HESI A2 Practice Test Biology

Correct Answer: B

Rationale: The correct answer is B: Cell membrane. The cell membrane is a selectively permeable barrier that protects the cell, regulates communication with the external environment, and allows substances to enter and exit the cell. It is composed of a phospholipid bilayer with embedded proteins that facilitate transport and signaling. The other choices are incorrect because: A: Nucleus - The nucleus houses the cell's genetic material and is responsible for controlling cell activities, but it does not directly contribute to protection or substance passage. C: Endoplasmic reticulum - The ER is involved in protein synthesis and lipid metabolism, but it does not have a primary role in protection or communication. D: Cytoplasm - The cytoplasm is the fluid-filled region of the cell where organelles are suspended, but it does not play a direct role in protection or communication at the cell's boundary.

Correct Answer: D

Rationale: The correct answer is D because DNA controls the synthesis of enzymes, which are essential for carrying out metabolic activities in the cell. Enzymes are biological catalysts that regulate chemical reactions in the cell. DNA contains the genetic information needed to produce specific enzymes through the process of transcription and translation. Enzymes play a crucial role in breaking down nutrients, synthesizing molecules, and regulating metabolic pathways. A: DNA does not initiate cellular mitosis; that is controlled by other molecules. B: DNA is not responsible for providing cell wall stability; that is primarily the role of the cell wall structure itself. C: DNA is not directly involved in increasing glucose absorption; that is regulated by other mechanisms such as insulin signaling.

Correct Answer: A

Rationale: The correct answer is A: Transcription. During protein synthesis, transcription is the process where an RNA strand is synthesized using DNA as a template. This RNA strand is complementary to the DNA template and serves as a messenger to carry genetic information from the DNA to the ribosomes for translation. Explanation for incorrect choices: B: Translation is the process where the information carried by the mRNA is decoded to produce a protein, not to produce a complementary DNA strand. C: Transfer synthesis is not a recognized term in protein synthesis processes. D: Codon synthesis is not a correct term for the process of producing a complementary DNA strand using an RNA template.

Correct Answer: B

Rationale: The correct answer is B: Golgi apparatus. The Golgi apparatus is responsible for modifying, sorting, and packaging proteins and lipids from the endoplasmic reticulum for transport throughout the cell. It receives materials from the ER, processes them, and then directs them to their final destinations. Ribosomes (choice A) are responsible for protein synthesis, lysosomes (choice C) are involved in digestion and waste removal, and vacuoles (choice D) are storage organelles. Therefore, B is the correct answer as it specifically functions in the transportation of materials within the cell.

Correct Answer: C

Rationale: The correct answer is C: covalent. In DNA, the bond connecting sugar and phosphate is a covalent bond. This is because covalent bonds involve the sharing of electrons between atoms, which is essential for forming the strong backbone structure of the DNA molecule. Hydrogen bonds (choice A) are important for holding the nitrogenous bases together in the DNA double helix, but they do not connect sugar and phosphate. Ionic bonds (choice B) involve the transfer of electrons between atoms, not sharing, and are not typically found in the structure of DNA. "Overt" (choice D) is not a type of chemical bond and is an incorrect term in this context. Thus, the correct choice is covalent based on the nature of the bond required to connect sugar and phosphate in DNA.