HESI A2 Biology Practice Test 2024

Correct Answer: B

Rationale: The magnification of an ocular lens on a microscope is typically 10x. This is because the ocular lens standard magnification is 10x, which, when combined with the objective lens magnification (e.g., 4x, 40x, 100x), gives the total magnification. Therefore, the correct answer is B (10x). Choice A (4x) is incorrect as it is typically the magnification of a lower-powered objective lens, not the ocular lens. Choice C (40x) and Choice D (100x) are incorrect as they are higher magnifications typically associated with objective lenses, not the ocular lens.

Correct Answer: C

Rationale: The correct answer is C: Cytoskeleton. The cytoskeleton provides structural support to the cell, helps maintain its shape, and allows it to adapt to external stimuli. It is composed of microfilaments, intermediate filaments, and microtubules. Microfilaments (choice A) play a role in cell movement but are not primarily responsible for maintaining cell shape. Cytoplasm (choice B) is the gel-like substance within the cell where organelles are suspended, but it does not directly contribute to maintaining cell shape. Centrioles (choice D) are involved in cell division and organization of microtubules, but they do not primarily help the cell maintain its shape and adapt.

Correct Answer: B

Rationale: The correct answer is B: Vacuoles (contractile). Contractile vacuoles are responsible for pushing excess water out of the cell through a process called osmoregulation. They maintain the cell's internal water balance by collecting and expelling water to prevent the cell from bursting due to osmotic pressure. Lysosomes (A) are involved in cellular waste disposal, mitochondria (C) are the powerhouse of the cell, and the nucleus (D) contains genetic material but does not play a role in expelling water from the cell.

Correct Answer: B

Rationale: The correct answer is B: DNA. DNA, or deoxyribonucleic acid, is the molecule that stores the genetic code for each person. It is located in the cell nucleus and organized into structures called chromosomes. DNA contains the instructions for building and maintaining an organism, including traits and characteristics. RNA (choice A) is involved in protein synthesis but does not store the complete genetic information. The nucleus (choice C) is the cellular organelle where DNA is located, not the genetic code itself. Chromosomes (choice D) are made up of DNA and proteins and contain the genetic material in a condensed form. Therefore, the correct choice is DNA as it is the primary storage location for the genetic code.

Correct Answer: B

Rationale: The magnification of an ocular lens on a microscope is typically 10x. This is because the ocular lens standard magnification is 10x, which, when combined with the objective lens magnification (e.g., 4x, 40x, 100x), gives the total magnification. Therefore, the correct answer is B (10x). Choice A (4x) is incorrect as it is typically the magnification of a lower-powered objective lens, not the ocular lens. Choice C (40x) and Choice D (100x) are incorrect as they are higher magnifications typically associated with objective lenses, not the ocular lens.