HESI A2
HESI A2 Biology Practice Test 2024
1. What is the fundamental unit of life?
- A. Atom
- B. Cell
- C. Tissue
- D. Organ
Correct answer: B
Rationale: The correct answer is 'B: Cell.' Cells are indeed the fundamental unit of life as they are responsible for all living functions, including growth, reproduction, and maintaining homeostasis. While atoms are the basic building blocks of matter, cells are the smallest structural and functional unit of living organisms. Choices C and D, tissue and organ respectively, are composed of multiple cells working together and are not considered the basic unit of life.
2. Dogs are part of a larger animal group, the Carnivora. What classification is this?
- A. Kingdom
- B. Class
- C. Order
- D. Genus
Correct answer: C
Rationale: The classification 'Carnivora' refers to an order in the taxonomic hierarchy. In the Linnaean classification system, the order comes below the class but above the family level. Therefore, Carnivora is a higher classification that includes dog species as well as other carnivorous mammals like cats, bears, and weasels. Option A (Kingdom) is too broad and refers to the highest taxonomic rank. Option B (Class) is a lower taxonomic rank than order. Option D (Genus) is a much more specific rank that comes below the family level in the Linnaean hierarchy.
3. How many chromosomes do sperm and egg produce in meiosis?
- A. 46
- B. 23
- C. 45
- D. 24
Correct answer: B
Rationale: Sperm and egg cells undergo meiosis to form gametes with half the number of chromosomes found in somatic cells. Each sperm and egg cell produces 23 chromosomes through meiosis. Choice A is incorrect because 46 chromosomes represent the diploid number found in somatic cells. Choice C is incorrect as it is an uncommon number for chromosome production in human gametes. Choice D is incorrect as the total number of chromosomes in sperm or egg cells is 23, not 24.
4. In nature, water vapor becomes liquid water through the process of ___________.
- A. condensation
- B. sublimation
- C. precipitation
- D. absorption
Correct answer: A
Rationale: In nature, water vapor becomes liquid water through the process of condensation. Condensation occurs when water vapor cools and changes its state from a gas to a liquid, forming droplets that we commonly see as water droplets on surfaces or clouds in the sky. Sublimation refers to the transition from a solid to a gas without passing through the liquid phase. Precipitation is the process where water in the atmosphere falls to the ground as rain, snow, sleet, or hail. Absorption is the process of one substance being taken in by another.
5. 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.
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