HESI A2
HESI A2 Biology Practice Test 2024
1. Which organelle is involved in the synthesis of proteins?
- A. Endoplasmic Reticulum
- B. Ribosomes
- C. Lysosomes
- D. Vacuoles
Correct answer: B
Rationale: Ribosomes are the organelles involved in the synthesis of proteins. They are the cellular machinery responsible for translating mRNA into proteins, making them essential for cell function and structure. The other organelles listed, such as the Endoplasmic Reticulum, Lysosomes, and Vacuoles, have different functions unrelated to protein synthesis. The Endoplasmic Reticulum plays a role in protein processing and transport, Lysosomes are involved in digestion and waste removal, and Vacuoles are responsible for storage and maintaining cell turgor pressure.
2. What kind of symbiosis exists between a pneumonia bacterium and a human?
- A. Mutualism
- B. Parasitism
- C. Commensalism
- D. Competition
Correct answer: B
Rationale: In the case of a pneumonia bacterium and a human, the relationship is best described as parasitism. The bacterium benefits by causing harm to the human host, while the human is negatively affected by the presence of the bacterium, leading to illness or infection. This is a classic example of a parasitic relationship where one organism benefits at the expense of the other. Mutualism (Choice A) is a type of symbiotic relationship where both organisms benefit from each other. Commensalism (Choice C) is a symbiotic relationship where one organism benefits, and the other is neither helped nor harmed. Competition (Choice D) refers to a relationship where both organisms are negatively affected by each other as they compete for resources.
3. In a phospholipid molecule, the head:
- A. Is hydrophilic
- B. Is hydrophobic
- C. Is on the inner side of the layer
- D. Both A and C
Correct answer: D
Rationale: The head of a phospholipid is hydrophilic (water-loving) and is located on the outer side of the lipid bilayer, interacting with water molecules. This arrangement positions the hydrophobic tails inward, away from water. Therefore, the correct answer is D. Choice A is incorrect because the head is hydrophilic, not hydrophobic. Choice B is incorrect as the head is on the outer side, not the inner side of the layer.
4. 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.
5. Two organisms live in a relationship from which both benefit. What is this called?
- A. Mutualism
- B. Parasitism
- C. Commensalism
- D. Competition
Correct answer: A
Rationale: Mutualism is a type of symbiotic relationship between two organisms in which both parties benefit from the association. It is a mutually beneficial interaction where both organisms gain something valuable, such as food, protection, or some other resource. This contrasts with parasitism, where one organism benefits at the expense of the other, commensalism, where one organism benefits while the other is unaffected, and competition, where both organisms are negatively affected by their interaction.
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