1. During a healthy heartbeat, the P wave on an ECG represents

A. The repolarization of the ventricles.
B. The electrical conduction through the AV node.
C. The contraction phase of the ventricles (systole)
D. The depolarization of the atria.

Correct answer: D

Rationale: The correct answer is D: The P wave on an ECG represents the depolarization of the atria. During a healthy heartbeat, the P wave is the first positive deflection seen on the ECG and reflects the initiation of the electrical impulse in the atria, leading to atrial contraction. It is followed by the QRS complex, which represents the depolarization of the ventricles. Options A, B, and C are incorrect because the P wave specifically corresponds to atrial depolarization, not repolarization of the ventricles, electrical conduction through the AV node, or ventricular contraction. Understanding the sequence of electrical events in the heart as represented on an ECG is crucial for interpreting cardiac function and identifying potential abnormalities.

2. Which type of joint allows for the widest range of motion, like the shoulder joint?

A. Hinge joint
B. Ball-and-socket joint
C. Gliding joint
D. Fixed joint

Correct answer: B

Rationale: The correct answer is B: Ball-and-socket joint. A ball-and-socket joint, like the shoulder joint, allows for the widest range of motion in all directions, including flexion, extension, abduction, adduction, and rotation. This type of joint consists of a rounded, ball-like end of one bone fitting into a cup-like socket of another bone, providing great mobility and flexibility. Hinge joints, like the elbow, only allow movement in one plane (like a door hinge), gliding joints permit limited sliding movements between bones, and fixed joints, such as those in the skull, have no movement at all.

3. A car skids on a wet road. What is the main force preventing the car from stopping?

A. Friction
B. Gravitational force
C. Normal force from the road
D. Air resistance

Correct answer: A

Rationale: Friction opposes the motion of the car, trying to bring it to a stop. However, due to the wet surface, the friction force is not enough to overcome the car's inertia.

4. The basic unit of communication in the nervous system is called a:

A. Neuron
B. Astrocyte
C. Neurotransmitter
D. Synapse

Correct answer: A

Rationale: The basic unit of communication in the nervous system is a neuron. Neurons are specialized cells that transmit information through electrical and chemical signals. They form complex networks to relay messages throughout the body. Astrocytes are support cells that help maintain the environment around neurons. Neurotransmitters are chemicals that transmit signals between neurons at synapses. A synapse is a junction between two neurons where communication occurs. However, the primary unit responsible for communication in the nervous system is the neuron, making it the correct answer.

5. Vaccines work by stimulating the immune system to develop:

A. A physical barrier against pathogens
B. An inflammatory response
C. Immunological memory to a specific pathogen
D. Phagocytes to engulf pathogens

Correct answer: C

Rationale: The correct answer is C: 'Immunological memory to a specific pathogen.' Vaccines work by introducing a harmless form of a pathogen or a piece of it to stimulate the immune system. This exposure triggers the production of antibodies and memory cells specific to that pathogen. These memory cells 'remember' the pathogen, allowing the immune system to respond more effectively and rapidly if exposed to the actual pathogen in the future. Options A, B, and D are incorrect because vaccines do not create a physical barrier, induce a general inflammatory response, or directly cause phagocytes to engulf pathogens; instead, vaccines enhance the immune system's ability to recognize and combat specific pathogens.

6. She knows that there are external forces that influence changes in his unit. Which of the

A. Memo from the CEO to cut down on electrical consumption
B. Demands of the labor sector to increase wages
C. Low morale of staff in her unit
D. Exacting regulatory and accreditation standards

Correct answer: A

Rationale: The correct answer is option A: 'Memo from the CEO to cut down on electrical consumption.' This choice represents an external force that can influence changes in the unit by setting a directive from top management to reduce electricity usage, impacting operations and decisions within the unit. While options B, C, and D may also affect the unit to some extent, they are not as directly tied to external influences as the CEO's memo. The demands of the labor sector (option B) and low staff morale (option C) are internal factors, while regulatory and accreditation standards (option D) are more overarching guidelines rather than specific external forces impacting the unit. Therefore, the most direct and relevant external force in this scenario is the directive from the CEO, making option A the correct choice.