1. The measurable electrical activity of the brain is recorded by a:

A. CAT scan
B. MRI scan
C. Electroencephalogram (EEG)
D. X-ray

Correct answer: C

Rationale: The correct answer is C: "Electroencephalogram (EEG)". An EEG is a non-invasive test that measures the electrical activity of the brain by placing electrodes on the scalp. It is specifically designed to record brain wave patterns, making it a valuable tool in diagnosing conditions such as epilepsy, sleep disorders, and brain injuries. A CAT scan (A) and MRI scan (B) are imaging techniques that show the structure of the brain, while an X-ray (D) is not typically used to measure brain electrical activity.

2. The term "barn" is a unit commonly used in nuclear physics to quantify:

A. Energy (Electron volts are the standard unit for energy in nuclear physics)
B. Radioactivity
C. Nuclear cross-section
D. Half-life

Correct answer: C

Rationale: The term 'barn' is a unit of measurement used in nuclear physics to quantify nuclear cross-section. Nuclear cross-section refers to the measure of the probability of a specific interaction occurring between particles during a nuclear reaction. The term 'barn' was coined based on its relation to the physical size of a nucleus, as it is a small unit of area used to describe the likelihood of a particle interacting with a nucleus. It is not used to quantify energy, radioactivity, or half-life, making options A, B, and D incorrect in this context.

3. The WBC (white blood cell) type responsible for the initial attack on pathogens is:

A. Red blood cells
B. Platelets
C. Phagocytes
D. Lymphocytes

Correct answer: C

Rationale: The correct answer is C: Phagocytes. Phagocytes are a type of white blood cell that plays a crucial role in the immune response by engulfing and destroying pathogens. They are the first line of defense against invading microorganisms, initiating the initial attack on pathogens. Red blood cells (option A) are responsible for carrying oxygen, not for immune responses. Platelets (option B) are involved in blood clotting. Lymphocytes (option D) are another type of white blood cell but are mainly responsible for specific immune responses rather than the initial attack on pathogens.

4. Which property of matter refers to the measure of the force of gravity acting on an object?

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

Correct answer: b

Rationale: Weight is the measure of the force of gravity acting on an object. It is calculated as mass multiplied by the acceleration due to gravity.

5. The phenomenon responsible for the creation of rainbows is:

A. Reflection only
B. Diffraction
C. Refraction and reflection
D. Polarization

Correct answer: C

Rationale: The correct answer is C: Refraction and reflection. Rainbows are formed when sunlight is refracted and reflected inside raindrops. The sunlight entering the raindrop is refracted, then internally reflected off the back surface of the droplet, and finally refracted again as it exits the droplet. This dispersion of light causes the separation of colors we see in a rainbow. Reflection alone (option A) does not account for the formation of rainbows. Diffraction (option B) is the bending of light around obstacles, not the main mechanism behind rainbows. Polarization (option D) refers to the orientation of light waves, which is not the primary process involved in creating rainbows.

6. In a food chain, which trophic level captures energy from the sun?

A. Decomposers
B. Carnivores
C. Producers
D. Omnivores

Correct answer: C

Rationale: Rationale: Producers, such as plants, algae, and some bacteria, are the organisms in a food chain that capture energy from the sun through the process of photosynthesis. They convert sunlight into chemical energy, which is then passed on to other organisms in the food chain. Producers are at the base of the food chain and form the foundation for all other trophic levels to obtain energy. Decomposers (option A) break down organic matter, carnivores (option B) consume other animals, and omnivores (option D) consume both plants and animals, but they do not directly capture energy from the sun.