HESI A2 Biology 2024

Correct Answer: B

Rationale: The correct answer is B: Pistil. The ovary is the female reproductive part of a flower, and it is located within the pistil. The pistil consists of three main parts: the stigma, style, and ovary. The ovary is the swollen base of the pistil that contains ovules, which develop into seeds after fertilization. A: Anther is the male reproductive part of a flower, responsible for producing and releasing pollen. C: Stamen is the male reproductive organ of a flower, consisting of the anther and filament. D: Calyx is the outermost whorl of a flower, consisting of sepals that protect the flower bud.

Correct Answer: A

Rationale: The correct answer is A: Mutualism. This is because mutualism is a symbiotic relationship where both organisms benefit. In this type of relationship, both organisms obtain advantages such as food, protection, or other resources. On the other hand, choices B, C, and D are incorrect. Parasitism (B) involves one organism benefiting at the expense of the other. Commensalism (C) is a relationship where one organism benefits while the other is neither helped nor harmed. Competition (D) is a relationship where organisms compete for limited resources, resulting in one or both organisms being negatively affected. Thus, the most suitable term for a relationship where both organisms benefit is mutualism.

Correct Answer: A

Rationale: The correct answer is A: Hydrogen atoms. Saturated fats have all of their carbon atoms bonded to hydrogen atoms, with no double bonds between carbon atoms. This results in a "saturated" molecule with as many hydrogen atoms as possible. Choices B, C, and D are incorrect because saturated fats are not saturated with carbon, oxygen, or nitrogen atoms. These choices do not accurately reflect the chemical structure of saturated fats, which are primarily composed of carbon and hydrogen atoms.

Correct Answer: D

Rationale: The correct answer is D (2 females : 1 male) because in this scenario, the male offspring will inherit the X chromosome without the hemophilia gene from the mother. The female offspring will inherit one X chromosome with the hemophilia gene from the carrier mother and one X chromosome without the gene from the father. Therefore, 2 out of 3 offspring are predicted neither to carry nor manifest the disease. Choice A (0 females : 1 male) is incorrect because females can also be carriers of hemophilia. Choice B (1 female : 1 male) is incorrect because it doesn't account for the possibility of female carriers. Choice C (1 female : 0 males) is incorrect because it doesn't consider the transmission of the X chromosome from the mother to the sons.

Correct Answer: D

Rationale: To facilitate active transport through a membrane, ATP (adenosine triphosphate) is necessary. ATP provides the energy required for active transport processes to move molecules against their concentration gradient. Glucose (Choice A) and Sodium (Choice C) are often transported through active transport mechanisms, but they are not the energy source themselves. Oxygen (Choice B) is typically transported through passive diffusion due to its small size. Therefore, the correct answer is D (ATP) as it directly supplies the energy needed for active transport to occur.