D. Water and the xylem are both polar. Water molecules have the ability to form hydrogen bonds with each other and with the walls of the xylem.

Which of the following is the dependent variable in the experiment?

The absorbance of 460 nm light by the treatment solutions.

A mutation in the gene coding for a single-polypeptide enzyme results in the substitution of the amino acid serine, which has a polar R group, by the amino acid phenylalanine, which as a nonpolar R group. When researchers test the catalysis of the normal enzyme and the mutated enzyme, they find that the mutated enzyme has much lower activity than the normal enzyme does. Which of the following most likely explains how the amino acid substitution has resulted in decreased catalytic activity by the mutated enzyme?

The substitution altered the secondary and tertiary structure of the enzyme so that the mutated enzyme folds into a different shape than the normal enzyme does.