HESI A2
HESI A2 Biology Practice Test
1. Which organelle would you expect to be present in a cell responsible for detoxifying multiple molecules?
- A. rough ER
- B. smooth ER
- C. lysosome
- D. Golgi apparatus
Correct answer: B
Rationale: The smooth endoplasmic reticulum (ER) is the organelle responsible for detoxifying multiple molecules in a cell. It contains enzymes that help break down toxins and drugs, making it an essential organelle for detoxification processes. The rough ER, lysosome, and Golgi apparatus do not play direct roles in detoxification. The rough ER is mainly involved in protein synthesis and transport. Lysosomes are responsible for digestion and recycling within the cell. The Golgi apparatus is involved in modifying, sorting, and packaging proteins for secretion or for use within the cell.
2. What organelle is responsible for packaging, processing, and shipping?
- A. Nucleus
- B. Golgi Apparatus
- C. Endoplasmic Reticulum
- D. Ribosomes
Correct answer: B
Rationale: The Golgi Apparatus is the correct answer. It is responsible for packaging, processing, and shipping proteins and lipids within the cell. The nucleus houses genetic material, the endoplasmic reticulum is involved in protein synthesis and lipid metabolism, and ribosomes are responsible for protein synthesis. Therefore, choices A, C, and D are not the correct answers for the functions of packaging, processing, and shipping.
3. Which system maintains the body's balance through the release of hormones directly into the bloodstream?
- A. The gastrointestinal system
- B. The endocrine system
- C. The digestive system
- D. The endocrine system
Correct answer: D
Rationale: The correct answer is D: The endocrine system. The endocrine system maintains the body's balance through the release of hormones directly into the bloodstream. Hormones produced by glands in the endocrine system regulate various bodily functions such as metabolism, growth, and reproduction. This system plays a crucial role in maintaining homeostasis by releasing hormones that help control and coordinate different processes in the body. Choices A, C, and B are incorrect. The gastrointestinal system is responsible for digestion, absorption of nutrients, and excretion of waste; the digestive system includes the gastrointestinal system and other accessory organs; and choice B is a duplicate of the correct answer.
4. Which of the following is not true about enzymes?
- A. They catalyze reactions
- B. They lower the activation energy needed
- C. They have an active site
- D. They are typically proteins
Correct answer: B
Rationale: Enzymes lower the activation energy needed for a reaction to occur, not raise it. By lowering the activation energy, enzymes facilitate reactions, making them occur more easily and rapidly. Choice A is correct as enzymes indeed catalyze reactions. Choice C is correct as enzymes have specific active sites where substrates bind. Choice D is correct as enzymes are commonly proteins, although some RNA molecules also exhibit catalytic properties.
5. 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.
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