Ch 2 - Carbon and Oxygen Cycles

Question 1

Rapid + Slow cycling

Answer 1

Rapid cycling - involves substances that can cycle between nutrient reservoirs quickly. Substances are temporarily stored in nutrient reservoirs. e. g. soil, air, water.

Slow cycling - substances accumulate and are unavailable to organisms. Substances stored for long periods of time. e. g. fossil fuels deposits, carbon and oil.

Question 2

How are the carbon and oxygen cycles interconnected?

Answer 2

Through photosynthesis and cellular respiration.

Example: slow cycling - large producers (trees) store carbon for long periods of time in their tissues. Carbon is not recycled until the tree dies and is not broken down by decomposers.
*trees = carbon sink.

Question 3

How is the movement of matter through an ecosystem different than the movement of energy?

Answer 3

• matter is recycled + reused (like nutrients and chemicals) *continuous cycle.
• energy only flows one way.
  *eventually lost as heat.

Question 4

Why is Earth a closed system with regards to matter but an open system with regards to energy?

Answer 4

Closed system - matter doesn’t enter or leave.

Open system - sunlight energy flows in and heat energy escapes.

Question 5

Carbon sinks

Answer 5

• reservoirs that absorb more carbon than they emit to the environment.
• Largest in biosphere is ocean.
  > contains billions of dissolved CO2.
• Natural processes that return carbon through:
  > rapid cycling - forest fires.
  > slow cycling - weathering of limestone.

Question 6

Human influences on the carbon cycle

Answer 6

Influences slow cycling of carbon.
1. Combustion of petroleum deposits.
> releases carbon back into atmosphere increasing CO2 levels in the atmosphere.

Question 7

What is the necessity of cycles?

Answer 7

• Limited amount of matter in our ecosystem means that chemicals must be recycled constantly.
• Recycling of matter through the abiotic and biotic parts of the ecosystems allows all organisms to obtain essential nutrients.