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: B

Rationale: The correct answer is B: Cell wall. Plant cells have a rigid cell wall made of cellulose, which provides structural support and protection. Animal cells lack cell walls and instead have a flexible cell membrane for support. Choices A, C, and D (Cell membrane, Ribosome, Chloroplast) are present in both plant and animal cells. The cell membrane controls what enters and leaves the cell, ribosomes are responsible for protein synthesis, and chloroplasts are the site of photosynthesis in plant cells.

Correct Answer: C

Rationale: The correct answer is C. Antibiotics do not cause more bacteria to grow; in fact, they aim to kill or inhibit the growth of bacteria. Antibiotics interfere with the bacteria's ability to survive by targeting specific processes essential for their growth and reproduction (A). They can affect how bacteria multiply by inhibiting cell wall synthesis, protein synthesis, or DNA replication (B). Lastly, antibiotics specifically target bacteria and do not work on viruses or fungi (D). Therefore, choice C is the only statement that is not true about antibiotics.

Correct Answer: B

Rationale: The correct answer is B: heterozygous. In a heterozygous situation, an individual carries two different alleles for a particular gene, resulting in different forms of the allele. This creates genetic diversity and can lead to varying phenotypic expressions. The term phenotype (A) refers to the physical characteristics of an organism, not specifically related to different forms of alleles. Homolog (C) refers to chromosomes that are similar in structure and function but not necessarily different forms of alleles. Homozygous (D) describes a situation where an individual carries two identical alleles for a gene, which does not involve different forms of alleles.

Correct Answer: A

Rationale: Enzymes can catalyze reactions by lowering the activation energy required for the reaction to occur, thus increasing the reaction rate. This is achieved through the formation of enzyme-substrate complexes. Inhibition refers to the process of preventing enzyme activity, which is contrary to the function of enzymes. Stopping reactions is not the role of enzymes. Therefore, the correct answer is A: Catalyze.