5.The best time to measure an animal's basal metabolic rate is when the animal
(A) is resting and has not eaten its first meal of the day.
(B) is resting and has just completed its first meal of the day.
(C) has recently eaten a sugar-free meal.
(D) has not consumed any water for at least 48 hours.
(E) has just completed 30 minutes of vigorous exercise.

1.Where does the Krebs cycle take place? (A) Mitochondrial matrix (B) Inner membrane of the mitochondrion (C) Outer membrane of the mitochondrion (D) Intermembrane space of the mitochondrion (E) Cytoplasm (outside the mitochondria)

2.Nitrogen fixation can occur in which of the following organisms? (A) prokaryotes (B) plants (C) animals (D) prokaryotes and plants (E) prokaryotes, plants and animals

3.The use of mRNA and reverse transcriptase is part of a strategy to solve the problem of (A) epigenetic regulation. (B) post-translational processing. (C) nucleic acid hybridization. (D) restriction fragment ligation. (E) post-transcriptional processing.

4.What is the most common transported sugar in the plant? (A) Glyceraldehyde 3-phosphate (B) Fructose (C) Mannose (D) Starch (E) Sucrose

6.When human beings choose a mate, they usually prefer people with the same skin color, same culture, same language, and similar living habits. Which of the following is related to this phenomenon? (A) panmixia (B) heterosis (C) outcrossing (D) backcrossing (E) assortative mating

7.Cytoskeleton of a eukaryotic cell is made up of (a)microtubule, (b)microfilament and (c)intermediated filaments. Which of them exhibits polarity? (A) a (B) b (C)c (D) a and b (E) b and c

8.Mitochondria are thought to be the descendants of certain alpha proteobacteria. They are, however, no longer able to lead independent lives because most genes originally present on their chromosomes have moved to the nuclear genome. Which phenomenon accounts for the movement of these genes? (A) homologous recombination (B) plasmolysis (C) horizontal gene transfer (D) conjugation (E) translation

9.What controls sex determination in American alligator? (A) Temperature (B) Behavioral interactions (C) Y Chromosome (D) Ratio of X chromosomes to autosomes (E) SRY gene

10. Why are action potentials usually conducted in only one direction along an axon? (A) The nodes of Ranvier can conduct potentials in only one direction. (B) The brief refractory period prevents reopening of voltage-gated Nat channels. (C) The axon hillock has a higher membrane potential than the terminals of the axon. (D) Ions can flow along the axon in only one direction. (E) Voltage-gated channels for both Na+ and K+ open in only one direction.

11. Which statement about biological homology is correct? (A) Paralogs: Insect wings and bat wings are both used for flight. (B) Orthologs: Humans use different MHC gene copies to identify different pathogens. (C) Analogs: The human eye is structurally similar to the octopus's eye. (D) Homologs: The needles of cacti (仙人掌) and hedgehogs (刺蝟) are used for physical defense. (E) Paralogs: Differentiation of the functions of the forelimb and hindlimb in humans.