1. Which of the following represents the most reduced form of carbon?
reduced form of carbon?
(A) R-CH3
(B) R-COOH
(C) R-CHO
(D) R-CH2OH
(E) CO2
2. The Km (Michaelis constant) of an enzyme for a substrate is defined operationally as
(A) half the substrate concentration at which
the reaction rate is maximal
(B) the substrate concentration at which the
reaction rate is half maximal
(C) the dissociation constant of the enzyme-
substrate complex
(D) the dissociation constant of the enzyme-
product complex
(E) the rate constant of the reaction at saturation
3. The reversible reaction in which dihydroxyacetone phosphate and glyceraldehyde 3-phosphate com- bine to form fructose 1,6-bisphosphate
characterized as
(A) an aldol condensation
(B) a Grignard reaction
(C) a free-radical reaction
(D) a hydrolytic reaction
(E) a zero-order reaction
4. Dinitrophenol (DNP) uncouples mitochondrial electron transport from oxidative phosphoryl-ation by
(A) dissipating the proton gradient
(B) inhibiting cytochrome oxidase
(C) dissociating the F0 and F1 units of the
ATP synthase complex
(D) binding irreversibly to ubiquinone
(E) blocking the adenine nucleotide carrier
(ATP/ADP exchanger)
5. Most of the dry mass in the trunk of a tree was originally derived from
(A) the soil
(B) light energy
(C) amino acids
(D) CO2
(E) glucose
6. Which of the following cell compartments is associated with a protein skeleton composed of lamins?
(A) Chloroplast
(B) Basement membrane
(C) Mitochondrion
(D) Nucleus
(E) Peroxisome
7. Initiation of mitogenesis by epidermal growth factor and depolarization of the membrane of a skeletal muscle cell by acetylcholine are similar
in that each
(A) involves, as an essential early step, an ion flux
across the plasma-membrane receptor of the
responding cell
(B) requires a ligand-mediated conformational
change in a plasma-membrane receptor of
the responding cell
(C) requires activation of a G protein on the
cytoplasmic face of the plasma membrane
in the responding cell
(D) is mediated by phosphorylation of the ligand
receptor in the responding cell
(E) completes its primary task by direct activation
of specific regulatory DNA sequences in the
nucleus of the responding cell
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