HESI A2 Biology 2024

Correct Answer: B

Rationale: The correct answer is B: It is reliable, but not valid. The measurement is reliable because it consistently gives the same result (75 kg), indicating good precision. However, it is not valid because it does not accurately reflect Patient A's actual weight (68 kg). Validity refers to the accuracy of the measurement in assessing what it is supposed to measure. In this case, the scale consistently overestimates Patient A's weight, making it not valid. Choices A, C, and D are incorrect because they do not accurately reflect the situation described.

Correct Answer: B

Rationale: The correct answer is B: Enzymes are made from proteins. Proteins are complex molecules made up of amino acids, which are the building blocks of enzymes. Enzymes are biological catalysts that speed up chemical reactions in living organisms. They have specific shapes that allow them to bind to substrates and facilitate reactions. Lipids (choice A) are not typically involved in enzyme structure. Double chains of DNA (choice C) refer to the structure of DNA, not enzymes. Enzymes themselves are catalysts (choice D) and do not bind with other catalysts.

Correct Answer: B

Rationale: The correct answer is B because enzymes speed up chemical reactions by lowering the activation energy required for the reaction to occur. This is achieved by binding to the substrate, forming an enzyme-substrate complex, and facilitating the conversion of substrate into product. Enzymes do not slow down or stop reactions, as suggested in choices A and D. Choice C is incorrect as enzymes play a crucial role in catalyzing reactions.

Correct Answer: B

Rationale: The correct answer is B: It is reliable, but not valid. The measurement is reliable because it consistently gives the same result (75 kg), indicating good precision. However, it is not valid because it does not accurately reflect Patient A's actual weight (68 kg). Validity refers to the accuracy of the measurement in assessing what it is supposed to measure. In this case, the scale consistently overestimates Patient A's weight, making it not valid. Choices A, C, and D are incorrect because they do not accurately reflect the situation described.

Correct Answer: B

Rationale: The correct answer is B (25%). When two heterozygous parents (Hh) with Huntington's disease reproduce, they can produce offspring with genotypes HH, Hh, or hh. The only genotype that results in the disease is HH. Therefore, 25% of the offspring are predicted to be disease-free (hh), as they would inherit the recessive allele from both parents. The other choices are incorrect because 0% is not possible since the parents are heterozygous, 50% would mean all offspring are disease-free which is not the case, and 100% would mean all offspring have the disease, which is also not true.