Topic 6, 7, 8
A typical eukaryotic cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen to an individual when they exhaust their ATP supply?
Catabolic processes will be activated to generate additional ATP.
Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. Which of the following best explains the association between malignant tumors and chromosomal abnormalities?
Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.
If an animal cell suddenly loses the ability to produce GTP, what will most likely happen to its signaling system?
It will not be able to activate G proteins on the cytoplasmic side of the plasma membrane.
Progression beyond the G2 checkpoint into mitosis is triggered by which of the following molecules?
MPF
The standard free energy for the complete oxidation of glucose to CO2 and water is -686 kcal/mol, and the standard free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Which of the following statements best explains why only two molecules of NADH are formed in glycolysis when up to 12 molecules could theoretically be produced?
Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
Depletion of which of the following molecules from the mitochondria will most directly inhibit the citric acid cycle?
NAD+
Which of the following statements best describes a characteristic of NAD+?
NAD+ is reduced to NADH in glycolysis, pyruvate oxidation, and the citric acid cycle.
Which of the following statements best explains why testosterone, a lipid-soluble signaling molecule that crosses the membranes of all cells, affects only target cells?
Only target cells contain the intracellular receptors for testosterone.
Which of the following statements best describes the relationship between the wavelength of light and the quantity of energy per photon?
They are inversely related.
The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. About 10% of Springer spaniels suffer from canine PFK deficiency. Dogs affected with this disorder most likely display which of the following symptoms?
They are lethargic and readily tire from exercise.
Amount of DNA per nucleus over the cell division cycle.Which region of the accompanying figure represents S phase?
2
Glycolysis results in the net production of which of the following sets of molecules per glucose molecule?
2 NADH, 2 pyruvate, and 2 ATP
A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 10 picograms of DNA per nucleus. Approximately how many picograms of DNA would be found in a nucleus at prophase of mitosis?
20
Which of the sequences below best describes the sequential steps (numbered 1-5) in a signal transduction pathway that utilizes a G protein-coupled receptor? 1.The signal-receptor complex activates a G protein. 2.Protein kinases are activated. 3.A signal molecule binds to a receptor. 4.Target proteins are phosphorylated. 5.cAMP is produced.
3, 1, 5, 2, 4
Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?
30-32
For each glucose molecule (C6H12O6) oxidized by cellular respiration, how many molecules of CO2 are released in the citric acid cycle (see the accompanying figure)?
4
A loss of function of Apaf1, the human homologue of ced-4 in nematodes, is most likely to result in which of the following?
a form of cancer in which normal apoptosis fails
Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely ________.
a plant cell in the process of cytokinesis
Which of the following is one of the molecules formed by the removal of a carboxyl group (as CO2) from a molecule of pyruvate?
acetyl CoA
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location than the active site. This is an example of which of the following?
allosteric regulation
Which of the following processes is driven by the free energy released as electrons move through photosystem II and I in the thylakoid membranes?
establishment of a proton gradient
Which of the following metabolic processes take place in the cytosol of a eukaryotic cell?
glycolysis and fermentation
Lipid-soluble signaling molecules, such as aldosterone, cross the membranes of all cells but affect only target cells because ________.
intracellular receptors are present only in target cells
In mechanism, photophosphorylation is most similar to ________.
oxidative phosphorylation in cellular respiration
The mechanism of photophosphorylation is most similar to which of the following processes?
oxidative phosphorylation in cellular respiration
When a glucose molecule loses a hydrogen atom in an oxidation-reduction reaction, the glucose molecule is _______
oxidized
A type of localized signaling in which a cell secretes a signal molecule that affects neighboring cells is best described as which of the following?
paracrine signaling
ATP is synthesized in plant cells by chemiosmosis in which of the following processes?
photosynthesis and cellular respiration
In which of the following organisms did the process of photosynthesis most likely originate?
prokaryotes
Which of the following events takes place in the electron transport chain?
the harnessing of energy from redox reactions to generate a proton gradient
In a plant, which of the following reactions produces molecular oxygen (O2)?
the light reactions alone
Which of the following statements best describes the electron transport chain?
It consists of a series of redox reactions.
In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the net production of which of the following sets of molecules?
ATP, CO2, and ethanol
which of the following statements best describes the mechanism by which the ced-9 protein in the nematode C. elegans prevents apoptosis in normal cells?
Active ced-9 prevents activation of the caspase activity of ced-3.
Which of the following statements about steroid hormones is true?
Steroid hormones bind to specific receptor proteins and the complex acts as a gene activator.
Which of the following statements best describes the conditions under which the Calvin cycle and cellular respiration occur in plants?
The Calvin cycle and cellular respiration both occur in the dark and the light.
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol prevents microtubule depolymerization, which interferes with which of the following processes?
chromosome separation
The drug cytochalasin B blocks the polymerization of actin microfilaments. Which of the following events of the cell cycle in animal cells would be most directly disrupted by cytochalasin B?
cleavage furrow formation and cytokinesis
Binding of epinephrine to its receptor results in which of the following events?
Elevation of cytosolic concentrations of cyclic AMP.
Which of the following statements is a correct distinction between autotrophs and heterotrophs?
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.
Some cases of human melanoma have been shown to result from inhibition of apoptosis in these cells. The human analogue of which of the following defects in C. elegans could cause these cancers?
A ced-3 protein that is always inactive.
A mutation that disrupts cyclic electron flow in the light reactions of photosynthesis will specifically reduce the production of which of the following molecules?
ATP
The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis and is inhibited by high levels of which of the following molecules?
ATP and citrate
Which of the following structures or molecules is required in order for motor proteins to facilitate movement of chromosomes toward the poles in mitosis?
ATP as an energy source
which of the following statements best describes density-dependent inhibition?
As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells, and they signal each other to stop dividing.
Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in ________.
G1
Which of the following observations suggests that a second messenger is required for the activation of glycogen phosphorylase by epinephrine?
Glycogen breakdown occurs only when epinephrine is administered to intact cells.
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the ________.
H+ concentration gradient across the membrane holding ATPsynthase
Amount of DNA per nucleus over the cell division cycle.G1 is represented by which numbered part(s) of the cell division cycle in the accompanying figure?
I and V
Energy released from the electron transport chain is used to pump H+ ions into which location in eukaryotic cells? Group of answer choices
Iintermembrane space
Which of the following statements best describes how a reducing agent is chemically altered in a biological redox reaction?
It loses a hydrogen atom and loses potential energy.
Upon completion of the citric acid cycle, most of the energy originally stored in each glucose molecule catabolized by cellular respiration is stored in which of the following molecules?
NADH
Which of the following products result from the oxidation of pyruvate to acetyl-CoA?
NADH and CO2
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is ________.
O2
If pyruvate oxidation is blocked, what is the most likely effect on the levels of oxaloacetate and citrate in the citric acid cycle shown in the accompanying figure?
Oxaloacetate will accumulate and citrate will decrease.
Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal to form small vesicles that contain the intermembrane space. These vesicles can transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements best describes what will happen to the vesicles when NADH is added?
The inside of the vesicles will become acidic.
Which of the following events are associated with chemiosmosis in chloroplasts?
The pH of the cytosol outside the chloroplast decreases and ATP is synthesized.
Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. Which of the following statements best describes a related function they serve in plants?
They protect against oxidative damage from excessive light energy.
Which of the following statements describes a primary benefit of having photosystem reaction centers composed of several structurally different pigments?
This arrangement enables the plant to absorb light energy of a variety of wavelengths.
Lab students placed ten spinach leaf disks in each of three test tubes containing a baking soda solution and a control tube without baking soda. The volume of liquid in each tube and the temperature of the solutions were held constant. All tubes were placed an equal distance from a light source as indicated in the accompanying table. After 10 minutes, the amount of oxygen present in each sample was measured. Which tube is expected to contain the greatest quantity of oxygen?
Tube 3
Which of the following responses is stimulated by cell signaling the formation of biofilms?
aggregation of bacteria
Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal "inside out" to form small vesicles. The fact that these vesicles can transfer electrons from NADH to oxygen and synthesize ATP suggests that which of the following components must be present?
all of the electron transport system and ATP synthase
Which of the following types of metabolic poison would most directly interfere with glycolysis?
an agent that closely mimics the structure of glucose but is not metabolized
Consider the following pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP Which of the following molecules serves as the second messenger in this pathway?
cAMP
Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger.
cAMP
Which of the following occurs during the Calvin cycle?
carbon fixation
The synthesis of ATP by oxidative phosphorylation is an example of which of the following processes?
coupling of an endergonic reaction to an exergonic reaction
Researchers discovered that carbon fixation in spinach leaves utilizes 45,000 molecules of ATP and 30,000 molecules of NADPH in an hour. The deficit in ATP required for carbon fixation is most directly made up for by which of the following processes?
cyclic electron flow
The activation of receptor tyrosine kinases is characterized by ________.
dimerization and phosphorylation
Catabolism of fatty acids produces two-carbon molecules that are converted to acetyl CoA. The acetyl CoA molecules will most likely be metabolized in aerobic cellular respiration by which of the following mechanisms?
directly entering the citric acid cycle
In chemiosmosis, the most direct source of energy used to convert ADP + i to ATP is energy released ________.
from movement of protons through ATP synthase, down their electrochemical gradient
Which of the following sequences describes the path by which electrons move from high-energy to lower-energy molecules in aerobic respiration?
glucose → NADH → electron transport chain → oxygen
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?
glycolysis
Which of the following metabolic processes normally occurs in most cells regardless of oxygen (O2) availability?
glycolysis
In which reactions of cellular respiration does substrate-level phosphorylation occur?
in both glycolysis and the citric acid cycle
At what stage of the cell cycle is the cyclin component of MPF destroyed?
in late M
If the proteins of the electron transport chain were labeled with a fluorescent tag, the fluorescence observed by microscopy will be localized to which of the following regions of the mitochondria?
inner membrane
Which of the following statements best would best explain the inability of an animal cell to reduce the Ca2+ concentration in its cytosol?
insufficient amounts of ATP are present in the cytosol.
Besides the ability of some cancer cells to over proliferate, which of the following situations is most likely to result in a tumor?
lack of appropriate cell death
Which of the following statements best describes scaffolding proteins?
large molecules that increase the signal transduction efficiency by grouping together different proteins involved in the same pathway
If all chromosomes are not attached to the mitotic spindle at the M phase checkpoint, the cells would most likely be arrested at which of the following points in the cell division cycle or mitosis?
metaphase
Energy released from the electron transport chain is used to pump H+ ions into which location in eukaryotic cells?
mitochondrial intermembrane space
Assume that it is possible to label each of the molecules below with 18O a heavy isotope of oxygen. As a result of cellular respiration, water containing 18O would most quickly be detected if cells are provided with which one of the following molecules labeled with 18O?
molecular oxygen (O2)
The unlettered circle at the top of the accompanying figure shows a diploid nucleus with four chromosomes that have not yet replicated. The circles labeled 1 to 5 show various combinations of these chromosomes. Which chromosomal configuration would be observed in one daughter cell after telophase of mitosis?
not 2
Which of the following processes is most directly driven by light energy? Group of answer choices
oxidation of chlorophyll pigment molecules
In liver cells, the inner mitochondrial membranes contain about five times the surface area of the outer mitochondrial membranes, which allows for increased rates of which process below?
oxidative phosphorylation
Which of the following processes is driven by chemiosmosis?
oxidative phosphorylation
What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+
pyruvate
Activation of which of the following molecules generally requires protein phosphorylation?
receptor tyrosine kinases
Which of the following signal transduction proteins typically functions by forming dimers after binding to a signal molecule?
receptor tyrosine kinases
When electrons are passed from one atom to a more electronegative atom, the more electronegative atom is ________.
reduced, and energy is released
A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. In which of the following forms did the lost fat most likely leave the body?
released as CO2 and H2O.
Students in a biology lab isolated cells in various phases of the cell cycle. A population of cells that have 1 1/2 times the DNA of G1 phase cells was most likely isolated from which of the following parts of the cell cycle?
s phase
Paper chromatography is a technique used to separate molecules based upon their polarity. If pigments from oak leaves are extracted and subjected to paper chromatography, which of the following statements best describes the pigment bands that would be observed?
several bands that appear green, yellow, or orange
Movement of the chromosomes during anaphase would be most directly affected by a drug that prevents which of the following events?
shortening of microtubules
After DNA replication, each duplicated chromosome consists of two of which of the following structures?
sister chromatids
Which of the following reactions produces the majority of the CO2 released by the complete oxidation of glucose?
the citric acid cycle
FtsZ is a bacterial protein that forms a contractile ring involved in binary fission. Its function is likely analogous to which of the following structures in eukaryotic cells?
the cleavage furrow of eukaryotic animal cells
The decline of MPF activity at the end of mitosis is due to ________.
the degradation of cyclin
When a cell is deprived of oxygen, which of the following processes will be inhibited?
the electron transport chain
