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.

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.

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.

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.

57. The Genetic Code is almost universal, that is, it is the same in all living systems. What is the exception? (A) fungi (B) virus (C) plants (D) prokaryotes (E) mitochondria

58. The direct energy source that drives ATP synthesis during oxidative phosphorylation is (A) the oxidation of glucose and other organic compounds. (B) the endergonic flow of electrons down the electron transport chain. (C) the affinity of oxygen for electrons. (D) a difference of H+ concentration on opposite sides of the inner mitochondrial membrane. (E) the transfer of phosphate from Krebs cycle intermediates to ATP.

59. Which of the following statements is a correct distinction between autotrophs and heterotrophs? (A) Only heterotrophs need to acquire chemical compounds from the environment. (B) Cellular respiration is unique to heterotrophs. (C) Only heterotrophs have mitochondria. (D) Autotrophs, but not heterotrophs, can nourish themselves beginning with nutrients that are entirely inorganic. (E) Only heterotrophs require oxygen.