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.

11. Phylogenetic trees are best described as (A) true and inerrant statements about evolutionary relationships. (B) the most accurate representations possible of genetic relationships among taxa. (C) theories of evolution. (D) hypothetical portrayals of evolutionary relationships. (E) the closest things to absolute certainty that modern systematics can produce.

12. Estimates of the number of species present in a community (A) are not affected by the sampling effort devoted to estimation. (B) usually require only limited effort by ecologists. (C) can usually be made more easily by sampling only a single indicator taxon. (D) are all that is necessary to calculate species diversity. (E) must, to be useful, be based on standardized sampling techniques.

13. A major perturbation of the carbon cycle by human activity is associated with (A) release of carbon from carbonate rocks. (B) release of carbon from fossil fuel deposits. (C) removal of carbon from the atmosphere in the industrial production of fertilizers. (D) accelerated removal of carbon from the atmosphere by forests. (E) respiratory production of CO2 by the large human population.

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.

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.

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

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.