18. When light strikes the rod cell, it becomes ______ and glutamate release onto bipolar cells ______.
(A) excited, increases
(B) depolarized, increases
(C) depolarized, decreases
(D) hyperpolarized, increases
(E) hyperpolarized, decreases

14. The last common ancestor of all animals was probably a ______. (A) flagellated protest (B) unicellular yeast (C) unicellular chytrid (D) multicellular algae (E) multicellular fungus

15. Fire suppression by humans: (A) can change the species composition within biological communities. (B) will always result in an increase in species diversity in a given biome. (C) is necessary for the protection of threatened and endangered forest species. (D) will result ultimately in sustainable production of increased amounts of forest products for human use. (E) is a management goal of conservation biologists to maintain the healthy condition of forest communities.

16. A person has his/her gall bladder removed and as a result: (A) can only eat liquid meals. (B) can only eat very small meals. (C) can only eat small amounts of fat. (D) can now eat as much fat as desired and not absorb it. (E) none of these choices are correct.

17. The primary difference between estrous and menstrual cycles is that: (A) most estrous cycles are of much longer duration compared to menstrual cycles. (B) behavioral changes during estrous cycles are much less apparent than those of menstrual cycles. (C) season and climate have less pronounced effects on estrous cycles than they do on menstrual cycles. (D) copulation normally occurs across the estrous cycle, whereas in menstrual cycles copulation only occurs during the period surrounding ovulation. (E) the endometrium shed by the uterus during the estrous cycle is reabsorbed, whereas the shed endometrium of menstrual cycles is excreted from the body.

19. "Accommodation" is the process in the eye of ______. (A) regulation of vitreous humor volume (B) bending light rays to varying degrees by the lens (C) converting light energy into electrical signals by the retina (D) adjustment to varying light levels by altering the sensitivity of the eye (E) adjustment of the amount of light admitted to the eye by adjusting pupil diameter

20. Biofuels are mainly produced by ______. (A) plants that convert hemicellulose into gasoline (B) plants that are easy to grow in arid environments (C) transgenic crops that have cell walls containing ethylene (D) the genetic engineering of ethanol-generating genes into plants (E) the breakdown of cell wall biopolymers into sugars that can be fermented

21. Liver cells, mammary cells, and skin cells all contain the same genome; however, their respective proteomes vary drastically. This observation is best explained by what phenomenon? (A) cell growth (B) cell division (C) crossing over (D) cell differentiation (E) evolution

22. The first heart sound is produced at ______. (A) closing the semilunar valve (B) the beginning of systole (C) the end of systole (D) the beginning of diastole (E) the end of diastole 

23. Which of the following statements about fluid mosaic model is FALSE? (A) Lipid-anchored proteins are a part of the original fluid mosaic. (B) The fluid part of the model is the phospholipid bilayer. (C) The mosaic part of the model is the protein. (D) The model was proposed by S. Jonathan Singer and Garth Nicolson. (E) This model can provide explanations for most of the criticisms of the “lipid bilayer plus protein sheets” model.

24. Which of the following statements about the cell cycle is FALSE? (A) Maturation-promoting factor (MPF) stimulates nuclear envelope breakdown by phosphorylating the lamin proteins of nuclear lamina. (B) Active MPF phosphorylates microfilament-associated proteins to facilitate formation of the mitotic spindle. (C) Active MPF phosphorylates histones to allow chromosome condensation. (D) Epidermal growth factor can induce cells to pass through the G1 checkpoint and into S phase through the Ras pathway. (E) The p21 protein functions to suppress the activity of Cdk-cyclin complex to block passage through the G1 checkpoint.