1. The protective fluid surrounding the brain and spinal cord is called:

A. Blood
B. Cerebrospinal fluid
C. Plasma
D. Myelin

Correct answer: B

Rationale: The correct answer is B: Cerebrospinal fluid. Cerebrospinal fluid is a clear, colorless liquid that surrounds the brain and spinal cord, providing cushioning and protection against physical impact. It also helps to maintain a stable environment for the central nervous system by regulating pressure and removing waste products. Blood (option A) is not the fluid that directly surrounds the brain and spinal cord. Plasma (option C) is the liquid component of blood and is not specific to the central nervous system. Myelin (option D) is a fatty substance that forms a protective sheath around nerve fibers but is not the fluid surrounding the brain and spinal cord.

2. When a car brakes to a stop, friction between the tires and the road acts as:

A. A balanced force
B. An unbalanced force causing acceleration
C. An unbalanced force causing the car to remain at rest
D. No force at all

Correct answer: B

Rationale: Friction opposes the car's motion, acting as an unbalanced force that decelerates the car and brings it to a stop.

3. The author expresses concern about the...

A. high cost and limited efficiency of traditional fossil fuel power plants.
B. unpredictable weather patterns and their impact on renewable energy production.
C. increasing dependence on technology and potential cybersecurity risks.
D. negative environmental consequences of renewable energy infrastructure.

Correct answer: B

Rationale: The passage's focus on managing the intermittency of renewable energy due to weather conditions implies concern about B.

4. The body's first line of defense against pathogens is the innate immune system. Which of the following is NOT a component of the innate immune system?

A. Physical barriers like skin and mucous membranes
B. Phagocytes that engulf and destroy pathogens
C. Inflammatory response to isolate and contain infection
D. Production of antibodies specific to a particular pathogen

Correct answer: D

Rationale: The innate immune system is the body's first line of defense against pathogens and includes physical barriers like skin and mucous membranes, phagocytes that engulf and destroy pathogens, and the inflammatory response to isolate and contain infection. However, the production of antibodies specific to a particular pathogen is a function of the adaptive immune system, not the innate immune system. The innate immune system provides immediate, nonspecific defenses, while the adaptive immune system generates specific responses to target pathogens. Therefore, option D is NOT a component of the innate immune system, making it the correct answer in this question.

5. What property of a wave is measured in Hertz (Hz)?

A. Amplitude
B. Wavelength
C. Speed
D. Frequency

Correct answer: d

Rationale: Frequency, the number of oscillations per second, is measured in Hertz (Hz).

6. Which of the following structures is responsible for preventing the backflow of blood from the left ventricle into the left atrium?

A. Aortic valve
B. Pulmonary valve
C. Tricuspid valve
D. Mitral valve

Correct answer: D

Rationale: The correct answer is D, the mitral valve. The mitral valve, also known as the bicuspid valve, is located between the left atrium and the left ventricle. Its main function is to prevent the backflow of blood from the left ventricle into the left atrium during ventricular contraction. The aortic valve (A) is responsible for preventing the backflow of blood from the aorta into the left ventricle, the pulmonary valve (B) prevents backflow from the pulmonary artery into the right ventricle, and the tricuspid valve (C) prevents backflow from the right ventricle into the right atrium. Therefore, the mitral valve is specifically responsible for preventing backflow in the left side of the heart, making it the correct answer in this case.