Nursing Elites

1. A keystone species plays a critical role in an ecosystem because its removal would:

• A. Lead to a decrease in competition among other species
• B. Cause a slight increase in primary productivity
• C. Have a minimal impact on the overall ecosystem structure
• D. Disrupt the food web and cause cascading effects on other populations

Correct answer: D

Rationale: Rationale: Keystone species are species that have a disproportionately large effect on their environment relative to their abundance. They play a critical role in maintaining the structure and function of an ecosystem. If a keystone species is removed from an ecosystem, it can disrupt the food web by causing imbalances in predator-prey relationships. This disruption can lead to cascading effects on other populations within the ecosystem, potentially causing population declines or even extinctions. Therefore, the removal of a keystone species would have significant impacts on the overall ecosystem structure, making option D the correct answer.

2. Saliva contains an enzyme that breaks down carbohydrates. What is the name of this enzyme?

• A. Pepsin
• B. Amylase
• C. Lipase
• D. Trypsin

Correct answer: B

Rationale: The correct answer is B: Amylase. Saliva contains the enzyme amylase, which is responsible for breaking down carbohydrates into simpler sugars like maltose and glucose. Pepsin (A) is an enzyme found in the stomach that breaks down proteins. Lipase (C) is an enzyme that breaks down fats, and trypsin (D) is another enzyme that breaks down proteins, but both of these are not found in saliva. Knowing the function of amylase in saliva helps in the digestion of carbohydrates, making it the correct answer.

3. Define "friction" in terms of opposing motion.

• A. A force that increases motion
• B. A force that accelerates motion
• C. A force that opposes motion
• D. A force that creates motion

Correct answer: c

Rationale: Friction acts opposite to the direction of motion, resisting or slowing down the movement of objects.

4. What is the scientific unit used to measure the radioactivity of a substance?

• A. Becquerel (Bq)
• B. Joule (J)
• C. Newton (N)
• D. Kelvin (K)

Correct answer: A

Rationale: Becquerel measures the number of nuclear decays per second in a radioactive sample.

5. What type of inheritance pattern results in a 3:1 ratio of dominant to recessive phenotypes in the F2 generation?

• A. Incomplete dominance
• B. Codominance
• C. Sex-linked inheritance
• D. Autosomal dominant inheritance

Correct answer: D

Rationale: Rationale: A) Incomplete dominance: In incomplete dominance, the heterozygous phenotype is a blend of the two homozygous phenotypes. This does not result in a 3:1 ratio of dominant to recessive phenotypes in the F2 generation. B) Codominance: In codominance, both alleles are fully expressed in the heterozygous phenotype. This also does not result in a 3:1 ratio of dominant to recessive phenotypes in the F2 generation. C) Sex-linked inheritance: Sex-linked inheritance involves genes located on the sex chromosomes and does not typically result in a 3:1 ratio of dominant to recessive phenotypes in the F2 generation. D) Autosomal dominant inheritance: In autosomal dominant inheritance, a single copy of the dominant allele is sufficient to express the dominant phenotype. When a heterozygous individual (Aa) is crossed with another

6. Which neurotransmitter is associated with pleasure, reward, and motivation, and is often implicated in conditions such as addiction?

• A. Acetylcholine
• B. Dopamine
• C. Serotonin
• D. GABA (Gamma-aminobutyric acid)

Correct answer: b

Rationale: The correct answer is B: Dopamine. Dopamine is a neurotransmitter that is commonly associated with pleasure, reward, and motivation. It plays a crucial role in the brain's reward system and is often implicated in conditions such as addiction. Dopamine is released in response to rewarding stimuli, reinforcing behaviors that lead to pleasure. Acetylcholine is involved in muscle contraction and memory, not pleasure and reward. Serotonin is known for regulating mood and emotions, while GABA is an inhibitory neurotransmitter that helps reduce neural activity. Therefore, dopamine is the neurotransmitter most closely linked to pleasure, reward, and motivation in the brain.

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