HESI A2 Biology Practice Test 2024

Correct Answer: B

Rationale: The correct answer is B: Vacuoles (contractile). Contractile vacuoles are responsible for pushing excess water out of the cell through a process called osmoregulation. They maintain the cell's internal water balance by collecting and expelling water to prevent the cell from bursting due to osmotic pressure. Lysosomes (A) are involved in cellular waste disposal, mitochondria (C) are the powerhouse of the cell, and the nucleus (D) contains genetic material but does not play a role in expelling water from the cell.

Correct Answer: B

Rationale: In meiosis, sperm and egg cells produce haploid gametes with half the number of chromosomes as the parent cell. Since humans have 46 chromosomes in each somatic cell, sperm and egg cells produce 23 chromosomes each in meiosis. This ensures that when fertilization occurs, the resulting zygote has the correct diploid number of chromosomes. Choice A (46) is incorrect because somatic cells have 46 chromosomes, not gametes. Choice C (45) and D (24) are incorrect because they do not represent the correct haploid number of chromosomes produced in meiosis.

Correct Answer: B

Rationale: The correct answer is B: 23 pairs. Humans have a total of 46 chromosomes, with 23 pairs. This is because we inherit one set of 23 chromosomes from each parent. Each pair consists of one chromosome from the mother and one from the father. Choices A, C, and D are incorrect because they do not align with the established fact that humans have 23 pairs of chromosomes. It's crucial to understand the basics of human genetics to grasp the correct answer in this case.

Correct Answer: B

Rationale: The correct answer is B: Glycolysis. This is the initial step in the metabolism of food to cellular energy because it involves the breakdown of glucose to produce ATP, the cell's energy currency. Glycolysis occurs in the cytoplasm and does not require oxygen. The Citric Acid Cycle (A) and Electron Transport Chain (C) occur after glycolysis in cellular respiration. Photosynthesis (D) is the process by which plants convert light energy into chemical energy, not the metabolism of food for cellular energy.

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.