HESI A2 Biology 2024

Correct Answer: A

Rationale: The correct answer is A because it involves testing the impact of radiation from a single cell phone on the temperature of water in a test tube in a controlled manner. By letting the phone ring for two minutes and recording the temperature before and after, the researcher can isolate the effects of radiation. Choice B introduces additional variables by varying the ringing time, making it difficult to determine the specific impact of radiation. Choice C introduces the factor of different cell phone brands, which may have varying radiation levels and could confound the results. Choice D also introduces multiple variables by using different ringing times and phone brands, making it challenging to attribute any temperature changes solely to radiation from the cell phones. Therefore, choice A is the most appropriate as it ensures a controlled experiment to directly test the hypothesis regarding the impact of cell phone radiation on water temperature.

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: A

Rationale: The correct answer is A: Red cedar. Gymnosperms are a group of seed-producing plants that do not have enclosed seeds. Red cedar is a gymnosperm because it produces naked seeds that are not enclosed in a fruit or ovary. Japanese cherry (B), Flowering dogwood (C), and American chestnut (D) are examples of angiosperms, which are seed-producing plants with enclosed seeds within a fruit or ovary. Therefore, they are not examples of gymnosperms.

Correct Answer: B

Rationale: The correct answer is B: Earthworm. Earthworms have an open circulatory system where the blood is pumped by the rhythmic contraction of vessels and flows among the tissues. This system allows for direct exchange of nutrients and waste products with body tissues. The other choices (A, C, D) have a closed circulatory system where blood is contained within vessels and does not directly contact body tissues, making them incorrect options.

Correct Answer: C

Rationale: In telophase, the correct answer, new nuclear membranes form around sets of chromosomes. During this phase, the chromosomes become enclosed within their own distinct nuclei. Prophase (A) is the initial phase of mitosis where chromosomes condense but nuclear membranes have not yet formed. Anaphase (B) is when chromosomes are pulled apart towards opposite poles, with no nuclear membrane formation. Interphase (D) is not a phase of mitosis, but the resting phase between cell divisions. Therefore, the correct answer is C as it specifically describes the formation of new nuclear membranes around chromosomes in telophase.