Nursing Elites

1. Which type of cell has a nucleus but lacks membrane-bound organelles?

• A. Plant cell
• B. Prokaryotic cell
• C. Animal cell
• D. Fungal cell

Correct answer: B

Rationale: The correct answer is B: Prokaryotic cell. Prokaryotic cells are characterized by having a nucleus that is not enclosed within a membrane (nuclear envelope) and lacking membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus. Plant, animal, and fungal cells are eukaryotic cells, which have a true nucleus enclosed within a nuclear envelope and contain membrane-bound organelles. Therefore, options A, C, and D are incorrect as they all represent eukaryotic cells that possess membrane-bound organelles.

2. Which of the following is the control group in the above experiment?

• A. tank A
• B. tank B
• C. tank C
• D. There is no control group in this experiment.

Correct answer: D

Rationale: The correct answer is D: There is no control group in this experiment. A control group is a group in an experiment that does not receive the treatment being studied in order to serve as a baseline for comparison. In this case, all three tanks (A, B, and C) are being treated with different amounts of fertilizer, and there is no group that is left untreated to serve as a control for comparison. Choices A, B, and C are incorrect because they all represent tanks that are part of the experimental groups receiving different amounts of fertilizer, thus none of them can be considered the control group.

3. Which blood type is considered a universal donor?

• A. A
• B. B
• C. AB
• D. O

Correct answer: D

Rationale: Blood type O is considered the universal donor because individuals with type O blood can donate red blood cells to individuals with any ABO blood type (A, B, AB, or O) without causing an adverse reaction. Type O blood lacks A or B antigens on the surface of red blood cells, minimizing the risk of an immune response when transfused into individuals with different blood types. Therefore, type O blood is in high demand for blood transfusions in emergency situations when the recipient's blood type is unknown or when there is a shortage of specific blood types. Choices A, B, and AB are not considered universal donors. Individuals with blood types A, B, or AB can only donate to individuals with compatible blood types to avoid adverse reactions since they have A and/or B antigens on the surface of their red blood cells, making them incompatible with all blood types.

4. Molecular clocks utilize the accumulation of mutations in DNA sequences to estimate the evolutionary divergence time between species. This method relies on the assumption that:

• A. The rate of mutation is constant across all genes and all species.
• B. Species with more morphological similarities diverged more recently.
• C. Mutations are always beneficial and contribute to increased fitness.
• D. The fossil record provides the most accurate estimates of evolutionary relationships.

Correct answer: A

Rationale: A molecular clock is a method used to estimate the time of divergence between species by measuring the accumulation of mutations in DNA sequences. This method relies on the assumption that mutations occur at a relatively constant rate over time. If the rate of mutation were not constant, it would be challenging to accurately estimate the evolutionary divergence time between species. Therefore, option A is the most appropriate choice as it aligns with the fundamental principle underlying the molecular clock hypothesis. Option B is incorrect because the assumption that species with more morphological similarities diverged more recently does not directly relate to the concept of molecular clocks and the accumulation of mutations in DNA sequences. Option C is incorrect because mutations are not always beneficial and do not always contribute to increased fitness. Mutations can be neutral or deleterious as well, and their accumulation is what is used to estimate evolutionary di

5. Which of these body parts does not contain melanin?

• A. Hair
• B. Nails
• C. Skin
• D. Iris

Correct answer: D

Rationale: The iris is the colored part of the eye that determines the eye's color. Melanin is not present in the iris, unlike hair, nails, and skin. Melanin gives color to hair, nails, and skin, but not to the iris. Therefore, the correct answer is the iris (Choice D). Choices A, B, and C contain melanin and are incorrect.

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