1. Which part of the nervous system is responsible for transmitting signals from the sensory organs to the central nervous system?

A. Autonomic nervous system
B. Somatic nervous system
C. Peripheral nervous system
D. Central nervous system

Correct answer: C

Rationale: The correct answer is C: Peripheral nervous system. The peripheral nervous system is responsible for transmitting signals from the sensory organs to the central nervous system. It consists of nerves outside of the brain and spinal cord that carry information to and from the central nervous system. The autonomic nervous system (A) regulates internal bodily functions, the somatic nervous system (B) controls voluntary movements, and the central nervous system (D) includes the brain and spinal cord where processing of signals occurs, rather than transmitting signals from the sensory organs.

2. When ice melts, it undergoes aâ€¦

A. Chemical change
B. Physical change
C. Nuclear change
D. Radioactive decay

Correct answer: B

Rationale: Melting is a change in physical state, not a change in the chemical composition of the ice.

3. Decomposers in an ecosystem play a vital role by:

A. Photosynthesizing and producing organic matter
B. Breaking down dead organisms and returning nutrients to the environment
C. Preying on herbivores and controlling their populations
D. Fixing nitrogen from the atmosphere and making it available to plants

Correct answer: B

Rationale: Rationale: Decomposers are organisms that break down dead organic matter, such as dead plants and animals, into simpler substances. By doing so, they help to recycle nutrients back into the environment, making them available for other organisms to use. This process is essential for the functioning of ecosystems, as it ensures that nutrients are not lost but instead are continuously cycled through the ecosystem. Photosynthesis (option A) is the process by which plants and some other organisms convert light energy into chemical energy in the form of glucose, and it is not a role of decomposers. Preying on herbivores (option C) is a role typically carried out by predators, not decomposers. Fixing nitrogen from the atmosphere (option D) is a process carried out by nitrogen-fixing bacteria, not decomposers.

4. What property of a substance remains constant regardless of changes in its shape or size?

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

Correct answer: a

Rationale: Mass remains constant regardless of changes in an object's shape or size.

5. What is the main component of stomach acid?

A. Hydrochloric acid
B. Bicarbonate
C. Bile salts
D. Enzymes

Correct answer: A

Rationale: Rationale: Stomach acid, also known as gastric acid, is primarily composed of hydrochloric acid. Hydrochloric acid plays a crucial role in the digestive process by helping to break down food and kill bacteria in the stomach. Bicarbonate is a base that helps neutralize stomach acid in the small intestine. Bile salts are produced by the liver and stored in the gallbladder, aiding in the digestion and absorption of fats. Enzymes are proteins that help catalyze chemical reactions in the body, including the breakdown of food molecules during digestion.

6. The muscular diaphragm plays a vital role in respiration. When it contracts, it:

A. Increases lung volume for inhalation
B. Decreases lung volume for exhalation
C. Filters dust and particles from inhaled air
D. Produces mucus to lubricate the airways

Correct answer: A

Rationale: The diaphragm is a crucial muscle involved in respiration. When the diaphragm contracts, it flattens and moves downwards, increasing the volume in the thoracic cavity. This expansion creates a negative pressure in the lungs, causing air to rush in during inhalation. Therefore, option A, 'Increases lung volume for inhalation,' is the correct answer. The diaphragm's contraction facilitates the breathing process by creating space for the lungs to expand and take in air, making it essential for proper respiration.