Biology HESI A2 Practice Test

Correct Answer: C

Rationale: The correct answer is C: Uracil. DNA bases consist of Adenine, Thymine, Cytosine, and Guanine, whereas Uracil is only found in RNA. DNA uses Thymine, while RNA uses Uracil as one of its bases. Therefore, Uracil is not a part of DNA bases. Adenine, Thymine, and Cytosine are all essential components of DNA.

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.

Correct Answer: A

Rationale: The correct answer is A: hypothesis. A hypothesis is a statement that proposes an explanation for a phenomenon based on available evidence. It helps guide scientific inquiry by providing a testable prediction. Observations (B) are simply data collected through senses. Experiments (C) involve testing hypotheses through controlled conditions. Conclusions (D) are interpretations drawn from the data collected. Therefore, a hypothesis is the initial statement or explanation of certain events or happenings in the scientific process.

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: B

Rationale: The correct answer is B because the Krebs cycle involves the oxidation of acetyl CoA, a product of glycolysis, leading to the production of NADH and FADH2. Choice A is incorrect because the proteins are not directly involved in the Krebs cycle. Choice C is incorrect because protons are not passed along a gradient in the Krebs cycle; they are used in the electron transport chain to produce ATP. Choice D is incorrect because the Krebs cycle is not known as the glycolic acid cycle; glycolysis is the pathway that produces glycolic acid.