Substrate-level phosphorylation occurs _____.
- A. in glycolysis
- B. in both glycolysis and the citric acid cycle
- C. in the citric acid cycle
- D. during oxidative phosphorylation
The electron transport chain _____.
- A. is driven by ATP consumption
- B. is a series of redox reactions
- C. is a series of substitution reactions
- D. takes place in the cytoplasm of prokaryotic cells
A cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen when an athlete exhausts his or her ATP supply?
- A. Catabolic processes are activated that generate more ATP.
- B. ATP is transported into the cell from the circulatory system.
- C. Other cells take over, and the muscle cells that have used up their ATP cease to function.
- D. He or she has to sit down and rest.
New biosensors, applied like a temporary tattoo to the skin, can
alert serious athletes that they are about to "hit the wall"
and find it difficult to continue exercising. These biosensors monitor
lactate, a form of lactic acid, released in sweat during strenuous
Which of the statements below is the best explanation of why athletes would need to monitor lactate levels?
- A. During anaerobic respiration, lactate levels increase when muscles cells need more energy, however muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.
- B. During aerobic respiration, muscles cells produce too much lactate which causes a rise in the pH of the muscle cells, thus athletes must consume increased amounts of sports drinks, high in electrolytes, to buffer the pH.
- C. During anaerobic respiration, muscle cells receive too little oxygen and begin to convert lactate to pyruvate (pyruvic acid), thus athletes experience cramping and fatigue
- D. During aerobic respiration, muscle cells cannot produce enough lactate to fuel muscle cell contractions and muscles begin to cramp, thus athletic performance suffers.
Which of the listed statements describes the results of the following
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy
- A. O2 is reduced and CO2 is oxidized.
- B. CO2 is reduced and O2 is oxidized.
- C. O2 is oxidized and H2O is reduced.
- D. C6H12O6 is oxidized and O2 is reduced.
Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of _____.
- A. pyruvate
- B. acetyl-CoA
- C. NADH
- D. glucose
Which process is most directly driven by light energy?
- A. carbon fixation in the stroma
- B. creation of a pH gradient by pumping protons across the thylakoid membrane
- C. removal of electrons from chlorophyll molecules
- D. reduction of NADP+ molecules
In its mechanism, photophosphorylation is most similar to _____.
- A. the Calvin cycle
- B. oxidative phosphorylation in cellular respiration
- C. substrate-level phosphorylation in glycolysis
- D. reduction of NADP+
In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and _____.
- A. water supply to the leaves has been reduced
- B. the degraded chlorophyll changes into many other colors
- C. carotenoids and other pigments are still present in the leaves
- D. sugars are sent to most of the cells of the leaves
In a plant, the reactions that produce molecular oxygen (O2) take place in _____.
- A. neither the light reactions nor the Calvin cycle
- B. the Calvin cycle alone
- C. the light reactions and the Calvin cycle
- D. the light reactions alone
What would be the expected effect on plants if the atmospheric CO2 concentration was doubled?
- A. C4 plants would have faster growth; C3 plants would be minimally affected.
- B. C3 plants would have faster growth; C4 plants would be minimally affected.
- C. C3 plants would have faster growth; C4 plants would have slower growth.
- D. All plants would experience increased rates of photosynthesis.
Suppose a plant has a unique photosynthetic pigment and the leaves of this plant appear to be reddish yellow. What wavelengths of visible light are absorbed by this pigment?
- A. blue, green, and red
- B. green and yellow
- C. blue and violet
- D. red and yellow
Why are there several structurally different pigments in the reaction centers of photosystems?
- A. They enable the plant to absorb more photons from light energy, all of which are at the same wavelength.
- B. This arrangement enables the plant to absorb light energy of a variety of wavelengths.
- C. Excited electrons must pass through several pigments before they can be transferred to electron acceptors of the electron transport chain.
- D. They enable the reaction center to excite electrons to a higher energy level.
Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities?
- A. Cancer cells are no longer density-dependent.
- B. Cancer cells are no longer anchorage-dependent.
- C. Transformation introduces new chromosomes into cells.
- D. Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.
Motor proteins require which of the following to function in the movement of chromosomes toward the poles of the mitotic spindle?
- A. intact centromeres
- B. synthesis of cohesin
- C. ATP as an energy source
- D. a microtubule-organizing center
In eukaryotic cells, chromosomes are composed of _____.
- A. DNA and proteins
- B. DNA only
- C. DNA and phospholipids
- D. DNA and RNA
Metaphase is characterized by _____.
- A. separation of sister chromatids
- B. splitting of the centromeres
- C. cytokinesis
- D. aligning of chromosomes on the equator
MPF is a dimer consisting of _____.
- A. a growth factor and mitotic factor
- B. ATP synthetase and a protease
- C. cyclin and a cyclin-dependent kinase
- D. cyclin and tubulin
Kinetochore microtubules assist in the process of splitting centromeres by _____.
- A. creating tension by pulling toward opposite poles
- B. using motor proteins to split the centromere at specific arginine residues
- C. phosphorylating the centromere, thereby changing its conformation
- D. sliding past each other like actin filaments
The M-phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does not happen, cells would most likely be arrested in _____.
- A. prophase
- B. metaphase
- C. prometaphase
- D. telophase
Starting with a fertilized egg (zygote), a series of five cell
divisions would produce an early embryo with how many cells?
At which phase are centrioles beginning to move apart in animal
If there are 20 centromeres in a cell at anaphase, how many
chromosomes are there in each daughter cell following cytokinesis?
Taxol is an anticancer drug extracted from the Pacific yew tree. In
animal cells, Taxol disrupts microtubule formation by binding to
microtubules and accelerating their assembly from the protein
precursor, tubulin. Surprisingly, this stops mitosis. Specifically,
Taxol must affect
A) the formation of the mitotic spindle.
C) formation of the centrioles.
D) chromatid assembly.
E) the S phase of the cell cycle.
During which phase of mitosis do the chromatids become chromosomes?
Which of the following is released by platelets in the vicinity of an
C) protein kinase
Which of the following triggers the cell's passage past the G₂
checkpoint into mitosis?
C) protein kinase
For a chemotherapeutic drug to be useful for treating cancer cells,
which of the following is most desirable?
A) It is safe enough to limit all apoptosis.
B) It does not alter metabolically active cells.
C) It only attacks cells that are density dependent.
D) It interferes with cells entering G₀.
E) It interferes with rapidly dividing cells.
Which of the following does not occur during mitosis?
A) condensation of the chromosomes
B) replication of the DNA
C) separation of sister chromatids
D) spindle formation
E) separation of the spindle poles
The drug cytochalasin B blocks the function of actin. Which of the
following aspects of the cell cycle would be most disrupted by
A) spindle formation
B) spindle attachment to kinetochores
C) DNA synthesis
D) cell elongation during anaphase
E) cleavage furrow formation and cytokinesis
Which of the following are directly associated with photosystem I?
A) harvesting of light energy by ATP
B) receiving electrons from the thylakoid membrane electron transport chain
C) generation of molecular oxygen
D) extraction of hydrogen electrons from the splitting of water
E) passing electrons to the thylakoid membrane electron transport chain
In a plant cell, where are the ATP synthase complexes located?
A) thylakoid membrane only
B) plasma membrane only
C) inner mitochondrial membrane only
D) thylakoid membrane and inner mitochondrial membrane
E) thylakoid membrane and plasma membrane
Which of the following statements best describes the relationship
between photosynthesis and respiration?
A) Respiration runs the biochemical pathways of photosynthesis in reverse.
B) Photosynthesis stores energy in complex organic molecules, whereas respiration releases it.
C) Photosynthesis occurs only in plants and respiration occurs only in animals.
D) ATP molecules are produced in photosynthesis and used up in respiration.
E) Respiration is anabolic and photosynthesis is catabolic.
In photosynthetic cells, synthesis of ATP by the chemiosmotic
mechanism occurs during
A) photosynthesis only.
B) respiration only.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration only.
Carotenoids are often found in foods that are considered to have
antioxidant properties in human nutrition. What related function do
they have in plants?
A) They serve as accessory pigments to increase light absorption.
B) They protect against oxidative damage from excessive light energy.
C) They shield the sensitive chromosomes of the plant from harmful ultraviolet radiation.
D) They reflect orange light and enhance red light absorption by chlorophyll.
E) They take up and remove toxins from the groundwater.
A flask containing photosynthetic green algae and a control flask
containing water with no algae are both placed under a bank of lights,
which are set to cycle between 12 hours of light and 12 hours of dark.
The dissolved oxygen concentrations in both flasks are monitored.
Predict what the relative dissolved oxygen concentrations will be in
the flask with algae compared to the control flask.
A) The dissolved oxygen in the flask with algae will always be higher.
B) The dissolved oxygen in the flask with algae will always be lower.
C) The dissolved oxygen in the flask with algae will be higher in the light, but the same in the dark.
D) The dissolved oxygen in the flask with algae will be higher in the light, but lower in the dark.
E) The dissolved oxygen in the flask with algae will not be different from the control flask at any time.
Why are C₄ plants able to photosynthesize with no apparent
A) They do not participate in the Calvin cycle.
B) They use PEP carboxylase to initially fix CO₂.
C) They are adapted to cold, wet climates.
D) They conserve water more efficiently.
E) They exclude oxygen from their tissues.
Compared to C₃ plants, C₄ plants
A) can continue to fix CO₂ even at relatively low CO2 concentrations and high oxygen concentrations.
B) have higher rates of photorespiration.
C) do not use rubisco for carbon fixation.
D) grow better under cool, moist conditions.
E) make a four-carbon compound, oxaloacetate, which is then delivered to the citric acid cycle in mitochondria.
In mechanism, photophosphorylation is most similar to
A) substrate-level phosphorylation in glycolysis.
B) oxidative phosphorylation in cellular respiration.
C) the Calvin cycle.
D) carbon fixation.
E) reduction of NADP⁺.
Which process is most directly driven by light energy?
A) creation of a pH gradient by pumping protons across the thylakoid membrane
B) carbon fixation in the stroma
C) reduction of NADP⁺ molecules
D) removal of electrons from chlorophyll molecules
E) ATP synthesis
When electrons move closer to a more electronegative atom, what
A) The more electronegative atom is reduced, and energy is released.
B) The more electronegative atom is reduced, and energy is consumed.
C) The more electronegative atom is oxidized, and energy is consumed.
D) The more electronegative atom is oxidized, and energy is released.
E) The more electronegative atom is reduced, and entropy decreases.
When a molecule of NAD⁺ (nicotinamide adenine dinucleotide) gains a
hydrogen atom (not a proton), the molecule becomes
The free energy for the oxidation of glucose to CO₂ and water is -686
kcal/mol and the free energy for the reduction of NAD⁺ to NADH is +53
kcal/mol. Why are only two molecules of NADH formed during glycolysis
when it appears that as many as a dozen could be formed?
A) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis.
B) Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat.
C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
D) There is no CO₂ or water produced as products of glycolysis.
E) Glycolysis consists of many enzymatic reactions, each of which extracts some energy from the glucose molecule.
Starting with one molecule of glucose, the energy-containing products
of glycolysis are
A) 2 NAD⁺, 2 pyruvate, and 2 ATP.
B) 2 NADH, 2 pyruvate, and 2 ATP.
C) 2 FADH₂, 2 pyruvate, and 4 ATP.
D) 6 CO₂, 2 ATP, and 2 pyruvate.
E) 6 CO₂, 30 ATP, and 2 pyruvate.
In glycolysis, for each molecule of glucose oxidized to pyruvate
A) two molecules of ATP are used and two molecules of ATP are produced.
B) two molecules of ATP are used and four molecules of ATP are produced.
C) four molecules of ATP are used and two molecules of ATP are produced.
D) two molecules of ATP are used and six molecules of ATP are produced.
E) six molecules of ATP are used and six molecules of ATP are produced.
During aerobic respiration, H₂O is formed. Where does the oxygen atom
for the formation of the water come from?
A) carbon dioxide (CO₂)
B) glucose (C₆H₁₂O₆)
C) molecular oxygen (O₂)
D) pyruvate (C₃H₃O₃-)
E) lactate (C₃H₅O₃-)
The synthesis of ATP by oxidative phosphorylation, using the energy
released by movement of protons across the membrane down their
electrochemical gradient, is an example of
A) active transport.
B) an endergonic reaction coupled to an exergonic reaction.
C) a reaction with a positive ΔG .
E) allosteric regulation.
Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in
A) all cells, but only in the presence of oxygen.
B) only eukaryotic cells, in the presence of oxygen.
C) only in mitochondria, using either oxygen or other electron acceptors.
D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors.
E) all cells, in the absence of respiration.
In the presence of oxygen, the three-carbon compound pyruvate can be
catabolized in the citric acid cycle. First, however, the pyruvate (1)
loses a carbon, which is given off as a molecule of CO₂, (2) is
oxidized to form a two-carbon compound called acetate, and (3) is
bonded to coenzyme A.
These three steps result in the formation of
A) acetyl CoA, O₂, and ATP.
B) acetyl CoA, FADH₂, and CO₂.
C) acetyl CoA, FAD, H₂, and CO₂.
D) acetyl CoA, NADH, H⁺, and CO₂.
E) acetyl CoA, NAD⁺, ATP, and CO₂.