Cell Membrane Transport
Which of these is active transport?
a) Facilitated Diffusion
b) Exocytosis
c) Osmosis
d) Moving small nonpolar particles towards their concentration gradient.
b) Exocytosis
Catalysts are essential to allowing many reactions to occur.
What happens to a catalyst in a reaction?
a. It is incorporated into the products.
b. It is incorporated into the reactants.
c. It is unchanged.
d. It evaporates away.
c. It is unchanged.
What is required to go through aerobic cellular respiration?
Oxygen
If something is reduced, it _____ electrons.
a) gains
b) loses
Gains.
An exergonic (spontaneous) reaction is a chemical reaction that __________.
a) releases energy when proceeding in the forward direction
b) is common in anabolic pathways
c) cannot occur outside of a living cell
d) occurs only when an enzyme or other catalyst is present
e) leads to a decrease in the entropy of the universe
a) releases energy when proceeding in the forward direction
Which of the following is FALSE in regard to facilitated diffusion?
a) Facilitated diffusion requires a concentration gradient.
b) Facilitated diffusion can occur by means of transport proteins.
c) Facilitated diffusion can occur through protein channels.
d) Facilitated diffusion requires the hydrolysis of ATP.
e) Facilitated diffusion can move ions across membranes.
d) Facilitated diffusion requires the hydrolysis of ATP.
The inhibition of enzyme activity by allosteric repressors can be reduced:
a) By a decrease in the concentration of substrate.
b) By an unbinding of the repressors.
c) By an increase in the concentration of substrate.
d) By a decrease in the concentration of allosteric enzymes.
e) By an increase in the concentration of a competitive inhibitor.
b) By an unbinding off the repressors.
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
A) oxidation of glucose and other organic compounds.
B) Flow of electrons down the electron transport chain.
C) H+ concentration gradient across the membrane holding ATP synthase.
D) Transfer of phosphate to ADP.
C) H+ concentration gradient across the membrane holding ATP synthase.
Which of these statements about enzyme inhibitors is true?
A) A noncompetitive inhibitor does not change the shape of the active site.
B) A competitive inhibitor binds to the enzyme at a place that is separate from the active site.
C) When the product of an enzyme or an enzyme sequence acts as its inhibitor, this is known as positive feedback.
D) Inhibition of enzyme function by compounds that are not substrates is something that only occurs under controlled conditions in the laboratory.
E) The action of competitive inhibitors may be reversible or irreversible.
E) The action of competitive inhibitors may be reversible or irreversible.
Which of the following enables a cell to pick up and concentrate a specific kind of molecule?
a) passive transport
b) facilitated diffusion
c) receptor-mediated endocytosis
d) channel proteins
e) osmosis
c) receptor-mediated endocytosis
This type of solution causes a cell to swell.
A) Hypertonic
B) Isotonic
C) Hypotonic
Hypotonic solution.
Explain how anabolism and catabolism are linked.
Some of the energy released from a catabolic reaction goes to the anabolic reaction, allowing it to occur.
What is the final electron acceptor in the cellular respiration process?
Oxygen.
1.What is the difference between carrier proteins and channel proteins?
a. Carrier proteins change shape when a specific molecule binds to move it across the membrane while channel proteins provide corridors for specific molecules to pass through.
b. Channel proteins change shape when a specific molecule binds to move it across the membrane while carrier proteins provide corridors for specific molecules to pass through.
c. Carrier proteins assist molecules via diffusion.
d. Channel proteins are attracted to glycolipids and carrier proteins change shape slightly when a specific molecule binds to help.
a. Carrier proteins change shape when a specific molecule binds to move it across the membrane while channel proteins provide corridors for specific molecules to pass through.
A single plant cell is placed in an isotonic solution. Salt is then added to the solution. Which of the following would occur as a result of the salt addition?
A) The added salt would enter the cell, causing the cell to take up water and swell.
B) There would be no osmotic movement of water in response to the added salt.
C) Water would leave the cell by osmosis, causing the volume of the cytoplasm to decrease.
D) The added salt makes the solution hypotonic compared to the cell. Water will enter the cell by osmosis.
E) Water would enter the cell by osmosis, and the cell would swell.
C) Water would leave the cell by osmosis, causing the volume of the cytoplasm to decrease.
Which of the following molecules is most likely to passively diffuse across the plasma membrane?
A) hemoglobin
B) carbon dioxide
C) DNA
D) glucose
E) sodium ion
B) Carbon dioxide
What factors affect the rate of diffusion of a substance?
1) Diameter of molecules
2) Temperature
3) Concentration gradient
Name an organism that goes through aerobic respiration, alcohol fermentation, and lactic acid fermentation.
1) Many (name one)
2) Yeast
3) Bacteria
In glycolysis in the absence of oxygen, cells need a way to regenerate which compound?
A) carbon dioxide
B) NAD+
C) ethanol
D) glucose
E) lactate
B) NAD+
In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the production of which of the following sets of molecules?
A) ATP, CO2, and acetyl CoA
B) ATP, NADH, and ethanol
C) ATP, CO2 and ethanol
D) ATP, CO2, and lactate
C) ATP, CO2 and ethanol
Put these in the correct order:
Na+ binding stimulates phosphorylation by ATP
Na+ from the cytoplasm binds to the sodium-potassium pump
Loss of the phosphate group restores the protein's original shape, decreasing affinity for K+
K+ is released; affinity for Na+ is high again, and the cycle repeats.
The new shape has a high affinity for K+, which binds on the extracellular side and triggers release of the phosphate group.
Phosphorylation leads to a change in protein shape, reducing its affinity for Na+, which is released outside.
1) Na+ from the cytoplasm binds to the sodium-potassium pump
2) Na+ binding stimulates phosphorylation by ATP
3) Phosphorylation leads to a change in protein shape, reducing its affinity for Na+, which is released outside.
4) The new shape has a high affinity for K+, which binds on the extracellular side and triggers release of the phosphate group.
5) Loss of the phosphate group restores the protein's original shape, decreasing affinity for K+
6) K+ is released; affinity for Na+ is high again, and the cycle repeats.
A plot of reaction rate (velocity) against temperature for an enzyme indicates little activity at 10°C and 45°C, with peak activity at 35°C. The most reasonable explanation for the low velocity at 10°C is that __________.
A) the hydrogen bonds that define the structure of the enzyme's active site are unstable
B) the enzyme was denatured
C) the cofactors required by the enzyme system lack the thermal energy required to activate the enzyme
D) the substrate becomes a competitive inhibitor at lower temperature
E) there is too little activation energy available
E) there is too little activation energy available
Which of the following events accompanies the conversion of pyruvate to acetyl CoA before the citric acid cycle?
A) formation of CO2 and synthesis of ATP
B) removal of coenzyme A
C) regeneration of NAD+
D) release of CO2 and synthesis of NADH
E) release of CO2 and release of coenzyme A
D) release of CO2 and synthesis of NADH
If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to
A) add more of the enzyme
B) heat the solution to 90 degree C
C) add more substrate
D) add a noncompetitive inhibitor
A) add more of the enzyme
If muscle cells in the human body consume O2 faster than it can be supplied, which of the following is likely to result?
A) The muscle cells will have more trouble making enough ATP to meet their energy requirements.
B) The cells will not be able to carry out oxidative phosphorylation.
C) The cells will consume glucose at an increased rate.
D) Only the first two answers are correct.
E) The first three answers are correct.
E) The first three answers are correct.