Biology HESI A2 Practice Test

Correct Answer: B

Rationale: Proteins are the best choice to increase muscle mass and strength because they are essential for muscle repair and growth. Proteins are made up of amino acids, which are the building blocks of muscles. Consuming enough protein provides the body with the necessary nutrients to repair and build muscle tissue. Carbohydrates are primarily for energy, lipids are for long-term energy storage, and nucleic acids are not directly involved in muscle growth. Therefore, proteins are the most suitable option for athletes looking to increase muscle mass and strength.

Correct Answer: C

Rationale: The correct answer is C: Proteins embedded in lipid bilayer. This arrangement is seen in the plasma membrane based on the fluid mosaic model. The lipid bilayer provides a barrier for the cell, while proteins are embedded within the bilayer, performing various functions like transport, signaling, and structural support. This arrangement allows for selective permeability and communication with the external environment. A: Lipids with embedded proteins - While proteins are indeed embedded in the lipid bilayer, the primary arrangement is not lipids with embedded proteins. B: An outer lipid layer and an inner lipid layer - This describes the structure of the lipid bilayer itself, but it does not address the arrangement of proteins within the membrane. D: Altering protein and lipid layers - This choice does not accurately describe the typical arrangement of proteins and lipids in the plasma membrane.

Correct Answer: C

Rationale: The correct answer is C: epididymis. The epididymis is the structure in the male reproductive system that stores spermatozoa during the maturation process. Sperm are produced in the testes and then move to the epididymis for storage and maturation before being ejaculated. The vas deferens is the tube that carries mature sperm from the epididymis to the urethra during ejaculation. The scrotum is the external sac that holds the testes and helps regulate their temperature. The testicular artery supplies blood to the testes but is not directly involved in storing spermatozoa.

Correct Answer: B

Rationale: The correct answer is B: They lower the activation energy needed. Enzymes lower the activation energy required for a reaction to occur, facilitating the reaction without being consumed in the process. This is crucial in speeding up biological processes. Choices A, C, and D are all true statements about enzymes. A: Enzymes catalyze reactions by speeding up the rate of a chemical reaction. C: Enzymes have an active site where substrate molecules bind, facilitating the reaction. D: Enzymes are typically proteins, although some RNA molecules can also exhibit catalytic activity.

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.