HESI A2 Biology Practice Test

Correct Answer: C

Rationale: The correct answer is C: Prometaphase. This phase of mitosis is characterized by the disintegration of the nuclear envelope. During prometaphase, the breakdown of the nuclear envelope allows the spindle fibers to access the chromosomes. This is crucial for the proper alignment and separation of the chromosomes during mitosis. In prophase (choice A), the nuclear envelope starts to break down but is not fully disintegrated. In metaphase (choice D), the nuclear envelope is already broken down, and the chromosomes are aligned at the metaphase plate. Therefore, prometaphase is the specific phase where the nuclear envelope completely disintegrates, making it the correct answer.

Correct Answer: A

Rationale: The correct answer is A: Dominant. When a genotype consists of a dominant and a recessive allele, the dominant allele will determine the phenotype. This is because the presence of a dominant allele masks the expression of the recessive allele. In this case, the dominant allele will be expressed phenotypically, resulting in a trait that is like the dominant allele. Choices B, C, and D are incorrect because in this scenario, the dominant allele will be the one that is visibly expressed, not the recessive allele, both alleles, or neither allele.

Correct Answer: A

Rationale: The correct answer is A: Connective tissue. Fat is a type of adipose tissue, which is a specialized form of connective tissue that stores energy in the form of fat cells. Connective tissue provides support, structure, and insulation to the body. Muscle tissue (B) is responsible for movement, nervous tissue (C) transmits signals, and epithelial tissue (D) forms protective barriers. Fat does not perform these functions, hence choices B, C, and D are incorrect.

Correct Answer: B

Rationale: To focus an image using a compound microscope, adjusting the fine adjustment is correct as it allows for precise focusing when switching magnifications. Coarse adjustment is only used initially to bring the specimen into view, while the stage adjustment is used to center the specimen. Therefore, B is correct as it ensures clear and sharp image focus without unnecessary readjustments. Choices A and C are incorrect as they do not address the specific need for precise focusing when changing magnifications, leading to potential blurriness or loss of focus in the image.

Correct Answer: D

Rationale: The correct answer is D: They are denoted Aa. Heterozygous traits refer to the presence of different alleles at a specific gene locus. In this case, A and a represent two different alleles for the same trait. When an individual is heterozygous, one allele is dominant (A) and the other is recessive (a). Therefore, the correct notation for a heterozygous trait is Aa. Option A is incorrect because heterozygous traits are not haploid (having one set of chromosomes), but diploid (having two sets). Option B is incorrect as it denotes a homozygous dominant genotype. Option C is incorrect as it denotes a homozygous recessive genotype.