HESI A2
Biology HESI A2 2024
1. The scientific name for a house cat is Felis catus. This indicates the house cat’s ___________ and ___________.
- A. kingdom; family
- B. order; subspecies
- C. phylum; class
- D. genus; species
Correct answer: D
Rationale: The scientific name for an organism consists of its genus and species. In this case, 'Felis' refers to the genus, while 'catus' refers to the species, thus indicating the house cat's genus and species as Felis catus. Therefore, the correct answer is 'D.' Choices A, B, and C are incorrect because a scientific name does not include information about the kingdom, family, order, subspecies, phylum, or class of an organism.
2. Why do we perceive chlorophyll as green?
- A. It absorbs yellow and blue light.
- B. It primarily absorbs green light.
- C. It fails to absorb green light.
- D. It primarily absorbs red light.
Correct answer: A
Rationale: Chlorophyll appears green to us because it primarily absorbs yellow and blue light while reflecting green light. The wavelengths of yellow and blue light are absorbed by chlorophyll for photosynthesis, which results in the green color we perceive. Choice B is incorrect because chlorophyll absorbs yellow and blue light, not green light. Choice C is incorrect because chlorophyll does absorb green light, but it also absorbs other wavelengths, primarily yellow and blue. Choice D is incorrect because chlorophyll primarily absorbs yellow and blue light, not red light.
3. How many pairs of chromosomes do all humans have?
- A. 24 pairs
- B. 23 pairs
- C. 22 pairs
- D. 20 pairs
Correct answer: B
Rationale: All humans have 23 pairs of chromosomes, totaling 46 chromosomes. Choice A is incorrect because humans do not have 24 pairs. Choice C is incorrect as humans have 23 pairs, not 22 pairs. Choice D is incorrect as humans have 23 pairs of chromosomes, not 20 pairs.
4. 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.
5. Most enzymes are made up of what?
- A. proteins
- B. lipids
- C. starches
- D. simple sugars
Correct answer: A
Rationale: Most enzymes are made up of proteins. Proteins are large biomolecules composed of amino acids that are vital for the structure and function of enzymes. Enzymes act as catalysts in biochemical reactions, speeding up the rate of chemical reactions in living organisms. They exhibit high specificity and efficiency due to their unique protein structures. Lipids, starches, and simple sugars are not typically the primary components of enzymes, making them incorrect choices.
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