HESI A2 Biology 2024

Correct Answer: B

Rationale: The correct answer is B: Amino acids bond. In the final step of protein synthesis, amino acids bond together to form a polypeptide chain. This process occurs on the ribosomes, where transfer RNA delivers the specific amino acids according to the codons on the messenger RNA. DNA unzipping (A) happens during transcription, while transfer RNA bonding to messenger RNA (C) is part of the initiation step of translation. Messenger RNA moving to ribosomes (D) is essential for protein synthesis but is not the final step where amino acids bond.

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: B

Rationale: The correct answer is B: Virus. A virus is a structure composed of a core of nucleic acid (either RNA or DNA) surrounded by a protein coat. This structure allows viruses to infect host cells and replicate. Blue-green algae (option C) are photosynthetic organisms composed of cells with chlorophyll. RNA (option A) is a type of nucleic acid but does not necessarily have a protein coat. Saprophytes (option D) are organisms that obtain nutrients from decaying organic matter and do not typically have a core of nucleic acid surrounded by a protein coat.

Correct Answer: C

Rationale: Commensalism is the correct answer because it is a symbiotic relationship where one organism benefits while the other is neither benefited nor harmed. This is different from mutualism where both organisms benefit, parasitism where one benefits at the expense of the other, and competition where both organisms are negatively affected by vying for resources. Therefore, in commensalism, one organism benefits while the other remains unaffected, making it the most fitting choice for the scenario described.

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.