38. What hormone is essential for a tadpole to develop into an adult frog?
(A) growth hormone
(B) insulin
(C) calcitonin
(D)glucagons
(E) thyroxine

34. Which of the following can be used as a cloning vector? (A) E. coli (B) Eco RI (C) lambda phage (D) bacterial plasmid (E) Both C and D are correct

35. Which of the following is not true of a codon? (A) It consists of three nucleotides. (B) It may code for the amino acid as another codon does. (C) It never codes for more than one amino acid. (D) It extends from one end of a tRNA molecule. (E) It is the basic unit of the genetic code.

36. The theory that suggests that eukaryotic organelles such as mitochondria and chloroplasts may have originated from a mutualistic relationship between two prokaryotes is referred to as (A) eukaryotic symbiosis. (B) eukaryotic germ theory. (C) eukaryotic coevolution. (D) eukaryotic microevolution. (E) endosymbiotic theory.

37. What percentage of the DNA in a typical eukaryotic cell is expressed at any given time? (A) 3-5% (B) 5-20% (C) 20-40% (D) 40-60% (E) 60-90%

39. Three kinds of selection occur that cause changes in the normal distribution of phenotypes in a population. They are (A) directional selection, disruptive selection, and stabilizing selection. (B) natural selection, artificial selection, and environmental selection. (C) natural selection, genetic drift, and stabilizing selection. (D) microevolution, macroevolution and natural selection. (E) natural selection, artificial selection, and differential selection.

40. In a population that is in Hardy-Weinberg equilibrium, the frequency of the allele a is 0.2. What is the percentage of the population that is heterozygous for this allele? (A) 2 (B) 4 (C) 16 (D) 8 (E) 32

41. Yeast is a member of which division? (A) Ascomycota (B) Zygomycota (C) Basidiomycota (D) Deuteromycota (E) Chytridiomycota

42. What is the important component retain the violet dye in the Gram-positive bacteria cell wall? (A) peptidoglycan (B) lipopolysaccharide (C) phospholipids (D) fibers (E) chitin

43. Among the invertebrates, arthropods are unique in possessing (A) a notochord. (B) open circulation. (C) segmented bodies. (D) ventral nerve cords. (E) jointed appendages.

44. Important terrestrial adaptations that evolved exclusively in seed plants include all of the following except (A) pollination by wind or animal instead of fertilization by swimming sperm. (B) transport of water through vascular tissue. (C) retention of the gametophyte plant within the sporophyte. (D) dispersal of new plants by seed. (E) protection and nourishment of the embryo within the seed.