Nursing Elites

1. What is the pH of a solution with a hydrogen ion concentration of (1x10^{-9}) M?

• A. 5
• B. 7
• C. 9
• D. 11

Correct answer: C

Rationale: The pH of a solution can be calculated using the formula: pH = -log[H+]. Given that the hydrogen ion concentration is \(1 \times 10^{-9}\) M, the pH can be calculated as pH = -log(1 x 10^-9) = 9. Therefore, the correct answer is C) 9.

2. Which of the following is specialized tissue in the right atrium that acts as the heart’s natural pacemaker by generating the electrical signal for the heartbeat?

• A. sinus venosus
• B. sinoatrial node
• C. atrioventricular node
• D. tricuspid valve

Correct answer: B

Rationale: The sinoatrial node, often referred to as the SA node, is specialized tissue located in the right atrium of the heart. It functions as the heart's natural pacemaker by generating the electrical signal that initiates each heartbeat. This electrical signal spreads to the atrial muscles and then to the atrioventricular node, causing the heart to contract rhythmically and efficiently. The other options listed do not serve as the heart's natural pacemaker responsible for generating the electrical signal for the heartbeat. Sinus venosus is a developmental structure in fetal hearts, the atrioventricular node delays the electrical signal, and the tricuspid valve is a heart valve that prevents backflow of blood from the right ventricle to the right atrium.

3. Which of the following macromolecules will always contain nitrogen?

• A. Fatty acids
• B. Proteins
• C. Lipids
• D. Carbohydrates

Correct answer: B

Rationale: The correct answer is B: Proteins. Proteins are the only macromolecules that always contain nitrogen in their amino acid structure. Nitrogen is a key element found in the amino groups of amino acids, which are the building blocks of proteins. Fatty acids (Choice A), lipids (Choice C), and carbohydrates (Choice D) do not always contain nitrogen in their structure. Fatty acids are composed of long hydrocarbon chains and do not contain nitrogen. Lipids consist mainly of carbon, hydrogen, and oxygen, with some classes of lipids containing phosphorus but not nitrogen. Carbohydrates are made up of carbon, hydrogen, and oxygen, forming structures like sugars and starches, but they do not contain nitrogen.

4. Which vitamin plays a crucial role in calcium absorption in the small intestine?

• A. Vitamin A
• B. Vitamin C
• C. Vitamin D
• D. Vitamin E

Correct answer: C

Rationale: The correct answer is Vitamin D. Vitamin D plays a crucial role in calcium absorption in the small intestine by enhancing the absorption of calcium and phosphorus. This helps in regulating the levels of these minerals in the body, which are essential for maintaining healthy bones. Vitamin A (Choice A) is important for vision and immune function, but it is not directly related to calcium absorption. Vitamin C (Choice B) is primarily known for its role in collagen synthesis and antioxidant functions, not calcium absorption. Vitamin E (Choice D) acts as an antioxidant and is not directly involved in calcium absorption in the small intestine.

5. What determines the magnitude of the frictional force acting on a book sliding across a table?

• A. Only the mass of the book
• B. Only the normal force from the table
• C. Both the mass of the book and the normal force from the table
• D. Neither the mass of the book nor the normal force from the table

Correct answer: C

Rationale: The magnitude of the frictional force acting on the book sliding across a table is determined by both the mass of the book and the normal force from the table. Frictional force is proportional to the normal force (which is influenced by the weight of the book, i.e., its mass) and is affected by the surfaces in contact and other friction-related factors. Therefore, both the mass of the book and the normal force from the table are essential in determining the frictional force experienced by the book during its sliding motion. Choices A, B, and D are incorrect because friction is a result of the interaction between the surfaces and is influenced by both the mass of the object and the normal force acting on it.

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