18. A chemist wishes to make an organic molecule less acidic. Which of the following functional groups should be added to the molecule in order to do so?
(A) phosphate
(B) amino
(C) sulfonyl
(D) sulfhydryl
(E) carboxyl

14. Which statement about variation is true? (A) All new alleles are the result of nucleotide variability. (B) All phenotypic variation is the result of genotypic variation. (C) All genetic variation produces phenotypic variation. (D) All nucleotide variability results in neutral variation. (E) All geographic variation results from the existence of clines.

15. In a hypothetical situation, the genes for sex pilus construction and for tetracycline resistance are located together on the same plasmid within a particular bacterium. If this bacterium readily performs conjugation involving a copy of this plasmid, then the result should be ____. (A) the rapid spread of tetracycline resistance to other bacteria in that habitat. (B) the subsequent loss of tetracycline resistance from this bacterium. (C) the production of endospores among the bacterium's progeny. (D) the temporary possession by this bacterium of a completely diploid genome. (E) a transformed bacterium.

16. Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division? (A) Anaphase of mitosis (B) Prophase I of meiosis (C) Prophase II of meiosis (D) Metaphase I of meiosis (E) Anaphase I of meiosis

17. Abnormal chromosomes are frequent in malignant tumors. Errors such as translocations may place a gene in close proximity to different control regions. Which of the following might then occur to make the cancer worse? (A) Sensitivity of the immune system (B) An increase in non-disjunction (C) Expression of inappropriate gene products (D) A decrease in mitotic frequency (E) Death of the cancer cells in the tumor

19. RFLP analysis can be used to distinguish between alleles based on differences in which of the following? (A) the ability of nucleic acid probes to hybridize to the alleles (B) the proteins expressed from the alleles (C) the ability of the alleles to be replicated in bacterial cells (D) the amount of DNA amplified from the alleles during PCR (E) restriction enzyme recognition sites between the alleles

20. The volume enclosed by the plasma membrane of plant cells is often much larger than the corresponding volume in animal cells. The most reasonable explanation for this observation is that ____. (A) plant cells contain a large vacuole that increases the volume of the cell. (B) plant cells are capable of having a much higher surface-to-volume ratio than animal cells. (C) plant cells have a much more highly convoluted (folded) plasma membrane than animal cells. (D) animal cells are more spherical, while plant cells are elongated. (E) the basic functions of plant cells are very different from those of animal cells.

21. In the thylakoid membranes, what is the main role of the antenna pigment molecules? (A) concentrate photons within the stroma (B) split water and release oxygen to the reaction-center chlorophyll (C) harvest photons and transfer light energy to the reaction-center chlorophyll (D) synthesize ATP from ADP and Pi (E) transfer electrons to ferredoxin and then NADPH

22. How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cells when it was in G1 of the cell cycle? (A) The daughter cells have the same number of chromosomes and half the amount of DNA. (B) The daughter cells have the same number of chromosomes and the same amount of DNA. (C) The daughter cells have the same number of chromosomes and twice the amount of DNA. (D) The daughter cells have half the amount of cytoplasm and half the amount of DNA. (E) The daughter cells have half the number of chromosomes and half the amount of DNA.

23. What is a karyotype? (A) The combination of chromosomes found in a gamete. (B) A system of classifying cell nuclei. (C) A display of every pair of homologous chromosomes within a cell, organized according to size and shape. (D) The set of unique physical characteristics that define an individual. (E) The collection of all the mutations present within the genome of an individual.

24. What is the function of DNA polymerase III? (A) to rejoin the two DNA strands (one new and one old) after replication (B) to degrade damaged DNA molecules (C) to add nucleotides to the end of a growing DNA strand (D) to seal together the broken ends of DNA strands (E) to unwind the DNA helix during replication