HESI A2 Practice Test Biology

Correct Answer: B

Rationale: The correct answer is B: ATP. ATP (adenosine triphosphate) is the primary molecule responsible for storing and transferring energy in cells through its high-energy phosphate bonds. Glucose (choice A) is a source of energy but not a storage molecule. Fatty acids (choice C) are primarily used for long-term energy storage. Starch (choice D) is a polysaccharide used for energy storage in plants, but ATP is the main energy currency in all cells for immediate use.

Correct Answer: B

Rationale: The correct answer is B: hemoglobin. Hemoglobin is a protein because it is composed of amino acids linked together in a specific sequence to form a complex structure that carries oxygen in red blood cells. Cellulose (choice A) is a carbohydrate, estrogen (choice C) is a hormone, and ATP (choice D) is a nucleotide that serves as a source of energy in cells. Hemoglobin's role in oxygen transport and its structural composition as a sequence of amino acids classify it as a protein.

Correct Answer: A

Rationale: The correct answer is A: two diploid cells. During mitosis in humans, a single diploid cell divides into two identical diploid cells. This process ensures that each new cell receives a complete set of chromosomes, maintaining the same genetic information. This is essential for growth, repair, and maintenance of tissues in the body. Choices B, C, and D are incorrect because mitosis results in the production of genetically identical diploid cells, not haploid cells or additional copies of diploid cells. Haploid cells are produced through meiosis, not mitosis.

Correct Answer: C

Rationale: The correct answer is C, fermentation and cellular respiration, because both are catabolic pathways that lead to cellular energy production. Fermentation occurs in the absence of oxygen, producing a small amount of ATP. Cellular respiration, on the other hand, occurs in the presence of oxygen and is a more efficient process, producing a significantly higher amount of ATP. Choices A, B, and D are incorrect because internal respiration, external respiration, and anaerobic respiration do not directly lead to cellular energy production through catabolic pathways.

Correct Answer: C

Rationale: The correct answer is C: ribosome. Ribosomes are the organelles responsible for organizing protein synthesis. They are the site where proteins are assembled based on instructions from the cell's DNA. Ribosomes can be found in the cytoplasm and on the endoplasmic reticulum. Mitochondria (A) are responsible for energy production, the nucleus (B) contains genetic material but does not directly organize protein synthesis, and vacuoles (D) are primarily involved in storage and maintaining cell structure. Therefore, the ribosome is the only organelle directly involved in protein synthesis among the choices provided.