HESI A2
HESI A2 Biology Practice Test 2024
1. What organelle in the cell produces energy through the process of respiration?
- A. Nucleus
- B. Mitochondria
- C. Golgi Apparatus
- D. Chloroplasts
Correct answer: B
Rationale: The correct answer is B: Mitochondria. The mitochondria are known as the powerhouse of the cell and are responsible for producing energy through respiration in eukaryotic cells. Choice A, the Nucleus, is not involved in energy production but rather houses the cell's genetic material. Choice C, the Golgi Apparatus, is responsible for packaging and processing proteins, not energy production. Choice D, Chloroplasts, are responsible for photosynthesis in plant cells, not respiration for energy production.
2. Which of the following types of hormones can diffuse through the cell membrane to bind to receptors inside the cell and stimulate a chemical response to a target cell?
- A. fat-soluble hormones
- B. amino acid derivatives
- C. hydrophilic hormones
- D. water-soluble hormones
Correct answer: A
Rationale: The correct answer is A: fat-soluble hormones. Fat-soluble hormones are able to diffuse through the cell membrane to bind to receptors inside the cell. This is because they are lipophilic, allowing them to cross the lipid bilayer easily. Once inside the cell, fat-soluble hormones can directly affect gene expression or cell function. Choice B, amino acid derivatives, and choice C, hydrophilic hormones, are not able to diffuse through the cell membrane as they are not lipophilic. Therefore, they cannot bind to receptors inside the cell. Choice D, water-soluble hormones, also cannot diffuse through the cell membrane as it is hydrophilic, making it unable to reach receptors inside the cell.
3. 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.
4. What cycle is the sequence of reactions by which most living cells generate energy during aerobic respiration?
- A. Calvin Cycle
- B. Krebs Cycle
- C. Photosynthesis
- D. Fermentation
Correct answer: B
Rationale: The Krebs Cycle is the correct answer. It is a series of reactions occurring in the mitochondria and is a crucial part of aerobic respiration. The Calvin Cycle is a part of photosynthesis, not respiration, making choice A incorrect. Photosynthesis (choice C) is the process by which plants, algae, and some bacteria convert light energy into chemical energy. Fermentation (choice D) is an anaerobic process that does not require oxygen and is not the primary energy-generating pathway during aerobic respiration, so it is incorrect.
5. Which statement is untrue?
- A. RNA is single-stranded.
- B. RNA contains uracil.
- C. DNA codes for proteins.
- D. DNA cannot be altered.
Correct answer: D
Rationale: DNA can be altered through various processes such as mutations, genetic engineering, and epigenetic modifications. Changes in DNA can occur naturally or through external influences, leading to variations in the genetic code. Therefore, the statement that DNA cannot be altered is untrue. Choices A, B, and C are true statements. RNA is indeed single-stranded, RNA contains uracil instead of thymine, and DNA serves as a template for protein synthesis.
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