HESI A2
HESI A2 Biology Practice Test
1. What is the purpose of the mitochondria?
- A. Control the cell
- B. Create energy
- C. Create proteins
- D. Package waste for removal
Correct answer: B
Rationale: The correct answer is B: Create energy. The primary purpose of the mitochondria is to generate energy for the cell. Mitochondria are known as the 'powerhouses' of the cell because they produce ATP (adenosine triphosphate), which is the energy currency used by cells to carry out various functions and processes. Choice A is incorrect as the mitochondria do not control the cell but rather produce energy. Choice C is incorrect as protein synthesis primarily occurs in the ribosomes. Choice D is incorrect as packaging waste for removal is a function associated with lysosomes, not mitochondria.
2. Which color of light is least effective at driving photosynthesis?
- A. Violet
- B. Green
- C. Orange
- D. Red
Correct answer: B
Rationale: Green light is the least effective at driving photosynthesis because chlorophyll, the primary pigment responsible for absorbing light in plants, does not absorb green light well. Instead, chlorophyll absorbs more effectively in the blue and red regions of the light spectrum. Therefore, green light is relatively less efficient in promoting photosynthesis compared to violet, orange, and red light. Violet light, although at the shorter wavelength end of the spectrum, can still drive photosynthesis better than green light. Orange and red light are more efficiently absorbed by chlorophyll, making them more effective in driving the process of photosynthesis.
3. Which one of the following best describes the function of a cell membrane?
- A. It controls the substances entering and leaving the cell.
- B. It maintains the cell's shape.
- C. It controls the substances entering the cell.
- D. It supports the cell's structures.
Correct answer: A
Rationale: The correct answer is A. The function of a cell membrane is to control the substances entering and leaving the cell. The cell membrane is selectively permeable, allowing it to regulate the movement of ions and molecules in and out of the cell to maintain internal balance and proper function. Choice B is incorrect because while the cell membrane does provide some structural support, its primary function is not to maintain the cell's shape. Choice C is incorrect because the cell membrane controls both the substances entering and leaving the cell, not just those entering. Choice D is incorrect as the primary function of the cell membrane is not to support the cell's structures but to regulate the movement of substances.
4. What are plasma membranes mostly made of?
- A. Proteins
- B. Carbohydrates
- C. Lipids
- D. Nucleotides
Correct answer: C
Rationale: The correct answer is C: Lipids. Plasma membranes are primarily composed of lipids, specifically phospholipids, which form a lipid bilayer. While proteins are also an essential component of plasma membranes, they are not the primary constituent. Carbohydrates are present on the outer surface of the membrane but are not the main structural component. Nucleotides are the building blocks of nucleic acids like DNA and RNA and are not the main constituents of plasma membranes.
5. Why doesn't an antibiotic work for treating the flu?
- A. The antibiotic is for a different type of infection
- B. The antibiotic is not effective against viruses
- C. The antibiotic is not prescribed in a high enough dosage
- D. None of the above
Correct answer: B
Rationale: The correct answer is B. Antibiotics are used to treat bacterial infections, not viral infections like the flu. The flu is caused by a virus, and antibiotics are ineffective against viruses. Choice A is incorrect because it does not address the fact that antibiotics do not work on viruses. Choice C is incorrect as the issue is not related to the dosage amount, but rather the nature of the infection. Choice D is incorrect as there is a specific reason why antibiotics do not work for the flu.
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