Carbon Cycle Comprehension

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Carbon cycle diagram showing movement through Earth's spheres

📖 Reading Passage: The Carbon Cycle

Carbon is one of the most important elements on Earth, constantly moving through four main spheres. The atmosphere contains carbon dioxide gas that plants use for photosynthesis. The biosphere includes all living things - plants absorb carbon dioxide and animals release it through respiration. When organisms die, carbon becomes part of the soil and rocks in the lithosphere. The hydrosphere (oceans, lakes, and rivers) dissolves carbon dioxide from the atmosphere, and marine plants use it for growth. This continuous movement of carbon between spheres is called the carbon cycle.

Human activities like burning fossil fuels add extra carbon dioxide to the atmosphere. Forests act as carbon sinks, storing carbon in trees and soil. Ocean currents help distribute carbon around the planet, while volcanic eruptions can release stored carbon from deep in the Earth back to the atmosphere.

🧠 Part 1: Multiple Choice Questions

1. Which sphere contains carbon dioxide gas that plants use for photosynthesis?

Lithosphere

Atmosphere

Hydrosphere

Biosphere

2. What happens to carbon when organisms die?

It disappears completely

It becomes part of the soil and rocks

It only stays in the atmosphere

It moves directly to the ocean

3. Which of the following are ways carbon moves between spheres? (Select all that apply)

Photosynthesis

Animal respiration

Ocean currents

Volcanic eruptions

4. Forests act as carbon ________ because they store carbon in trees and soil.

sources

sinks

cycles

spheres

✏️ Part 2: Short Answer Questions

5. Explain how carbon moves from the atmosphere to the biosphere.

6. Describe two ways that carbon can be released back into the atmosphere.

7. Fill in the blanks using words from the passage:

The four Earth spheres are the _____________, _____________, _____________, and _____________.

8. How do human activities affect the carbon cycle? Give one example.

9. Draw and label a simple diagram showing how carbon moves between at least three of the four Earth spheres. Include arrows to show the direction of carbon movement.