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: A

Rationale: The correct answer is A: Adenine. Adenine is a nucleotide base that consists of two fused carbon rings, making it a purine base. The two rings in adenine are essential for its structure, function, and hydrogen bonding with thymine in DNA. The other choices, B, C, and D, are all pyrimidine bases, which have only one carbon ring. Therefore, adenine is the only base among the options that has two carbon rings, making it the correct answer.

Correct Answer: D

Rationale: The correct answer is D: species. Within the biological hierarchical system, species is the least inclusive category. A species consists of organisms that can interbreed and produce fertile offspring. Moving up the hierarchy, species are grouped into genera, then families, orders, classes, phyla, and finally kingdoms. Phylum (A), order (B), and kingdom (C) are all more inclusive categories than species. Phylum includes multiple classes, order includes multiple families, and kingdom includes multiple phyla. Therefore, species is the least inclusive category within this system.

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: 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.