HESI A2
HESI A2 Practice Test Biology
1. What is the function of water in photosynthesis?
- A. Combine with carbon dioxide
- B. Absorb light energy
- C. Supply electrons in the light reactions
- D. Transport hydrogen ions in the dark reactions
Correct answer: C
Rationale: The correct answer is C: 'Supply electrons in the light reactions.' In photosynthesis, water is split during the light reactions of photosynthesis, releasing electrons that are used in the formation of ATP and NADPH, crucial for the synthesis of glucose. Choice A is incorrect because water does not combine with carbon dioxide in photosynthesis. Choice B is incorrect as water does not absorb light energy directly. Choice D is incorrect because the transportation of hydrogen ions mainly occurs in the electron transport chain, which is part of the light reactions, not the dark reactions.
2. 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.
3. What is the classification of organisms into different categories based on their physical characteristics and presumed natural relationship?
- A. Biology
- B. Taxonomy
- C. Grouping
- D. Nomenclature
Correct answer: B
Rationale: Taxonomy is the correct answer. Taxonomy is the branch of biology that deals with the classification of organisms into different categories based on their physical characteristics and presumed natural relationship. It involves naming and categorizing organisms into hierarchical groups to show their evolutionary relationships. Choice A, 'Biology,' is incorrect as it is the broader field of science that encompasses the study of living organisms. Choice C, 'Grouping,' is incorrect as it is a general term that does not specifically refer to the systematic classification of organisms. Choice D, 'Nomenclature,' is incorrect as it refers to the system of naming organisms rather than the classification based on physical characteristics and natural relationships.
4. What is the main component of blood plasma?
- A. Proteins
- B. Water
- C. Red Blood Cells
- D. Platelets
Correct answer: B
Rationale: The correct answer is B: Water. Blood plasma is composed mostly of water, which acts as a solvent for various nutrients and substances. Choices A, C, and D are incorrect. Proteins are indeed present in blood plasma but are not the main component. Red blood cells and platelets are cellular components of blood, not the main component of blood plasma.
5. Physical factors such as temperature and pH can alter enzyme activity because they have an effect on the enzyme's ___________.
- A. acidity
- B. shape
- C. chemistry
- D. substrate
Correct answer: B
Rationale: Physical factors such as temperature and pH can alter enzyme activity by affecting the enzyme's shape. Enzymes rely on their specific shapes to function properly and catalyze reactions. Any changes in temperature or pH can disrupt these shapes, causing the enzyme to become denatured and lose its functionality. Therefore, alterations in temperature and pH can impact enzyme activity by directly affecting their shapes. Choices A, C, and D are incorrect because while pH can affect acidity and chemical properties of the enzyme, and temperature can influence the enzyme-substrate interaction, the primary reason for enzyme activity alteration due to temperature and pH is the change in the enzyme's shape.
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