Chapter 5 test
The average human male uses about 8,000 grams of ATP per hour. However, the body has on hand only 50 grams at any given time. This paradox can be explained by understanding that _____.
ATP is recycled
Which statement is NOT correct in the cycling of ATP?
Because we need ATP for all cell energy needs, huge amounts of ATP are stored.
Which of the following statements regarding enzymes is true?
Enzymes increase the rate of a reaction.
When ATP releases some energy, it also releases inorganic phosphate. What purpose does this serve (if any) in the cell?
It can be added to other molecules in order to activate them.
Which of the following statements is correct about diffusion?
It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.
Why is ATP an important molecule in metabolism?
It provides energy coupling between exergonic and endergonic reactions.
What happens to the chemical energy that is extracted from molecules by cellular activities but that is not used for cellular work?
The energy contributes to the entropy of the system.
A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water, equal to the volume of blood lost, is transferred directly into one of his veins. What will be the most probable result of this transfusion?
The patient's red blood cells will swell because the blood fluid is hypotonic compared to the cells.
Of the following functions, which is most important for the glycoproteins of animal cell membranes?
a cell's ability to distinguish one type of neighboring cell from another
A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What is substance X?
a substrate
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's
activation energy.
A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. Substance A functions as
an inhibitor
Cofactors
are usually metal ions which increase enzyme activity.
When you have a severe fever, what may be a grave consequence if this is not controlled?
change in the folding of enzymes that change shape of the active site
Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n)
cofactor necessary for enzyme activity.
Which of the following types of reactions would decrease the entropy within a cell?
dehydration reactions
According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly
embedded in a lipid bilayer.
Sam, a biologist, was told by a friend that the electric power company was able to create electricity to be used in homes. Sam said that this was impossible because ____.
energy cannot be created or destroyed but only converted from one form to another form
Which of the following comparisons is NOT correct?
energy—constantly cycled back and forth through living things
Whenever energy is transformed, there is always an increase in the
entropy of the universe.
Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?
facilitated diffusion
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known a
feedback inhibition
Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment
is hypotonic to the protozoan
An organism with a cell wall would have the most difficulty doing which process?
phagocytosis
White blood cells engulf bacteria through what process?
phagocytosis
Which of the following types of molecules are the major structural components of the cell membrane?
phospholipids and proteins
When muscles contract, chemical energy is converted to mechanical energy with the loss of heat. This is an example of the ______ law of thermodynamics.
second
Each enzyme can speed up only one particular reaction. This specificity is due to the ______.
shape of both the enzyme's active site and the substrate
What kinds of molecules pass through a cell membrane most easily?
small and hydrophobic
A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because
the activation energy barrier for this reaction cannot be overcome.
When a plant cell, such as one from a rose stem, is submerged in a very hypotonic solution, what is likely to occur?
the cell will become turgid
The force driving simple diffusion is _____, while the energy source for active transport is _____.
the concentration gradient; ATP
A steer (young ox) must eat at least 100 pounds of grain to gain less than 10 pounds of muscle tissue. This illustrates
the second law of thermodynamics.
