Nursing Elites

1. Which of the following statements regarding the working of the heart is not correct?

• A. The atria contract, and the valves open to allow blood into the ventricles.
• B. The heartbeat begins when the heart muscles relax, and blood flows into the atria.
• C. The valves close to stop blood from flowing backward.
• D. The ventricles contract, forcing blood to leave the heart.

Correct answer: B

Rationale: The correct answer is B because the heartbeat actually begins when the heart muscles relax, allowing the chambers to fill with blood. The contraction phase follows, which propels blood out of the heart. The other statements are accurate in describing the normal sequence of events in the heart's functioning: the atria contract to push blood into the ventricles, the valves close to prevent backflow of blood, and the ventricles contract to pump blood out of the heart.

2. If a biochemist isolates a large amount of pyruvate, which part of the cell is he working with?

• A. Chloroplasts
• B. Cytoplasm
• C. Mitochondria
• D. Nucleus

Correct answer: B

Rationale: The correct answer is B: Cytoplasm. Pyruvate is a product of glycolysis, a metabolic pathway that takes place in the cytoplasm of the cell. Therefore, a biochemist isolating a large amount of pyruvate would be working with the cytoplasm of the cell. Choice A, Chloroplasts, is incorrect because pyruvate is not produced in chloroplasts, which are responsible for photosynthesis. Choice C, Mitochondria, is incorrect as pyruvate is produced in the cytoplasm before entering the mitochondria for further metabolism. Choice D, Nucleus, is incorrect as the nucleus is not involved in the production or isolation of pyruvate, which is a metabolic intermediate.

3. What is the primary function of the liver?

• A. To produce bile, which aids in the digestion of fats
• B. To store energy in the form of glycogen
• C. To produce proteins that assist in blood clotting
• D. To detoxify harmful substances in the body

Correct answer: D

Rationale: The primary function of the liver is to detoxify harmful substances in the body. While the liver does produce bile to aid in the digestion of fats, this is not its primary function. Bile is stored in the gallbladder and released into the small intestine for fat digestion. Storing energy in the form of glycogen is a function of the liver, but not its primary one. Glycogen serves as a reserve of glucose. Although the liver produces proteins that assist in blood clotting, such as fibrinogen and prothrombin, this is not its main function. These proteins play a crucial role in blood clotting to prevent excessive bleeding. Therefore, the primary role of the liver is to detoxify harmful substances by processing and removing toxins, drugs, alcohol, and other harmful substances from the bloodstream, thereby reducing their harmful effects.

4. How is inertia related to Newton's first law?

• A. Objects in motion stay in motion unless acted upon by an external force.
• B. Objects at rest stay at rest unless acted upon by an external force.
• C. An object's resistance to a change in its state of motion.
• D. The force required to lift an object.

Correct answer: C

Rationale: Inertia is an object's resistance to a change in its state of motion, as described by Newton's first law. This means that an object will maintain its current state, whether it is stationary or moving at a constant velocity, unless it experiences an external force. Choices A and B illustrate specific instances of inertia where objects in motion or at rest continue as such without external interference. Option D refers to the force necessary to elevate an object, which is not directly linked to the concept of inertia.

5. What is the function of the cell membrane?

• A. To protect the cell and control what enters and exits
• B. To store energy
• C. To produce proteins
• D. To synthesize lipids

Correct answer: A

Rationale: The cell membrane, also known as the plasma membrane, serves as a protective barrier for the cell, separating the internal environment of the cell from the external environment. It is selectively permeable, meaning it controls the passage of substances in and out of the cell. This regulation of what enters and exits the cell is crucial for maintaining the cell's internal environment and ensuring proper functioning. Options B, C, and D are incorrect because storing energy, producing proteins, and synthesizing lipids are functions carried out by other cellular structures such as mitochondria, ribosomes, and endoplasmic reticulum, respectively, not the cell membrane.

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