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HESI A2

Biology HESI A2 Practice Test

1. Which of the following is true of optical microscopy?

Correct answer: D

Rationale: The correct answer is D, 'More than one of the above is true.' Optical microscopy utilizes visible light (Choice B) and often involves the use of dyes for samples (Choice C). Using dyes helps enhance contrast, making it easier to visualize the structures being observed. Choice A is incorrect as optical microscopy does not utilize scanning electrons, but rather visible light.

2. Which statement is untrue?

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.

3. During which phase is the chromosome number reduced from diploid to haploid?

Correct answer: D

Rationale: The correct answer is 'meiosis I.' During meiosis I, the chromosome number is reduced from diploid to haploid through two rounds of division. Choice A ('S phase') is incorrect as the S phase is part of the cell cycle where DNA is replicated. Choice B ('interphase') is also incorrect as interphase is the phase where the cell prepares for division. Choice C ('mitosis') is incorrect as mitosis is a process where a diploid cell divides to produce two identical diploid daughter cells, maintaining the chromosome number.

4. What process do cells in the tip of a plant’s root undergo to increase in number?

Correct answer: D

Rationale: Cells in the tip of a plant's root undergo the process of mitosis to increase in number. Mitosis is a type of cell division that results in two daughter cells with the same number of chromosomes as the parent cell. This process allows for growth and maintenance of tissues in plants by producing new cells through division. Choice A, Meiosis, is incorrect as meiosis is a type of cell division that reduces the number of chromosomes in cells to produce gametes. Choice B, Cytokinesis, is incorrect as it is the division of the cytoplasm following cell division. Choice C, Fractioning, is not a biological process related to cell division.

5. What is the most important component of the cell, contributing to protection, communication, and the passage of substances?

Correct answer: B

Rationale: The cell membrane is the correct answer. It is the most important component of the cell as it provides protection, facilitates communication, and regulates the passage of substances in and out of the cell. The cytoplasm (Choice A) is the gel-like substance within the cell that holds organelles, but it is not primarily responsible for the functions mentioned in the question. The cytoskeleton (Choice C) provides structural support to the cell but is not directly involved in protection, communication, or substance passage. Vacuoles (Choice D) are responsible for storage and maintaining turgor pressure but do not play a primary role in the functions specified in the question.

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