HESI A2
Biology HESI A2 2024
1. Beeswax is an example of what kind of molecule?
- A. Lipid
- B. Carbohydrate
- C. Protein
- D. Nucleic acid
Correct answer: A
Rationale: Beeswax is primarily composed of esters of long-chain aliphatic alcohols and fatty acids, making it a type of lipid. Lipids are a diverse group of molecules that are hydrophobic in nature and have important functions in energy storage, signaling, and forming cellular membranes. Beeswax's chemical composition and properties categorize it as a lipid rather than a carbohydrate, protein, or nucleic acid. Carbohydrates are composed of sugars, proteins are made up of amino acids, and nucleic acids consist of nucleotides; none of which match the chemical composition of beeswax.
2. Which of the following are components of the endocrine system?
- A. The pituitary gland
- B. The thyroid gland
- C. The adrenal glands
- D. All of the Above
Correct answer: D
Rationale: The endocrine system comprises a network of glands that produce and release hormones to regulate bodily functions. The pituitary gland, thyroid gland, and adrenal glands are essential components of this system. The pituitary gland secretes various hormones that control other glands and some body functions. The thyroid gland regulates metabolism, growth, and energy levels by producing thyroid hormones. The adrenal glands produce hormones involved in stress response, metabolism, and immune function. Therefore, all of the above glands are integral parts of the endocrine system, making choice D the correct answer.
3. What is represented by this formula: 6COâ‚‚ + 6Hâ‚‚O → C₆Hâ‚â‚‚O₆ + 6Oâ‚‚?
- A. Glycolysis
- B. Cellular respiration
- C. Photosynthesis
- D. Electronic transport
Correct answer: C
Rationale: The formula represents the process of photosynthesis, where carbon dioxide (COâ‚‚) and water (Hâ‚‚O) are converted into glucose (C₆Hâ‚â‚‚O₆) and oxygen (Oâ‚‚) using light energy. This process is essential for plants and some microorganisms to produce food and oxygen. Glycolysis and cellular respiration involve breaking down glucose to produce energy, and the electron transport chain is part of cellular respiration, not photosynthesis.
4. Which structure controls the passage of substances into and out of the cell?
- A. Vacuole
- B. Cell Membrane
- C. Nuclear Membrane
- D. Cytoplasm
Correct answer: B
Rationale: The correct answer is the Cell Membrane. The cell membrane acts as a barrier that controls the passage of substances into and out of the cell. It is selectively permeable, allowing only certain molecules to pass through. Vacuole (Choice A), Nuclear Membrane (Choice C), and Cytoplasm (Choice D) do not primarily regulate the passage of substances in and out of the cell. Vacuoles are responsible for storage, the nuclear membrane surrounds the nucleus providing protection, and the cytoplasm is the fluid where organelles are suspended.
5. What is the role of tRNA during protein synthesis?
- A. Carries amino acids to the ribosome
- B. Links nucleotides together
- C. Copies DNA sequences
- D. Replicates genetic material
Correct answer: A
Rationale: During protein synthesis, tRNA plays the crucial role of carrying amino acids to the ribosome. This process ensures that the correct amino acids are brought to the ribosome according to the mRNA sequence. Choice B, linking nucleotides together, refers to the role of RNA polymerase in transcription, not tRNA. Choice C, copying DNA sequences, is the function of DNA polymerase during DNA replication, while choice D, replicating genetic material, is an overarching function of DNA replication, not specific to tRNA's role in protein synthesis.
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