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.

11. Otto Loewi performed an experiment in which he electrically stimulated the vagus nerve connected to one frog heart. Loewi also let the fluid bathing this first heart pass to a second chamber containing a second frog heart not connected to a nerve. What did Loewi observe? (A) There was no effect on the beating of either heart. (B) The first heart showed a decrease in beat rate and so did the second heart. (C) The first heart showed an increase in beat rate and so did the second heart. (D) The first heart showed a decrease in beat rate, but there was no change in the second heart. (E) The first heart showed an increase in beat rate, but there was no change in the second heart.

12. All of the following are primary functions of flowers EXCEPT: (A) meiosis (B) photosynthesis (C) egg production (D) pollen production (E) sexual reproduction

13. The series of metabolic events that occurs within tomato plants in response to wounding is ______. (A) a waterfall effect (B) the hypersensitive response (C) resistance to coevolution (D) a systemic response (E) a pathogen-specific response

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

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.

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

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