Nursing Elites

1. Which cellular structure is largely protective in function?

• A. Mitochondrion
• B. Vacuole
• C. Cell membrane
• D. Ribosome

Correct answer: C

Rationale: The correct answer is C: Cell membrane. The cell membrane, also known as the plasma membrane, is largely protective in function as it serves as a selectively permeable barrier that surrounds the cell, providing structural support and helping to maintain cell integrity. It regulates the movement of substances in and out of the cell, thus protecting the cell from harmful external factors while allowing essential nutrients to enter. Mitochondrion (choice A) is responsible for energy production, not primarily protective. Vacuole (choice B) is mainly involved in storage and transport. Ribosome (choice D) is involved in protein synthesis, not protective functions.

2. Which organelle is found in protists but not in monerans?

• A. Golgi apparatus
• B. Chromosome
• C. Cytoplasm
• D. Cell membrane

Correct answer: A

Rationale: The Golgi apparatus is the correct answer. The Golgi apparatus is a cellular organelle responsible for processing and packaging proteins before they are transported to their final destination. Protists, being eukaryotic organisms, have membrane-bound organelles including the Golgi apparatus, which are absent in monerans. Monerans are prokaryotic organisms that lack membrane-bound structures such as the Golgi apparatus. Choices B, C, and D are incorrect as chromosomes, cytoplasm, and cell membranes are present in both protists and monerans.

3. If bacteria are placed in a strong solution of salt water, they will shrink as water moves out of the bacteria. What is this process called?

• A. Dehydration synthesis
• B. Hydrolysis
• C. Osmosis
• D. Isotonic transport

Correct answer: C

Rationale: Osmosis is the process by which water molecules move across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. In this case, when bacteria are placed in a strong solution of salt water, the high concentration of solutes outside the bacteria causes water to move out of the bacteria, leading to shrinkage. This process is known as osmosis. Dehydration synthesis (Choice A) is a process where molecules combine by removing water. Hydrolysis (Choice B) is the breakdown of molecules by the addition of water. Isotonic transport (Choice D) does not accurately describe the specific movement of water in or out of bacterial cells in a hypertonic solution.

4. In a phospholipid molecule, the head:

• A. Is hydrophilic
• B. Is hydrophobic
• C. Is on the inner side of the layer
• D. Both A and C

Correct answer: D

Rationale: The head of a phospholipid is hydrophilic (water-loving) and is located on the outer side of the lipid bilayer, interacting with water molecules. This arrangement positions the hydrophobic tails inward, away from water. Therefore, the correct answer is D. Choice A is incorrect because the head is hydrophilic, not hydrophobic. Choice B is incorrect as the head is on the outer side, not the inner side of the layer.

5. Which names a final step in protein synthesis?

• A. DNA unzips.
• B. Amino acids bond.
• C. Transfer RNA bonds to messenger RNA.
• D. Messenger RNA moves to ribosomes.

Correct answer: B

Rationale: The final step in protein synthesis is when amino acids bond together to form a protein chain. This process occurs during translation, where transfer RNA (tRNA) brings specific amino acids to the ribosome, and the ribosome catalyzes the formation of peptide bonds between the amino acids. This step ultimately leads to the synthesis of a complete protein based on the instructions from messenger RNA (mRNA). Choice A ('DNA unzips') is incorrect as it refers to the initiation of transcription, not the final step of protein synthesis. Choice C ('Transfer RNA bonds to messenger RNA') is incorrect as it describes the process of translation initiation rather than the final step. Choice D ('Messenger RNA moves to ribosomes') is also incorrect as mRNA is already present at the ribosomes throughout the translation process, not just in the final step.

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