5. If a newborn were accidentally given a drug that destroyed the thymus, what would most likely happen?
(A) His cells would lack class I MHC molecules on their surface.
(B) His humoral immunity would be missing.
(C) Genetic rearrangement of antigen receptors would not occur.
(D) His T cells would not mature and differentiate appropriately.
(E) His B cells would be reduced in number and antibodies would not form.

I.【單選題】1-50 題，每題 1 分，共計 50 分。答錯 1 題倒扣 0.25 分，倒扣至本大題零分為止，未作答，不給分亦不 扣分。 1. Most of the neurons in the human brain are _____. (A) sensory neurons (B) motor neurons (C) interneurons (D) auditory neurons (E) olfactory neurons

2. Contact of a sperm with signal molecules in the coat of an egg causes the sperm to undergo _____. (A) mitosis (B) depolarization (C) apoptosis (D) vitellogenesis (E) the acrosomal reaction

3. Only certain cells in the body are target cells for the steroid hormone aldosterone. Which of the following is the best explanation for why these are the only cells that respond to this hormone? (A) Only target cells are exposed to aldosterone. (B) Only target cells contain receptors for aldosterone. (C) Aldosterone is unable to enter nontarget cells. (D) Nontarget cells destroy aldosterone before it can produce its effect. (E) Nontarget cells convert aldosterone to a hormone to which they do respond.

4. Which of the following is a local regulator responsible for activating an enzyme that relaxes smooth muscle cells? (A) nitric oxide (B) prostaglandin F (C) epinephrine (D) A and B (E) A, B, and C

6. A specialized function shared by the many cells lining the lungs and the lumen of the gut is _____. (A) decreased oxygen demand due to the lack of oxygen in foods (B) increased exchange surface provided by their membranes (C) greater numbers of cell organelles contained within their cytoplasm (D) greater protection due to increased cellular mass (E) lowered basal metabolic rate due to cooperation between cells

7. What is proteomics? (A) the linkage of each gene to a particular protein (B) the study of the full protein set encoded by a genome (C) the totality of the functional possibilities of a single protein (D) the study of how amino acids are ordered in a protein (E) the study of how a single gene activates many proteins

8. What is the difference between a linkage map and a physical map? (A) For a linkage map, markers are spaced by recombination frequency, whereas for a physical map they are spaced by numbers of base pairs (bp). (B) For a physical map, the ATCG order and sequence must be achieved, but not for the linkage map. (C) For a linkage map, it is shown how each gene is linked to every other gene. (D) For a physical map, the distances must be calculable in units such as nanometers. (E) There is no difference between the two except in the type of pictorial representation.

9. What does transformation involve in bacteria? (A) the creation of a strand of DNA from an RNA molecule (B) the creation of a strand of RNA from a DNA molecule (C) the infection of cells by a phage DNA molecule (D) the type of semiconservative replication shown by DNA (E) assimilation of external DNA into a cell 

10. Males are more often affected by sex-linked traits than females because _____. (A) males are hemizygous for the X chromosome (B) male hormones such as testosterone often alter the effects of mutations on the X chromosome (C) female hormones such as estrogen often compensate for the effects of mutations on the X chromosome (D) X chromosomes in males generally have more mutations than X chromosomes in females (E) mutations on the Y chromosome often worsen the effects of X-linked mutations

11. Paracrine signaling _____. (A) involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid (B) requires nerve cells to release a neurotransmitter into the synapse (C) occurs only in paracrine yeast cells (D) has been found in plants but not animals (E) involves mating factors attaching to target cells and causing production of new paracrine cells