1. Which vitamin is essential for calcium absorption and bone health?

A. Vitamin A
B. Vitamin C
C. Vitamin D
D. Vitamin E

Correct answer: C

Rationale: The correct answer is Vitamin D. Vitamin D plays a crucial role in calcium absorption in the intestines, which is essential for maintaining strong and healthy bones. It helps regulate calcium and phosphorus levels in the body, promoting bone mineralization and growth. Vitamin A is important for vision and immune function, not specifically for bone health. Vitamin C is essential for collagen synthesis but not directly involved in calcium absorption. Vitamin E is an antioxidant that protects cells from damage but does not have a direct role in bone health. Therefore, Vitamin D is the correct choice for supporting calcium absorption and bone health.

2. The energy required to break a chemical bond is called:

A. Kinetic energy
B. Potential energy
C. Activation energy
D. Bond energy

Correct answer: C

Rationale: Rationale: Activation energy is the energy required to break a chemical bond and initiate a chemical reaction. Kinetic energy (option A) is the energy of motion, potential energy (option B) is stored energy, and bond energy (option D) is the energy required to break a particular chemical bond in a molecule. Among the options provided, activation energy best describes the energy required to break a chemical bond.

3. What is the process of converting ammonia, a byproduct of protein digestion, into a less toxic form?

A. Deamination
B. Transamination
C. Decarboxylation
D. Hydrolysis

Correct answer: A

Rationale: Rationale: Deamination is the process of removing an amino group from a molecule, such as converting ammonia (NH3) into a less toxic form like urea. Ammonia is a byproduct of protein digestion and needs to be converted into a less toxic form to be excreted from the body. Deamination is a key step in this process, which occurs mainly in the liver through the urea cycle. Transamination involves the transfer of an amino group from one molecule to another, not the removal of an amino group as in deamination. Decarboxylation is the removal of a carboxyl group from a molecule, and hydrolysis is the breakdown of a compound by adding water.

4. What happens to the frequency of a wave if its wavelength decreases while the speed remains constant?

A. Frequency decreases
B. Frequency increases
C. Frequency remains constant
D. Frequency becomes zero

Correct answer: b

Rationale: If the speed of the wave remains constant while the wavelength decreases, the frequency of the wave increases.

5. Which of the following is NOT a function of the integumentary system?

A. Regulation of body temperature
B. Protection from pathogens
C. Synthesis of vitamin D
D. Production of digestive enzymes

Correct answer: D

Rationale: The correct answer is D: "Production of digestive enzymes." The integumentary system primarily consists of the skin, hair, nails, and glands. Its main functions include regulating body temperature through processes like sweating and shivering, protecting the body from pathogens and external threats, and synthesizing vitamin D when exposed to sunlight. However, the production of digestive enzymes is not a function of the integumentary system. Digestive enzymes are primarily produced by organs such as the pancreas and salivary glands to aid in the breakdown of food in the digestive system, which is separate from the functions of the integumentary system.

6. What is the main function of calcitonin, a hormone produced by the thyroid gland?

A. Stimulate metabolism and heat production
B. Increase calcium absorption from the intestines
C. Enhance bone growth and development
D. Lower blood calcium levels

Correct answer: D

Rationale: The correct answer is D: 'Lower blood calcium levels.' Calcitonin is a hormone produced by the thyroid gland that helps regulate calcium levels in the blood. It works by inhibiting the breakdown of bone, which in turn lowers the amount of calcium released into the bloodstream. This process helps to decrease blood calcium levels when they are too high. Options A, B, and C are not functions of calcitonin; instead, they are more closely associated with other hormones such as thyroid hormones, vitamin D, and growth hormone, respectively.