HESI A2
HESI A2 Biology Practice Test 2024
1. What is the most important component of the cell, contributing to protection, communication, and the passage of substances?
- A. Cytoplasm
- B. Cell Membrane
- C. Cytoskeleton
- D. Vacuole
Correct answer: B
Rationale: The cell membrane is the correct answer. It is the most important component of the cell as it provides protection, facilitates communication, and regulates the passage of substances in and out of the cell. The cytoplasm (Choice A) is the gel-like substance within the cell that holds organelles, but it is not primarily responsible for the functions mentioned in the question. The cytoskeleton (Choice C) provides structural support to the cell but is not directly involved in protection, communication, or substance passage. Vacuoles (Choice D) are responsible for storage and maintaining turgor pressure but do not play a primary role in the functions specified in the question.
2. As cattle graze, cattle egrets consume the insects they stir up. This is an example of ___________.
- A. Mutualism
- B. Parasitism
- C. Commensalism
- D. Competition
Correct answer: C
Rationale: Commensalism is a relationship between two species in which one benefits without affecting the other species. In this scenario, the cattle egrets benefit from the insects stirred up by cattle while the cattle are not significantly impacted by the presence of the egrets. The egrets obtain food easily, and the cattle are neither harmed nor helped by the egrets' presence, making it an example of commensalism. Mutualism involves both species benefiting, parasitism involves one species benefiting at the expense of the other, and competition involves both species being negatively affected by their interactions, none of which apply to the relationship between cattle and cattle egrets in this context.
3. Where is the genetic code for each person stored?
- A. RNA
- B. DNA
- C. Nucleus
- D. Chromosomes
Correct answer: B
Rationale: The genetic code for each person is stored in DNA. DNA carries all the hereditary information, including unique traits and characteristics. RNA (Choice A) is involved in protein synthesis but does not hold the complete genetic code. The nucleus (Choice C) is a cellular organelle that houses the DNA, but it is not the genetic code itself. Chromosomes (Choice D) are structures made of DNA and proteins, but the genetic code is specifically encoded in the DNA molecule.
4. What is another name for the light-independent reaction in plants?
- A. Photosynthesis
- B. Calvin cycle
- C. Germination
- D. Phosphorus cycle
Correct answer: B
Rationale: The light-independent reaction in plants is also known as the Calvin cycle. This biochemical pathway, named after Melvin Calvin who discovered it, takes place in the stroma of chloroplasts and is responsible for converting carbon dioxide into glucose using ATP and NADPH generated during the light-dependent reactions of photosynthesis. The Calvin cycle does not directly require light to function, hence the alternative name as the light-independent reaction. Choices A, C, and D are incorrect. Photosynthesis is the overall process of converting light energy into chemical energy, which includes both light-dependent and light-independent reactions. Germination is the process where a seed sprouts into a new plant. The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.
5. Which molecule is primarily responsible for storing energy in cells?
- A. Glucose
- B. ATP
- C. Fatty acids
- D. Starch
Correct answer: B
Rationale: ATP is the correct answer because it is the molecule responsible for storing and providing energy in cells. Glucose is a source of energy but not primarily for storage. Fatty acids are more involved in energy production through oxidation. Starch is a polysaccharide used for energy storage in plants.
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