HESI A2
Biology HESI A2 2024
1. What is the purpose of phloem tissue in plant stems?
- A. It conducts water up through the stem.
- B. It conducts the energy of light to leaves.
- C. It conducts food throughout the plant.
- D. It conducts carbon dioxide throughout the plant.
Correct answer: C
Rationale: The purpose of phloem tissue in plant stems is to conduct food, particularly sugars produced in the leaves during photosynthesis, throughout the plant. The phloem transports these organic compounds to various parts of the plant where they are needed for growth and energy. Choice A is incorrect because water is primarily transported by xylem tissue, not phloem. Choice B is incorrect as the energy of light is captured by chlorophyll in the process of photosynthesis, not conducted by phloem. Choice D is incorrect because carbon dioxide is mainly absorbed through the leaves and transported to other parts of the plant through diffusion, not by phloem.
2. The scientific name for a house cat is Felis catus. This indicates the house cat’s ___________ and ___________.
- A. kingdom; family
- B. order; subspecies
- C. phylum; class
- D. genus; species
Correct answer: D
Rationale: The scientific name for an organism consists of its genus and species. In this case, 'Felis' refers to the genus, while 'catus' refers to the species, thus indicating the house cat's genus and species as Felis catus. Therefore, the correct answer is 'D.' Choices A, B, and C are incorrect because a scientific name does not include information about the kingdom, family, order, subspecies, phylum, or class of an organism.
3. How are lipids different from other organic molecules?
- A. They are indivisible.
- B. They are not water soluble.
- C. They contain zinc.
- D. They form long proteins.
Correct answer: B
Rationale: The correct answer is B: 'They are not water soluble.' Lipids are not water-soluble, which distinguishes them from other organic molecules. Choice A is incorrect because lipids are not indivisible; they can be broken down into fatty acids and glycerol. Choice C is incorrect as lipids do not necessarily contain zinc; they are a diverse group of molecules. Choice D is incorrect because lipids do not form long proteins; proteins are made up of amino acids, not lipids.
4. How is mitosis different from meiosis?
- A. Mitosis is the process by which body cells are formed.
- B. Meiosis creates cells with half the chromosomes of the parent cell.
- C. Telophase occurs in both mitosis and meiosis.
- D. Spermatogenesis and oogenesis occur via meiosis.
Correct answer: B
Rationale: Meiosis is the type of cell division that creates cells with half the number of chromosomes compared to the parent cell. This is essential for sexual reproduction as it ensures that when the sex cells (sperm and egg) combine during fertilization, the resulting offspring has the correct number of chromosomes. In contrast, mitosis results in two identical daughter cells with the same number of chromosomes as the parent cell. Choice A is incorrect because mitosis is responsible for the division of body cells, not sex cells. Choice C is incorrect because telophase is a phase that occurs in both mitosis and meiosis. Choice D is incorrect because spermatogenesis and oogenesis involve meiosis, not mitosis.
5. Cells that line the inner or outer surfaces of organs or body cavities are often linked together by intimate physical connections. These connections are referred to as ______.
- A. Separate desmosomes
- B. Ronofilaments
- C. Tight junctions
- D. Fascia adherens
Correct answer: C
Rationale: The correct answer is C: Tight junctions. Tight junctions, also known as zonula occludens, are the intimate physical connections between cells that line the inner or outer surfaces of organs or body cavities. These junctions form a virtually impermeable barrier to fluid, creating a tight seal between the cells. This helps in maintaining the integrity and function of the tissue as well as regulating the movement of substances across the cell layer. Choice A, Separate desmosomes, are cell structures that provide strong adhesion between cells but do not create a barrier to fluid. Choice B, Ronofilaments, is not a term used to describe the connections between cells. Choice D, Fascia adherens, are another type of cell junction involved in cell adhesion, but they are different from tight junctions in terms of their structure and function.
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