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

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.

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.

52. Which of the following is true? (A) The leaves of both angiosperms and gymnosperms are covered by a waxy cuticle that helps to protect the leaves from desiccation. (B) Both angiosperms and gymnosperms produce ovules in a specialized structure called an ovary. (C) “Double fertilization” to produce a fertilized egg and a triploid endosperm is characteristic of both angiosperms and gymnosperms. (D) The gametophyte is the dominant generation in both the angiosperms and gymnosperms. (E) All of the statements are true.

53. Two animal species live in the same biome but on different continents. Although these two are not closely related, they may appear quite similar as a result of (A) gene flow. (B) parallel evolution. (C) convergent evolution. (D) divergent evolution. (E) allopatric speciation.

54. Suppose a mutation occurred in Drosophila in the region of DNA that codes for the protein called bicoid. What is most likely to happen during development? (A) The fertilized egg will be bipolar. (B) The embryos will express their father’s genotype. (C) The polarity of the fertilized egg will be disrupted. (D) The transcription of developmental genes will stop. (E) Two sets of limbs will form in a mirror-image arrangement.

55. What is the basis for the difference in the synthesis of the leading and lagging strands of DNA molecules? (A) The origins of replication occur only at the 5’ end of the molecule. (B) Helicases and single-strand binding proteins work at the 5’ end. (C) DNA polymerase can join new nucleotides only to the 3’ end of the growing strand. (D) DNA ligase works only in the 3’ →5’ direction. (E) Polymerase can only work on one strand at a time.

56. Which of the following statements about photosynthesis is not true? (A) Photosynthesis is a redox process in which water is oxidized and carbon dioxide is reduced. (B) There are two linked stages of photosynthesis: the light reaction and the Calvin cycle. (C) The light reaction occurs in stroma, and the Calvin cycle occurs in grana. (D) The Calvin cycle uses ATP for energy and NADPH for reducing power to form sugar from CO2. (E) The flow of electron during photosynthesis is H2O→NADPH→ Calvin cycle.