HESI A2
Biology HESI A2 Practice Test
1. 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.
2. Which organelle is the site of photosynthesis in plant cells?
- A. Mitochondria
- B. Chloroplasts
- C. Ribosomes
- D. Endoplasmic Reticulum
Correct answer: B
Rationale: The correct answer is B: Chloroplasts. Chloroplasts are responsible for conducting photosynthesis in plant cells. They contain chlorophyll, a pigment that captures light energy and converts it into chemical energy through the process of photosynthesis. Mitochondria (choice A) are known as the powerhouse of the cell and are involved in cellular respiration, not photosynthesis. Ribosomes (choice C) are responsible for protein synthesis. The endoplasmic reticulum (choice D) is involved in protein and lipid synthesis and transport within the cell, not photosynthesis.
3. If a hard-boiled egg is placed in a beaker of saltwater, what will happen to the egg?
- A. Expand because water will move into the egg
- B. Shrivel because water will leave the egg
- C. Remain the same
- D. None of the above
Correct answer: B
Rationale: The correct answer is B. When a hard-boiled egg is placed in a beaker of saltwater, the egg will shrivel because water will leave the egg through osmosis. Osmosis is the movement of water from an area of lower solute concentration to an area of higher solute concentration, in this case, from the egg into the saltwater. The higher concentration of solute in the saltwater causes water to move out of the egg, leading to the egg shrinking or shriveling. Choices A, C, and D are incorrect because the egg will not expand, remain the same, or have an outcome different from shriveling when placed in a beaker of saltwater.
4. What is the main function of the ribosomes in the cell?
- A. DNA Replication
- B. Protein Synthesis
- C. Lipid Breakdown
- D. Cell Division
Correct answer: B
Rationale: The correct answer is B: Protein Synthesis. Ribosomes are cellular organelles responsible for synthesizing proteins. This process is crucial for various cellular functions. Choice A, DNA Replication, is incorrect as ribosomes are not involved in this process. Choice C, Lipid Breakdown, is also incorrect as ribosomes do not play a role in lipid metabolism. Choice D, Cell Division, is incorrect as ribosomes are not directly involved in the process of cell division.
5. How do animal cells divide?
- A. Through a contractile ring
- B. Via a cell plate
- C. Both methods
- D. None of the above
Correct answer: A
Rationale: Animal cells divide through a contractile ring made of actin and myosin filaments. The ring contracts, pinching the cell membrane in the middle to form two daughter cells. Plant cells use a cell plate due to their rigid cell walls, making choices B and C incorrect. Choice D is incorrect as animal cells do use the contractile ring method for division.
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