HESI A2
HESI A2 Biology 2024
1. ___________ is a symbiotic relationship in which one organism benefits and the other is not affected.
- A. Mutualism
- B. Parasitism
- C. Commensalism
- D. Competition
Correct answer: C
Rationale: The correct answer is 'Commensalism.' In commensalism, one organism benefits from the relationship while the other is neither helped nor harmed. This type of symbiotic relationship is characterized by one organism deriving a benefit, such as food or shelter, without impacting the other organism in any significant way. Choice A, 'Mutualism,' is a symbiotic relationship in which both organisms benefit. Choice B, 'Parasitism,' is a symbiotic relationship in which one organism benefits at the expense of the other. Choice D, 'Competition,' refers to a relationship in which organisms compete for limited resources, with both being affected in terms of access to resources.
2. Which of the following is the structure of the male reproductive system that stores spermatozoa during the maturation process?
- A. vas deferens
- B. scrotum
- C. epididymis
- D. testicular artery
Correct answer: C
Rationale: The epididymis is the structure of the male reproductive system that stores spermatozoa during the maturation process. Sperm cells produced in the testes move to the epididymis, where they mature and become motile before being ejaculated. The vas deferens is responsible for transporting mature sperm to the urethra during ejaculation, the scrotum holds the testes and helps regulate their temperature for sperm production, and the testicular artery supplies blood to the testes. Therefore, choices A, B, and D are incorrect as they do not play a direct role in storing spermatozoa during the maturation process.
3. Anaerobic respiration happens in _ because _ .
- A. Animals; they need energy
- B. Plants; they use sunlight
- C. Bacteria; they live in environments with low oxygen
- D. None of the above
Correct answer: C
Rationale: Anaerobic respiration happens in bacteria because they live in environments with low oxygen. Bacteria, unlike animals and plants, do not have easy access to oxygen for aerobic respiration and must find alternative ways to produce energy to survive. This makes anaerobic respiration essential for their metabolic processes. Choice A is incorrect because although animals need energy, they generally rely on aerobic respiration when oxygen is available. Choice B is incorrect because plants primarily perform photosynthesis using sunlight to produce energy. Choice D is incorrect as anaerobic respiration does occur in specific organisms like bacteria when oxygen is scarce.
4. What are saturated fats saturated with?
- A. Hydrogen atoms
- B. Carbon atoms
- C. Oxygen atoms
- D. Nitrogen atoms
Correct answer: A
Rationale: Saturated fats are saturated with hydrogen atoms. This means that each carbon atom in the fatty acid chains forming saturated fats is bonded to as many hydrogen atoms as possible. This saturation results in the fatty acid chains being straight and closely packed together, making saturated fats solid at room temperature. Choice B (Carbon atoms), C (Oxygen atoms), and D (Nitrogen atoms) are incorrect because saturated fats are specifically saturated with hydrogen atoms, not carbon, oxygen, or nitrogen atoms.
5. What are the two catabolic pathways that lead to cellular energy production?
- A. Fermentation and internal respiration
- B. Fermentation and external respiration
- C. Fermentation and cellular respiration
- D. Fermentation and anaerobic respiration
Correct answer: C
Rationale: The correct answer is 'Fermentation and cellular respiration.' Fermentation is an anaerobic catabolic process that occurs in the absence of oxygen, producing limited amounts of ATP. Cellular respiration, on the other hand, is the aerobic catabolic pathway that occurs in the presence of oxygen and is the most efficient way of producing ATP. Choices A, B, and D are incorrect because internal respiration, external respiration, and anaerobic respiration are not the correct pathways leading to cellular energy production.
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