1. Which vitamin is crucial for calcium absorption and synthesized in the skin upon sun exposure?

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

Correct answer: C

Rationale: The correct answer is C: Vitamin D. Vitamin D is crucial for calcium absorption as it helps the body absorb calcium from the diet. When the skin is exposed to sunlight, it produces vitamin D. This is why sunlight is often referred to as the 'sunshine vitamin.' Vitamin A (choice A) is important for vision and immune function, but not specifically for calcium absorption. Vitamin C (choice B) is essential for collagen production and immune function, but not directly related to calcium absorption. Vitamin E (choice D) is an antioxidant that helps protect cells from damage, but it is not primarily involved in calcium absorption like vitamin D.

2. How is power related to time?

A. Power is inversely proportional to time
B. Power is directly proportional to time
C. Power is unrelated to time
D. Power is the product of time and work

Correct answer: c

Rationale: Power is the rate at which work is done or energy is transferred, and it is not directly linked to time.

3. Which hormone, produced by the thyroid gland, regulates calcium levels in the blood by enhancing calcium absorption in the intestines and reducing calcium loss in the kidneys?

A. Calcitonin
B. Parathyroid hormone (PTH)
C. Thyroxine
D. Insulin

Correct answer: a

Rationale: The correct answer is A: Calcitonin. Calcitonin is a hormone produced by the thyroid gland that plays a crucial role in regulating calcium levels in the blood. It works by enhancing calcium absorption in the intestines and reducing calcium loss in the kidneys. This helps to maintain the proper balance of calcium in the body. Parathyroid hormone (PTH) works in the opposite way, increasing calcium levels in the blood when they are low. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism and growth, not calcium levels. Insulin is a hormone produced by the pancreas that regulates blood sugar levels, not calcium levels. Therefore, the correct hormone in this case is Calcitonin.

4. Which type of mutation involves a change in the number of chromosomes?

A. Point mutation
B. Frameshift mutation
C. Missense mutation
D. Aneuploidy

Correct answer: D

Rationale: Rationale: A) Point mutation: Involves a change in a single nucleotide base pair within the DNA sequence. B) Frameshift mutation: Involves the insertion or deletion of nucleotides, causing a shift in the reading frame of the genetic code. C) Missense mutation: Involves a single nucleotide change that results in a codon that codes for a different amino acid. D) Aneuploidy: Involves a change in the number of chromosomes, where an individual may have an extra chromosome (trisomy) or a missing chromosome (monosomy). Aneuploidy can lead to genetic disorders such as Down syndrome (trisomy 21) or Turner syndrome (monosomy X).

5. Which of the following numbers is a perfect square?

A. 10
B. 12
C. 15
D. 16

Correct answer: D

Rationale: A perfect square is a number obtained by squaring an integer. 16 is the result of squaring 4 (4 x 4 = 16). The other answer choices are not the product of squaring any whole number.

6. Within a nuclear reactor, control rods serve the primary purpose of:

A. Reflecting neutrons back into the core
B. Absorbing excess neutrons to control criticality
C. Moderating the velocity of neutrons
D. All of the above

Correct answer: C

Rationale: Control rods within a nuclear reactor serve the primary purpose of absorbing excess neutrons to control criticality. By adjusting the position of the control rods, the reactor operators can regulate the rate of fission reactions and prevent the reactor from overheating or reaching a state of uncontrolled chain reaction. Reflecting neutrons back into the core and moderating the velocity of neutrons are not the primary functions of control rods. Reflectors are used to bounce neutrons back into the core, while moderators slow down fast neutrons to increase the likelihood of fission. Therefore, the correct answer is B: 'Absorbing excess neutrons to control criticality.'