Biology HESI A2 Practice Exam

Correct Answer: C

Rationale: The correct answer is C: One daughter may have the disease. This is because Duchenne muscular dystrophy is a recessive sex-linked trait carried on the X chromosome. In this scenario, the unaffected father will pass his Y chromosome to his sons, making them unaffected carriers. The mother, being a carrier, has a 50% chance of passing the affected X chromosome to each daughter, resulting in a 50% chance that one daughter may have the disease. The other choices are incorrect because both sons cannot inherit the disease from the mother, and both daughters cannot carry the disease as they would either be unaffected carriers or affected themselves.

Correct Answer: A

Rationale: Condensation is the process in which water vapor cools down and transforms into liquid water. This occurs when the temperature of the air decreases, causing the water vapor to lose energy and condense into liquid droplets. Sublimation is the direct transition from solid to gas phase, not liquid. Precipitation is the process of water falling from the sky in various forms, such as rain or snow, but it does not specifically refer to the transformation of water vapor to liquid. Absorption involves one substance taking in another substance, which is not the process of water vapor becoming liquid water. Therefore, the correct answer is A: condensation.

Correct Answer: C

Rationale: The correct answer is C because observing the birds in the wild and recording them in predawn and postdawn hours every day for six months allows the researcher to capture their vocalization pattern accurately. This method ensures that the data collected cover a wide range of time periods and seasons, providing a comprehensive understanding of when the birds vocalize the most. Choice A is incorrect because observing birds in captivity may not reflect their natural behavior, and recording at two-hour intervals might miss the peak vocalization times around dawn. Choice B is incorrect because observing the birds in the wild at one-hour intervals in several seasons could provide useful data but may not specifically target the hypothesis about vocalization around dawn. Choice D is incorrect because comparing recordings of different species does not directly address the hypothesis about the vocalization pattern of the particular bird species around dawn.

Correct Answer: C

Rationale: The correct answer is C: Commensalism. In this scenario, the cattle benefit from having the insects controlled by the cattle egrets, while the cattle egrets benefit from the insects stirred up by the cattle. The cattle are unaffected by the presence of the egret, making it a one-sided relationship where one species benefits (egrets) while the other is neither harmed nor helped (cattle). This is a classic example of commensalism, where one species benefits while the other remains unaffected. A: Mutualism refers to a relationship where both species benefit, which is not the case here. B: Parasitism involves one species benefiting while the other is harmed, which is not the case in this scenario. D: Competition occurs when two or more species compete for limited resources, which is not the case here as the cattle and cattle egrets are not competing but rather benefiting from each other's presence.

Correct Answer: A

Rationale: The correct answer is A: Anther. The anther is the part of the plant responsible for producing pollen. It is located at the top of the stamen, one of the male reproductive parts of a flower. Pollen contains the male gametes necessary for fertilization. The other choices, B: Style, C: Stigma, and D: Pistil, are all parts of the female reproductive system of a flower. The style is the tube connecting the stigma to the ovary, the stigma is the sticky part that receives pollen, and the pistil is the entire female reproductive structure. Therefore, they are not involved in the production of pollen.