45. Which of the following enzymes has the lowest pH optimum?
(A) lipase
(B) pepsin
(C) trypsin
(D)sucrase
(E) amylase

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.

46. Which of the following definitions of “Animal” is not true? (A) Animals are multicellular eukaryotes distinguished by a specific type of heterotrophy called ingestion. (B) In most animals, cells are successively organized into tissues, organs, and organ systems. (C) Animal cells lack cell walls and store carbohydrate reserves as starch. (D) Animal reproduction is primarily sexual; asexual budding or regeneration occurs in some species. (E) Muscles and nerves, which control active behavior, are unique to animals.

47. Transport in plants include all of the following except (A) absorption of water and minerals from the soil by cells of a root. (B) that transpiration creates a force within leaves that pulls xylem sap upward. (C) leaves exchange gases through stomata, taking in the CO2 that provides carbon for photosynthesis and expelling O2. (D) active transport of sugar from one sieve-tube to the next. (E) that potassium is uptaken by guard cells during stomatal opening.

48. A hummingbird with a beak that is too short to pollinate a flower is an example of (A) behavioral isolation. (B) temporal isolation. (C) gametic isolation. (D) mechanical isolation. (E) postzygotic isolation.

49. Antibodies of the different classes IgM, IgG, IgA, IgD and IgE differ from each other in (A) the way they are produced. (B) the type of cell that produces them. (C) the way they interact with the antigen. (D) the antigenic determinants that they recognize. (E) the number of carbohydrate subunits they have.

50. Which of the following signal transduction molecules is not bound to the plasma membrane? (A) G proteins (B) Phospholipase C (C) Adenylyl cyclase (D) Second messengers (E) Receptors for peptide hormones

51. Reabsorption of useful components of glomerular filtrate occurs in (A) Bowman’s capsule. (B) proximal convoluted tubule. (C) distal convoluted tubule. (D) collecting duct. (E) gall bladder.