HESI A2
HESI A2 Biology Practice Test
1. Genes control heredity in man and other organisms. This gene is ___
- A. A segment of DNA
- B. A bead-like structure on the chromosomes
- C. A protein molecule
- D. A segment of RNA
Correct answer: A
Rationale: Genes are sections of DNA that contain instructions for building and operating living organisms. These sections of DNA contain the genetic information that is passed on from one generation to the next. Genes are composed of specific sequences of nucleotides within the DNA molecule. Therefore, genes are best described as segments of DNA. Choice A is correct. Choice B is incorrect because genes are not bead-like structures on chromosomes but specific sequences of DNA. Choice C is incorrect because genes are not protein molecules but rather sequences of nucleotides. Choice D is incorrect because genes are not segments of RNA but DNA.
2. Which one is not a reactant in photosynthesis?
- A. Water
- B. Light energy
- C. Glucose
- D. Carbon dioxide
Correct answer: C
Rationale: The correct answer is C: Glucose. Glucose is not a reactant in photosynthesis but a product. During photosynthesis, plants use water, carbon dioxide, and light energy as reactants to produce glucose and oxygen. Water is essential for the process of photosynthesis, along with carbon dioxide and light energy. Light energy is necessary for the light-dependent reactions to occur, which eventually leads to the production of glucose. Carbon dioxide is absorbed by plants through tiny pores called stomata and is used in the Calvin cycle to synthesize glucose. Therefore, glucose is the product of photosynthesis, not a reactant.
3. Why is polarity the most important characteristic of water?
- A. the results of the polarity are hydrogen bonding, a high specific heat value, and its versatile solvent properties
- B. the results of the polarity are covalent bonding, a low specific heat value, and its versatile solvent properties
- C. the results of the polarity are ionic bonding, a high specific heat value, and its versatile solvent properties
- D. the results of the polarity are hydrogen bonding, a low specific heat value, and its versatile solvent properties
Correct answer: A
Rationale: Polarity is the most important characteristic of water because it results in hydrogen bonding, a high specific heat value, and its versatile solvent properties. These unique properties enable water to form hydrogen bonds with other substances, resist temperature changes, and dissolve a wide variety of solutes, making it essential for life processes. Choice B is incorrect because water exhibits hydrogen bonding, not covalent bonding. Choice C is incorrect as water does not form ionic bonds. Choice D is incorrect because water has a high, not low, specific heat value, which is vital for its role in temperature regulation.
4. What is the term for the breakdown of glycogen into glucose subunits?
- A. Hydrolysis
- B. Reduction
- C. Metabolism
- D. Transpiration
Correct answer: A
Rationale: Hydrolysis is the term used to describe the breakdown of large molecules into smaller units by adding water. In the case of glycogen being broken down into glucose subunits, this process involves the addition of water molecules to break the glycosidic bonds between glucose molecules, resulting in the release of individual glucose subunits. This process is crucial for providing cells with a source of energy when needed. Choice B, Reduction, refers to a chemical reaction involving a gain of electrons or a decrease in oxidation state, not the breakdown of glycogen into glucose subunits. Choice C, Metabolism, is a broad term encompassing all biochemical processes in an organism, including anabolism and catabolism, but does not specifically describe the breakdown of glycogen into glucose subunits. Choice D, Transpiration, is the process of water movement through a plant and is not related to the breakdown of glycogen into glucose subunits.
5. Which is not one of the raw materials needed for cellular respiration?
- A. ADP
- B. Phosphate
- C. Water
- D. Glucose
Correct answer: C
Rationale: Water is not one of the raw materials needed for cellular respiration. The essential raw materials for cellular respiration include glucose (which is broken down to produce energy), oxygen, and ADP (adenosine diphosphate) and phosphate (which are necessary for the formation of ATP, the energy currency of cells). While water is crucial for many cellular processes and makes up a significant portion of cells, it is not directly involved as a raw material in the cellular respiration process.
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