1. Myelin sheath is a fatty substance that insulates and protects the long extensions of some nerve cells. It is produced by:

A. Schwann cells
B. Astrocytes
C. Neurons
D. Oligodendrocytes

Correct answer: A

Rationale: The correct answer is A: Schwann cells. Schwann cells are a type of glial cell in the peripheral nervous system that produce the myelin sheath around axons. Myelin sheath is essential for the rapid conduction of nerve impulses and provides insulation and protection to nerve fibers. Astrocytes are glial cells that provide support and maintain homeostasis in the central nervous system, but they do not produce myelin. Neurons are the main functional units of the nervous system responsible for transmitting nerve impulses. Oligodendrocytes are another type of glial cell in the central nervous system that produce myelin sheath around axons in that region, not in the peripheral nervous system where Schwann cells are responsible for myelination.

2. The speed of light in a vacuum is measured in units of:

A. Meters per second
B. Hertz
C. Candela
D. Newton

Correct answer: A

Rationale: The correct answer is A: 'Meters per second.' The speed of light in a vacuum is a fundamental constant of nature and is approximately 299,792,458 meters per second. This speed is constant and does not vary based on the frequency or wavelength of light. Hertz (B) is a unit of frequency, Candela (C) is a unit of luminous intensity, and Newton (D) is a unit of force. Understanding the units used to measure the speed of light is important in physics and related fields to accurately describe the propagation of light in different mediums.

3. What is the process of cells dividing to produce new cells called?

A. Cell division
B. Cell differentiation
C. Cell growth
D. Cell regeneration

Correct answer: A

Rationale: Rationale: A) Cell division is the process by which a parent cell divides into two or more daughter cells, allowing for growth, repair, and reproduction in living organisms. This process ensures that genetic material is accurately passed on to the new cells. B) Cell differentiation refers to the process by which cells become specialized to perform specific functions in an organism. While cell division is essential for cell differentiation, they are distinct processes. C) Cell growth is the increase in size or mass of a cell, which can occur before or after cell division. While cell growth is a component of the cell division process, it is not the primary process of cells dividing to produce new cells. D) Cell regeneration is the process by which damaged or lost cells are replaced by new cells. While cell division is involved in cell regeneration, it specifically refers to the overall process of cells dividing to produce new cells. Therefore, the most appropriate answer to the ques

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 C: Vitamin D. Vitamin D plays a crucial role in calcium absorption in the small intestine because it helps regulate the levels of calcium and phosphorus in the body. When vitamin D is present, it stimulates the production of proteins that facilitate the absorption of calcium from the intestine into the bloodstream. Without adequate levels of vitamin D, the body struggles to absorb calcium efficiently, which can lead to weakened bones and other health issues. While vitamins A, C, and E are important for various functions in the body, they do not directly impact calcium absorption in the same way that vitamin D does.

5. In a chemical reaction, the total amount of:

A. Matter remains the same
B. Matter increases
C. Matter decreases
D. Energy remains the same

Correct answer: A

Rationale: The Law of Conservation of Mass states that matter cannot be created or destroyed in a chemical reaction, only rearranged

6. What happens to the force of gravity between two objects when the distance between them is doubled?

A. ) The force increases by a factor of 2
B. The force increases by a factor of 4
C. The force decreases by a factor of 2
D. The force decreases by a factor of 4

Correct answer: d

Rationale: According to the inverse square law of gravity, the force of gravity decreases by a factor of 4 when the distance between two objects is doubled.