HESI A2
Biology HESI A2 2024
1. Why do we perceive chlorophyll as green?
- A. It absorbs yellow and blue light.
- B. It primarily absorbs green light.
- C. It fails to absorb green light.
- D. It primarily absorbs red light.
Correct answer: A
Rationale: Chlorophyll appears green to us because it primarily absorbs yellow and blue light while reflecting green light. The wavelengths of yellow and blue light are absorbed by chlorophyll for photosynthesis, which results in the green color we perceive. Choice B is incorrect because chlorophyll absorbs yellow and blue light, not green light. Choice C is incorrect because chlorophyll does absorb green light, but it also absorbs other wavelengths, primarily yellow and blue. Choice D is incorrect because chlorophyll primarily absorbs yellow and blue light, not red light.
2. Epithelial cells are:
- A. Polarized
- B. Neutral
- C. Larger than other cells
- D. None of the above
Correct answer: A
Rationale: Epithelial cells have a distinct top (apical) and bottom (basal) side, demonstrating polarity. This polarity is essential for their specialized functions, such as secretion, absorption, and barrier formation. Choice B, 'Neutral,' is incorrect as epithelial cells exhibit polarity. Choice C, 'Larger than other cells,' is incorrect as epithelial cells come in various sizes and are not specifically larger than other cell types. Choice D, 'None of the above,' is incorrect as epithelial cells are indeed polarized.
3. Patient A, who weighs 68 kilograms, steps onto a scale 20 times. The scale consistently weighs Patient A as 75 kilograms. What is true of the measurement?
- A. It is valid, but not reliable.
- B. It is reliable, but not valid.
- C. It is both valid and reliable.
- D. It is neither reliable nor valid.
Correct answer: B
Rationale: The correct answer is B: 'It is reliable, but not valid.' The measurement is reliable because it consistently provides the same result (75 kg). However, it is not valid because it does not accurately reflect the true weight of Patient A (68 kg). Choice A is incorrect because if the scale consistently shows the same weight (75 kg), it is reliable. Choice C is incorrect because although the scale is consistent, the measurement does not reflect the true weight, making it not valid. Choice D is incorrect as the measurement is reliable but lacks validity.
4. What organelle pushes water out of the cell?
- A. Lysosomes
- B. Vacuoles (contractile)
- C. Mitochondria
- D. Nucleus
Correct answer: B
Rationale: The correct answer is B: Vacuoles (contractile). Vacuoles (contractile) are responsible for expelling excess water out of the cell. Lysosomes are involved in the digestion and removal of waste materials, mitochondria are the powerhouse of the cell involved in energy production, and the nucleus contains the cell's genetic material but does not play a role in pushing water out of the cell.
5. What is the purpose of phloem tissue in plant stems?
- A. It conducts water up through the stem.
- B. It conducts the energy of light to leaves.
- C. It conducts food throughout the plant.
- D. It conducts carbon dioxide throughout the plant.
Correct answer: C
Rationale: The purpose of phloem tissue in plant stems is to conduct food, particularly sugars produced in the leaves during photosynthesis, throughout the plant. The phloem transports these organic compounds to various parts of the plant where they are needed for growth and energy. Choice A is incorrect because water is primarily transported by xylem tissue, not phloem. Choice B is incorrect as the energy of light is captured by chlorophyll in the process of photosynthesis, not conducted by phloem. Choice D is incorrect because carbon dioxide is mainly absorbed through the leaves and transported to other parts of the plant through diffusion, not by phloem.
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