44. 'When nutrients are supplied to a cell, the last fluid through which they must pass before encountering the plasma membrane is the
(A) plasma.
(B) interstitial fluid.
(C) blood.
(D) intracellular fluid.
(E) cerebrospinal fluid.

40. 'Which of the following mechanisms for osmoregulation or nitrogen removal is INCORRECTLY paired with its corresponding animal? (A) metanephridium-earthworm. (B) Malpighian tubule-insect. (C) kidney-frog. (D) flame bulb-snake. (E) direct cellular exchange-marine invertebrate.

41. 'Which of the following respiratory systems is not closely associated with a blood supply? (A) vertebrate lungs. (B) fish gills. (C) tracheal systems of insects. (D) the outer skin of an earthworm. (E) the parapodia of a polychaete worm.

42. Where do air-breathing insects carry out gas exchange? (A) in specialized external gills. (B) in specialized internal gills. (C) in the alveoli of their lungs. (D) across the membranes of cells. (E) across the thin cuticular exoskeleton.

43. A mutation results in a cell that no longer produces a normal protein kinase for the M phase checkpoint. Which of the following would likely be the immediate result of this mutation? (A) The cell would prematurely enter anaphase. (B) The cell would never leave metaphase. (C) The cell would never enter metaphase. (D) The cell would never enter prophase. (E) The cell would undergo normal mitosis, but fail to enter the next G1 phase.

45. During meiosis ll, (A) cytokinesis results in the formation of a total of two cells. (B) sister chrorriatids of each chromosome are separated from each other. (C) homologous chromosomes pair up. (D) homologous chromosomes separate. (E) sister chromatids exchange parts.

46. Which of these is NOT found in the epidermis? (A) stratified epithelium.(B) blood vessels.(C) tight cell junctions. (D) keratin.  (E) melanin.

47. The first vertebrates are most closely related phylogenetically to which of the following phyla? (A) Echinodermata. (B) Annelida. (C) Mollusca. (D) Arthropoda. (E) None of these.

48. The classic Hershey and Chase (1952) experiment which offered evidence in support of DNA being the genetic material in bacteriophage made use of which of the following labeled components? (A) phosphorus and sulfur. (B) phosphorus and nitrogen. (C) phosphorus and oxygen. (D) nitrogen and oxygen. (E) nitrogen and sulfur.

49. Which of the following terms best characterizes catabolite repression associated with the lactose operon in E. coli? (A) inducible system. (B) repressible system. (C) negative control. (D) positive control. (E) constitutive.

50. Developmental similarities observed in most vertebrates are probably due to (A) chance. (B) the similar environments in which they live. (C) homeoboxes. (D) their phylogenetic histories. (E) homeoboxes and their phylogenetic histories.