Biology 1107 Chapter 5-9 quiz
The oxygen consumed during cellular respiration is involved directly in which process or event?
accepting electrons at the end of the electron transport chain
The primary function of kinases in signal transduction is to
activate protein kinases or other relay molecules in a series.
Progression through the M phase checkpoint is stimulated by a complex that does which of the following things?
activates separase to cleave cohesin proteins
The cellular process of synthesizing large molecules from smaller ones is defined as
anabolism
At which phase of mitosis do the sister chromatids become daughter chromosomes?
anaphase
The fluid mosaic model of membrane structure suggests that membranes
are composed of protein molecules embedded in a fluid bilayer of phospholipids.
Which of the following terms describes metabolic pathways that break down complex molecules to release stored energy?
catabolic pathways
Where do the microtubules of the spindle originate during mitosis in animal cells?
centrosome
A noncompetitive inhibitor decreases the rate of an enzymatic reaction by
changing the shape of the enzyme active site.
Where does glycolysis occur in animal cells?
cytosol
A chemical reaction that has a positive ΔG is best described as
endergonic
CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they
fix CO2 into organic acids during the night when temperatures are cooler.
In mitochondria, the electron transport chain pumps protons from the matrix into the intermembrane space. In what direction are protons pumped by the electron transport chain in chloroplasts?
from the stroma to the thylakoid space
Yeast cells with defective mitochondria are incapable of cellular respiration. Catabolism of which of the following energy sources would allow these to grow?
glucose
Which of the following indicates a primary path by which electrons travel downhill energetically during aerobic respiration?
glucose → NADH → electron transport chain → oxygen
Which of the following reactions release energy?
hydrolysis reactions
Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly acquires mutations with amino acid changes that make them resistant to these competitive inhibitors. Where in the reverse transcriptase enzyme would such amino acid changes most likely occur in drug-resistant viruses?
in or near the active site
Under a particular set of conditions in the lab, the enzyme in a chemical reaction is saturated. Which of the following alterations to the reaction will increase the rate at which substrate is converted to product?
increasing the amount of enzyme in the reaction
Submerging a red blood cell in distilled water will result in
lysis of the cell.
What will be the result if a eukaryotic cell completes mitosis but does not undergo cytokinesis?
one cell with two nuclei, each identical to the nucleus of the parent cell
Which of the following metabolic pathways occur(s) in mitochondria?
oxidation of pyruvate to acetyl CoA and the citric acid cycle
When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the glucose molecule becomes
oxidized
What is the source of the energy used to generate the proton gradient across the inner mitochondrial membrane?
redox reactions in the electron transport chain
What kinds of molecules pass through a cell membrane most easily?
small hydrophobic
Which of the following reactions produces the oxygen released by photosynthesis?
splitting of water molecules
Where does the Calvin cycle take place?
stroma of the chloroplast
Which chemical process generates the ATP produced in glycolysis?
substrate-level phosphorylation
Which of the following metabolic pathways generates a proton gradient?
the electron transport chain
What is the proton-motive force?
the energy provided by a transmembrane hydrogen ion gradient
If plants are grown in the light with CO2 containing a radioactive isotope of oxygen (18O), subsequent analysis will show that 18O incorporated in organic molecules first appears in
the stroma
What is the primary function of cyclic electron flow?
to produce additional ATP
The primary function of G proteins in signal transduction is
transmitting the signal from an activated receptor to the next protein in the pathway.
The ∆G for a particular enzyme-catalyzed reaction is -20 kcal/mol. If the amount of enzyme in the reaction is doubled, what will be the ∆G for the new reaction?
-20 kcal/mol
The ∆G for a particular enzyme-catalyzed reaction is -20 kcal/mol. If the enzyme is removed, what will be the ∆G for the noncatalyzed reaction?
-20 kcal/mol
Approximately what percentage of the ATP formed by the reactions of glycolysis is produced by substrate-level phosphorylation?
100%
How many carbon atoms from one molecule of pyruvate enter the citric acid cycle?
2
Assuming glucose is the only energy source for a cell, what fraction of the carbon dioxide produced by aerobic respiration is generated by the reactions of the citric acid cycle?
2/3
A cell in G2 of the cell division cycle contains 20 chromatids. How many centromeres are present in this cell?
20
Somatic cells in elephants have 56 chromosomes. How many chromosomes would be carried by the gametes produced by elephants?
28
Which of the following molecules are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
ATP and NADPH
Which of the following statements best describes the critical role that ATP plays in cellular metabolism?
ATP serves as an energy shuttle in the cell, coupling exergonic and endergonic reactions
Density-dependent inhibition is explained by which of the following statements?
As cells become more numerous, the cell surface proteins of adjacent cells bind to each other and send signals that inhibit cell division.
Which of the following statements is representative of the second law of thermodynamics?
Cells require a constant input of energy to maintain their high level of organization
Which of the following components make(s) up eukaryotic chromatin?
DNA and proteins
Which of the following is a statement of the first law of thermodynamics?
Energy cannot be created or destroyed
Which of the following statements is a logical consequence of the second law of thermodynamics?
Every chemical reaction must increase the total entropy of the universe.
Following activation of a receptor, which sequence below represents the correct order in which components will be involved in a signaling pathway that utilizes the second messenger cAMP?
G protein → adenyl cyclase → cAMP → protein kinase
An aminoacyl-tRNA synthetase is the enzyme that catalyzes the attachment of a particular amino acid to its corresponding tRNA. This reaction requires energy from ATP. The enzyme initially binds the amino acid and ATP, but it is unable to bind the tRNA at this point. Which of the following would be a likely next step in the reaction by which the enzyme ultimately binds the tRNA and attaches the amino acid?
Hydrolysis of ATP phosphorylates the amino acid, which results in a conformational change in the active site that allows the tRNA to bind.
Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms
Which of the following statements about diffusion is correct?
It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.
In an oxidation-reduction reaction, how is the reducing agent changed?
It loses electrons and loses potential energy
Why might a severe fever result in death if it is not brought under control?
It may alter the tertiary and quaternary structures of cellular enzymes
P680+ is often considered the strongest biological oxidizing agent. Given its function, why is this necessary?
It obtains electrons from the oxygen atom in a water molecule, so it must have a greater affinity for electrons than oxygen has
Why does photorespiration decrease the efficiency of photosynthesis?
It reduces the amount of sugar produced
For a chemotherapeutic drug to be useful for treating cancer cells, which of the following characteristics is most desirable?
It targets only rapidly dividing cells.
Which of the following is the most comprehensive definition of metabolism in living organisms?
Metabolism consists of all the energy transformation reactions in an organism.
Which of the following statements about NAD+ is true?
NAD+ is reduced to NADH during glycolysis
In addition to ATP, what are the products of glycolysis?
NADH and pyruvate
ATP hydrolysis in a test tube releases only about half as much energy as ATP hydrolysis in the cell. Which of the following statements is the best explanation for this observation?
Reactant and product concentrations in the cell are different from the standard conditions used in a test tube.
Which of the following describes the result of transferring an electron from a less electronegative atom to a more electronegative atom?
The more electronegative atom is reduced, and energy is released
Based on the first law of thermodynamics, which of the following statements about a living organism is true?
The organism ultimately must obtain all of the necessary energy for life from its environment.
Which of the following statements is true for all exergonic reactions?
The reaction proceeds with a net release of free energy
What is the relationship between wavelength of light and the quantity of energy per photon?
They are inversely related
Based on the fluid mosaic model of cell membranes, which of the following statements about membrane phospholipids is true?
They can move laterally along the plane of the membrane.
Anabolic pathways share which of the following characteristics?
They consume energy to synthesize polymers from monomers.
Why are carbohydrates and fats considered high-energy foods?
They have a large number of electrons associated with hydrogen
When a cell is in late anaphase of mitosis, which of the following may be observed?
a clear area in the center of the dividing cell
Zinc, an essential trace element for most organisms, is required in the active site of the enzyme carboxypeptidase in order for the enzyme to function properly. The zinc most likely functions as a(n)
a cofactor necessary for enzyme activity
The electrochemical gradient across a membrane would generally be increased by which of the following membrane proteins?
a hydrogen ion pump
A protein that spans the phospholipid bilayer one or more times is
a transmembrane protein.