Biology final

47. 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?

650 micrometers

9. Figure 1. Formation of a peptide bond. Which of the following best describes the formation of the bond shown in Figure 1 ?

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

31. Site of conversion of chemical energy of glucose to ATP

A, the mitochondria

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

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

42. Mitochondria are found in most eukaryotic cells and contain their own DNA and ribosomes that are similar to those typical of many prokaryotic cells. Which of the following statements is justified by these observations?

An ancestral cell most likely engulfed anaerobic prokaryote in a relationship that proved beneficial for both cells.

45. Which of the following best describes the numbered areas?

Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules

79. 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?

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

14. Both myoglobin and hemoglobin are proteins that bind reversibly with molecular oxygen. The graph below shows the oxygen-binding saturation of each protein at different concentrations of oxygen. Which of the following statements is correct?

At 40 mm Hg partial pressure, myoglobin has a greater affinity for oxygen than hemoglobin has.

30. The following questions refer to the following diagram. For each phrase or sentence, select the labeled part to which it is most closely related. Each option may be used once, more than once, or not at all for each group. Evolved from a photoautotrophic prokaryote.

B, the chloroplast

74. An increase in the rate of oxygen production by algae would be accompanied by a comparable increase in the rate of production of which of the following substances?

C6H12O6

53. Two different models of a living cell are represented in the figure. Of the two cells represented in the figure, which would likely be more efficient at exchanging substances with the surrounding environment?

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

27. 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?

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

68. Which two cellular organelles in eukaryotes have both electron transport systems and chemiosmotic mechanisms?

Chloroplasts and mitochondria

72. Alcohol dehydrogenase (ADH) 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?

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

87. 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?

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

33. 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?

Enzymatic modification of newly synthesized integral membrane proteins.

77. 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

FADH2

40. 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?

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

99. Which of the following is most likely to result if oxygen is added to the tissue culture?

For each glucose molecule consumed, more ATP will be formed.

91. Which metabolic process is common to both aerobic cellular respiration and alcoholic fermentation?

Glycolysis

38. Liver cells manufacture glycoproteins, while adipose cells store fat. Which of the following subcellular structures is likely to be more prominent in liver cells than in adipose cells?

Golgi apparatus

16. 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 for those proteins on membrane-bound ribosomes. The hydrolytic enzymes are most likely to accumulate in which of the following cellular structures?

Golgi complex

88. The O2 released during photosynthesis comes from

H2O

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

Heat energy is required to establish the electron transport chain.

62. Cystic fibrosis is a recessively inherited disorder that results from a mutation in the gene encoding CFTR chloride ion channels located on the surface of many epithelial cells. As shown in the figure, the mutation prevents the normal movement of chloride ions from the cytosol of the cell to the extracellular fluid. As a consequence of the mutation, the mucus layer that is normally present on the surface of the cells becomes exceptionally dehydrated and viscous. An answer to which of the following questions would provide the most information about the association between the CFTR mutation and the viscous mucus?

How does the disrupted chloride movement affect the movement of sodium ions and water by the cell?

13. Which of the following is responsible for the cohesive property of water?

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

85. Graphs representing enzymes sensitive to changes in pH include which of the following?

I, II, and III only

84. Enzymes with their highest activity at an alkaline (basic) pH are represented by which of the following graphs?

II only

65. Which of the following conclusions is best supported by the data presented in Figure 1 ?

Implanted hESC-β cells are effective at regulating blood glucose levels in the absence of mouse β- cells.

28. 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?

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

81. Cyanobacteria contain a variety of pigment molecules, as shown in Table 1. As a result, the color of cyanobacteria cultures can vary significantly based on the relative amount of each pigment produced. A researcher placed a culture of cyanobacteria under green lights. Within a few weeks, the appearance of the cyanobacteria changed from green to red. The researcher claimed the color change in the culture was the result of an adaptation allowing greater photosynthesis. Which of the following provides the best reasoning to justify the researcher's claim?

In green light, more phycoerythrin molecules are produced, allowing more green light to be absorbed, thus increasing photosynthesis.

29. 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 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?

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

61. A model of the plasma membrane showing several biological molecules, including a transmembrane protein, is shown in Figure 1. Figure 1. Phospholipid bilayer with transmembrane protein. Which statement best explains why correct protein folding is critical in the transmembrane protein shown above?

Interactions of the hydrophobic and hydrophilic amino acids help to anchor the protein in the membrane.

67. Which of the following statements is true regarding the movement of substances across cell membranes?

Ions are unable to move through the phospholipid bilayer because the nonpolar tail regions of the phospholipids are hydrophobic.

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

Is the phosphorylation of ADP by ATP synthase dependent on the formation of a proton gradient?

55. Which of the following is true about the structure of the prokaryotic cell represented in the figure?

It has a cell wall exterior to the plasma membrane and contains ribosomes.

10. Polypeptides are continuously being formed and degraded. One of these processes is shown. Figure 1. Polypeptide reaction Which statement is the most accurate description of the reaction shown in Figure 1?

It represents a polypeptide chain that is broken down through a hydrolysis reaction.

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

It will affect the primary, secondary, and tertiary structures of the CFTR protein.

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

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

34. 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. 34. If, instead of the bag, a potato slice were placed in the beaker of distilled water, which of the following would be true of the potato slice?

It would gain mass

97. Which of the following would most adversely affect the validity of this experiment?

Large variation in metabolic rates between individuals of a species

66. Which of the following processes is most likely to occur as a result of an animal cell receiving a signal to initiate apoptosis?

Lysosomes will release digestive enzymes into the cytosol.

96. Which of the following hypotheses is best supported by the results of this experiment?

Metabolic rate per gram of tissue is higher in smaller mammals

63. Which of the following best supports the statement that mitochondria are descendants of endosymbiotic bacteria-like cells?

Mitochondria and bacteria possess similar ribosomes and DNA.

37. 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?

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

57. The function of which of the following organelles directly requires oxygen?

Mitochondrion

5. Mutations in DNA are usually caused by chemical or radiation damage to DNA molecules, followed by imperfect repair of the damage. Immediately after this kind of imperfect repair, there may be a mismatched base pair in the DNA. The illustration below shows an example of a mismatch, with the relevant pair bases in bold. Which of the following best represents the DNA of the two daughter cells produced when a bacterial cell with this particular mismatch replicates its DNA and divides?

Mutant strand on top, normal strand on bottom.

76. An intermediate electron acceptor for oxidations that occur in both glycolysis and in Krebs cycle reactions

NAD+

54. 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?

Na+ transport out of the cell requires ATP hydrolysis.

7. Which of the following conclusions is most clearly supported by the representations of nucleic acid #1 and nucleic acid #2?

Nucleic acid #1=contains adenine-thymine base pairs, whereas nucleic acid #2 does not.

20. To model a plant cell, a permeable, nonflexible case is placed around each piece of dialysis tubing. The greatest pressure potential will develop within dialysis tube number

Number 4

19. The contents of which dialysis tube are initially isotonic to the distilled water in the beaker?

Number 5

18. A net movement of water into the beaker occurs in which of the following dialysis tubes?

Number 6

90. Which of the following best predicts how the structure and function of pepsin will change as it enters the small intestine?

Pepsin will change in shape because of the basic environment of the small intestine; therefore, its enzymatic activity will decrease.

75. Based on the data shown, changes in the light intensity resulted in changes in the rate of which of the following processes?

Photosynthesis

69. What most likely causes the trends in oxygen concentration shown in the graph above?

Photosynthesis produces more oxygen than is consumed by respiration during the day

23. A prokaryotic cell has which of the following?

Plasma membrane

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

Protein

52. Synthesized at the ribosome

Proteins

95. Which of the following can be used to determine the rate of enzyme-catalyzed reactions?

Rate of disappearance of the substrate

49. Prokaryotic and eukaryotic cells generally have which of the following features in common?

Ribosomes

1. 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?

Single stranded DNA

DNA and RNA 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 DNA and RNA?

The backbone of DNA contains deoxyribose, whereas the backbone of RNA contains ribose.

22. A pathogenic bacterium has been engulfed by a phagocytic cell as part of the nonspecific (innate) immune response. Which of the following illustrations best represents the response?

The bacteria is digested by the lysosome.

51. A spherical bacterial cell has a radius of . The human egg cell has a radius of. Which statement correctly indicates the cell that is able to more efficiently exchange materials with the external environment and provides a correct explanation?

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

35. Which of the following best describes the condition expected after 24 hours?

The bag will contain more water than it did in the original condition

60. Which of the following graphs is the most appropriate representation of the experimental data?

The bar graph with error bars.

56. 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?

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

44. 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 O2 and CO2 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?

The drug is a small nonpolar molecule

8. Figure 1 represents a common process that occurs in organisms. Figure 1. Structural formula for a common biological reaction Which of the following is an accurate description of the process shown in Figure 1?

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

94. Which of the following best describes why the disks rose to the surface faster in the more concentrated hydrogen peroxide solutions?

The higher substrate concentrations in the more concentrated solutions speeded the reaction.

46. The model below shows the structure of a portion of a plasma membrane in an animal cell. Which statement best explains the orientation of the phospholipid molecules in this model?

The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments.

Which of the following characteristics of Figure 1 best shows that the fragment is RNA and not DNA?

The identity of each nitrogenous base

86. The figure above shows an organelle typically found in eukaryotic cells. Which of the following best describes the function of the double membrane system of this organelle?

The inner membrane has specialized proteins that create a hydrogen ion concentration gradient between the intermembrane space and the matrix.

11. Which of the following best describes how amino acids affect the tertiary structure of a protein?

The interactions of the different -groups with other -groups and with their environment determine the tertiary structure of the protein.

39. 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 pH, and lysosomes maintain an internal acidic pH 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?

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

98. Which of the following is an important difference between light-dependent and light independent reactions of photosynthesis?

The light-dependent reactions produce ATP and NADPH; the light-independent reactions use energy stored in ATP and NADPH.

41. 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 and potassium ions across the plasma membrane is presented in 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 function?

The membrane potential will be disrupted by an increase K+ in concentration inside the cell.

5. Water and ammonia interact to form hydrogen bonds, as represented in the figure. Which statement best helps explain the formation of the hydrogen bond represented in the figure?

The nitrogen has a partial negative charge, and the hydrogen attached to the oxygen has a partial positive charge.

21. Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed by a larger cell, as shown in Figure 1. Figure 1. A model showing a cell engulfing a smaller cell. Which of the following provides evidence to best support the researchers' claim?

The organelle has a double membrane.

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

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

50. Simple cuboidal epithelial cells line the ducts of certain human exocrine glands. Various materials are transported into or out of the cells by diffusion. (The formula for the surface area of a cube is 6 X S 2, and the formula for the volume of a cube is S 3, where S = the length of a side of the cube.) Which of the following cube-shaped cells would be most efficient in removing waste by diffusion?

The smallest one

48. 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. The results of an experiment using aquatic plant cells. Which of the following statements best explains the observations represented in Figure 1 ?

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.

92. Which of the following best describes the function of the coenzymes NAD+ and FAD in eukaryotic cellular respiration?

They accept electrons during oxidation-reduction reactions.

32. 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?

They both have highly folded membranes.

15. Which of the following best describes the physiological significance of the different oxygen-binding capabilities of hemoglobin and myoglobin?

They enhance movement of oxygen from the blood into the muscles.

93. Which of the following best describes why ice was used during this experiment?

To retard the breakdown of catalase

59. The student analyzed the data from the investigation and concluded that the estimate of the mean of one treatment group was unreliable. Which of the following identifies the treatment group most likely to have provided an unreliable estimate of the mean, and correctly explains why the estimate appears unreliable?

Treatment group II; it has a lower than expected mean absorbance and the largest standard error of the mean.

24. A sample of human blood was placed in a test tube containing a physiological saline solution (0.9% sodium chloride). This type of solution is often used intravenously to quickly rehydrate patients. A drop of the blood from the test tube was placed on a slide and red blood cells (RBCs) were observed under a microscope. Three possible outcomes are diagrammed below. Which of the following best predicts which diagrammed microscope view the laboratory worker would see and best explains why?

View 2 because the rate of water movement into the RBCs equals the rate of water movement out of the cells

12. The synthesis of protein or carbohydrate polymers always produces which of the following as a byproduct?

Water

17. A common laboratory investigation involves putting a solution of starch and glucose into a dialysis bag and suspending the bag in a beaker of water, as shown in the figure below. The investigation is aimed at understanding how molecular size affects movement through a membrane. Which of the following best represents the amount of starch, water, and glucose in the dialysis bag over the course of the investigation?

Water increases, starch stays constant, glucose decreases.

58. Which of the following scientific questions is most relevant to the model represented in the figure above?

Which molecular substance is actively transported across the plasma membrane?

89. The reactions of glycolysis occur in the

cytosol

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

its energy can be easily transferred to do cellular work

101. Within the cell, many chemical reactions that, by themselves, require energy input (have a positive free-energy change) can occur because the reactions

may be coupled to the hydrolysis of ATP

71. According to the data, the crickets at 25oC have greater oxygen consumption per gram of tissue than do the crickets at 10oC. This trend in oxygen consumption is the opposite of that in the mice. The difference in trends in oxygen consumption among crickets and mice is due to their

mode of internal temperature regulation

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

nuclear envelope

43. Which of the following statements best predicts the effect of increasing the permeability of the mitochondrial membranes to large molecules?

production will decrease because of an increase in the occurrence of uncontrolled chemical reactions.

80. Carbohydrate-synthesizing reactions of photosynthesis directly require

products of the light reactions

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

protons down a concentration gradient

36. In the first step of an experiment, rat liver cells were exposed for 5 minutes to amino acids labeled with a radioactive isotope. The cells were then washed to stop any further incorporation of radioactive amino acids. The cells were sampled periodically thereafter, and the radioactivity of a certain protein (protein X) was measured in various cell components, as shown below. In graphing the data from this experiment, the sampling time would be shown on the x-axis because

sampling time is the independent variable