74. Which of the followings is NOT true of G protein-coupled receptors (GPCRs)?
(A) GPCRs are cell-surface transmembrane receptors that work with the help of monomer G proteins.
(B) GPCRs have similar structure in which a single polypeptide has seven transmembrane helices.
(C) Epinephrine can target the same type of GPCR in liver cell and skeletal muscle blood vessel.
(D) G protein systems are involved in cholera and pertussis diseases.
(E) G protein functions as a molecular switch that is either on or off depending on GTP or GDP is attached.

70. Inbreeding and small population size of a threatened species can combine to form a downward spiral for the species known as a(n) _____. (A) extinction vortex (B) random change of allele frequencies attributable to chance (C) random mutation (D) accelerated evolution of new traits (E) none of the possibilities are correct

71. Which is NOT a recognized hypothesis to account for the strong competitive ability of invasives? (A) Enemy release (B) Superior competition (C) Lack of environmental constraints (D) Propagule pressure (E) Climate pre-adaptation

72. If a community exhibits lognormal rank abundance, we may conclude there are _____. (A) a large number of rare species, a large number of common species, and a few species of intermediate rank (B) a few rare species, a few common species, and a large number of species of intermediate rank (C) a few rare species and a large number of very common species (D) a few common species and a large number of rare species (E) rare species are very common

73. A new menstrual cycle begins with the production of _____, following the removal of inhibition by combination of _____. (A) GnRH, FSH and LH (B) GnRH, estradiol and progesterone (C) LH, estradiol and progesterone (D) estradiol, FSH and LH (E) estradiol, GnRH and LH

75. Which of the following statements about genome is FALSE? (A) Usually, the gene density of archaea genome is higher than eukaryotes. (B) Usually, the number of genes of archaea genome is more than eukaryotes genome. (C) The genome size of archaea is less than eukaryotes. (D) The number of genes of fruit fly genome is less than Arabidopsis thaliana genome. (E) The number of genes of fruit fly genome is less than C. elegans genome.

76. Which of the following statements concerning human embryonic development is correct? (A) Inner cell mass is a group of cells that cluster at one end of the gastrula. (B) The trophoblast, the outer epithelium of the gastrula, supports embryo growth. (C) The trophoblast continues to expand into the endometrium, and four new extraembryonic membranes appear. (D) By the end of blastocyst, three embryonic germ layers have formed. (E) By the end of gastrulation, the extraembryonic ectoderm and extraembryonic membranes surround the embryo.

77. Which of the following descriptions about muscle and skeletal system is NOT true? (A) The strength of a muscular contraction is determined by the number of neurons delivering action potentials. (B) Skeletal, cardiac, and smooth muscle all have transverse tubules. (C) A hydrostatic skeleton consists of fluid held under pressure in a closed body compartment. (D) Gap junctions provide direct electrical coupling between the cardiac muscle cells. (E) Calcium ions cause smooth muscle contraction by binding to calmodulin.

78. The correct sequence of the cardiac cycle in a healthy adult human is _____. (1. atrial systole and ventricular diastole 2. ventricular systole and atrial diastole 3. atrial and ventricular systole 4.atrial and ventricular diastole)(A) 1 → 3→2(B) 4 → 1 → 2(C) 4 → 2 → 1(D) 2 → 4 → 3(E) 1 → 4 → 3

79. Which of the following statements concerning hormonal control of digestion is FALSE? (A) Secretin stimulates the pancreas to release bicarbonate. (B) Cholecystokinin (CCK) stimulates the release of digestive enzymes form the pancreas and of bile from the gallbladder. (C) Both secretin and CCK act on the stomach to promote secretion of gastric juices. (D) Secretin and CCK are released from duodenum. (E) Gastrin is released from stomach and regulates production of gastric juices.

80. Which of the following statements concerning regulation of eukaryotic gene expression is FALSE? (A) DNA methylation can activate or inactivate gene expression. (B) Acetylation of histone tails promotes condensation of the chromatin. (C) Enhancers are segments of DNA that may be within an intron. (D) Unlike operons in E. coli, dispersed genes can be coordinately controlled by transcription activators or repressors in eukaryotes. (E) Alternative RNA splicing can produce different mRNA molecules from the same primary transcript.