1. What is the main function of the urinary system?

A. Transporting oxygen
B. Fighting off infections
C. Maintaining acid-base balance
D. All of the above

Correct answer: D

Rationale: The correct answer is D: 'All of the above.' The main function of the urinary system is not just limited to one specific task but encompasses multiple important functions. It is responsible for maintaining acid-base balance by regulating the pH of the blood through the excretion of acids and bases. Additionally, the urinary system plays a crucial role in filtering waste products from the blood and expelling them from the body, which helps in fighting off infections. Moreover, the urinary system is not involved in transporting oxygen, as this function is primarily carried out by the respiratory system. Therefore, 'All of the above' is the correct choice as it includes the comprehensive functions of the urinary system.

2. Which neurotransmitter is associated with mood regulation, sleep, and appetite?

A. Acetylcholine
B. Dopamine
C. Serotonin
D. GABA (Gamma-aminobutyric acid)

Correct answer: c

Rationale: The correct answer is C: Serotonin. Serotonin is a neurotransmitter that plays a crucial role in mood regulation, sleep, and appetite. It is often referred to as the 'feel-good' neurotransmitter because it helps regulate mood and emotional well-being. Serotonin is also involved in controlling sleep patterns and appetite, making it essential for maintaining a healthy balance in these areas. Acetylcholine is mainly associated with muscle movement and memory, while dopamine is linked to pleasure and reward pathways. GABA is an inhibitory neurotransmitter that helps reduce neuronal excitability. Therefore, serotonin is the neurotransmitter most closely associated with mood regulation, sleep, and appetite.

3. The human eye focuses light by adjusting the shape of its:

A. Cornea
B. Iris
C. Lens
D. Retina

Correct answer: C

Rationale: The human eye focuses light by adjusting the shape of its lens. The cornea is the transparent outer covering of the eye that helps to focus light, but it does not change shape. The iris regulates the amount of light entering the eye through the pupil but does not adjust the shape of the light. The retina is the layer at the back of the eye that receives and processes light signals but does not play a role in focusing light. Therefore, the correct answer is C, the lens, as it changes shape to focus light onto the retina, allowing for clear vision.

4. A nurse needs to dilute 2 milliliters of a concentrated medication with 8 milliliters of sterile water. What is the final concentration of the solution in percent?

A. 16.67%
B. 20%
C. 25%
D. 50%

Correct answer: B

Rationale: Calculate the total volume of the solution (2 ml + 8 ml = 10 ml). Then, divide the volume of the concentrated medication by the total volume and multiply by 100%: (2 ml / 10 ml) * 100% = 20%.

5. What is the name for the process where a solid changes directly into a gas?

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

Correct answer: B

Rationale: Sublimation occurs when a solid directly transforms into a gas without passing through a liquid phase.

6. What is the atomic number of an element?

A. The number of protons in an atom's nucleus.
B. The number of neutrons in an atom's nucleus.
C. The number of electrons in an atom's valence shell.
D. The number of isotopes of an element.

Correct answer: B

Rationale: The atomic number of an element is a fundamental property that defines the identity of an element. It is the number of protons in the nucleus of an atom. The number of protons determines the element's position in the periodic table and its chemical properties.