1. What is the process by which the body maintains a relatively constant blood pH level, even with changes in blood carbon dioxide concentration?

A. Cellular respiration
B. Gas exchange
C. Buffering system
D. Deoxygenation

Correct answer: C

Rationale: The correct answer is C: Buffering system. The body maintains a relatively constant blood pH level through the buffering system, which consists of chemical substances that can absorb excess hydrogen ions or release hydrogen ions to adjust pH levels. This system helps prevent drastic changes in blood pH even when there are fluctuations in blood carbon dioxide concentration. Cellular respiration and gas exchange are processes related to obtaining and utilizing oxygen, while deoxygenation refers to the removal of oxygen from a substance. Therefore, the buffering system is specifically responsible for regulating blood pH levels in response to changes in carbon dioxide concentration.

2. The element responsible for the green color of leaves is:

A. Magnesium
B. Iron
C. Copper
D. Zinc

Correct answer: A

Rationale: Magnesium is the central element of chlorophyll, the pigment responsible for photosynthesis

3. Recognize the opposing muscle pair.

A. Bicep and tricep (Arm flexion and extension)
B. Hamstring and quadriceps (Knee extension and flexion)
C. Pectoralis major and pectoralis minor (Chest muscles)
D. Trapezius and deltoid (Shoulder movement)

Correct answer: A

Rationale: The bicep and tricep muscles are antagonistic muscle pairs, meaning they work in opposition to each other. The bicep is located on the front of the upper arm and is responsible for flexing the elbow joint. The tricep is located on the back of the upper arm and is responsible for extending the elbow joint.

4. Which of the following is an example of a chemical change?

A. Dissolving sugar in water
B. Boiling water
C. Rusting iron
D. Crushing ice

Correct answer: C

Rationale: Rusting is a chemical reaction where iron reacts with oxygen and water to form iron oxide (rust).

5. Which sentence uses the passive voice correctly?

A. The letter was written by Mary.
B. John built the house.
C. She gave the flowers to him.
D. They were eating dinner.

Correct answer: A

Rationale: Option a clearly identifies the object (letter) acted upon and the agent (Mary) performing the action in the passive voice.

6. Which element is used in semiconductors like computer chips and solar panels?

A. Germanium
B. Silicon
C. Gallium
D. Arsenic

Correct answer: B

Rationale: Silicon's unique properties allow it to be manipulated to conduct or not conduct electricity, making it ideal for various electronic applications.