HESI A2 Biology Practice Test 2024

Correct Answer: B

Rationale: The correct answer is B: DNA. DNA, or deoxyribonucleic acid, is the molecule that stores the genetic code for each person. It is located in the cell nucleus and organized into structures called chromosomes. DNA contains the instructions for building and maintaining an organism, including traits and characteristics. RNA (choice A) is involved in protein synthesis but does not store the complete genetic information. The nucleus (choice C) is the cellular organelle where DNA is located, not the genetic code itself. Chromosomes (choice D) are made up of DNA and proteins and contain the genetic material in a condensed form. Therefore, the correct choice is DNA as it is the primary storage location for the genetic code.

Correct Answer: B

Rationale: The main function of ribosomes is protein synthesis. Ribosomes are responsible for translating the genetic information encoded in mRNA into proteins. This process involves decoding the mRNA sequence and linking amino acids together to form a protein. Ribosomes do not participate in DNA replication (Choice A), lipid breakdown (Choice C), or cell division (Choice D). DNA replication occurs in the nucleus, lipid breakdown is carried out by enzymes in the cytoplasm, and cell division involves processes such as mitosis and cytokinesis. Therefore, the correct answer is B because ribosomes are directly involved in protein synthesis.

Correct Answer: B

Rationale: The main component of blood plasma is water. Plasma is the liquid component of blood, making up about 55% of total blood volume. It serves as a carrier for various substances such as nutrients, waste products, hormones, and electrolytes. Water helps maintain blood volume, regulates body temperature, and facilitates the transport of essential components throughout the body. Proteins, red blood cells, and platelets are also present in blood plasma but are not the main component. Proteins play a role in clotting and immune function, red blood cells carry oxygen, and platelets aid in blood clotting. Water is the correct answer as it is the primary constituent of blood plasma.

Correct Answer: B

Rationale: The correct answer is B: Mitochondria. Mitochondria are known as the powerhouse of the cell as they produce energy through the process of respiration. They contain enzymes responsible for converting nutrients into ATP, the energy currency of the cell. The nucleus (A) is responsible for storing genetic material, Golgi Apparatus (C) is involved in protein processing and packaging, and Chloroplasts (D) are responsible for photosynthesis in plant cells, not respiration.

Correct Answer: C

Rationale: The correct answer is C: 4. Mitosis consists of four phases: prophase, metaphase, anaphase, and telophase. In prophase, chromosomes condense. In metaphase, chromosomes align at the cell equator. In anaphase, sister chromatids separate and move to opposite poles. In telophase, the nuclear envelope reforms. Choices A, B, and D are incorrect because mitosis is a complex process that involves more than 2 or 3 phases.