HESI A2
HESI A2 Biology Practice Test
1. 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.
2. Why is DNA important for metabolic activities of the cell?
- A. It controls the synthesis of enzymes.
- B. It stabilizes the cell wall.
- C. It initiates cell division.
- D. It prevents diffusion of nutrients.
Correct answer: A
Rationale: The correct answer is A. DNA plays a crucial role in metabolic activities by controlling the synthesis of enzymes. Enzymes are the biological catalysts that regulate and facilitate metabolic reactions within the cell. Choice B is incorrect because DNA is not involved in stabilizing the cell wall; that role is usually associated with other components like the cell membrane. Choice C is incorrect as cell division is primarily regulated by different processes and molecules, not directly by DNA. Choice D is incorrect because DNA is not related to preventing the diffusion of nutrients; instead, it is involved in coding for proteins that aid in various cellular functions.
3. Prokaryotic cells:
- A. Have a nucleus
- B. Have a capsule
- C. Have membrane-bound organelles
- D. Cannot move on their own
Correct answer: B
Rationale: Prokaryotic cells do not have a nucleus or membrane-bound organelles. One characteristic feature of prokaryotic cells is the presence of a capsule, which is a protective layer outside the cell wall. This capsule helps the prokaryotic cell adhere to surfaces, evade the host immune system, and protect against desiccation. Choice A is incorrect because prokaryotic cells lack a nucleus. Choice C is incorrect as prokaryotic cells do not have membrane-bound organelles. Choice D is incorrect as prokaryotic cells can move using structures like flagella or pili.
4. Which of the following are considered the most important molecules in biology?
- A. Carbohydrates, lipids, protein, and nucleic acids
- B. Carbohydrates, lipids, protein, and calcium
- C. Carbohydrates, lipids, protein, and sulfur
- D. Carbohydrates, lipids, protein, and iron
Correct answer: A
Rationale: The correct answer is A: Carbohydrates, lipids, protein, and nucleic acids are considered the most important molecules in biology. Carbohydrates are essential for providing energy, lipids for storing energy and forming cell membranes, proteins for various structural and functional roles, and nucleic acids (DNA and RNA) for storing genetic information. Choices B, C, and D are incorrect because while carbohydrates, lipids, and proteins are crucial biomolecules, calcium, sulfur, and iron are not considered among the most important molecules in biology.
5. What type of cells are involved in meiosis (sex cells)?
- A. Somatic Cells
- B. Gametes
- C. Zygote
- D. Diploid Cells
Correct answer: B
Rationale: The correct answer is B, Gametes. Gametes are the specialized sex cells involved in meiosis, such as sperm and eggs. Somatic cells (A) are non-reproductive cells found in the body, not involved in meiosis. Zygote (C) is the result of fertilization, formed when gametes unite. Diploid cells (D) have two sets of chromosomes, but in meiosis, gametes are produced through a process of cell division that reduces the chromosome number by half to haploid.
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