Download Test 2 - Lone Star College

Test 2
Biology 1408 Summer
Dr. Shmaefsky
Name___________________________________
Place multiple choice answers on ScanTron sheet
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 2 Point each
- Answers on ScanTron!
1) Cyanide inhibits mitochondrial function; as a result, the rate of
A) ATP synthesis would decrease.
B) ATP synthesis would increase.
C) protein synthesis would increase.
D) photosynthesis would increase.
E) lipid synthesis would increase.
1)
2) Mitochondria differ from chloroplasts in that mitochondria
A) convert solar energy to chemical energy, whereas chloroplasts convert one form of chemical
energy to another.
B) are not found in plants, whereas chloroplasts are not found in animals.
C) contain three different membrane-bound compartments, whereas chloroplasts contain two.
D) produce glucose, whereas chloroplasts break glucose down.
E) contain membrane folds called cristae, whereas chloroplasts contain disklike vesicles in stacks
called grana.
2)
3) In living organisms, kinetic energy differs from chemical energy in that
A) kinetic energy can be converted into various forms of energy, whereas chemical energy can
only be converted into heat.
B) kinetic energy is the energy of a moving object, whereas chemical energy is the potential
energy of molecules.
C) chemical energy is a particular form of kinetic energy.
D) kinetic energy is stored energy that has the potential to do work, and chemical energy is the
energy of movement.
E) kinetic energy depends on the movement of atoms, whereas chemical energy depends on the
movement of molecules.
3)
4) Anything that prevents ATP formation will most likely
A) have no effect on the cell.
B) result in cell death.
C) result in the conversion of kinetic energy to potential energy.
D) force the cell to rely on ADP for energy.
E) force the cell to rely on lipids for energy.
4)
5) Most of a cell's enzymes are
A) proteins.
B) lipids.
C) amino acids.
D) nucleic acids.
E) carbohydrates.
5)
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6) The active site of an enzyme is
A) the highly changeable portion of an enzyme that adapts to fit the substrates of various
reactions.
B) the region of an enzyme that attaches to a substrate.
C) the region of a product that detaches from the enzyme.
D) the region of a substrate that is changed by an enzyme.
E) None of the choices are correct.
6)
7) Which one of the following is true?
A) All enzymes depend on protein cofactors to function.
B) Enzymes are inorganic.
C) Enzymes carry out specific reactions.
D) Enzymes are the reactants in a chemical reaction.
E) An enzyme's function is unaffected by changes in pH.
7)
8) Which of the following substances could be an enzyme cofactor?
A) a vitamin
B) a polypeptide
C) a protein
D) a ribosome
E) None of the choices are correct.
8)
9) A child is brought to the hospital with a fever of 107°F. Doctors immediately order an ice bath to
lower the child's temperature. Which explanation offers the most logical reason for this action?
A) Elevated body temperatures cause molecules to vibrate more quickly and prevent enzymes
from easily attaching to reactants. This would slow vital body reactions.
B) Elevated body temperature will increase reaction rates in the child's cells and overload the
limited number of enzymes found in the cell.
C) Elevated body temperatures may denature enzymes. This would interfere with the cell's
abilities to catalyze various reactions.
D) Elevated body temperatures will increase the energy of activation needed to start various
chemical reactions in the body. This will interfere with the ability of enzymes to catalyze vital
chemical reactions.
E) Elevated body temperatures easily break the covalent bonds linking biologically important
molecules. This will cause a general breakdown of cell structures.
9)
10) Heating inactivates enzymes by
A) changing the enzyme's three-dimensional shape.
B) removing phosphate groups from the enzyme.
C) breaking the covalent bonds that hold the molecule together.
D) causing enzyme molecules to stick together.
E) None of the choices are correct.
10)
11) Which of the following can affect the rate of an enzyme-catalyzed reaction?
A) temperature
B) pH
C) noncompetitive inhibitors
D) competitive inhibitors
E) All of the choices are correct.
11)
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12) The term anaerobic means
A) without O2 .
12)
B) without bacteria.
C) without CO2.
D) without ATP.
E) with O2.
13) How do cells capture the energy released by cellular respiration?
A) They store it in molecules of carbon dioxide.
B) They produce ATP.
C) The energy is coupled to oxygen.
D) They produce glucose.
E) None of the choices are correct.
13)
14) Which one of the following is true?
A) Cellular respiration occurs in mitochondria and in chloroplasts.
B) Photosynthesis occurs in mitochondria and cellular respiration occurs in chloroplasts.
C) Photosynthesis occurs in mitochondria and in chloroplasts.
D) Photosynthesis occurs in chloroplasts and cellular respiration occurs in mitochondria.
E) Neither cellular respiration nor photosynthesis occurs in mitochondria and in chloroplasts.
14)
15) Which of the following are products of cellular respiration?
A) oxygen and energy to make ATP
B) oxgyen and carbon dioxide
C) energy to make ATP and carbon dioxide
D) oxygen and glucose
E) glucose and carbon dioxide
15)
16) Humans use the calories they obtain from __________ as their source of energy.
A) water
B) food
C) minerals
D) sunlight
E) carbon dioxide
16)
17) Which one of the following is the correct sequence of stages in cellular respiration?
A) glycolysis, oxidative phosphorylation, and the citric acid cycle
B) oxidative phosphorylation, the citric acid cycle, and glycolysis
C) the citric acid cycle, oxidative phosphorylation, and glycolysis
D) oxidative phosphorylation, glycolysis, and the citric acid cycle
E) glycolysis, the citric acid cycle, and oxidative phosphorylation
17)
18) The nucleus of a cell
A) is contained within the nucleolus.
B) is the region of the cell where ribosomes are degraded.
C) is surrounded by a single layer of membrane.
D) contains DNA.
E) both is contained within the nucleolus and contains DNA.
18)
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19) Which one of the following is false?
A) An enzyme's function depends on its three-dimensional shape.
B) Enzymes are used up in chemical reactions.
C) Enzymes are very specific for certain substrates.
D) An enzyme binds to its substrate at the enzyme's active site.
E) Enzymes emerge unchanged from the reactions they catalyze.
19)
20) A medical research team is concerned about the outbreak of a new disease in humans. The bacteria
that cause the disease resemble bacteria that cause a similar disease in cattle. The bovine disease is
treated with a drug that inhibits a bacterial enzyme crucial to bacterial cell division. As the
researchers prepare to test the drug in humans, they will
A) be concerned about its safety; since all living cells contain the same enzymes, the drug is
likely to cause cell damage; the question is whether the damage is too large to be tolerated.
B) be uncertain about its safety; human cells contain some enzymes that are very similar to those
found in bacterial cells; the drug may inhibit these enzymes and damage the human cells.
C) be fairly confident about its safety; although bacteria produce all of the same enzymes as
human cells, the small size of bacteria make them more susceptible to damage.
D) be fairly confident about its safety; bacterial enzymes are all very different from human
enzymes, so the drug should only affect the bacteria.
E) None of the choices are correct.
20)
21) Malathion and tetracycline are both enzyme inhibitors. Malathion is used to kill insects; tetracycline
to kill bacteria. Malathion is more toxic to human cells than is tetracycline. Which of the following
explanations for the difference in toxicity to human cells would be reasonable?
A) Human cells contain the enzymes inhibited by both compounds, but the enzyme inhibited by
malathion is not metabolically crucial.
B) Malathion is a competitive inhibitor; tetracycline is a noncompetitive inhibitor.
C) Human cells do not contain the enzymes inhibited by malathion or tetracycline.
D) Malathion binds to its enzyme reversibly; tetracycline binds to its enzyme irreversibly.
E) None of the choices are correct.
21)
22) Plasma membranes are selectively permeable. This means that
A) cholesterol cannot enter the cell.
B) glucose cannot enter the cell.
C) the plasma membrane allows some substances to enter or leave a cell more easily than others.
D) anything can pass into or out of a cell as long as the membrane is intact and the cell is healthy.
E) plasma membranes must be very thick.
22)
23) Which one of the following is not a function of the plasma membrane? The plasma membrane
A) plays a role in signal transduction.
B) is involved in self-recognition.
C) is the control center of the cell.
D) forms a selective barrier around the cell.
E) has receptors for chemical messages.
23)
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24) When two aqueous solutions that differ in solute concentration are placed on either side of a
semipermeable membrane, and osmosis is allowed to take place, the water will
A) exhibit a net movement to the side with lower water concentration.
B) exhibit a net movement to the side with higher water concentration.
C) not cross the membrane.
D) exhibit a net movement to the side with lower solute concentration.
E) exhibit an equal movement in both directions across the membrane.
24)
25) Osmosis can be defined as
A) active transport.
B) the diffusion of water.
C) endocytosis.
D) the diffusion of a solute.
E) the diffusion of nonpolar molecules.
25)
26) Kinetic energy differs from chemical energy in that
A) kinetic energy is stored energy that has the potential to do work, and chemical energy is the
energy of movement.
B) chemical energy is a particular form of kinetic energy.
C) kinetic energy depends on the movement of atoms, whereas chemical energy depends on the
movement of molecules.
D) kinetic energy can be converted into various forms of energy, whereas chemical energy can
only be converted into heat.
E) kinetic energy is the energy of a moving object, whereas chemical energy is the potential
energy of molecules.
26)
27) Glucose molecules provide energy to power the swimming motion of sperm. In this example, the
sperm are changing
A) kinetic energy into potential energy.
B) kinetic energy into chemical energy.
C) chemical energy into potential energy.
D) chemical energy into kinetic energy.
E) None of the choices are correct.
27)
28) Active transport
A) uses ATP as an energy source.
B) requires the cell to expend energy.
C) is necessary to allow nerves to function properly.
D) can move solutes up a concentration gradient.
E) All of the choices are correct.
28)
29) Most of the functions of a cell membrane are performed by
A) phospholipids.
B) cholesterol.
C) glycolipids.
D) proteins.
E) nucleotides.
29)
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30) Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of
A) exocytosis.
B) phagocytosis.
C) endocytosis.
D) active transport.
E) passive transport.
30)
31) The molecules responsible for membrane transport are
A) phospholipids.
B) carbohydrates.
C) ATP.
D) proteins.
E) steroids.
31)
32) You are adrift in the Atlantic Ocean, and, being thirsty, drink the surrounding seawater. As a result,
A) your cells lyse, due to the excessive intake of salt.
B) you quench your thirst.
C) your cells become turgid.
D) you dehydrate yourself.
E) None of the choices are correct.
32)
33) Pyruvate
A) is the molecule that starts the citric acid cycle.
B) forms at the end of glycolysis.
C) is the end product of oxidative phosphorylation.
D) is a six-carbon molecule.
E) is the end product of chemiosmosis.
33)
34) The enzymes of the citric acid cycle cycle are located in the
A) outer mitochondrial membrane.
B) cytoplasm.
C) mitochondrial matrix.
D) intermembrane space of the mitochondrion.
E) inner mitochondrial membrane.
34)
35) The oxygen released into the air as a product of photosynthesis comes from
A) carbon dioxide.
B) water.
C) glucose.
D) chlorophyll.
E) None of the choices are correct.
35)
36) What is the source of energy that provides the boost for electrons during photosynthesis?
A) electromagnetism
B) cellular respiration
C) light
D) ATP
E) None of the choices are correct.
36)
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37) Which of the following are produced during the light reactions of photosynthesis?
A) glucose, ADP, NADP+ , CO2
37)
B) ADP, NADP+ , O2
C) ATP, NADPH, O2
D) glucose, ADP, NADP+
E) ATP, NADPH, CO2
38) Which of the following are produced during the Calvin cycle?
A) ADP, NADP+ , O2
38)
B) ATP, NADPH, CO2
C) ATP, NADPH, O2
D) glucose, ADP, NADP+ , CO2
E) glucose, ADP, NADP+
39) Photosynthetic organisms derive their carbon from
A) carbon dioxide.
B) hydrocarbons.
C) methane.
D) carbon monoxide.
E) All of the choices depend on environmental conditions.
39)
40) Which one of the following substances would have the most trouble crossing a biological
membrane by diffusing through the lipid bilayer?
A) O2
40)
B) CO2
C) a small, nonpolar molecule such as butane (C4H10)
D) H2 O
E) salts such as sodium
ESSAY. Write your answer in the space provided or on a separate sheet of paper. 10 points each.
41) Read the study below and answer the followin g questions:
Identify the dependent variable(s)
Identify the independent variable(s)
Does this study show cause-and-effect?
Explain if this is a controlled experiment
Free Radical Shift: Antioxidants may not increase life span
The antioxidant theory of aging states that some of the oxygen molecules used by the body become negatively
charged, making them reactive. As a result, they compromise health and age the body by damaging cell
structures, proteins and DNA. Cells have a natural defense—superoxide dismutase (SOD), a special class of
antioxidant that neutralizes the chemicals and prevents them from harming cells. According to the theory,
proposed in 1956 by Denham Harman, now emeritus professor of medicine at the University of Nebraska, when
the body gets older, SODs become less efficient at preventing oxidative stress. Over the past 50 years this widely
accepted theory has held up in studies: when the SOD gene is knocked out in mice, flies or yeast, the organisms
develop cancers and have shorter life spans.
But in the February PLoS Genetics, Siegfried Hekimi and Jeremy M. Van Raamsdonk, both at McGill University,
report that removing SODs from tiny Caenorhabditis elegans soil worms has the exact opposite effect—they live
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longer. In the experiment, each of the worms’ five SOD genes, which primarily work in the mitochondria (the
cells’ energy-producing organelles), was disabled in different combinations, hampering the worms’ ability to
make the antioxidant. When the researchers turned off one SOD gene (namely, sod-2), the nematodes actually
lived 30 percent longer. When four were disabled in follow-up work, the worms still had a normal life span.
Hekimi believes that the findings throw a wrench in the entire free radical theory of aging. Instead he claims
that cell damage is a product of aging, not the actual cause. “It’s like the sun coming up every morning—they
can’t prove that it will,” he says in reference to free radical proponents. “But I have to prove that it won’t.”
These modified worms are not healthy, though; they show evidence of oxidative stress. Without the
antioxidants, their cells are left unprotected, and outside the lab the worms would have died from disease or
cancer. But Hekimi separates such a condition from having a normal life span. The organism may be sicker, he
observes, but it is living longer.
Other scientists doubt that the findings discredit free radicals entirely. “You can’t take a single paper studying a
single gene in a single organism and make sweeping conclusions about a theory,” remarks John Phillips of the
University of Guelph in Ontario, who has examined SODs in the fruit fly Drosophila melanogaster. Moreover,
C. elegans has five SOD genes, whereas humans have two. “I think we need to know where the extra SODs are
operating, like in tissues or muscles, and in which cellular compartments” to fully understand oxygen
metabolism in C. elegans, Phillips says. Knowing the biological idiosyncrasies in the worm would elucidate
how SODs work in general.
Hekimi proposes that his findings could bolster an alternative aging theory—specifically, the idea that a slower
metabolism or lower temperatures decelerate the body and allow an organism to live longer. Several studies
have challenged the rate of living theory of aging, but Hekimi thinks that “you have to take a broader version of
the theory, that the rate at which things happen affects life span.” As he sees it, in SOD-deficient worms, free
radicals damage the mitochondria, which produce less energy and thereby slow the organism down.
42) Homeostasis is the process by which organisms keep their internal environment the same. For instance,
sweating is one such process that keeps the temperature of our bodies at a constant 98.6 degrees Farenheit.
Based on your knowledge of enzymes, why is it important that living organisms maintain "homeostasis"?
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Answer Key
Testname: 1408 T2SUMMER
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A
E
B
B
A
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D
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B
B
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C
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E
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