the system maintains the bodys balance through the release of directly into the bloodstream

HESI A2

Biology HESI A2 Practice Test

1. Which system maintains the body's balance through the release of hormones directly into the bloodstream?

A. The gastrointestinal system
B. The endocrine system
C. The digestive system
D. The endocrine system

Correct answer: D

Rationale: The correct answer is D: The endocrine system. The endocrine system maintains the body's balance through the release of hormones directly into the bloodstream. Hormones produced by glands in the endocrine system regulate various bodily functions such as metabolism, growth, and reproduction. This system plays a crucial role in maintaining homeostasis by releasing hormones that help control and coordinate different processes in the body. Choices A, C, and B are incorrect. The gastrointestinal system is responsible for digestion, absorption of nutrients, and excretion of waste; the digestive system includes the gastrointestinal system and other accessory organs; and choice B is a duplicate of the correct answer.

2. 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.

3. Which organelle is responsible for organizing protein synthesis?

A. Nucleus
B. Ribosome
C. Lysosome
D. Vacuole

Correct answer: B

Rationale: The correct answer is B: Ribosome. Ribosomes are responsible for organizing protein synthesis by assembling amino acids. They are the cellular machinery where proteins are synthesized. The other choices, such as the nucleus, lysosome, and vacuole, do not directly participate in protein synthesis. The nucleus contains DNA and controls cell activities, the lysosome is involved in digestion and waste removal, and the vacuole is responsible for storage and maintaining cell turgor pressure.

4. What is the first step in the conversion of glucose to pyruvate?

A. Glycolysis
B. Krebs cycle
C. Electron transport chain
D. Aerobic respiration

Correct answer: A

Rationale: The correct answer is Glycolysis. Glycolysis is the initial step in the conversion of glucose to pyruvate. During glycolysis, glucose is broken down into pyruvate through a series of enzymatic reactions. Choice B, the Krebs cycle, occurs after glycolysis in aerobic cellular respiration. Choice C, the Electron transport chain, is the final step in aerobic respiration where the majority of ATP is produced. Choice D, Aerobic respiration, is a broader term that encompasses glycolysis, the Krebs cycle, and the electron transport chain, but it is not the specific first step in the conversion of glucose to pyruvate.

5. Which organelle is responsible for making proteins?

A. Ribosome
B. Chloroplast
C. Lysosome
D. Mitochondrion

Correct answer: A

Rationale: Ribosomes are the organelles responsible for protein synthesis within the cell. They are the sites where amino acids are linked together to form proteins based on the instructions carried by mRNA (messenger RNA). Ribosomes can be found free-floating in the cytoplasm or attached to the endoplasmic reticulum, and they play a crucial role in translating genetic information into proteins. Chloroplasts are responsible for photosynthesis, lysosomes are involved in digestion and waste removal, and mitochondria are known as the powerhouse of the cell responsible for energy production through cellular respiration. Therefore, the ribosome is the correct organelle responsible for making proteins.