HESI A2
HESI A2 Biology Practice Test
1. Why does cytokinesis happen?
- A. DNA can duplicate
- B. Organelles can convert energy
- C. Bacteria can be killed
- D. Daughter cells can divide
Correct answer: D
Rationale: Cytokinesis happens at the end of mitosis to physically separate the newly formed daughter cells. This allows the cell to divide into two separate daughter cells, each containing a complete set of genetic material (DNA) and organelles. The purpose of cytokinesis is to ensure that each daughter cell receives the necessary components to function independently. Choices A, B, and C are incorrect because cytokinesis does not directly involve DNA duplication, organelles converting energy, or killing bacteria.
2. Which of the following are considered the most important molecules in biology?
- A. Carbohydrates, lipids, protein, and nucleic acids
- B. Carbohydrates, lipids, protein, and calcium
- C. Carbohydrates, lipids, protein, and sulfur
- D. Carbohydrates, lipids, protein, and iron
Correct answer: A
Rationale: The correct answer is A: Carbohydrates, lipids, protein, and nucleic acids are considered the most important molecules in biology. Carbohydrates are essential for providing energy, lipids for storing energy and forming cell membranes, proteins for various structural and functional roles, and nucleic acids (DNA and RNA) for storing genetic information. Choices B, C, and D are incorrect because while carbohydrates, lipids, and proteins are crucial biomolecules, calcium, sulfur, and iron are not considered among the most important molecules in biology.
3. Tonicity refers to the movement of:
- A. Water
- B. Solute
- C. Cells
- D. None of the above
Correct answer: A
Rationale: Tonicity refers to the movement of water across a membrane in response to differences in solute concentration. In a hypertonic solution, where there is a higher concentration of solutes outside the cell, water will move out of the cell to try to reach equilibrium. In a hypotonic solution, where there is a lower concentration of solutes outside the cell, water will move into the cell to balance the concentrations. Cells and solutes themselves do not actively move in response to tonicity; it is the movement of water that helps achieve equilibrium. Therefore, the correct answer is water (Choice A). Choices B, C, and D are incorrect as tonicity specifically refers to water movement and not the movement of solutes, cells, or none of the above.
4. The difference between diploid and haploid is as follows:
- A. Diploid organisms are multicellular
- B. Diploid cells are somatic
- C. Diploid cells have two sets of homologous chromosomes
- D. More than one of the above is true
Correct answer: D
Rationale: Option B correctly states that diploid cells are somatic cells that make up the body tissues and organs in an organism, while haploid cells are gametes involved in sexual reproduction. Option C accurately differentiates diploid and haploid cells based on their chromosome sets – diploid cells have two sets of homologous chromosomes (one from each parent), whereas haploid cells have one set of unpaired chromosomes. Therefore, the correct choice is D, as both statements in options B and C are accurate descriptions of the differences between diploid and haploid cells. Option A is incorrect because diploid and haploid refer to the number of sets of chromosomes in a cell, not whether the organism is multicellular or not.
5. Humans, or Homo sapiens, are part of the family ___________.
- A. Animalia
- B. Hominidae
- C. Mammalia
- D. Chordata
Correct answer: B
Rationale: Humans, or Homo sapiens, are part of the family Hominidae, which includes great apes such as gorillas, chimpanzees, and orangutans. This family belongs to the order Primates within the class Mammalia. Choice A (Animalia) refers to the animal kingdom, not the family of humans. Choice C (Mammalia) is the class to which the family Hominidae belongs, not the family itself. Choice D (Chordata) is the phylum to which humans and other animals with a notochord belong, not the specific family.
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