ICAS Science 3 — Questions and Answers
Question 1: Which layer of Earth is made of molten rock and is located directly beneath the crust?
- Inner core
- Outer core
- Mantle (Correct answer)
- Lithosphere
Correct answer: Mantle
The mantle is the thick layer of partially molten rock beneath Earth's crust, and its movement drives plate tectonics.
Question 2: A student notices that plants near a window grow toward the light. This response is called:
- Gravitropism
- Phototropism (Correct answer)
- Hydrotropism
- Thigmotropism
Correct answer: Phototropism
Phototropism is the growth response of a plant toward a light source, controlled by the hormone auxin.
Question 3: Sound travels fastest through which medium?
- Vacuum
- Air
- Water
- Steel (Correct answer)
Correct answer: Steel
Sound travels fastest through solids like steel because the particles are closely packed, allowing vibrations to transfer more quickly.
Question 4: Which process do green plants use to convert sunlight into food?
- Respiration
- Fermentation
- Photosynthesis (Correct answer)
- Decomposition
Correct answer: Photosynthesis
Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to produce glucose and oxygen.
Question 5: If a scientist repeats an experiment five times and gets similar results each time, this supports which conclusion?
- The experiment has no variables
- The results are reliable (Correct answer)
- The hypothesis is definitely correct
- No further testing is needed
Correct answer: The results are reliable
Consistent results across multiple trials indicate that the experiment's findings are reliable and reproducible.
Question 6: Which type of rock is formed when magma cools and solidifies?
- Sedimentary
- Metamorphic
- Igneous (Correct answer)
- Limestone
Correct answer: Igneous
Igneous rocks form when magma (underground) or lava (at the surface) cools and solidifies.
Question 7: An astronaut weighs less on the Moon than on Earth. This is because the Moon has:
- Less atmosphere
- Weaker gravity (Correct answer)
- Smaller size relative to the astronaut
- Lower temperature
Correct answer: Weaker gravity
The Moon's gravity is about one-sixth that of Earth's because the Moon has less mass, resulting in a lower gravitational pull.
ICAS Science 3
Which layer of Earth is made of molten rock and is located directly beneath the crust?