Nursing Elites

1. 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.

2. What happens to the momentum of an object when there is no external force acting upon it?

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

Correct answer: C

Rationale: When there is no external force acting upon an object, the law of conservation of momentum dictates that the momentum of the object remains constant. This means that the momentum does not increase or decrease; it stays the same. Choice A is incorrect because momentum does not increase. Choice B is incorrect because momentum does not decrease. Choice D is incorrect as momentum does not become zero; it remains constant as per the conservation law. Therefore, the correct answer is C, as the object's momentum is unchanged in the absence of external forces.

3. Which of the following substances is NOT typically found in healthy urine?

• A. Urea
• B. Glucose
• C. Creatinine
• D. Electrolytes

Correct answer: B

Rationale: Glucose is not typically found in healthy urine because the kidneys usually filter glucose from the blood and reabsorb it back into the bloodstream. The presence of glucose in urine, known as glucosuria, is usually indicative of diabetes or other medical conditions affecting glucose regulation. On the other hand, urea, creatinine, and electrolytes are commonly present in healthy urine as byproducts of metabolism and electrolyte balance. Urea is a waste product of protein metabolism, creatinine is a waste product of muscle metabolism, and electrolytes are essential for various physiological functions in the body. Therefore, choices A, C, and D are typically found in healthy urine, making them incorrect answers.

4. What type of energy does a stretched rubber band possess?

• A. Kinetic energy
• B. Potential energy
• C. Thermal energy
• D. Mechanical energy

Correct answer: B

Rationale: When a rubber band is stretched, it stores potential energy due to its position or configuration. This potential energy can be converted into kinetic energy when the rubber band is released and returns to its original shape. Therefore, the correct answer is potential energy, as the energy is stored in the stretched rubber band and can be released upon returning to its original state. Choices A, C, and D are incorrect because kinetic energy is associated with motion, thermal energy is related to heat, and mechanical energy is a broader category that includes both potential and kinetic energy.

5. Which of the following structures is unique to eukaryotic cells?

• A. Cell walls
• B. Nuclei
• C. Cell membranes
• D. Vacuoles

Correct answer: B

Rationale: Nuclei are structures that are unique to eukaryotic cells. Prokaryotic cells lack a defined nucleus, and their genetic material floats freely in the cytoplasm. Eukaryotic cells have nuclei that house the genetic material in the form of chromosomes, separated from the cytoplasm by a nuclear membrane. This distinct organelle is a key feature that sets eukaryotic cells apart from prokaryotic cells. Cell walls (Choice A) are found in plant cells, fungi, and some prokaryotes but are not unique to eukaryotic cells. Cell membranes (Choice C) are present in both prokaryotic and eukaryotic cells, serving as a barrier that encloses the cell contents. Vacuoles (Choice D) are membrane-bound organelles found in both plant and animal cells, making them not unique to eukaryotic cells.

Similar Questions