HESI A2
Biology HESI A2 Practice Exam
1. Duchenne muscular dystrophy is a recessive sex-linked trait carried on the X chromosome. In an example of an unaffected father and a female carrier who have two daughters and two sons, which is the predicted outcome?
- A. Both daughters will carry the disease.
- B. Both sons will carry the disease.
- C. One daughter may have the disease.
- D. One son may have the disease.
Correct answer: C
Rationale: Duchenne muscular dystrophy is a recessive sex-linked trait carried on the X chromosome. Since the father is unaffected and does not carry the disease, he must have a normal X chromosome. The mother is a carrier, which means she has one normal X chromosome and one X chromosome with the disease allele. The daughters will inherit one X chromosome from each parent; one would be normal, and the other has a chance of carrying the disease allele. So, there is a 50% chance that one daughter may have the disease, as she could inherit the X chromosome with the disease allele. The sons will inherit the Y chromosome from the father and the X chromosome from the mother, so they will not be affected by the disease. Therefore, the predicted outcome is that one daughter may have the disease, while the sons will not carry the disease. This rules out choices A, B, and D.
2. 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.
3. Which cells in the human body lack nuclei?
- A. Nerve cells
- B. Red blood cells
- C. Liver cells
- D. Connective tissue cells
Correct answer: B
Rationale: Red blood cells, also known as erythrocytes, lack nuclei in humans. This absence of a nucleus allows more space for hemoglobin, the protein responsible for carrying oxygen, making red blood cells efficient at their function of oxygen transport in the body. Nerve cells (Choice A), liver cells (Choice C), and connective tissue cells (Choice D) all possess nuclei as they require genetic material for their functions, such as cell signaling, protein synthesis, and structural support.
4. Which form of fermentation is used to produce beer?
- A. Lactic acid fermentation
- B. Acetic acid fermentation
- C. Propionic acid fermentation
- D. Ethyl alcohol fermentation
Correct answer: D
Rationale: The correct answer is D, Ethyl alcohol fermentation. During beer production, yeast metabolizes sugars in the wort to produce ethanol (ethyl alcohol) and carbon dioxide, which are responsible for the alcohol content and carbonation in beer. Choices A, B, and C are incorrect because lactic acid fermentation produces lactic acid, acetic acid fermentation produces acetic acid, and propionic acid fermentation produces propionic acid, none of which are used in the production of beer.
5. 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.
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