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: C

Rationale: The correct answer is C: Capillaries. Capillaries are found in both open and closed circulatory systems as they are the smallest blood vessels where nutrient and gas exchange occurs. In open systems, capillaries allow direct exchange with tissues, while in closed systems, they connect arteries and veins. Arteries (A) are found in closed systems, not open systems. Red blood cells (B) are present in both systems, but this question specifically asks for a structure, not a component. Immune cells (D) are not typically part of the circulatory system.

Correct Answer: D

Rationale: The correct answer is D: Ethyl alcohol fermentation. Beer production involves the conversion of sugars into ethyl alcohol and carbon dioxide by yeast through the process of fermentation. Lactic acid fermentation (A) produces lactic acid, not ethyl alcohol. Acetic acid fermentation (B) produces acetic acid, not ethyl alcohol. Propionic acid fermentation (C) produces propionic acid, not ethyl alcohol. Therefore, option D is the only choice that aligns with the process of beer production.

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: Sucrose. Sucrose is a disaccharide composed of one molecule of glucose and one molecule of fructose. It is formed by a condensation reaction between these two monosaccharides. Fructose (choice B), glucose (choice C), and galactose (choice D) are all monosaccharides, not disaccharides. Therefore, they are incorrect choices for this question.