44. Green algae differ from land plants in that many green algae_______.
(A) have alternation of generations
(B) have plastids
(C) are unicellular
(D) have cell walls containing cellulose

40. The chemical structure of prostaglandins is derived from______. (A) oligosaccharides (B) fatty acids (C)steroids (D) amino acids

41. It is important for pregnant women to consume folic acid supplements because______.  (A) the fetus is not able to acquire oxygen by breathing on its own (B) the fetus stores folic acid in high quantities (C)folic acid deprivation is associated with neural tube defects in a fetus (D) folic acid deprivation is a cause of heart abnormalities in a newborn

複選題42. Consider the following reaction. Which of the following would happen if the pH of the blood was decreased?(A)the amount of carbon dioxide would increase (B)the bicarbonate concentration in the blood would increase (C)the amount of oxygen in the blood will decrease (D) the amount of protons in the blood will increase

43. In animals, the catabolism of which molecules contributes most to the production of nitrogenous wastes? (A)starch and cellulose (B) triglycerides and steroids (C) proteins and nucleic acids (D) phospholipids and glycolipids

45. Retinoic acid, a metabolite of vitamin A, plays a key role in vertebrate development, differentiation, and organogenesis. Retinoic acid normally binds to the RAR receptor to initiate changes in gene expression. Researchers have determined that one type of RAR receptor is found at high levels in muscles, but is not found at all in neurons. How can you explain these findings? (A) Muscle cells, but not neurons, contain the gene for the RAR receptor. (B) The RAR receptor gene is expressed in muscle cells but not neurons. (C) Neurons can produce retinoic acid, so they do not need RARs for development. (D) RAR transcripts are hydrolyzed by lysosomes in neurons but not in muscle cells.

46. Vertebrate immune cells, which are phagocytic, include which of the following? I neutrophils； II) macrophages； III) dendritic cells； IV) natural killer cells (A) I and III only (B) II and IV only (C) I and IV only (D) I, II, and III

47. Stem cell transplants may someday be used to treat Parkinson's disease. How could stem cell transplants alleviate the symptoms of Parkinson's disease? (A) by preventing temporal lobe seizures (B) by repairing sites of traumatic brain injury (C) by replenishing missing ion channels (D) by secreting the neurotransmitter dopamine

48. Most of the ATP supplies for a skeletal muscle undergoing prolonged exercise come from________. (A) glucose metabolized by aerobic respiration (B) glycolysis (C) tropomyosin binding to calcium (D) the transfer of a phosphate group from creatine phosphate

49. Coral reefs occur on the southeast coast of the United States, near Florida, but not at similar latitudes on the southwest coast near Los Angeles. Differences in which of the following most likely account for this? (A) air temperatures driven by precipitation (B) day length (C) water temperatures driven by ocean currents (D) marine salinity differences

50. The feeding relationships among the species in a community determine the community's__________. (A)secondary succession (B) ecological niche (C)species richness (D) trophic structure