Biology HESI A2 2024

Correct Answer: B

Rationale: The correct answer is B: Precise. The measurements are precise because they are consistent with each other, showing low variability. However, they are not accurate as they do not reflect the true value of 30 g. Option A is incorrect because accuracy refers to how close measurements are to the true value. Option C is incorrect as the measurements are not accurate. Option D is incorrect because the measurements are precise but not accurate.

Correct Answer: B

Rationale: The correct answer is B: shape. Enzyme activity is highly dependent on the enzyme's specific three-dimensional shape. Changes in temperature and pH can disrupt the hydrogen bonds and other interactions that maintain the enzyme's shape, leading to denaturation. This alters the active site of the enzyme, making it unable to bind effectively with its substrate and catalyze the reaction. Incorrect options: A: Acidity is related to pH, which can affect enzyme activity, but the primary reason for the alteration is the change in shape. C: While changes in pH can affect the chemical properties of enzymes, the main impact on enzyme activity is the alteration of shape. D: Substrate is the molecule upon which the enzyme acts, and while changes in substrate concentration can affect enzyme activity, alterations in temperature and pH primarily impact the enzyme's shape, not the substrate itself.

Correct Answer: A

Rationale: The correct answer is A: It will swell and possibly burst. This is because the solution outside the cell is hypotonic compared to the inside, causing water to move into the cell through osmosis, leading to swelling. If the influx of water is excessive, the cell may burst. Explanation for other choices: B: It will shrivel and shrink - This would happen if the solution outside the cell is hypertonic, causing water to move out of the cell, leading to shrinkage. C: It will maintain its current size - In an isotonic solution, there would be no net movement of water, so the cell would maintain its size. D: It will grow a supportive cell wall - Cell walls are typically found in plant cells and serve different functions. The growth of a cell wall is not directly related to the concentration of solutes inside and outside the cell.

Correct Answer: B

Rationale: The correct answer is B: Parasitism. In parasitism, one organism benefits (the pneumonia bacterium) at the expense of the other (the human). The bacterium causes harm to the human by causing pneumonia, which is detrimental. In mutualism (A), both organisms benefit; in commensalism (C), one benefits while the other is unaffected; in competition (D), both organisms are harmed by vying for the same resources. Hence, parasitism is the most fitting description of the relationship between the pneumonia bacterium and the human in this scenario.

Correct Answer: D

Rationale: Correct Answer: D - DNA cannot be altered. Rationale: 1. DNA can be altered through mutations, recombination, and other genetic processes. 2. DNA repair mechanisms exist to correct alterations. 3. Alterations in DNA are essential for evolution and genetic diversity. Summary: A: True - RNA is single-stranded. B: True - RNA contains uracil. C: True - DNA codes for proteins.