Biology HESI A2 2024

Correct Answer: A

Rationale: Beeswax is a lipid because it is a natural substance primarily composed of esters of fatty acids and long-chain alcohols. Lipids are hydrophobic molecules that include fats, oils, and waxes. Beeswax fits this description due to its insolubility in water and its role in providing a protective barrier for bees' hives. Carbohydrates are composed of sugars, proteins are made up of amino acids, and nucleic acids are the building blocks of DNA and RNA. Therefore, choices B, C, and D are incorrect as they do not align with the chemical composition and characteristics of beeswax.

Correct Answer: D

Rationale: Correct Answer: D - DNA cannot be altered. Rationale: 1. DNA can be altered through mutations, recombination, and other genetic processes. 2. DNA repair mechanisms exist to correct alterations. 3. Alterations in DNA are essential for evolution and genetic diversity. Summary: A: True - RNA is single-stranded. B: True - RNA contains uracil. C: True - DNA codes for proteins.

Correct Answer: C

Rationale: The correct answer is C: thymine. In DNA, adenine always pairs with thymine through two hydrogen bonds. This is a fundamental principle known as Chargaff's rule, where A pairs with T and C pairs with G. Thymine is a pyrimidine base, complementing adenine, which is a purine base. Therefore, thymine is the most suitable choice for adenine in a DNA strand. Choices A, B, and D are incorrect because adenine does not pair with cytosine (A), uracil (B), or guanine (D) in DNA.

Correct Answer: B

Rationale: During interphase, the cell prepares for division by replicating its DNA, including the chromosomes. This occurs before the actual cell division stages of mitosis or meiosis. Prophase is the stage where chromosomes condense, not replicate. Anaphase is when sister chromatids separate, and telophase is the final stage where chromosomes de-condense. Therefore, the correct answer is B (Interphase) as it is the specific phase where chromosome replication occurs.

Correct Answer: C

Rationale: The correct answer is C because yeast carries out fermentation, producing ethanol and carbon dioxide. During fermentation, yeast breaks down sugars in the dough into ethanol and carbon dioxide gas. The carbon dioxide gas gets trapped in the dough, causing it to rise. Choice A is incorrect because yeast does not engage in photosynthesis. Choice B is incorrect because yeast does not carry out photosynthesis at all. Choice D is incorrect because yeast primarily produces carbon dioxide through fermentation, not aerobic respiration.