Nursing Elites

1. Which of the following organs is NOT directly involved in the mechanical breakdown of food?

• A. Mouth
• B. Stomach
• C. Small intestine
• D. Esophagus

Correct answer: D

Rationale: The correct answer is the esophagus (D). The esophagus is not directly involved in the mechanical breakdown of food. Its primary function is to transport food from the mouth to the stomach through peristalsis, a series of muscular contractions. The mouth is involved in the initial mechanical breakdown by chewing and mixing food with saliva. The stomach mechanically breaks down food through churning movements, and the small intestine further breaks down food through peristalsis and segmentation. Choices A, B, and C are directly involved in mechanical breakdown processes. The mouth helps in chewing and mixing food with saliva, the stomach mechanically breaks down food through churning movements, and the small intestine continues the breakdown process with peristalsis and segmentation.

2. Where does gas exchange take place in the lungs?

• A. Bronchi
• B. Trachea
• C. Alveoli
• D. Pleura

Correct answer: C

Rationale: Gas exchange in the lungs occurs in the alveoli. Alveoli are tiny air sacs where oxygen from inhaled air diffuses into the bloodstream, and carbon dioxide from the blood diffuses into the alveoli to be exhaled. The bronchi are the main airways that branch off from the trachea, which is the windpipe connecting the larynx to the bronchi. The pleura is a membrane surrounding the lungs and lining the chest cavity, providing protection and lubrication for the lungs but not directly involved in gas exchange.

3. Which process allows for the movement of large molecules, such as proteins and polysaccharides, across the cell membrane?

• A. Endocytosis
• B. Exocytosis
• C. Active transport
• D. Facilitated diffusion

Correct answer: A

Rationale: Endocytosis is the process by which cells engulf large molecules or particles by wrapping the cell membrane around them to form a vesicle that is brought into the cell. This mechanism facilitates the movement of large molecules like proteins and polysaccharides across the cell membrane. Exocytosis involves the release of large molecules or particles from the cell, opposite to the scenario described in the question. Active transport requires energy to move molecules against their concentration gradient and is not primarily used for transporting proteins and polysaccharides. Facilitated diffusion entails the movement of molecules aided by transport proteins but is not the primary mechanism for transporting large molecules such as proteins and polysaccharides.

4. Which of the following is responsible for generating the electrical impulses that regulate the heartbeat?

• A. Aorta
• B. Pulmonary veins
• C. Coronary arteries
• D. Sinoatrial (SA) node

Correct answer: D

Rationale: The Sinoatrial (SA) node is responsible for generating the electrical impulses that regulate the heartbeat. It is often referred to as the heart's natural pacemaker because it initiates the electrical signals that coordinate the heart's contractions. The other options listed (Aorta, Pulmonary veins, Coronary arteries) do not play a direct role in generating the electrical impulses for the heartbeat. The Aorta is a large artery that carries oxygen-rich blood away from the heart, the Pulmonary veins carry oxygen-rich blood from the lungs to the heart, and the Coronary arteries supply blood to the heart muscle itself, but none of them are involved in generating the electrical impulses that regulate the heartbeat.

5. What is the molarity of a solution made by dissolving 4.0 grams of NaCl into enough water to make 120 mL of solution? The atomic mass of Na is 23.0 g/mol, and Cl is 35.5 g/mol.

• A. 0.34 M
• B. 0.57 M
• C. 0.034 M
• D. 0.057 M

Correct answer: B

Rationale: To find the molarity, first calculate the moles of NaCl. Moles of NaCl = 4.0 g / (23.0 g/mol + 35.5 g/mol) = 0.068 mol. Next, use the formula for molarity: Molarity = moles of solute / liters of solution. Molarity = 0.068 mol / 0.120 L = 0.57 M. Therefore, the molarity of the solution is 0.57 M. Choice A, 0.34 M, is incorrect as it does not match the calculated molarity. Choice C, 0.034 M, is incorrect as it is a decimal point off from the correct molarity. Choice D, 0.057 M, is incorrect as it does not match the calculated molarity of 0.57 M.

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