HESI A2
HESI A2 Practice Test Biology
1. How are molecules of water bonded to each other?
- A. Ionic
- B. Covalent
- C. Hydrogen
- D. Molecular
Correct answer: C
Rationale: Water molecules are bonded to each other by 'hydrogen' bonds. These bonds are not as strong as covalent bonds, which hold the atoms within each water molecule together (Choice B). Ionic bonds (Choice A) involve the transfer of electrons between atoms, which is not the case in water molecules. The term 'molecular' (Choice D) is too general and doesn't specifically describe the type of bond between water molecules.
2. Which hormone is released by the adrenal medulla?
- A. Cortisol
- B. Adrenaline
- C. Insulin
- D. Somatostatin
Correct answer: B
Rationale: The correct answer is B, Adrenaline (also known as epinephrine), which is released by the adrenal medulla during the body's fight-or-flight response. Adrenaline helps prepare the body for action by increasing heart rate, dilating air passages, and mobilizing glucose and fats for energy, among other physiological responses. Choice A, Cortisol, is a steroid hormone released by the adrenal cortex involved in the stress response and regulation of metabolism. Choice C, Insulin, is produced by the pancreas and regulates blood sugar levels. Choice D, Somatostatin, is a hormone that inhibits the release of several other hormones in the body, but it is not released by the adrenal medulla.
3. If a hard-boiled egg is placed in a beaker of saltwater, what will happen to the egg?
- A. Expand because water will move into the egg
- B. Shrivel because water will leave the egg
- C. Remain the same
- D. None of the above
Correct answer: B
Rationale: The correct answer is B. When a hard-boiled egg is placed in a beaker of saltwater, the egg will shrivel because water will leave the egg through osmosis. Osmosis is the movement of water from an area of lower solute concentration to an area of higher solute concentration, in this case, from the egg into the saltwater. The higher concentration of solute in the saltwater causes water to move out of the egg, leading to the egg shrinking or shriveling. Choices A, C, and D are incorrect because the egg will not expand, remain the same, or have an outcome different from shriveling when placed in a beaker of saltwater.
4. Which structure in the kidney filters blood to form urine?
- A. Nephron
- B. Glomerulus
- C. Bowman's capsule
- D. Loop of Henle
Correct answer: B
Rationale: The glomerulus is a key structure in the kidney responsible for filtering blood. It consists of a network of capillaries that filter waste products and excess substances from the blood, allowing the formation of urine. While the nephron, Bowman's capsule, and Loop of Henle are also essential components of the kidney's filtration system, the glomerulus is specifically involved in the initial blood filtration process. The nephron is the functional unit of the kidney, Bowman's capsule surrounds the glomerulus and collects the filtrate, and the Loop of Henle is responsible for reabsorption and concentration of urine, not the initial blood filtration.
5. What is 39 ÷ 8 ÷ 7/6?
- A. 56/39
- B. 39/8
- C. 4 & 7/8
- D. 5 & 8/14
Correct answer: A
Rationale: To solve the division problem, we need to remember the rule 'Dividing by a fraction is the same as multiplying by its reciprocal.' Therefore, 39 ÷ 8 ÷ 7/6 is equivalent to 39 ÷ 8 × 6/7. Simplifying this gives (39 × 6) ÷ (8 × 7) = 234 ÷ 56 = 56/39. Therefore, the correct answer is A. Choices B, C, and D are incorrect as they do not correctly simplify the given division problem.
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