Question

How do marine organisms utilize carbon dioxide from the atmosphere?

• A. They use carbonates to form shells
• B. They help in the formation of limestone rocks
• C. They use it for respiration
• D. They use it for photosynthesis

Answer 1

Answer: (A), (B)

The correct options are
A They use carbonates to form shells
B They help in the formation of limestone rocks

Marine organisms like molluscs and foraminifera use carbonates to make their shells. After these organisms die, they sink to the sea floor. Over a period of time, layers of sediments and shells are cemented together eventually forming limestone rocks. During natural weathering and volcanic eruptions, this carbon is returned back to the atmosphere as carbon dioxide.