Nursing Elites

1. Which of the following molecules is an important component of the plasma membrane?

• A. Phospholipids
• B. Steroids
• C. Sugars
• D. Amino acids

Correct answer: A

Rationale: Phospholipids are indeed a crucial component of the plasma membrane. They have a unique structure with hydrophilic heads and hydrophobic tails, which allows them to form the lipid bilayer of the membrane. Steroids, sugars, and amino acids are not primary components of the plasma membrane. Steroids are a different type of lipid, sugars are often found in glycoproteins on the membrane surface, and amino acids are the building blocks of proteins, some of which are membrane proteins, but not the membrane itself.

2. What is another name for the light-independent reaction in plants?

• A. Photosynthesis
• B. Calvin cycle
• C. Germination
• D. Phosphorus cycle

Correct answer: B

Rationale: The light-independent reaction in plants is also known as the Calvin cycle. This biochemical pathway, named after Melvin Calvin who discovered it, takes place in the stroma of chloroplasts and is responsible for converting carbon dioxide into glucose using ATP and NADPH generated during the light-dependent reactions of photosynthesis. The Calvin cycle does not directly require light to function, hence the alternative name as the light-independent reaction. Choices A, C, and D are incorrect. Photosynthesis is the overall process of converting light energy into chemical energy, which includes both light-dependent and light-independent reactions. Germination is the process where a seed sprouts into a new plant. The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.

3. What kind of bond connects sugar and phosphate in DNA?

• A. hydrogen
• B. ionic
• C. covalent
• D. overt

Correct answer: C

Rationale: Sugar and phosphate are indeed connected by covalent bonds in DNA. Covalent bonds involve the sharing of electrons between atoms, which is essential for forming the backbone of the DNA molecule. Hydrogen bonds (Choice A) are important in holding the nitrogenous bases together in the DNA double helix but do not connect sugar and phosphate. Ionic bonds (Choice B) involve the transfer of electrons between atoms and are not the primary bond connecting sugar and phosphate in DNA. 'Overt' (Choice D) is not a type of chemical bond and is an incorrect distractor.

4. Tonicity refers to the movement of:

• A. Water
• B. Solute
• C. Cells
• D. None of the above

Correct answer: A

Rationale: Tonicity refers to the movement of water across a membrane in response to differences in solute concentration. In a hypertonic solution, where there is a higher concentration of solutes outside the cell, water will move out of the cell to try to reach equilibrium. In a hypotonic solution, where there is a lower concentration of solutes outside the cell, water will move into the cell to balance the concentrations. Cells and solutes themselves do not actively move in response to tonicity; it is the movement of water that helps achieve equilibrium. Therefore, the correct answer is water (Choice A). Choices B, C, and D are incorrect as tonicity specifically refers to water movement and not the movement of solutes, cells, or none of the above.

5. Duchenne muscular dystrophy is a recessive sex-linked trait carried on the X chromosome. In an example of an unaffected father and a female carrier who have two daughters and two sons, which is the predicted outcome?

• A. Both daughters will carry the disease.
• B. Both sons will carry the disease.
• C. One daughter may have the disease.
• D. One son may have the disease.

Correct answer: C

Rationale: Duchenne muscular dystrophy is a recessive sex-linked trait carried on the X chromosome. Since the father is unaffected and does not carry the disease, he must have a normal X chromosome. The mother is a carrier, which means she has one normal X chromosome and one X chromosome with the disease allele. The daughters will inherit one X chromosome from each parent; one would be normal, and the other has a chance of carrying the disease allele. So, there is a 50% chance that one daughter may have the disease, as she could inherit the X chromosome with the disease allele. The sons will inherit the Y chromosome from the father and the X chromosome from the mother, so they will not be affected by the disease. Therefore, the predicted outcome is that one daughter may have the disease, while the sons will not carry the disease. This rules out choices A, B, and D.

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