HESI A2 Biology Practice Test 2024

Correct Answer: B

Rationale: The correct answer is B: Cell. Cells are the fundamental unit of life because they are the basic building blocks of all living organisms. Cells carry out essential functions such as metabolism, growth, and reproduction. Tissues (C) are made up of cells, organs (D) are made up of tissues, and atoms (A) are the smallest unit of matter and are not considered the fundamental unit of life. Therefore, the correct choice is B as it represents the starting point of all living organisms.

Correct Answer: B

Rationale: The correct answer is B: Nucleotides. DNA is made up of nucleotides, which are composed of a sugar molecule, a phosphate group, and a nitrogenous base. This structure forms the double helix shape of DNA. Proteins (option A) are not the building blocks of DNA, but they are involved in various cellular functions. Lipids (option C) and carbohydrates (option D) are not the primary components of DNA. Overall, nucleotides are the fundamental units of DNA, making option B the correct answer.

Correct Answer: B

Rationale: The correct answer is B: Ribosomes. Ribosomes are the organelles responsible for protein synthesis. They are either free-floating in the cytoplasm or attached to the endoplasmic reticulum. Ribosomes read the mRNA and assemble amino acids into proteins during the process of translation. The other choices (A: Endoplasmic Reticulum, C: Lysosomes, D: Vacuoles) are incorrect because the endoplasmic reticulum is involved in protein processing and transport, lysosomes are involved in digestion and waste removal, and vacuoles are involved in storage and maintaining cell structure, not protein synthesis.

Correct Answer: B

Rationale: The correct answer is B: Gametes. Meiosis is the process of cell division that produces gametes (sex cells) such as sperm and eggs. During meiosis, a diploid cell undergoes two rounds of division to produce four haploid gametes. Somatic cells (choice A) are non-reproductive cells in the body. Zygote (choice C) is a fertilized egg formed by the fusion of sperm and egg, not involved in meiosis. Diploid cells (choice D) have two sets of chromosomes and are the starting cells for meiosis, not the end products. Therefore, gametes are the specific cells involved in meiosis.

Correct Answer: B

Rationale: The correct answer is B: Cell Membrane. The cell membrane is the most important component contributing to protection, communication, and the passage of substances. It acts as a barrier, protecting the cell from external threats. It also regulates the passage of substances in and out of the cell through selective permeability. Additionally, the cell membrane contains receptors and proteins that facilitate cell communication. A: Cytoplasm is important for various cellular functions but does not directly contribute to protection, communication, or substance passage. C: Cytoskeleton provides structural support but does not primarily contribute to protection, communication, or substance passage. D: Vacuole plays a role in storage and waste management but is not as critical for protection, communication, or substance passage as the cell membrane.