HESI A2
Biology HESI A2 Practice Test
1. Which of the following is true of homozygous traits?
- A. They are haploid
- B. They are denoted AA
- C. They are denoted aa
- D. They are denoted Aa
Correct answer: B
Rationale: Homozygous traits have two identical forms of the gene, either both dominant (AA) or both recessive (aa). Therefore, choices B and C are true for homozygous traits. Choice A is incorrect because being haploid refers to having a single set of chromosomes, not necessarily homozygous traits. Choice D is incorrect as homozygous traits have identical alleles, so they are not denoted as Aa.
2. Patient A, who weighs 68 kilograms, steps onto a scale 20 times. The scale consistently weighs Patient A as 75 kilograms. What is true of the measurement?
- A. It is valid, but not reliable.
- B. It is reliable, but not valid.
- C. It is both valid and reliable.
- D. It is neither reliable nor valid.
Correct answer: B
Rationale: The correct answer is B: 'It is reliable, but not valid.' The measurement is reliable because it consistently provides the same result (75 kg). However, it is not valid because it does not accurately reflect the true weight of Patient A (68 kg). Choice A is incorrect because if the scale consistently shows the same weight (75 kg), it is reliable. Choice C is incorrect because although the scale is consistent, the measurement does not reflect the true weight, making it not valid. Choice D is incorrect as the measurement is reliable but lacks validity.
3. Which organelle is responsible for detoxifying harmful substances in the cell?
- A. Endoplasmic Reticulum
- B. Lysosomes
- C. Peroxisomes
- D. Golgi Apparatus
Correct answer: C
Rationale: The correct answer is C, Peroxisomes. Peroxisomes are responsible for detoxifying harmful substances in the cell by breaking down fatty acids and producing hydrogen peroxide. This process helps protect the cell from damage caused by toxic substances. Choice A, Endoplasmic Reticulum, is involved in protein and lipid synthesis, not detoxification. Choice B, Lysosomes, contain enzymes for digestion and waste removal, not primarily detoxification. Choice D, Golgi Apparatus, is responsible for modifying, sorting, and packaging proteins for secretion, not detoxification.
4. Genes control heredity in man and other organisms. This gene is ___
- A. A segment of DNA
- B. A bead-like structure on the chromosomes
- C. A protein molecule
- D. A segment of RNA
Correct answer: A
Rationale: Genes are sections of DNA that contain instructions for building and operating living organisms. These sections of DNA contain the genetic information that is passed on from one generation to the next. Genes are composed of specific sequences of nucleotides within the DNA molecule. Therefore, genes are best described as segments of DNA. Choice A is correct. Choice B is incorrect because genes are not bead-like structures on chromosomes but specific sequences of DNA. Choice C is incorrect because genes are not protein molecules but rather sequences of nucleotides. Choice D is incorrect because genes are not segments of RNA but DNA.
5. In the scientific process, which of the following is a statement or explanation of certain events or happenings?
- A. hypothesis
- B. observation
- C. experiment
- D. conclusion
Correct answer: A
Rationale: A hypothesis is a statement or explanation of certain events or phenomena based on observations and prior knowledge. It is a testable prediction that guides the scientific investigation process. By formulating a hypothesis, scientists can make predictions and design experiments to gather data and test the validity of the hypothesis. Observations (choice B) involve gathering information through the senses. Experiments (choice C) are procedures carried out to support or refute a hypothesis. Conclusions (choice D) are deductions made based on the results of experiments and observations, but they are not the initial statement or explanation of events or happenings.
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