1. The adaptive immune system develops a targeted response to specific pathogens. What type of immune cell is responsible for producing antibodies?

A. Natural killer cells
B. Phagocytes
C. Helper T cells
D. B cells

Correct answer: D

Rationale: The correct answer is D: B cells. B cells are a type of lymphocyte responsible for producing antibodies, which play a crucial role in the adaptive immune response. When a pathogen enters the body, B cells are activated and differentiate into plasma cells that secrete specific antibodies to target and neutralize the pathogen. Natural killer cells (A) are part of the innate immune system and are responsible for killing infected or abnormal cells. Phagocytes (B) are another type of innate immune cell that engulfs and digests pathogens. Helper T cells (C) play a vital role in coordinating the immune response but do not directly produce antibodies.

2. The number of protons in the nucleus of an atom determines its:

A. Mass number
B. Atomic number
C. Isotope
D. Valence electron count

Correct answer: B

Rationale: The atomic number (Z) equals the number of protons in the nucleus and uniquely identifies an element. Mass number (A) includes both protons and neutrons, isotopes have different neutron numbers, and valence electrons are involved in bonding, not atomic identity.

3. Which sentence uses the possessive apostrophe correctly?

A. The cats meows filled the room.
B. I visited my friends' house.
C. She borrowed Johns book.
D. The childrens toys were scattered everywhere.

Correct answer: B

Rationale: Option b adds the apostrophe and "s" to show ownership of multiple friends.

4. Which number is the opposite of -3?

A. -6
B. 3
C. 0
D. 6

Correct answer: B

Rationale: The opposite of a number is the one with the same distance from zero but on the opposite side of the number line. So, the opposite of -3 is 3.

5. A medication must be taken twice daily, 12 hours apart. If the first dose is at 8:00 AM, what is the most convenient time for the second dose to avoid disrupting sleep?

A. 4:00 PM
B. 6:00 PM
C. 8:00 PM
D. 10:00 PM

Correct answer: B

Rationale: Rationale: To take the medication 12 hours apart from the first dose at 8:00 AM, the second dose should be taken at 8:00 PM. However, to avoid disrupting sleep, it is recommended to take the second dose a bit earlier. Taking the second dose at 6:00 PM ensures that the medication is still being taken 12 hours apart while allowing for a buffer before bedtime to avoid any potential disruptions to sleep.

6. The diaphragm is a dome-shaped muscle that plays a crucial role in breathing. When it contracts, what happens?

A. Air is expelled from the lungs.
B. The lungs expand to allow air intake.
C. The vocal cords vibrate to produce sound.
D. The trachea narrows to control airflow.

Correct answer: B

Rationale: The diaphragm is a dome-shaped muscle located beneath the lungs. When it contracts, it moves downward, creating more space in the chest cavity. This downward movement of the diaphragm allows the lungs to expand, which lowers the air pressure inside the lungs. As a result, air from the outside rushes in to equalize the pressure, leading to inhalation. Therefore, when the diaphragm contracts, it facilitates the intake of air into the lungs, making option B, 'The lungs expand to allow air intake,' the correct answer.