36. Which of the following about cardiac muscle is correct?
(A) They contract only when stimulated by neurons.
(B) They lack an orderly arranged actin and myosin.
(C) They lack the striations of skeletal muscle.
(D) They have less sacroplasmic reticulum and thus contract more slowly than smooth muscle.
(E) They are connected by intercalated discs, through which action potentials spread to all cells in the heart.

32. The following compounds function as neurotransmitters except ________. (A) acetylcholine (B) creatine (C) γ-aminobutyrate (D) 3,4-dihydroxyphenylalanine (DOPA) (E) glutamic acid

33. Which of the following about endocrine system is incorrect? (A) Testis is a part of endocrine system. (B) T3 and T4 are hormones derived from tyrosine. (C) The alpha cells of pancreas produce glucagon to increase the blood glucose level. (D) The heart is an endocrine organ because the cardiac cells produce atrial natriuretic peptide in response to high blood pressure. (E) Estrogen is a water-soluble hormone that regulates the female reproductive system and sex characteristics.

34. When electrons flow along the electron transport chain of mitochondria, which of the following changes occurs? (A) NAD+ is oxidized. (B) The pH of the matrix is increased. (C) ATP synthase pumps protons by active transport. (D) The cytochrome c of the electron transport chain phosphorylates ADP to ATP. (E) The electron donor of complex I in the chain is FADH2.

35. Which of the following is a true distinction between cellular respiration and lactate fermentation? (A) NADH is oxidized by the electron transport chain only in respiration. (B) Substrate-level phosphorylation is unique to lactate fermentation. (C) Only respiration oxidized glucose. (D) Respiration, but not lactate fermentation, is a catabolic pathway. (E) NAD+ functions as an oxidizing agent only in respiration.

37. Which of the following short-distance transport routes in plants goes through plasmodesmata? (A) symplastic route (B) transmembrane route (C) apoplastic route (D) apoptosis route (E) aquaporin route

38. In the process of photosynthesis, which of the following is not involved in the creation of H+ gradient thylakoid lumen and stroma that generates ATP? (A) reduction of NADP+ (B) splitting of water in the thylakoid lumen (C) PQ cycle of the electron transport chain and its reaction to cytochrome b6f complex (D) regeneration of RuBP (E) electron transport

39. X chromosome inactivation is an epigenetic mechanism that silences the majority of genes on one X chromosome. The inactivation appears to involve regions of . (A) mutated genes (B) intense transcription (C) hyper-methylated DNA (D) hypo-methylated DNA (E) inverted genes

40. According to the intermediate disturbance hypothesis, species richness is higher in areas of intermediate levels of disturbance. Why would species richness be lower at low levels of disturbance? (A) A high nutrient level poisons lots of species. (B) Competitive exclusion results in the extinction of species. (C) Ecological niches are less partitioned in places with high levels of disturbance. (D) Lack of disturbance slows down the evolution of new species. (E) Low level of disturbance results in low soil fertility.

41. Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, Taxol must affect . (A) the formation of the mitotic spindle (B) anaphase (C) formation of the centrioles (D) chromatid assembly (E) the S phase of the cell cycle

42. Which of the following about transposable elements is correct? (A) occurs only in bacteria (B) occurs only in plants (C) moves genes between homologous regions of DNA (D) scatters genes to a new loci in the genome (E) plays little role in evolution