18. Adenylyl cyclase is to cAMP as ____________ is to AMP.
(A) protein kinase C
(B) phospholipase C
(C) phosphodiesterase
(D) phosphatase
(E) Ras

14. Which statement about changing ecosystem properties during succession is FALSE? (A) Biomass increases. (B) Soil depths decrease. (C) Primary production increases. (D) Community respiration increases. (E) Stream spiraling lengths decrease.

15. The nuclear genomes of eukaryotes are composed of different categories of sequences. Repetitive sequences are one type of the categories. Which of the following is an example of highly repetitive sequences? (A) Histone gene cluster . (B) Ribosomal RNA genes. (C) Homologous genes. (D) Alu elements. (E) Multigene families.

16. If the genes of a cell's spliceosomes were mutated so the spliceosomes no longer action normally. Which of the following would occur? (A) A functional protein would be produced. (B) Transcription would stop. (C) A primary transcript would not be produced. (D) Translation would stop. (E) Intron(s) would stay in the mature mRNA. 

17. If the homeotic genes are mutated and cannot be expressed in an orchid during flower development. What would be the consequence? (A) The orchid will not develop cotyledons. (B) The orchid will die. (C) The orchid will become dwarf. (D) The orchid will develop flowers instead of leaves. (E) The orchid will develop leaves instead of flowers.

19. For cloning of genomic DNA sequences, yeast artificial chromosome (YAC) and bacterial artificial chromosome (BAC) are two popular cloning vector systems. Which of the following is NOT correct? (A) A BAC would be circular and a YAC would be linear. (B) A YAC would have telomeres and a BAC would not. (C) A YAC would have a centromere and a BAC would not. (D) A YAC would be bound to histones in the cell and a BAC would not. (E) A BAC would contain a much larger DNA insert than a YAC.

20. Which of the following processes does NOT occur in the eukaryotic nucleus? (A) RNA splicing. (B) RNA polyadenylation. (C) DNA synthesis. (D) RNA capping. (E) Production of charged tRNAs.

21. Which of the following is true of chromatin? (A) Heterochromatin has more acetyl groups on the histones. (B) Heterochromatin has fewer methyl groups on the DNA. (C) Active genes are not bound by nucleosomes. (D) Sequence-specific DNA binding proteins can only activate transcription. (E) The chromatin structure on a particular gene may be different in different cells.

22. In E. coli, biosynthesis of tryptophan can be repressed. The repressor protein of the trp operon (A) is activated by the binding of tryptophan. (B) is inactivated by the binding of tryptophan. (C) is not affected by tryptophan. (D) is activated by the binding of free tRNA. (E) is only synthesized in the presence of tryptophan.

23. The major lipids found in membranes are (A) triacylglycerols and cholesterol. (B) cholesterol and sphingomyelin. (C) phospholipids, glycolipids, and cholesterol. (D) phospholipids and free fatty acids. (E) cholesterol, inositol, and glycolipids.

24. During glycolysis NADH is produced in the cytosol. Under aerobic conditions, what is the primary fate of this NADH? (A) It accumulates in the cytosol. (B) It diffuses into the mitochondria. (C) It transfers its reducing equivalents directly to NADP+. (D) The reducing equivalents are transferred by a shuttle system to the mitochondrial electron transport system. (E) It is used to reduce glucose to sorbitol.