1. Certain medications can suppress the immune system to treat autoimmune diseases or prevent organ rejection after transplants. What is a potential risk associated with immunosuppressive drugs?

A. Increased risk of developing allergies
B. Increased susceptibility to infections
C. Both a and b
D. Neither a nor b

Correct answer: C

Rationale: The correct answer is C: 'Both a and b.' Immunocompromised individuals, who take immunosuppressive drugs, are at an increased risk of developing allergies due to the altered immune response. Additionally, these drugs suppress the immune system's ability to fight off infections, making individuals more susceptible to various pathogens. Therefore, both increased risk of developing allergies and increased susceptibility to infections are potential risks associated with immunosuppressive drugs, making option C the correct choice.

2. The primary source of energy entering most ecosystems is:

A. Chemical energy stored in bonds
B. Thermal energy from the Earth's core
C. Light energy from the sun
D. Kinetic energy from wind and water

Correct answer: C

Rationale: Rationale: In most ecosystems, the primary source of energy is sunlight. This energy is captured by plants and other photosynthetic organisms through the process of photosynthesis. These organisms convert light energy into chemical energy stored in the bonds of organic molecules, such as glucose. This stored chemical energy is then passed on to other organisms in the ecosystem through the food chain, making sunlight the fundamental source of energy for most ecosystems. Thermal energy from the Earth's core (option B) is not a primary source of energy for ecosystems, as it is not readily accessible to most organisms. Kinetic energy from wind and water (option D) can play a role in some ecosystems, but it is not the primary source of energy. Chemical energy stored in bonds (option A) is a form of energy that is derived ultimately from the sun through photosynthesis.

3. What is the name of the radioactive isotope commonly used in medical imaging techniques like PET scans?

A. Uranium-235
B. Plutonium-239
C. Potassium-40
D. Fluorine-18

Correct answer: D

Rationale: Fluorine-18 is the radioactive isotope commonly used in medical imaging techniques like PET scans. It is often used in the form of fluorodeoxyglucose (FDG) to detect areas of increased metabolic activity in the body, such as in cancer cells. Uranium-235 and Plutonium-239 are not typically used in medical imaging, and Potassium-40 is a naturally occurring radioactive isotope found in the human body but is not commonly used in medical imaging techniques.

4. Deuterium, a stable isotope of hydrogen, has a nucleus containing:

A. A single proton
B. A proton and a neutron
C. Two protons and an electron
D. Two neutrons

Correct answer: B

Rationale: The correct answer is B: 'A proton and a neutron.' Deuterium is an isotope of hydrogen with an atomic number of 1, meaning it has 1 proton in its nucleus. However, deuterium also has a neutron in its nucleus, making it different from regular hydrogen which only has a proton in its nucleus. Therefore, deuterium has a nucleus containing both a proton and a neutron, making option B the correct choice.

5. Which structure, located between the pons and the spinal cord, plays a crucial role in coordinating movements, maintaining balance, and posture?

A. Thalamus
B. Medulla oblongata
C. Cerebellum
D. Hypothalamus

Correct answer: c

Rationale: The correct answer is C: Cerebellum. The cerebellum is the structure located between the pons and the spinal cord that plays a crucial role in coordinating movements, maintaining balance, and posture. It receives information from sensory systems and integrates this input to fine-tune motor activity. The thalamus (A) is a relay station for sensory information, the medulla oblongata (B) is involved in vital functions like heartbeat and breathing, and the hypothalamus (D) regulates various metabolic processes and homeostasis. Therefore, the cerebellum is the most appropriate choice for a structure responsible for movement coordination and balance.

6. Which sentence uses comma splices incorrectly?

A. The baker kneaded the dough, flour dusted her apron, and the oven warmed up.
B. The mountains, shrouded in mist, seemed to disappear into the clouds.
C. He arrived late, having forgotten his keys, and the meeting had already started.
D. The movie, despite its flaws, was surprisingly enjoyable.

Correct answer: C

Rationale: Option (c) incorrectly combines two independent clauses with only a comma. A semicolon or conjunction is needed