Nursing Elites

1. As cattle graze, cattle egrets consume the insects they stir up. This is an example of ___________.

• A. Mutualism
• B. Parasitism
• C. Commensalism
• D. Competition

Correct answer: C

Rationale: Commensalism is a relationship between two species in which one benefits without affecting the other species. In this scenario, the cattle egrets benefit from the insects stirred up by cattle while the cattle are not significantly impacted by the presence of the egrets. The egrets obtain food easily, and the cattle are neither harmed nor helped by the egrets' presence, making it an example of commensalism. Mutualism involves both species benefiting, parasitism involves one species benefiting at the expense of the other, and competition involves both species being negatively affected by their interactions, none of which apply to the relationship between cattle and cattle egrets in this context.

2. What is the composition of the plasma membrane?

• A. Proteins
• B. Lipids
• C. Carbohydrates
• D. Nucleotides

Correct answer: B

Rationale: The plasma membrane is composed of lipids, proteins, and carbohydrates. While proteins are an essential component of the plasma membrane, it is not the only constituent. Carbohydrates and lipids also play crucial roles in the structure and function of the plasma membrane. Nucleotides are not part of the primary structural components of the plasma membrane, making this choice incorrect.

3. How are lipids different from other organic molecules?

• A. They are indivisible.
• B. They are not water soluble.
• C. They contain zinc.
• D. They form long proteins.

Correct answer: B

Rationale: The correct answer is B: 'They are not water soluble.' Lipids are not water-soluble, which distinguishes them from other organic molecules. Choice A is incorrect because lipids are not indivisible; they can be broken down into fatty acids and glycerol. Choice C is incorrect as lipids do not necessarily contain zinc; they are a diverse group of molecules. Choice D is incorrect because lipids do not form long proteins; proteins are made up of amino acids, not lipids.

4. Which of the following is not a product of the Krebs cycle?

• A. carbon dioxide
• B. oxygen
• C. adenosine triphosphate (ATP)
• D. energy carriers

Correct answer: B

Rationale: The correct answer is B: oxygen. Oxygen is not a product of the Krebs cycle. During the Krebs cycle, carbon dioxide, adenosine triphosphate (ATP), and energy carriers like NADH and FADH2 are produced. Carbon dioxide is a byproduct of the cycle, ATP is a form of energy produced, and energy carriers play a crucial role in transferring energy within the cell. Therefore, oxygen is the only option that is not a product of the Krebs cycle, making it the correct answer.

5. In an example of a male with hemophilia and a female carrier, what ratio of the offspring is predicted to have the disease?

• A. 0 female : 2 males
• B. 1 female : 0 males
• C. 1 female : 2 males
• D. 2 females : 1 male

Correct answer: C

Rationale: In this scenario, the male offspring will inherit the hemophilia trait from their mother due to the sex-linked inheritance pattern. The female offspring will inherit one X chromosome from their mother, becoming carriers of hemophilia. Therefore, the predicted ratio of offspring with the disease would be 1 female as a carrier and 2 males with hemophilia. Choice A is incorrect because there would be male offspring with the disease. Choice B is incorrect as there would be male offspring with hemophilia. Choice D is incorrect as it does not reflect the inheritance pattern of hemophilia.

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