HESI A2 Practice Test Biology

Correct Answer: A

Rationale: The correct answer is A: Phospholipids. Phospholipids are essential components of the plasma membrane due to their amphipathic nature, with hydrophilic heads and hydrophobic tails. This structure allows phospholipids to form a lipid bilayer, creating a barrier that separates the internal and external environments of the cell. Steroids (B) are not a major component of the plasma membrane. Sugars (C) are found in glycoproteins and glycolipids on the membrane surface, but they are not the main structural component. Amino acids (D) are the building blocks of proteins, which can be membrane proteins, but they are not the key structural component of the membrane itself.

Correct Answer: D

Rationale: The correct answer is D: DNA. DNA is not directly involved in translation. Translation is the process of synthesizing proteins from mRNA using tRNA and ribosomes. DNA serves as the template for transcription, where mRNA is synthesized. Once mRNA is formed, it carries the genetic information from DNA to the ribosome for translation. tRNA brings in amino acids based on the codons on the mRNA, and the ribosome facilitates the assembly of amino acids into a polypeptide chain. Therefore, DNA is not directly involved in the actual process of translation, making it the correct answer.

Correct Answer: A

Rationale: The correct answer is A because tRNA carries amino acids to the ribosome during protein synthesis. Firstly, tRNA molecules bind to specific amino acids through their anticodon region. Secondly, tRNA recognizes the mRNA codon at the ribosome, ensuring the correct amino acid is added to the growing polypeptide chain. This process is crucial for translating the genetic code into proteins. Choices B, C, and D are incorrect because tRNA does not link nucleotides together, copy DNA sequences, or replicate genetic material during protein synthesis.

Correct Answer: A

Rationale: The correct answer is A: Glycolysis. In the process of converting glucose to pyruvate, the first step is glycolysis. This is where glucose is broken down into two molecules of pyruvate, generating ATP and NADH. Glycolysis occurs in the cytoplasm and does not require oxygen. The Krebs cycle (B) occurs in the mitochondria and follows glycolysis, while the electron transport chain (C) and aerobic respiration (D) require oxygen and take place after glycolysis. Therefore, the correct first step in the conversion of glucose to pyruvate is glycolysis.

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.