HESI A2
Biology HESI A2 2024 Questions
Question 1 of 5
Why is yeast used to make bread rise?
Correct Answer: C
Rationale: The correct answer is C because yeast carries out fermentation, producing ethanol and carbon dioxide. During fermentation, yeast breaks down sugars in the dough into ethanol and carbon dioxide gas. The carbon dioxide gas gets trapped in the dough, causing it to rise. Choice A is incorrect because yeast does not engage in photosynthesis. Choice B is incorrect because yeast does not carry out photosynthesis at all. Choice D is incorrect because yeast primarily produces carbon dioxide through fermentation, not aerobic respiration.
Question 2 of 5
In a strand of DNA, you would expect to see adenine paired with ___________.
Correct Answer: C
Rationale: The correct answer is C: thymine. In DNA, adenine always pairs with thymine through two hydrogen bonds. This is a fundamental principle known as Chargaff's rule, where A pairs with T and C pairs with G. Thymine is a pyrimidine base, complementing adenine, which is a purine base. Therefore, thymine is the most suitable choice for adenine in a DNA strand. Choices A, B, and D are incorrect because adenine does not pair with cytosine (A), uracil (B), or guanine (D) in DNA.
Question 3 of 5
Physical factors such as temperature and pH can alter enzyme activity because they have an effect on the enzyme's ___________.
Correct Answer: B
Rationale: The correct answer is B: shape. Enzyme activity is highly dependent on the enzyme's specific three-dimensional shape. Changes in temperature and pH can disrupt the hydrogen bonds and other interactions that maintain the enzyme's shape, leading to denaturation. This alters the active site of the enzyme, making it unable to bind effectively with its substrate and catalyze the reaction. Incorrect options: A: Acidity is related to pH, which can affect enzyme activity, but the primary reason for the alteration is the change in shape. C: While changes in pH can affect the chemical properties of enzymes, the main impact on enzyme activity is the alteration of shape. D: Substrate is the molecule upon which the enzyme acts, and while changes in substrate concentration can affect enzyme activity, alterations in temperature and pH primarily impact the enzyme's shape, not the substrate itself.
Question 4 of 5
Which is not a step in the water cycle?
Correct Answer: C
Rationale: The correct answer is C: Nitrification. The water cycle includes evaporation, condensation, precipitation, and collection. Nitrification is a process in the nitrogen cycle, not the water cycle. Condensation is the conversion of water vapor into liquid water. Transpiration is the release of water vapor from plants. Absorption refers to water being taken up by plants or soil. Nitrification, the process of converting ammonia into nitrates, is unrelated to the movement of water in the water cycle.
Question 5 of 5
Which part of a plant's reproductive system is of a different "gender" than the others?
Correct Answer: A
Rationale: The correct answer is A: Stamen. The stamen is the male reproductive organ of a flower, producing pollen containing male gametes. The pistil, stigma, and style are all parts of the female reproductive system, involved in receiving pollen and supporting the development of seeds. Therefore, the stamen is of a different "gender" than the others, making it the correct choice. Stigma and style are specifically part of the pistil, which is the female organ of the flower.
Similar Questions
Join Our Community Today!
Join Over 10,000+ nursing students using Nurselytic. Access Comprehensive study Guides curriculum for HESI A2-HESI A2 and 3000+ practice questions to help you pass your HESI A2-HESI A2 exam.
Subscribe for Unlimited Access