HESI A2
Biology HESI A2 Practice Exam
1. If a test has poor internal consistency, which statement is true?
- A. The test produces different results at different times.
- B. The items do not correlate or measure similar things.
- C. The test produces different results depending on the researcher.
- D. The items never vary even when the test environment changes.
Correct answer: B
Rationale: Correct answer: If a test has poor internal consistency, it means that the items do not correlate or measure similar things. This lack of correlation indicates that the items in the test are not measuring the same underlying construct or concept, leading to unreliable results. Choice A is incorrect because poor internal consistency is not about producing different results at different times but rather about the lack of correlation among items. Choice C is incorrect because the issue lies within the test itself, not with different researchers. Choice D is incorrect because poor internal consistency implies that the items do vary in their measurement, contributing to the unreliability of the test.
2. 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.
3. Huntington’s disease is carried on the dominant allele. In a situation where two heterozygous parents have the disease, what percentage of their offspring are predicted to be disease-free?
- A. 0%
- B. 25%
- C. 50%
- D. 100%
Correct answer: B
Rationale: In this scenario, both parents are heterozygous for Huntington's disease, meaning each carries one dominant allele (representing the disease) and one recessive allele (representing no disease). When they have offspring, there is a 25% chance that each child will inherit two recessive alleles, making them disease-free. The Punnett square for two heterozygous parents (Hh x Hh) yields a 25% probability of offspring being homozygous recessive (hh) and therefore disease-free. Choice A (0%) is incorrect because there is a possibility of disease-free offspring. Choice C (50%) is incorrect as it represents the likelihood of being a carrier. Choice D (100%) is incorrect as all offspring will not be disease-free in this scenario.
4. Which organelle provides storage space for the cell?
- A. Mitochondrion
- B. Vacuole
- C. Cell membrane
- D. Ribosome
Correct answer: B
Rationale: The correct answer is B: Vacuole. The vacuole is the organelle responsible for providing storage space in the cell. It stores water, nutrients, waste products, and other essential materials required by the cell. Vacuoles are crucial for maintaining cell structure and regulating cellular processes. Mitochondrion (choice A) is known as the powerhouse of the cell, responsible for producing energy. The cell membrane (choice C) is a protective barrier around the cell, regulating what enters and exits the cell. Ribosomes (choice D) are involved in protein synthesis, not storage.
5. What helps the cell maintain its shape and allows it to adapt?
- A. Microfilaments
- B. Cytoplasm
- C. Cytoskeleton
- D. Centrioles
Correct answer: C
Rationale: The cytoskeleton is the correct answer. It provides structural support to the cell, helps maintain its shape, and enables it to adapt to different environments. Microfilaments are part of the cytoskeleton, but they alone do not encompass the entire cytoskeleton's functions. Cytoplasm is the fluid inside the cell where organelles are suspended and is not directly responsible for maintaining cell shape. Centrioles are involved in cell division and do not primarily contribute to maintaining the cell's shape and adaptation.
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