B17 - Orgainsing an ecosystem

Question 1

B17 - Describe the processes involved in the cycling of carbon.

Answer 1

Carbon enters the atmosphere as carbon dioxide from respiration and combustion of fuels.

Carbon dioxide is absorbed by plants as they photosynthesise.

Animals eat plants, respiring as they go, producing carbon dioxide.

The animals and plants eventually die.

The dead organisms are eaten by decomposers which respire and return the carbon to the atmosphere as carbon dioxide.

Question 2

B17 - Describe the events in the decay cycle

Answer 2

Decomposers break down waste and dead animals and plants (examples: bacteria, fungi)

They grow, reproduce, and release CO2, water and minerals as waste products.

These waste products are then used by other organisms.

Decay returns carbon to the atmosphere as CO2 that can be used by plants for photosynthesis

Question 3

B17 - Explain how detritivores increase the rate of decay using ideas about surface area.

Answer 3

Detritivores help speed up decay by feeding on a substance called detritus.

Detritus is any material that is dead and decaying.

Detritivores break down detritus into smaller pieces, increasing it’s surface area.

This allows bacteria and fungi to start breaking down the detritus on a microscopic level.

Question 4

B17 - What are the word and symbol equations for respiration and photosynthesis?

Answer 4

Photosynthesis:
Carbon dioxide + water → glucose + oxygen

6CO2 + 6H20 → C6H12O6 + 6O2

Respiration:
Glucose + oxygen → carbon dioxide + water

C6H12O6 + 6O2→ 6CO2 + 6H20

Question 5

B17 - What are the word and symbol equations for Combustion?

Answer 5

Complete combustion:

Hydrocarbon (ethane) + oxygen → carbon dioxide + water

2C2H6 + 7O2 → 4CO2 + 6H2O

Incomplete combustion:

Hydrocarbon (ethane) + oxygen → carbon monoxide + carbon + water

C2H6 + 2O2 → CO + C + 3H2O