Biology HESI A2 Practice Test

Correct Answer: A

Rationale: The correct answer is A: Ribosome. Ribosomes are the organelles responsible for protein synthesis in the cell. They can be found in the cytoplasm or attached to the endoplasmic reticulum. Ribosomes read the mRNA and assemble amino acids into proteins through a process called translation. Summary of other choices: B: Chloroplast - responsible for photosynthesis in plant cells. C: Lysosome - contains enzymes for digesting waste materials. D: Mitochondrion - produces ATP through cellular respiration. These organelles are not directly involved in protein synthesis, making them incorrect choices for this question.

Correct Answer: A

Rationale: The correct answer is A: electron transport chain. This step in cellular respiration produces the greatest amount of ATP through oxidative phosphorylation, where electrons are passed through a series of protein complexes to generate a proton gradient used to produce ATP. In contrast, glycolysis only produces a small amount of ATP, the citric acid cycle produces some ATP but not as much as the electron transport chain, and fermentation doesn't produce ATP through oxidative phosphorylation. Therefore, the electron transport chain is the most efficient step in ATP production during cellular respiration.

Correct Answer: B

Rationale: The correct answer is B: Smooth, skeletal, cardiac. Smooth muscle tissue is found in organs and blood vessels, skeletal muscle tissue is attached to bones for movement, and cardiac muscle tissue is found in the heart. The other choices are incorrect because they do not accurately represent the types of muscle tissue in the human body. Choice A includes organs and structures that are not muscle tissues. Choice C lists a neuron (nerve cell), epithelial (covering and lining tissue), and collagen (connective tissue), which are not types of muscle tissue. Choice D is incorrect as it does not provide the correct types of muscle tissue.

Correct Answer: A

Rationale: Adenine is a purine base because it has a double-ring structure, which is a characteristic of purines. It pairs with thymine in DNA and uracil in RNA. Cytosine, thymine, and guanine are pyrimidines, which have a single-ring structure. Therefore, the correct answer is A. Cytosine, thymine, and guanine are incorrect choices as they are pyrimidines.

Correct Answer: B

Rationale: The correct answer is B: mitochondria. Heart muscle cells require a significant amount of energy to constantly contract and pump blood, making mitochondria crucial for energy production through aerobic respiration. Mitochondria are abundant in heart muscle cells to meet their high energy demands. Lysosomes (A) are involved in cellular waste disposal, mRNA (C) carries genetic information, and ribosomes (D) are involved in protein synthesis, but they are not expected to be unusually high in heart muscle cells.