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. Cells reproduce by different processes, all of which fall into what two categories?
- A. Sexual reproduction and binary fission
- B. Sexual reproduction and asexual reproduction
- C. Asexual reproduction and binary fission
- D. Asexual reproduction and mitosis
Correct answer: B
Rationale: Cells reproduce through two main processes: 'sexual reproduction and asexual reproduction.' Sexual reproduction involves the fusion of gametes to produce offspring with genetic variation, while asexual reproduction involves the production of offspring genetically identical to the parent. Choice A is incorrect because binary fission is a form of asexual reproduction, not sexual reproduction. Choice C is incorrect because it combines two forms of asexual reproduction. Choice D is incorrect because mitosis is a specific type of cell division, not a form of reproduction involving the production of offspring.
3. Why are bacteria and blue-green algae often classified together?
- A. Both are gymnosperms.
- B. Both are prokaryotes.
- C. Both are autotrophs.
- D. Both are pathogens.
Correct answer: B
Rationale: Bacteria and blue-green algae (cyanobacteria) are often classified together because they are both prokaryotes. Prokaryotes are unicellular organisms that lack a membrane-bound nucleus and other membrane-bound organelles. This characteristic distinguishes them from eukaryotic organisms, which have these membrane-bound structures. Choice A is incorrect because gymnosperms are seed-producing plants with naked seeds, not bacteria or blue-green algae. Choice C is incorrect because being an autotroph (able to produce its own food) is not a reason for classifying them together. Choice D is incorrect because not all bacteria and blue-green algae are pathogens; many of them are beneficial or neutral to other organisms.
4. A scientist needs 12 mL of a solution. They have a bottle with 12L in it. Do they have enough?
- A. Yes, they have exactly what they need
- B. Yes, they have more than what they need
- C. No, they do not have enough
- D. None of the above
Correct answer: B
Rationale: 1 liter has 1000 milliliters. To convert from milliliters to liters, the decimal point moves three places to the left. So, the bottle has 12000 mL of solution, which is a lot more than the required 12 mL. Therefore, the scientist has more than what they need. Choice A is incorrect as the bottle has more than the required amount. Choice C is incorrect as the bottle contains significantly more solution than needed. Choice D is incorrect as the scientist does have more than enough solution.
5. Where is the slide typically placed on a microscope?
- A. Eyepiece
- B. Stage
- C. Focus knob
- D. Objective lens
Correct answer: B
Rationale: The slide is typically placed on the stage of a microscope. The stage is the platform where the slide containing the specimen is positioned for viewing. The eyepiece is where you look through to view the specimen, the focus knob is used to sharpen the image, and the objective lens is responsible for magnification. Therefore, the correct answer is the stage.
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