9. Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called
(A)actins
(B)tubulins
(C)cyclins
(D)cyclin-dependent kinases
(E)growth factors

5. Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of (A)ATP(B)cAMP(C)adenylyl cyclase(D)activated G proteins(E)phosphorylated proteins

6. Apoptosis involves all of the following except (A)cell-signaling pathways (B)activation of cellular enzymes (C) fragmentation of the DNA (D)digestion of cellular contents by scavenger cells (E)lysis of the cell

7. Which of the following statements about steroid receptors is false? (A)The receptors are localized in the plasma membrane. (B)The receptors undergo a conformational change after binding the steroid. (C) Once the steroid binds the receptor, the steroid/receptor complexes dimerize. (D)Steroid receptors can be transported into the nucleus. (E)Steroid receptors act as transcriptional factors, regulating the expression of certain genes.  

8. Place the following events of mitosis in the correct order. I. Sister chromatids align on the metaphase plate. II. The cleavage furrow forms. III. The nuclear membrane breaks up. IV. Sister chromatids condense.  V. Sister chromatids separate. (A)I, II, III, IV, V(B)III, IV, I, V, II(C)IV, I, III, V, II(D)III, II, I, IV, V(E)IV, III, I, V, II

10. Which of the following statements about human sexual life cycle is false? (A)Gametes are the only haploid cells. (B)Gametes cannot divide by mitosis. (C) Gametes are the only cells produced by meiosis. (D)The zygote is the only diploid cells. (E)The zygote can divide by mitosis.

11. What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? (A)There is considerable genetic variation in garden peas. (B)Recessive genes occur more frequently in the F1 generation than do dominant ones. (C) Traits are inherited in discrete units, and are not the results of "blending." (D)Genes are composed of DNA. (E)An organism that is homozygous for many recessive traits is at a disadvantage.

12. In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? (A)0(B)1/2(C)1/4(D)1/6(E)1

13. If one nondisjunction event occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis? (A)All the 4 gametes will be diploid (2n). (B)2 of the 4 gametes will be 2n, and 2 will be n. (C) 2 of the 4 gametes will be n + 1, and 2 will be n - 1. (D)2 of the 4 gametes will be n + 1 and n – 1, and 2 will be n.

14. Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells are impaired in what way? (A)They cannot replicate DNA. (B)They cannot repair thymine dimers. (C) They cannot undergo mitosis. (D)They cannot exchange DNA with other cells. (E)They do not recombine homologous chromosomes during meiosis.

15. What is a ribozyme? (A)an RNA with enzymatic activity (B)an enzyme that modifies ribosomal RNA (C) an enzyme that uses RNA as a substrate (D)an enzyme that synthesizes RNA during the transcription process (E)an enzyme that synthesizes RNA primers during DNA replication