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Answers

D
Homeostasis is the maintenance of a stable internal physiological environment in an organism. Therefore answer choices (A), (B), (C), and (E) are incorrect as they are not part of this process.
E
Blood is made up of answer choices (A), (B), (C), and (D). Plasma is the liquid part of blood containing dissolved nutrients, wastes, proteins, hormones, and fibrinogen. Red blood cells are the anucleated, bi-concave discs filled with hemoglobin, which unites with oxygen to form oxyhemoglobin.

White blood cells are cells of the body's defense system. These large cells include phagocytes, which engulf bacteria, and lymphocytes, which are involved in the specific immune responses.
A
Amylase breaks down complex carbohydrates into disaccharides. There is salivary and pancreatic amylase. (B) is incorrect because gastrin is a hormone secreted by the stomach wall of mammals when food makes contact with the wall; it stimulates other parts of the wall to secrete gastric juice. (C) is incorrect because secretin is secreted by the small intestine and stimulates the pancreas to secrete pancreatic juice containing bicarbonate ions to buffer the chyme. (D) is incorrect because pepsin breaks down proteins into amino acids, and (E) is incorrect because maltase breaks down maltose into glucose.
C
The glomerulus is a capillary ball in the nephron where glucose, water, amino acids, ions, and urea enter, whereas plasma proteins and cells remain behind. (A) and (B) are filtered and completely reabsorbed and (D) is incorrect because urea is filtered and excreted. (E) is incorrect because Na+ is filtered and partially reabsorbed. Plasma proteins are never filtered in a normal, healthy kidney and therefore (C) is the correct answer.
E
The lymphatic system collects the plasma from the interstitial spaces and filters out cellular debris, foreign material, and bacteria in the lymph nodes and the spleen. Fluid is propelled through the system of lymphatic vessels through the contraction of surrounding muscles. The lymphatic system joins the circulatory system at the thoracic duct located in the superior vena cava immediately before it enters the heart.
E
Addition of HX to alkenes proceeds through a carbocation intermediate. As with all such reactions, the intermediate with the most stable carbocation will react the fastest. The alkenes with halide substitution listed, (A) and (B), are poor choices because the electron-withdrawing effect of the halides will actually destabilize the carbocation. Of the three remaining choices, the one with the most substituted alkene will react the fastest. (C) and (D) would both yield secondary carbocations, whereas (E) would give one that is tertiary. (E) is therefore correct.

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	OAT -- Try Practice Questions Answers D Homeostasis is the maintenance of a stable internal physiological environment in an organism. Therefore answer choices (A), (B), (C), and (E) are incorrect as they are not part of this process. E Blood is made up of answer choices (A), (B), (C), and (D). Plasma is the liquid part of blood containing dissolved nutrients, wastes, proteins, hormones, and fibrinogen. Red blood cells are the anucleated, bi-concave discs filled with hemoglobin, which unites with oxygen to form oxyhemoglobin. White blood cells are cells of the body's defense system. These large cells include phagocytes, which engulf bacteria, and lymphocytes, which are involved in the specific immune responses. A Amylase breaks down complex carbohydrates into disaccharides. There is salivary and pancreatic amylase. (B) is incorrect because gastrin is a hormone secreted by the stomach wall of mammals when food makes contact with the wall; it stimulates other parts of the wall to secrete gastric juice. (C) is incorrect because secretin is secreted by the small intestine and stimulates the pancreas to secrete pancreatic juice containing bicarbonate ions to buffer the chyme. (D) is incorrect because pepsin breaks down proteins into amino acids, and (E) is incorrect because maltase breaks down maltose into glucose. C The glomerulus is a capillary ball in the nephron where glucose, water, amino acids, ions, and urea enter, whereas plasma proteins and cells remain behind. (A) and (B) are filtered and completely reabsorbed and (D) is incorrect because urea is filtered and excreted. (E) is incorrect because Na+ is filtered and partially reabsorbed. Plasma proteins are never filtered in a normal, healthy kidney and therefore (C) is the correct answer. E The lymphatic system collects the plasma from the interstitial spaces and filters out cellular debris, foreign material, and bacteria in the lymph nodes and the spleen. Fluid is propelled through the system of lymphatic vessels through the contraction of surrounding muscles. The lymphatic system joins the circulatory system at the thoracic duct located in the superior vena cava immediately before it enters the heart. E Addition of HX to alkenes proceeds through a carbocation intermediate. As with all such reactions, the intermediate with the most stable carbocation will react the fastest. The alkenes with halide substitution listed, (A) and (B), are poor choices because the electron-withdrawing effect of the halides will actually destabilize the carbocation. Of the three remaining choices, the one with the most substituted alkene will react the fastest. (C) and (D) would both yield secondary carbocations, whereas (E) would give one that is tertiary. (E) is therefore correct.	COMMUNITY THE BUZZ Your Application Essay Personal Statement… Statement of Purpose… Candidate's Admission Statement… These terms bring a shiver to the spine of many a potential grad student. Learn more. Recommendations Interviews Join the Kaplan Community and get more features. It's FREE! Optometry Scorematch—Find out how your OAT score measures up!