PCAT Biology Reinforcement Test 2B Explanations

PCAT Biology Reinforcement Test 2B Explanations - BIOLOGY...

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1 BIOLOGY REINFORCEMENT TEST 2B EXPLANATIONS 1. C The question stem asks you to correctly match the organisms with their classification in the food chain. Lettuce is the primary producer because it is a green plant that uses the energy of the sun to manufacture carbohydrates, proteins, and lipids. The mouse is a primary consumer because it feeds on primary producers (green plants). The snake is a secondary consumer because it feeds on primary consumers, such as mice. E. coli is considered to be a decomposer because it breaks down organic wastes and dead tissues to basic compounds. Thus, choice C is the correct answer because it correctly matches the organisms with their classification on the food chain. 2. A ADH (antidiuretic hormone) is produced by neurosecretory cells in the hypothalamus and is stored and released by the posterior pituitary. ADH is responsible for increasing the permeability of the nephron’s distal tubule and collecting duct to water, thereby promoting water reabsorption and increasing blood volume. Choices B, C, and D are all incorrect because TSH, ACTH, and FSH are all released by the anterior pituitary. ACTH stimulates the adrenal cortex to synthesize and secrete glucocorticoids. TSH stimulates the thyroid gland to synthesize and secrete thyroxine, and FSH causes maturation of ovarian follicles. 3. A During the first trimester of pregnancy, the corpus luteum is preserved by human chorionic gonadotropin (HCG)—a hormone produced by the blastocyst and the developing placenta. The corpus luteum secretes estrogen and progesterone, which maintain a healthy endometrium for the developing embryo. The high levels of estrogen and progesterone simultaneously inhibit the release of FSH and LH, preventing further ovulation. Choice B is incorrect because HCG does not stimulate the anterior pituitary to secrete progesterone. Choice C is incorrect because HCG does not directly inhibit GnRH. HCG preserves the corpus luteum, which continues to secrete progesterone and estrogen. High levels of estrogen and progesterone inhibit GnRH. Thus, choice C is incorrect. Choice D is incorrect because HCG preserves the corpus luteum, not the follicle. 4. B Carbon monoxide is lethal because it has a stronger affinity for hemoglobin than does oxygen. Thus, the carbon monoxide will preferentially replace oxygen on hemoglobin, so hemoglobin will not be able to deliver oxygen to the body tissues, and death could result. 5. A Red blood cells have characteristic cell-surface proteins (antigens) by which the blood can be classified. One of the major groups of blood antigens is the ABO system. In the ABO system, an individual can have the A antigen (type A), the B antigen (type B), both antigens (type AB), or neither antigen (type O) present on his or her red blood cells. The plasma of every individual contains antibodies,
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Kaplan PCAT Biology Reinforcement Test 2B Explanations 2 or agglutinins, for the antigens that are not present on the individual’s red blood cells. These blood groups
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PCAT Biology Reinforcement Test 2B Explanations - BIOLOGY...

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