53. During splicing, which molecular component of the spliceosome catalyzes the excision reaction?
(A) protein
(B) DNA
(C) RNA
(D) lipid
(E) sugar

49. In flowering plant, which one of the following is true characteristic of the gametophyte stage? (A) It is the obvious stage such as an oak tree. (B) Megasporangium (C) Seed embryo (D) Gamete producing (E) Diploid

50. In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein? (A) ligase (B) RNA polymerase I (C) RNA polymerase II (D) RNA polymerase III (E) primase

Ⅱ.【單選題】51-75 題，每題 2 分，共計 50 分。答錯 1 題倒扣 0.5 分，倒扣至本大題零分為止，未作答，不給分亦 不扣分。 51. In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage? (A) regulation via acetylation of histones (B) positive control mechanisms rather than negative (C) control of more than one gene in an operon (D) reliance on transcription activators (E) utilization of eukaryotic polymerases

52. A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. One of her colleagues suggested she try increased methylation of C nucleotides in a mammalian system. Which of the following results would she most likely see? (A) increased chromatin condensation (B) decreased chromatin concentration (C) abnormalities of mouse embryos (D) decreased binding of transcription factors (E) inactivation of the selected genes

54. A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates _____. (A) the blending model of genetics (B) true-breeding (C) dominance (D) a dihybrid cross (E) the mistakes made by Mendel

55. If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested? (A) anaphase (B) prophase (C) telophase (D) metaphase (E) interphase

56. Testosterone functions inside a cell by _____. (A) acting as a signal receptor that activates ion-channel proteins (B) binding with a receptor protein that enters the nucleus and activates specific genes (C) acting as a steroid signal receptor that activates ion-channel proteins (D) becoming a second messenger that inhibits adenylyl cyclase (E) coordinating a phosphorylation cascade that increases glycogen metabolism

57. Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large and complex lipids. Which cellular organelle must be involved in this condition? (A) the endoplasmic reticulum (B) the Golgi apparatus (C) the lysosome (D) mitochondria (E) membrane-bound ribosomes

58. Which of the following is an example of Batesian mimicry? (A) an insect that resembles a twig (B) a butterfly that resembles a leaf (C) a nonvenomous snake that looks like a venomous snake (D) a fawn with fur coloring that camouflages it in the forest environment (E) a snapping turtle that uses its tongue to mimic a worm, thus attracting fish

59. A patient who has a parasitic worm infection and another patient responding to an allergen such as ragweed pollen have which of the following in common? (A) an increase in cytotoxic T cell number (B) suffering from anaphylactic shock (C) risking development of an autoimmune disease (D) suffering from a decreased level of innate immunity (E) an increase in the levels of IgE