HESI A2
HESI A2 Biology 2024
1. What happens to messenger RNA when it reaches the cytoplasm?
- A. It attaches to a ribosome.
- B. It unzips, exposing nitrogen bases.
- C. It pairs with the DNA bases.
- D. It pulls free of the DNA strand.
Correct answer: A
Rationale: Messenger RNA (mRNA) carries genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm. When mRNA reaches the cytoplasm, it attaches to a ribosome. The ribosome functions as the site for protein synthesis through translation, where the genetic code carried by mRNA is read and translated into a specific sequence of amino acids. Choices B, C, and D are incorrect because mRNA does not unzip, expose nitrogen bases, pair with DNA bases, or pull free of the DNA strand in the cytoplasm. The primary function of mRNA in the cytoplasm is to serve as a template for protein synthesis by binding to ribosomes.
2. What organelle in the cell produces energy through the process of respiration?
- A. Nucleus
- B. Mitochondria
- C. Golgi Apparatus
- D. Chloroplasts
Correct answer: B
Rationale: The correct answer is B: Mitochondria. The mitochondria are known as the powerhouse of the cell and are responsible for producing energy through respiration in eukaryotic cells. Choice A, the Nucleus, is not involved in energy production but rather houses the cell's genetic material. Choice C, the Golgi Apparatus, is responsible for packaging and processing proteins, not energy production. Choice D, Chloroplasts, are responsible for photosynthesis in plant cells, not respiration for energy production.
3. Which of the following structures is not directly involved in translation?
- A. tRNA
- B. mRNA
- C. ribosome
- D. DNA
Correct answer: D
Rationale: The correct answer is 'D: DNA.' DNA is not directly involved in translation, which is the process of synthesizing proteins from mRNA. tRNA carries amino acids to the ribosome, mRNA provides the template for protein synthesis, and ribosomes are the cellular machinery where translation occurs. DNA's main role is in transcription, where it serves as the template for mRNA synthesis, not in translation.
4. Which of the following are components of the endocrine system?
- A. The pituitary gland
- B. The thyroid gland
- C. The adrenal glands
- D. All of the Above
Correct answer: D
Rationale: The endocrine system comprises a network of glands that produce and release hormones to regulate bodily functions. The pituitary gland, thyroid gland, and adrenal glands are essential components of this system. The pituitary gland secretes various hormones that control other glands and some body functions. The thyroid gland regulates metabolism, growth, and energy levels by producing thyroid hormones. The adrenal glands produce hormones involved in stress response, metabolism, and immune function. Therefore, all of the above glands are integral parts of the endocrine system, making choice D the correct answer.
5. Which organism reproduces via binary fission?
- A. Mushroom
- B. Blue whale
- C. Rainbow trout
- D. Salmonella
Correct answer: D
Rationale: The correct answer is D, Salmonella. Salmonella bacterium reproduces via binary fission, a form of asexual reproduction where the cell divides into two daughter cells with identical genetic material. This process is common among bacteria and single-celled organisms. Mushrooms reproduce through spores, blue whales and rainbow trout reproduce sexually, involving the fusion of male and female gametes. Therefore, choices A, B, and C are incorrect as they do not reproduce through binary fission.
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