Phosphofructokinase (PFK) is an enzyme that converts fructose 6-phosphate to fructose 1,6-bisphosphate, by adding a phosphate group. This is the first committed step of the metabolic pathway of glycolysis, and thus it is very tightly regulated. AMP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and stimulates the formation of fructose 1,6-bisphosphate. ATP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and inhibits the formation of fructose 1,6-bisphosphate. There are other regulators of this enzyme as well. What is the role of AMP in this example?
A. Catalyst
B. Noncompetitive inhibitor
C. Allosteric inhibitor
D. Competitive inhibitor
E. Allosteric activator
Answer: E
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The daughter nuclei produced by meiosis are
(a) genetically identical. (b) diploid. (c) haploid. (d) both a and b.
Although it is too simple an explanation, the concept of a key fitting into a lock is descriptive of the:
a. inhibition of enzymes by small molecules b. fit of coenzymes to enzymes c. matching of enzyme with substrate d. regeneration of ATP from ADP e. stepwise cascade of electrons in the oxidation-reduction reactions
The landscape can be thought of as a shifting mosaic of habitat patches, each in a phase of successional development
Indicate whether the statement is true or false
The deer, rabbit, grasshopper, and caterpillar are classified as the primary, or first-level, consumers in this ecosystem. What evidence from the food web supports this statement?
a) they feed on producers b) they compete with the carnivores for food c) they are eaten by other organisms in the food web d) they are prey for the herbivores in the food web