Biology final 2021

18. The energy required to run the Calvin cycle reactions of photosynthesis comes from which two substances produced during the light-dependent reactions?

(A) ATP and NADPH

44. Based on Figure 2, which of the following best supports the claim that drug inhibits oxygen consumption?

(C) Melanoma line 3 consumes statistically less oxygen per cell in the presence of drug than it does in the presence of the solvent alone.

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

0%

11. Antidiuretic hormone (ADH) is important in maintaining homeostasis in mammals. ADH is released from the hypothalamus in response to high tissue osmolarity. In response to ADH, the collecting duct and distal tubule in the kidney become more permeable to water, which increases water reabsorption into the capillaries. The amount of hormone released is controlled by a negative feedback loop. Based on the model presented, which of the following statements expresses the proper relationship between osmolarity, ADH release, and urine production?

(A) As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine.

Which of the following statements about the rate of CO2 fixation in the two types of plants is supported by the data shown in the figures?

(A) At 21% O2 , plant 2 type has a lower rate of CO2 fixation than plant type does in both types of soil.

16. The figures below illustrate the similarities between ATP synthesis in mitochondria and chloroplasts. 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?

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

(A) Embedded in the plasma membrane

51. An increase in the concentration of protons in the cytosol will most likely have which of the following effects on glycolysis?

(A) Glycolytic enzymes will denature as a result of the increased concentration.

31. 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.

20. 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

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

41. DNA replication occurs

(A) during the S phase of the cell cycle

34. 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

43. Which of the following best describes the data in Figure 1 ?

(B) At a concentration above μ , drug reduces melanoma cell survival.

53. Tarui disease is an inherited disorder that is caused by mutations in , the gene that encodes a subunit of phosphofructokinase, an enzyme in the glycolysis pathway. Individuals with Tarui disease produce little or no functional phosphofructokinase in skeletal muscle cells. Based on Figure 1, which of the following best explains why a low carbohydrate diet is recommended for those with Tarui disease?

(B) Carbohydrate metabolism requires all the reactions of glycolysis, and amino acids and fatty acids do not.

Which of the following is the best explanation for the pattern of change in mass of the organisms over time?

(B) Cellular respiration

Based on the data in Figure 1, which of the following most likely represents the change in energy that occurs when hydrolysis is coupled with the phosphorylation of a substrate?

(B) Line 1 represents hydrolysis, and line 4 represents phosphorylation of a substrate.

23. Which of the following components of the cell membrane is responsible for active transport?

(B) Protein

27. 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?

(B) The animal's body cells are defective in endocytosis.

2. 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.

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

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

15. During respiration, most ATP is formed as a direct result of the net movement of

(B) protons down a concentration gradient

19. 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?

(C) A defect in a cell-cycle checkpoint prevents a cell from entering the S phase.

5. Figure 1 shows a model of how a channel protein influences the movement of a particle across a cell's plasma 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?

(C) Add more of the proteins to the plasma membrane and measure the rate of the particle movement.

21. 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?

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

42. Newborn babies and hibernating animals contain a large amount of brown adipose (fat) tissue ( ). Certain proteins in the 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 ?

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

Based on Figure 1, which of the following best explains how exercise causes blood glucose levels to rise?

(C) Epinephrine activates alpha cells, causing the release of glucagon, and inhibits beta cells, blocking the release of insulin.

29. What evolutionary advantage does compartmentalization of core metabolic processes offer eukaryotes?

(C) Evolution of a nucleus in eukaryotes separates the processes of transcription and translation and they can be regulated separately.

10. An intermediate electron acceptor for oxidations that occur in both glycolysis and in Krebs cycle reactions (A) Cytochrome

(C) NAD+

8. Scientists examined the folded structure of a purified protein resuspended in water and found that amino acids with nonpolar R groups were primarily buried in the middle of the protein, whereas amino acids with polar R groups were primarily on the surface of the protein. Which of the following best explains the location of the amino acids in the folded protein?

(C) Nonpolar R groups that cannot form hydrogen bonds with water are pushed into the middle of the protein.

14. If ATP breakdown (hydrolysis) is inhibited, which of the following types of movement across cell membranes is also inhibited?

(C) Passage of a solute against its concentration gradient

22. Cell communication is critical for the function of both unicellular and multicellular eukaryotes. Which of the following is likely true of cell signaling?

(C) Similar cell signaling pathways in diverse eukaryotes are evidence of conserved evolutionary processes.

The diagram above represents a typical rod-shaped bacterium. 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.

13. ATP serves as a common energy source for organisms because

(C) its energy can be easily transferred to do cellular work

35. Damaged tissue releases chemicals that activate platelets and stimulate the formation of blood clots. Which of the following predictions about the activity of platelets best describes a positive feedback mechanism?

(D) Activated platelets release chemicals that activate more platelets.

6. Alcohol dehydrogenase ( ) is an enzyme that aids in the decomposition of ethyl alcohol into nontoxic substances. Methyl alcohol acts as a competitive inhibitor of ethyl alcohol by competing for the same active site on . When attached to , 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?

(D) Competitive inhibition will decrease because the proportion of the active sites occupied by substrate will increase.

52. Which of the following describes why a glucose transporter is needed to move glucose into the cell?

(D) Glucose is large and polar and cannot pass through the phospholipid bilayer.

7. The protein is made up of amino acids linked together in a chain. Some humans produce a version of the 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 protein?

(D) It will affect the primary, secondary, and tertiary structures of the protein.

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?

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

45. Based on the information presented, which of the following best explains why the researchers measured oxygen consumption as an indicator of the effectiveness of drug ?

(D) Oxygen accepts electrons in oxidative phosphorylation, a process necessary for melanoma cell survival.

9. The relative amount of in a cell at various stages of the cell cycle is shown in Figure 1 . Figure 1. Amount of per cell during different stages of the cell cycle, relative to the beginning of the stage Which of the following best describes how the amount of in the cell changes during phase?

(D) The amount of DNA is halved as the cell divides into two daughter cells.

26. 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

(D) electrons flowing along the electron transport chain

30. All of the following cell components are found in prokaryotic cells EXCEPT

(D) nuclear envelope

25. Which of the following statements about mitochondrial chemiosmosis is NOT true?

(E) Heat energy is required to establish the electron transport chain.

Figure 1 shows a model of the endocrine signaling pathway that regulates ovulation. Which of the following observations would provide evidence of a positive feedback mechanism in this system?

. (D) Estrogen from the ovaries stimulates the hypothalamus and anterior pituitary to secrete more GrnH, LH , and FSH

49. If NaF is added to cells undergoing cellular respiration, which of the following will most likely accumulate in the cells?

2 Phosphoglycelrate( )

The diagram above illustrates feedback control as exerted by the hormone thyroxine. Following surgical removal of the thyroid gland, the level of TSH in the blood will increase. Which of the following best explains this increase?

A decrease in thyroxine levels means a loss of inhibition to the hypothalamus and anterior pituitary, leading to increased TSH secretion.

4. The illustration shows the active transport of hydrogen ions through a membrane protein. Which of the following best predicts the effect of not having available to supply energy to this process?

A) ions will stop moving through the protein.

57. The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following demonstrates negative feedback by the endocrine system?

After a meal, blood glucose levels become elevated, stimulating beta cells of the pancreas to release insulin into the blood. Excess glucose is then converted to glycogen in the liver, reducing blood glucose levels.

28. Figure 1 shows the number of chromosomes observed in an actively dividing human cell at each stage of cell division. Which of the following presents a correct interpretation of the changes in chromosome number depicted in Figure 1 ?

the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate cells.