1. In an ecosystem, what is the primary role of a decomposer?
A. To produce food using sunlight
B. To hunt and eat other animals
C. To break down dead organisms and waste
D. To consume plants for energy
Answer: C. To break down dead organisms and waste
Explanation: Decomposers like fungi and bacteria recycle nutrients by breaking down dead matter, returning essential elements to the soil.
2. Which layer of the Earth is primarily composed of solid iron and nickel?
A. Crust
B. Mantle
C. Outer Core
D. Inner Core
Answer: D. Inner Core
Explanation: The inner core is a dense, solid ball of iron and nickel, while the outer core is liquid.
3. A scientific theory is best defined as:
A. A random guess
B. An unproven idea
C. A well-substantiated explanation of nature
D. A personal belief
Answer: C. A well-substantiated explanation of nature
Explanation: In science, a theory is a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence.
4. In the human body, which system is responsible for producing hormones?
A. Nervous System
B. Endocrine System
C. Digestive System
D. Circulatory System
Answer: B. Endocrine System
Explanation: The endocrine system is a network of glands (like the thyroid and adrenal glands) that produce and secrete hormones to regulate bodily functions.
5. What is the main cause of tides on Earth?
A. The wind
B. The rotation of the Earth
C. The gravitational pull of the moon
D. Earth’s magnetic field
Answer: C. The gravitational pull of the moon
Explanation: The moon’s gravitational force pulls on the Earth’s oceans, causing them to bulge and creating the daily cycle of high and low tides.
