1. 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.

2. Which of the following sentences uses figurative language?

A. The scientist conducted an experiment.
B. The child ran like a cheetah.
C. The book contained many pages.
D. The teacher explained the concept clearly.

Correct answer: B

Rationale: This sentence uses a simile, comparing the child's speed to a cheetah's.

3. A person throws a ball horizontally. What force changes the direction of the ball's motion?

A. The force of throwing
B. Gravitational force
C. Air resistance
D. Normal force from the ground

Correct answer: B

Rationale: When a person throws a ball horizontally, the initial force that propels the ball forward is the force of throwing (A). However, the force that changes the direction of the ball's motion is the gravitational force (B), which acts vertically downward and causes the ball to follow a curved path. Air resistance (C) and normal force from the ground (D) do not directly change the direction of the ball's motion in this scenario.

4. What is the main component of sweat?

A. Urea
B. Glucose
C. Water
D. Electrolytes

Correct answer: C

Rationale: Rationale: - Sweat is primarily composed of water, making up the majority of its content. Water helps regulate body temperature by evaporating from the skin's surface, which cools the body down. - While sweat does contain small amounts of other substances like urea, glucose, and electrolytes, water is the main component that is secreted by sweat glands to help regulate body temperature during physical activity or in response to heat.

5. Two objects with equal masses collide head-on, both initially moving at the same speed. After the collision, they stick together. What is their final velocity?

A. Zero
B. Half their initial velocity
C. Their initial velocity
D. Twice their initial velocity

Correct answer: A

Rationale: In an inelastic collision like this, kinetic energy is not conserved, but momentum is. Since the total momentum before the collision was zero (equal and opposite velocities), it must be zero after the collision as well, resulting in both objects stopping.

6. What is the primary factor that determines whether a solute will dissolve in a solvent?

A. Temperature
B. Pressure
C. Molecular structure
D. Particle size

Correct answer: c

Rationale: The molecular structure of the solute and solvent plays a key role in determining solubility. The other choices may influence solubility but are not the primary determining factor.