1. Melatonin is a hormone produced by the pineal gland. What is its primary function?

A. Regulate blood pressure
B. Stimulate the digestive system
C. Control sleep-wake cycles
D. Maintain bone density

Correct answer: C

Rationale: The correct answer is C: 'Control sleep-wake cycles.' Melatonin is a hormone that plays a key role in regulating the body's sleep-wake cycle, also known as the circadian rhythm. The pineal gland releases melatonin in response to darkness, helping to signal to the body that it is time to sleep. By influencing the timing and quality of sleep, melatonin helps maintain a healthy sleep pattern and overall well-being. While blood pressure, digestive system stimulation, and bone density are important functions in the body, melatonin's primary function is to regulate the sleep-wake cycle.

2. Which of the following colligative properties refers to the elevation of the boiling point of a solution?

A. Freezing point depression
B. Vapor pressure lowering
C. Osmotic pressure
D. Boiling point elevation

Correct answer: A

Rationale: The correct answer is A: Freezing point depression. Colligative properties are properties that depend on the number of solute particles in a solution, not the type of solute. Freezing point depression is the phenomenon where the freezing point of a solvent is lowered when a solute is added, while boiling point elevation is the opposite effect where the boiling point of a solution is raised. Therefore, the question specifically asked for the colligative property that refers to the elevation of the boiling point, making "Freezing point depression" the correct answer.

3. What property of a wave is responsible for determining its energy?

A. Amplitude
B. Wavelength
C. Frequency
D. Velocity

Correct answer: a

Rationale: The amplitude of a wave determines its energy, with higher amplitudes corresponding to higher energy levels.

4. Which word is most closely associated with the adjective "ambiguous"?

A. Precise
B. Vague
C. Definite
D. Straightforward

Correct answer: B

Rationale: "Ambiguous" implies uncertainty or multiple interpretations, making "vague" its closest synonym.

5. The van't Hoff factor (i) accounts for the number of particles a solute dissociates into in solution. For a compound that dissociates completely in water, i would be...

A. 0
B. Less than 1
C. 1
D. More than 1

Correct answer: C

Rationale: The van't Hoff factor (i) is used to account for the number of particles a solute dissociates into in solution. For a compound that dissociates completely in water, such as a strong electrolyte, i would be equal to the total number of ions produced by the dissociation. Since the compound dissociates completely, it forms an equal number of ions, resulting in an i value of 1. Therefore, the correct answer is C: 1.

6. When a muscle shortens and generates force, this is called a:

A. Contraction
B. Relaxation
C. Extension
D. Atrophy

Correct answer: A

Rationale: The correct answer is A: Contraction. When a muscle shortens and generates force, it is undergoing a contraction. During a contraction, the muscle fibers are actively pulling on the tendons, causing movement at a joint. This process requires energy and coordination between muscle fibers to contract simultaneously. In contrast, relaxation (option B) is when the muscle fibers return to their resting length and stop generating force. Extension (option C) refers to the movement that increases the angle at a joint, typically involving the lengthening of muscles. Atrophy (option D) is the wasting away or decrease in size of muscle tissue due to disuse or disease, not the active shortening and force generation of a muscle during a contraction.