Nursing Elites

1. Decomposers in an ecosystem play a vital role by:

• A. Photosynthesizing and producing organic matter
• B. Breaking down dead organisms and returning nutrients to the environment
• C. Preying on herbivores and controlling their populations
• D. Fixing nitrogen from the atmosphere and making it available to plants

Correct answer: B

Rationale: Decomposers are organisms that break down dead organic matter, such as dead plants and animals, into simpler substances. By doing so, they help to recycle nutrients back into the environment, making them available for other organisms to use. This process is essential for the functioning of ecosystems, as it ensures that nutrients are not lost but instead are continuously cycled through the ecosystem. Photosynthesis (option A) is the process by which plants and some other organisms convert light energy into chemical energy in the form of glucose, and it is not a role of decomposers. Preying on herbivores (option C) is a role typically carried out by predators, not decomposers. Fixing nitrogen from the atmosphere (option D) is a process carried out by nitrogen-fixing bacteria, not decomposers.

2. Which of the following colligative properties refers to the elevation of the boiling point of a solution?

• A. Freezing point depression
• B. Vapor pressure lowering
• C. Osmotic pressure
• D. Boiling point elevation

Correct answer: D

Rationale: The correct answer is D, 'Boiling point elevation.' Boiling point elevation is a colligative property that describes the increase in the boiling point of a solvent when a non-volatile solute is added to it. This occurs because the presence of solute particles in the solvent lowers the vapor pressure of the solution, requiring a higher temperature to reach the same vapor pressure as the pure solvent. Choices A, B, and C are incorrect. Freezing point depression refers to the lowering of the freezing point of a solution, vapor pressure lowering is the reduction in vapor pressure due to the presence of solute particles, and osmotic pressure is the pressure required to prevent the flow of solvent molecules across a semipermeable membrane in osmosis.

3. Which of the following systems does not include a transportation network throughout the body?

• A. Cardiovascular system
• B. Endocrine system
• C. Immune system
• D. Nervous system

Correct answer: B

Rationale: The endocrine system does not include a transportation network throughout the body. While the cardiovascular system transports blood, oxygen, and nutrients, the immune system has lymphatic vessels for immune cell transportation, and the nervous system transmits signals via neurons. In contrast, the endocrine system coordinates bodily functions by releasing hormones directly into the bloodstream, which then act on target organs or tissues. This delivery mechanism is different from the continuous transportation networks found in the other systems listed, making the endocrine system the correct choice for this question.

4. How does the potential energy of an object change when it is compressed?

• A. Potential energy decreases
• B. Potential energy increases
• C. Potential energy remains constant
• D. Potential energy becomes zero

Correct answer: B

Rationale: When an object is compressed, its potential energy increases. This is because work is done on the object to compress it, resulting in an increase in potential energy stored in the object as it is compressed against an opposing force. The potential energy is transformed and stored within the object due to the work done during the compression process, leading to an increase in its potential energy. Choice A is incorrect because compression involves doing work on the object, increasing its potential energy. Choice C is incorrect because compression involves a change in position and potential energy. Choice D is incorrect because compression does not reduce potential energy to zero; rather, it increases it due to the work done in compressing the object.

5. Which type of blood cell is responsible for clotting?

• A. Red blood cells
• B. Platelets
• C. White blood cells
• D. Plasma

Correct answer: B

Rationale: Platelets are responsible for blood clotting. They help prevent excessive bleeding by forming clots at the site of blood vessel injuries. Platelets release chemicals that initiate the clotting process, leading to the formation of a stable clot that stops bleeding. Red blood cells are primarily responsible for carrying oxygen throughout the body and do not play a direct role in clotting. White blood cells are part of the immune system, fighting off infections and foreign invaders. Plasma is the liquid component of blood that carries various substances such as nutrients, hormones, and waste products, but it is not directly involved in clotting.

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