HESI A2
Biology HESI A2 Practice Test
1. How does asexual reproduction differ from sexual reproduction?
- A. asexual reproduction results in all cells being identical to the original cell; sexual reproduction results in half of the cells being identical to the original cell
- B. asexual reproduction results in two cells that contribute genetic material to daughter cells, resulting in significantly greater variation
- C. sexual reproduction involves two cells that contribute genetic material to daughter cells, resulting in significantly greater variation
- D. sexual reproduction involves one cell that yields all cells produced to be identical
Correct answer: C
Rationale: Sexual reproduction involves two cells (gametes) that contribute genetic material to daughter cells, resulting in significantly greater genetic variation in the offspring. This genetic variation is essential for evolution and adaptation to environmental changes. In contrast, asexual reproduction involves one cell dividing to produce offspring that are genetically identical to the parent cell. Choice A is incorrect because sexual reproduction does not result in half of the cells being identical to the original cell; it involves two cells contributing genetic material. Choice B is incorrect because asexual reproduction does not result in significantly greater variation; it produces genetically identical offspring. Choice D is incorrect because sexual reproduction involves two cells contributing genetic material, not one cell yielding all identical cells.
2. 72 chromosomes undergo meiosis. How many chromosomes will be in each gamete?
- A. 18
- B. 36
- C. 72
- D. 144
Correct answer: A
Rationale: During meiosis, the number of chromosomes is halved in each gamete. Since 72 chromosomes undergo meiosis, each gamete will contain half of that number, which is 36 chromosomes. Therefore, the correct answer is 18 chromosomes in each gamete. Choice B (36 chromosomes) is incorrect because it represents the total number of chromosomes that undergo meiosis, not the number in each gamete. Choice C (72 chromosomes) is incorrect as it represents the initial number of chromosomes, not the number in each gamete after meiosis. Choice D (144 chromosomes) is incorrect as it doubles the initial number of chromosomes, which is not the outcome of meiosis.
3. Tundra, savannas, grasslands, deserts, and rainforests are examples of what?
- A. Biomasses
- B. Biospheres
- C. Biodiversity
- D. Biomes
Correct answer: D
Rationale: Tundra, savannas, grasslands, deserts, and rainforests are examples of biomes. A biome is a large geographical area with similar climatic conditions and distinct flora and fauna. Each biome has its unique characteristics, such as temperature, precipitation levels, and types of vegetation, which define the ecosystem within that region. Biomasses refer to the total mass of living organisms in a given area, biospheres are the global ecological system integrating all living beings and their relationships, and biodiversity represents the variety of life forms in a specific habitat.
4. 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.
5. How many bones are included in the human skeletal system?
- A. 412
- B. 103
- C. Over 300
- D. 206
Correct answer: D
Rationale: There are 206 bones in the human skeletal system. This includes bones in the skull, spine, ribs, arms, legs, hands, and feet. The correct answer is 206 because that is the standard number of bones in an adult human body. Choices A, B, and C are incorrect as they do not reflect the accurate count of bones in the human skeletal system.
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