Biology HESI A2 Practice Exam

Correct Answer: A

Rationale: The correct answer is A: Sulfate. Nucleic acids consist of nucleotides, which are composed of a phosphate group, a sugar molecule (carbon), and a nitrogenous base. Sulfate is not a component of nucleic acids. Phosphate is essential for forming the backbone of the nucleic acid molecule. Carbon is present in the sugar component of the nucleotide. Nitrogen is found in the nitrogenous bases that pair in DNA and RNA. Therefore, among the choices, only sulfate is not a part of nucleic acids.

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: A

Rationale: The correct answer is A: Sulfate. Nucleic acids consist of nucleotides, which are composed of a phosphate group, a sugar molecule (carbon), and a nitrogenous base. Sulfate is not a component of nucleic acids. Phosphate is essential for forming the backbone of the nucleic acid molecule. Carbon is present in the sugar component of the nucleotide. Nitrogen is found in the nitrogenous bases that pair in DNA and RNA. Therefore, among the choices, only sulfate is not a part of nucleic acids.

Correct Answer: C

Rationale: The correct answer is C (12 chromosomes). During mitosis, a cell replicates its chromosomes and divides into two daughter cells, each containing the same number of chromosomes as the parent cell. Since the parent cell has 12 chromosomes, each daughter cell will also have 12 chromosomes after division. Choice A (3 chromosomes) and B (6 chromosomes) are incorrect because they do not account for the full set of chromosomes in the parent cell. Choice D (24 chromosomes) is incorrect as it would only be the total number of chromosomes if each daughter cell received the full set, which is not the case in mitosis.

Correct Answer: A

Rationale: The correct answer is A: transcription. Transcription is the process where RNA is synthesized from a DNA template by RNA polymerase. It involves the synthesis of mRNA, tRNA, or rRNA. During transcription, the DNA double helix is unwound, and RNA polymerase reads the DNA sequence and creates a complementary RNA strand. This process occurs in the nucleus in eukaryotic cells and in the cytoplasm in prokaryotic cells. Choice B, synthesis, is a general term that does not specifically refer to the process of RNA synthesis from DNA. Choice C, translation, is the process where mRNA is used to build a polypeptide chain at the ribosome, not the synthesis of RNA from DNA. Choice D, replication, is the process of copying DNA to produce an identical copy of the original DNA molecule, not the synthesis of RNA from DNA.