1. What is the myelin sheath and what does it do?

A. A group of nerve cells that perform a specific function.
B. A fatty substance that insulates some nerve fibers.
C. A fluid-filled cavity within the brain.
D. The junction between two neurons.

Correct answer: B

Rationale: The correct answer is B. The myelin sheath is a fatty substance that insulates some nerve fibers. It is essential for the proper functioning of the nervous system as it acts as an insulator, allowing for faster transmission of nerve impulses along the axon. Without the myelin sheath, nerve signals could be disrupted or weakened, leading to issues with movement, sensation, and other neurological functions. Options A, C, and D are incorrect as they do not accurately describe the myelin sheath or its function.

2. The ability of a substance to dissolve in another is called:

A. Solubility
B. Miscibility
C. Immiscibility
D. Reactivity

Correct answer: A

Rationale: Solubility refers to the extent to which one substance can dissolve in another to form a homogeneous solution.

3. The process of a gas changing into a liquid is called:

A. Evaporation
B. Boiling
C. Condensation
D. Sublimation

Correct answer: C

Rationale: Condensation happens when gas particles lose energy and slow down, transitioning into the liquid state.

4. What is the name for the mixture of reactants and products present during a chemical reaction?

A. Solution
B. Mixture
C. Reaction mixture
D. Precipitate

Correct answer: C

Rationale: This mixture contains both the starting materials (reactants) and the newly formed substances (products) during the reaction process.

5. What is the unit of measurement for momentum?

A. Newton-second (N·s)
B. Kilogram-meter (kg·m)
C. Joule (J)
D. Meter per second (m/s)

Correct answer: A

Rationale: Momentum is defined as the product of an object's mass and its velocity. The unit of mass is kilograms (kg) and the unit of velocity is meters per second (m/s). Therefore, the unit of momentum is kilogram-meter per second (kg·m/s). By Newton's second law of motion (F = ma), force is measured in Newtons (N), which is equivalent to kg·m/s². Therefore, multiplying the unit of force (N) by the unit of time (s) gives the unit of momentum as Newton-second (N·s).

6. Which type of symbiosis is where both organisms benefit from the interaction?

A. Mutualism
B. Commensalism
C. Parasitism
D. Predation

Correct answer: A

Rationale: Rationale: Mutualism is a type of symbiosis in which both organisms involved benefit from the interaction. This relationship is characterized by cooperation and mutual support, leading to advantages for both parties. In mutualistic relationships, each organism provides something that the other needs, resulting in a mutually beneficial outcome. Examples of mutualism include the relationship between bees and flowers (pollination) and the partnership between nitrogen-fixing bacteria and leguminous plants.