HESI A2
Biology HESI A2 Practice Exam
1. Which cellular structure is largely protective in function?
- A. Mitochondrion
- B. Vacuole
- C. Cell membrane
- D. Ribosome
Correct answer: C
Rationale: The correct answer is C: Cell membrane. The cell membrane, also known as the plasma membrane, is largely protective in function as it serves as a selectively permeable barrier that surrounds the cell, providing structural support and helping to maintain cell integrity. It regulates the movement of substances in and out of the cell, thus protecting the cell from harmful external factors while allowing essential nutrients to enter. Mitochondrion (choice A) is responsible for energy production, not primarily protective. Vacuole (choice B) is mainly involved in storage and transport. Ribosome (choice D) is involved in protein synthesis, not protective functions.
2. What molecule is primarily responsible for providing energy to the cell?
- A. ATP
- B. DNA
- C. ADP
- D. Glycogen
Correct answer: A
Rationale: Correct! ATP (Adenosine Triphosphate) is the main molecule that stores and provides energy for cellular activities. ATP is known as the energy currency of the cell, where energy released from the breakdown of nutrients is stored in the high-energy phosphate bonds of ATP. Choices B, C, and D are incorrect because DNA carries genetic information, ADP is the precursor of ATP, and glycogen is a polysaccharide used for energy storage, not direct energy provision.
3. If both parents have polydactylism, what percentage of their offspring is predicted to manifest the anomaly?
- A. 25%
- B. 50%
- C. 75%
- D. 100%
Correct answer: B
Rationale: When both parents have polydactylism, they each possess at least one dominant allele for polydactylism. Through a Punnett square analysis, it can be determined that 50% of their offspring will inherit the dominant allele from both parents. This results in a 100% chance of manifesting the anomaly (2 out of 4 possibilities). Therefore, 50% of the offspring are predicted to manifest the anomaly. Choices A, C, and D are incorrect as they do not align with the principles of Mendelian genetics and Punnett square analysis.
4. How does water affect the temperature of a living thing?
- A. Water increases temperature.
- B. Water keeps temperature stable.
- C. Water decreases temperature.
- D. Water does not affect temperature.
Correct answer: B
Rationale: Water has a high specific heat capacity, which means it can absorb and release large amounts of heat with minimal temperature change. This property helps water regulate the temperature of living things by maintaining a stable environment. Choice A is incorrect because water does not consistently increase temperature, but rather helps in temperature regulation. Choice C is incorrect as water doesn't typically decrease temperature in living organisms. Choice D is incorrect since water does play a crucial role in regulating temperature.
5. The two catabolic pathways that lead to cellular energy production are:
- A. fermentation and protein synthesis
- B. cellular respiration and glycolysis
- C. fermentation and glycolysis
- D. cellular respiration and fermentation
Correct answer: D
Rationale: The correct answer is D: cellular respiration and fermentation. Cellular respiration involves the breakdown of glucose in the presence of oxygen to produce ATP, which is the primary source of energy for cells. Fermentation, on the other hand, occurs in the absence of oxygen and produces ATP through glycolysis followed by specific fermentation pathways. Choices A, B, and C are incorrect. Protein synthesis is a biosynthetic process, not a catabolic pathway for energy production. Glycolysis is a common step in both cellular respiration and fermentation, so it is not a pair of distinct catabolic pathways. Therefore, the most accurate pairing of catabolic pathways for cellular energy production is cellular respiration and fermentation.
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