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 sentence uses the semicolon correctly?

A. The play was long; however, it was very entertaining.
B. The guests arrived; Sarah greeted them at the door.
C. John likes apples; Mary prefers oranges.
D. He was tired; he went to bed early.

Correct answer: B

Rationale: Option B joins two independent clauses related to the same event.

3. What are the four main types of macromolecules that are essential for life?

A. Carbohydrates, lipids, proteins, and nucleic acids
B. Carbohydrates, proteins, fats, and vitamins
C. Minerals, vitamins, proteins, and fats
D. Carbohydrates, lipids, proteins, and hormones

Correct answer: A

Rationale: These four types of macromolecules are the building blocks of life and play essential roles in various cellular processes. Carbohydrates: Carbohydrates are the primary energy source for cells and provide structural support for cell membranes and other cellular components. They are composed of carbon, hydrogen, and oxygen atoms and are classified into monosaccharides (simple sugars), disaccharides (double sugars), and polysaccharides (complex sugars). Lipids: Lipids are a diverse group of molecules that include fats, oils, and waxes. They are composed of carbon, hydrogen, and oxygen atoms and are insoluble in water but soluble in nonpolar solvents. Lipids serve as energy storage molecules, provide insulation for cells and organs, and are essential components of cell membranes. Proteins: Proteins are complex molecules composed of amino acids linked together by peptide bonds. They are responsible for a vast array of cellular functions, including structural support, enzymatic catalysis,

4. What property of a substance remains constant regardless of its location in the universe?

A. Mass
B. Weight
C. Density
D. Volume

Correct answer: a

Rationale: Mass is an intrinsic property of matter that remains constant regardless of its location in the universe.

5. Electrons occupy specific energy levels around the nucleus, but not in fixed orbits. This concept is captured by the:

A. Bohr model
B. Quantum mechanical model
C. Lewis structure
D. Octet rule

Correct answer: B

Rationale: Quantum mechanical model. Unlike the Bohr model with its defined electron paths, the quantum mechanical model uses probability distributions to describe electron locations within energy levels.

6. How does the amplitude of a wave relate to its intensity or loudness?

A. They are inversely proportional.
B. They are directly proportional.
C. They have no relationship.
D. Amplitude affects frequency, not intensity.

Correct answer: B

Rationale: Higher amplitude corresponds to larger displacement from equilibrium and translates to higher intensity or perceived loudness in sound waves.