which is a byproduct of fermentation in muscle cells

HESI A2

HESI A2 Biology 2024

1. Which is a byproduct of fermentation in muscle cells?

A. Ethanol
B. Pyruvic acid
C. Lactic acid
D. Oxygen

Correct answer: C

Rationale: Lactic acid is a byproduct of fermentation in muscle cells. During intense exercise or when oxygen is limited, muscle cells use anaerobic respiration to generate energy. This process breaks down glucose into lactic acid, which can cause muscle fatigue and soreness. Choice A, Ethanol, is not produced in muscle cells during fermentation. Choice B, Pyruvic acid, is an intermediate product in glucose metabolism but is not a byproduct of fermentation in muscle cells. Choice D, Oxygen, is not a byproduct of fermentation but a reactant in aerobic respiration.

2. Which component is not found in the nucleotide of DNA?

A. Simple sugar
B. Nitrogen base
C. Phosphate group
D. Citric acid

Correct answer: D

Rationale: Citric acid is not found in the nucleotide of DNA. A DNA nucleotide is composed of a simple sugar (deoxyribose), a nitrogen base (adenine, thymine, cytosine, or guanine), and a phosphate group. Citric acid is not part of DNA nucleotides; instead, it is involved in the citric acid cycle of cellular respiration. Choices A, B, and C are essential components of DNA nucleotides, making them incorrect answers.

3. Which of the following structures is not directly involved in translation?

A. tRNA
B. mRNA
C. ribosome
D. DNA

Correct answer: D

Rationale: The correct answer is 'D: DNA.' DNA is not directly involved in translation, which is the process of synthesizing proteins from mRNA. tRNA carries amino acids to the ribosome, mRNA provides the template for protein synthesis, and ribosomes are the cellular machinery where translation occurs. DNA's main role is in transcription, where it serves as the template for mRNA synthesis, not in translation.

4. How should a researcher test the hypothesis that radiation from cell phones is significant enough to raise the temperature of water in a test tube?

A. Dial a cell phone that rests beside a test tube of water, let it ring for two minutes, and record the temperature of the water before and after the two-minute interval.
B. Dial a cell phone that rests beside a test tube of water; let it ring for two, three, and four minutes; and record the temperature of the water before and after each interval.
C. Use three different brands of cell phone; dial each as it rests beside its own test tube of water, let it ring for two minutes, and record the temperature of the water before and after the two-minute interval.
D. Use three different brands of cell phone, dial each and let one ring for two minutes, one for three minutes, and one for four minutes; record the temperature of the water before and after each interval.

Correct answer: A

Rationale: To test the hypothesis that radiation from cell phones raises the temperature of water in a test tube, the most appropriate method is to dial a cell phone next to a test tube of water, let it ring for a consistent two-minute interval, and record the temperature before and after. Choice A is correct because it provides a controlled approach to isolate the impact of the phone's radiation on the water temperature. Choices B, C, and D introduce additional variables that could confound the results. Choice B varies the duration of exposure, making it difficult to attribute temperature changes specifically to the radiation. Choice C introduces the factor of different cell phone brands, which could introduce variability not related to radiation. Choice D also varies exposure times and introduces the factor of multiple phone brands, making it harder to determine the direct impact of cell phone radiation on water temperature. Therefore, choice A is the most suitable option for this experiment.

5. What are saturated fats saturated with?

A. Hydrogen atoms
B. Carbon atoms
C. Oxygen atoms
D. Nitrogen atoms

Correct answer: A

Rationale: Saturated fats are saturated with hydrogen atoms. This means that each carbon atom in the fatty acid chains forming saturated fats is bonded to as many hydrogen atoms as possible. This saturation results in the fatty acid chains being straight and closely packed together, making saturated fats solid at room temperature. Choice B (Carbon atoms), C (Oxygen atoms), and D (Nitrogen atoms) are incorrect because saturated fats are specifically saturated with hydrogen atoms, not carbon, oxygen, or nitrogen atoms.