1. What is the difference between active and passive immunity?

A. Active immunity is short-lived, while passive immunity is long-lasting.
B. Active immunity involves the body's own immune response, while passive immunity provides immediate protection through antibodies from another source.
C. Active immunity only protects against bacterial infections, while passive immunity works against both bacteria and viruses.
D. Passive immunity requires repeated vaccinations, while active immunity is a one-time process.

Correct answer: A

Rationale: The correct answer is A: "Active immunity involves the body's own immune response, while passive immunity provides immediate protection through antibodies from another source." Active immunity is long-lasting because it involves the body's immune system producing memory cells that remember specific pathogens, providing long-term protection. Passive immunity, on the other hand, is short-lived as it involves receiving pre-formed antibodies from an external source, such as through maternal transfer or injection of antibodies, which do not create memory cells for long-lasting protection.

2. You test a new fertilizer on two groups of plants, one with fertilizer and one without. Both groups grow at the same rate. What is the most likely explanation?

A. The fertilizer has no effect on plant growth.
B. The control group accidentally received some fertilizer too.
C. Both groups received other nutrients from the soil, negating the fertilizer's effect.
D. The test period was too short to observe any difference.

Correct answer: C

Rationale: A true control group should be identical to the test group except for the variable being tested. If both groups grew the same despite the fertilizer, it suggests external factors like soil nutrients masked any potential fertilizer effect.

3. 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.

4. Hematopoietic tissue is responsible for

A. Building and repairing bone
B. Supporting and connecting tissues
C. Production of blood cells
D. Contracting for movement

Correct answer: C

Rationale: Hematopoietic tissue is responsible for the production of blood cells. This specialized tissue is found in the bone marrow and is crucial for the continuous generation of red blood cells, white blood cells, and platelets. These blood cells play essential roles in oxygen transport, immune defense, and blood clotting. Building and repairing bone (option A) is primarily the function of osteoblasts and osteoclasts in bone tissue. Supporting and connecting tissues (option B) is the role of connective tissues like tendons and ligaments. Contracting for movement (option D) is the function of muscle tissue. Therefore, the correct answer is C, as hematopoietic tissue specifically focuses on blood cell production.

5. Which force opposes the relative motion between surfaces in contact?

A. Tension force
B. Frictional force
C. Gravitational force
D. Magnetic force

Correct answer: b

Rationale: Friction is the force that opposes motion between surfaces in contact.

6. Lymph nodes, found along lymphatic vessels, are important for:

A. Storing blood
B. Producing antibodies
C. Filtering lymph and trapping harmful substances
D. All of the above

Correct answer: D

Rationale: The correct answer is D, 'All of the above.' Lymph nodes are important for various functions in the immune system. They filter lymph, trapping harmful substances like bacteria and viruses, which helps in preventing infections. Lymph nodes also play a crucial role in producing antibodies, which are essential for fighting off pathogens. Additionally, lymph nodes do not store blood; that is the function of the spleen. Therefore, the correct answer is D because lymph nodes perform all the mentioned functions in supporting the body's immune response.