HESI A2
Biology HESI A2 2024
1. How should a researcher test the hypothesis that eating chocolate leads to acne in teenagers?
- A. Take 100 teenagers and feed each one a different amount of chocolate daily for 60 days; then test for acne.
- B. Take 100 teenagers and feed 50 two bars of chocolate daily for 60 days while the other 50 eat no chocolate; then test for acne.
- C. Take 1 teenager and feed him or her two bars of chocolate for 30 days and no chocolate for 30 days; then test for acne.
- D. Take 100 teenagers and feed them no chocolate for 30 days and two bars of chocolate apiece for 30 days; then test for acne.
Correct answer: B
Rationale: Option B is the correct approach to test the hypothesis that eating chocolate leads to acne in teenagers. This method involves having a control group (50 teenagers not consuming chocolate) and an experimental group (50 teenagers consuming two bars of chocolate daily), which allows for comparison. By having two distinct groups, researchers can assess the impact of chocolate consumption on acne development. Option A lacks a control group for comparison, making it harder to attribute any observed effects specifically to chocolate consumption. Option C only involves a single subject, which limits the generalizability of the results. Option D, where all teenagers experience both conditions, does not allow for a direct comparison between chocolate consumption and acne development, as all subjects are exposed to both conditions.
2. Where can epithelial tissue be found?
- A. Organ lining
- B. Heart muscle
- C. Tendons
- D. Spinal cord
Correct answer: A
Rationale: Epithelial tissue is primarily found lining the surfaces of organs, such as the skin and the linings of various internal organs like the digestive tract, respiratory tract, and blood vessels. It serves as a protective barrier and helps with absorption and secretion. Heart muscle is made up of cardiac muscle tissue, tendons are primarily composed of dense connective tissue, and the spinal cord is composed of nervous tissue, none of which are classified as epithelial tissue.
3. Why do gardeners sometimes use salt to get rid of slugs?
- A. The salt moves from the exterior into the slug’s body.
- B. The salt causes water in the slug to move outward.
- C. The salt and slug slime merge to form a new compound.
- D. The salt’s corrosiveness breaks down the slug’s cell walls.
Correct answer: D
Rationale: Gardeners use salt to get rid of slugs because salt is corrosive and breaks down the slug's cell walls. When the slug comes into contact with salt, the salt draws moisture out of the slug's body, causing dehydration and ultimately leading to the slug's death. Choices A, B, and C are incorrect because the primary mechanism of salt in eliminating slugs is its corrosive action on the slug's body, not the movement of salt into the slug's body, outward movement of water in the slug, or merging with slug slime to form a new compound.
4. 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.
5. What are the three types of muscle tissue?
- A. Cardiac, spinal, stomach
- B. Smooth, skeletal, cardiac
- C. Neuron, epithelial, collagen
- D. None of the above
Correct answer: B
Rationale: The correct answer is B: Smooth, skeletal, cardiac. Smooth muscle is found in organs like the stomach and is involuntarily controlled. Skeletal muscle is found in voluntary muscles, like the bicep or quadriceps. Cardiac muscle is found only in the heart walls and works involuntarily to make the heart beat and pump blood. Choices A, C, and D are incorrect because they do not represent the three types of muscle tissue.
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