Biology HESI A2 Practice Test

Correct Answer: B

Rationale: The correct answer is B: Actual physical appearance. Phenotype refers to the observable characteristics of an individual, such as physical traits, behavior, and physiological properties. It is the result of the interaction between an individual's genetic makeup (genotype) and environmental factors. Choice A, genetic makeup, refers to genotype. Choice C, recessive alleles, specifically describes a type of gene variant and is not the definition of phenotype. Choice D, None of the above, is incorrect as the phenotype does refer to the actual physical appearance and observable traits of an individual.

Correct Answer: A

Rationale: Adenine is a purine base because it has a double-ring structure, which is a characteristic of purines. It pairs with thymine in DNA and uracil in RNA. Cytosine, thymine, and guanine are pyrimidines, which have a single-ring structure. Therefore, the correct answer is A. Cytosine, thymine, and guanine are incorrect choices as they are pyrimidines.

Correct Answer: C

Rationale: The correct answer is C: Tight junctions. Tight junctions are specialized connections between cells that form a barrier to prevent leakage of substances between cells. They are important for maintaining the integrity and function of epithelial and endothelial tissue. Separate desmosomes (choice A) are incorrect because desmosomes are anchoring junctions, not tight junctions. Ronofilaments (choice B) is not a term related to cell junctions. Fascia adherens (choice D) is incorrect as it refers to a type of adherens junction, not tight junctions.

Correct Answer: D

Rationale: The correct answer is D because optical microscopy utilizes visible light (B) to observe samples. This method does not use scanning electrons (A) as in electron microscopy. While some optical microscopes may use dyes (C), it is not a defining characteristic. Therefore, D is correct as it acknowledges both the use of visible light and the potential use of dyes in optical microscopy.

Correct Answer: B

Rationale: Proteins are the best choice to increase muscle mass and strength because they are essential for muscle repair and growth. Proteins are made up of amino acids, which are the building blocks of muscles. Consuming enough protein provides the body with the necessary nutrients to repair and build muscle tissue. Carbohydrates are primarily for energy, lipids are for long-term energy storage, and nucleic acids are not directly involved in muscle growth. Therefore, proteins are the most suitable option for athletes looking to increase muscle mass and strength.