HESI A2
HESI A2 Practice Test Biology
1. Which component of the cell contributes to the protection, communication, and passage of substances into and out of the cell?
- A. Nucleus
- B. Cell membrane
- C. Endoplasmic reticulum
- D. Cytoplasm
Correct answer: B
Rationale: The correct answer is the cell membrane. The cell membrane is responsible for protecting the cell, facilitating communication with the external environment, and regulating the passage of substances into and out of the cell. The nucleus (Choice A) is the control center of the cell and houses the genetic material but is not primarily involved in these functions. The endoplasmic reticulum (Choice C) is involved in protein synthesis and lipid metabolism, not primarily in protection or communication. The cytoplasm (Choice D) is the gel-like substance that fills the cell but does not specifically contribute to protection, communication, or substance passage.
2. Whose energy efficiency is greater?
- A. Herbivore
- B. Carnivore
- C. Omnivore
- D. Decomposer
Correct answer: D
Rationale: Decomposers have the greatest efficiency of energy among the given options. Decomposers break down organic matter, such as dead plants and animals, into simpler substances through the process of decomposition. This breakdown process results in the release of nutrients back into the ecosystem, making energy more readily available for other organisms to use. In contrast, herbivores, carnivores, and omnivores all derive their energy from the consumption of other living organisms, making their energy efficiency lower than that of decomposers. Herbivores consume plants for energy, which involves energy loss due to inefficiencies in converting plant matter into usable energy. Carnivores consume herbivores or other carnivores, leading to further energy loss through each trophic level. Omnivores consume both plant and animal matter, but their energy efficiency is still lower than decomposers because of the energy loss associated with consuming living organisms. Decomposers play a crucial role in recycling nutrients and energy in ecosystems, making them highly efficient in the utilization of energy.
3. What are saturated fats saturated with?
- A. Hydrogen atoms
- B. Carbon atoms
- C. Oxygen atoms
- D. Nitrogen atoms
Correct answer: A
Rationale: Saturated fats are saturated with hydrogen atoms. This means that each carbon atom in the fatty acid chains forming saturated fats is bonded to as many hydrogen atoms as possible. This saturation results in the fatty acid chains being straight and closely packed together, making saturated fats solid at room temperature. Choice B (Carbon atoms), C (Oxygen atoms), and D (Nitrogen atoms) are incorrect because saturated fats are specifically saturated with hydrogen atoms, not carbon, oxygen, or nitrogen atoms.
4. Select the strand of DNA that would match this segment: ACTTGCA
- A. TGAACGT
- B. GACCATG
- C. ACTTGCA
- D. None of the above
Correct answer: A
Rationale: The correct match for the DNA segment ACTTGCA is TGAACGT. In DNA, adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). Therefore, the complementary strand to ACTTGCA should be TGAACGT, making choice A the correct answer. Choice B (GACCATG) does not follow the base pairing rules; hence, it is incorrect. Choice C (ACTTGCA) is the original segment, not its complementary strand. Choice D is incorrect as well because a matching strand does exist.
5. What is the main function of the ribosomes in the cell?
- A. DNA Replication
- B. Protein Synthesis
- C. Lipid Breakdown
- D. Cell Division
Correct answer: B
Rationale: The correct answer is B: Protein Synthesis. Ribosomes are cellular organelles responsible for synthesizing proteins. This process is crucial for various cellular functions. Choice A, DNA Replication, is incorrect as ribosomes are not involved in this process. Choice C, Lipid Breakdown, is also incorrect as ribosomes do not play a role in lipid metabolism. Choice D, Cell Division, is incorrect as ribosomes are not directly involved in the process of cell division.
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