HESI A2 Biology Practice Test

Correct Answer: C

Rationale: The correct answer is C because plant cells have a rigid cell wall that prevents them from forming a contractile ring during cell division. The cell wall provides structural support, making it challenging for plant cells to constrict and pinch apart like animal cells. This rigidity limits the flexibility needed for the contractile ring to form and function effectively. Plant cells primarily rely on other mechanisms such as cell plate formation for division. Choices A and B are incorrect as they do not address the specific structural difference between plant and animal cells. Choice D is incorrect as it does not provide any relevant information on the topic.

Correct Answer: B

Rationale: Enzymes are typically proteins because they are biological catalysts made up of amino acids. Proteins have specific structures that allow them to bind to substrates and speed up chemical reactions. Fats, sugars, and neurons do not possess the specific structural properties required for enzyme function. Therefore, the correct answer is B (Proteins).

Correct Answer: D

Rationale: The correct answer is D because it follows the structure of a hypothesis: it states a relationship between two variables (exposure to red light and plant growth) that can be tested. It is specific, testable, and predicts an outcome. Choice A is a general statement, not a testable hypothesis. Choice B is subjective and not testable. Choice C lacks specificity and does not clearly define the relationship being tested.

Correct Answer: B

Rationale: Thymine is not present in RNA because thymine is a pyrimidine base found in DNA instead of RNA. RNA contains uracil as its complementary base to adenine, while DNA contains thymine. Adenine, uracil, and cytosine are all present in RNA, making them incorrect choices. Thymine is the only base not present in RNA, making option B the correct answer.

Correct Answer: A

Rationale: The correct answer is A: DNA-RNA-protein. This process is known as protein synthesis or gene expression. It starts with DNA being transcribed into RNA by RNA polymerase. The RNA then undergoes translation, where ribosomes read the RNA sequence and assemble amino acids into a protein. Choice B is incorrect because genes are segments of DNA, not chromosomes. Choice C is incorrect because ATP is not involved in protein synthesis. Choice D is incorrect because RNA is transcribed from DNA, not the other way around.