HESI A2
HESI A2 Biology Practice Test 2024
1. Where is the genetic code for each person stored?
- A. RNA
- B. DNA
- C. Nucleus
- D. Chromosomes
Correct answer: B
Rationale: The genetic code for each person is stored in DNA. DNA carries all the hereditary information, including unique traits and characteristics. RNA (Choice A) is involved in protein synthesis but does not hold the complete genetic code. The nucleus (Choice C) is a cellular organelle that houses the DNA, but it is not the genetic code itself. Chromosomes (Choice D) are structures made of DNA and proteins, but the genetic code is specifically encoded in the DNA molecule.
2. Which of the following organisms would not have eukaryotic cells?
- A. Bacteria
- B. Dog
- C. Human
- D. Onion
Correct answer: A
Rationale: The correct answer is A, Bacteria. Bacteria do not have eukaryotic cells. They are single-celled organisms with prokaryotic cells. Dogs, humans, and onions are all multicellular organisms that possess eukaryotic cells. Therefore, choices B, C, and D have eukaryotic cells and are not the correct answer.
3. Where is DNA stored?
- A. The nucleus
- B. Ribosomes
- C. Endoplasmic reticulum
- D. Mitochondria
Correct answer: A
Rationale: DNA is stored in the nucleus of a cell. The nucleus houses the cell's genetic material, including the DNA, which contains the instructions for building and operating the cell. The nucleus controls the activities of the cell and is essential for proper cell function and reproduction. Ribosomes are responsible for protein synthesis, not DNA storage. The endoplasmic reticulum is involved in protein and lipid synthesis, storage, and transport but does not store DNA. Mitochondria are known as the powerhouse of the cell, producing energy in the form of ATP, but they do not store DNA.
4. If bacteria are placed in a strong solution of salt water, they will shrink as water moves out of the bacteria. What is this process called?
- A. Dehydration synthesis
- B. Hydrolysis
- C. Osmosis
- D. Isotonic transport
Correct answer: C
Rationale: Osmosis is the process by which water molecules move across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. In this case, when bacteria are placed in a strong solution of salt water, the high concentration of solutes outside the bacteria causes water to move out of the bacteria, leading to shrinkage. This process is known as osmosis. Dehydration synthesis (Choice A) is a process where molecules combine by removing water. Hydrolysis (Choice B) is the breakdown of molecules by the addition of water. Isotonic transport (Choice D) does not accurately describe the specific movement of water in or out of bacterial cells in a hypertonic solution.
5. Which of the following are considered the most important molecules in biology?
- A. Carbohydrates, lipids, protein, and nucleic acids
- B. Carbohydrates, lipids, protein, and calcium
- C. Carbohydrates, lipids, protein, and sulfur
- D. Carbohydrates, lipids, protein, and iron
Correct answer: A
Rationale: The correct answer is A: Carbohydrates, lipids, protein, and nucleic acids are considered the most important molecules in biology. Carbohydrates are essential for providing energy, lipids for storing energy and forming cell membranes, proteins for various structural and functional roles, and nucleic acids (DNA and RNA) for storing genetic information. Choices B, C, and D are incorrect because while carbohydrates, lipids, and proteins are crucial biomolecules, calcium, sulfur, and iron are not considered among the most important molecules in biology.
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