Cycles Within Ecosystems

Question 1

how is carbon recycled in the CARBON CYCLE?

Answer 1

RESPIRATION- by living plants and animals releases CO2 back into the air
PHOTOSYNTHESIS- green plants use carbon dioxide from air to make food.
DECOMPOSITION- when plants and animals decompose they’re broken down by microorganisms (bacteria and fungi). decomposers release CO2 back into the air by respiration as they break down the material.
COMBUSTION- some useful plant and animal products are burnt eg. wood and fossil fuels. this releases CO2 back into the air.

Question 2

how is nitrogen recycled in the NITROGEN CYCLE?

Answer 2

1. NITROGEN FIXING BACTERIA- in soil and roots of some plants. turns atmospheric N2 into nitrogen compounds that plants can use
2. DECOMPOSERS- break down proteins in rotting organisms and urea and turn them into ammonia. this forms ammonium ions in the soil.
3. NITRIFYING BACTERIA- turn ammonium ions in decaying matter into nitrates (nitrification)
4. DENITRIFYING BACTERIA- turns nitrates back into N2 gas. this is of no benefit to living organisms.

Question 3

what is the role of nitrogen fixing bacteria in the nitrogen cycle?

Answer 3

• in soil and roots of some plants.

- turns atmospheric N2 into nitrogen compounds that plants can use

Question 4

what is the role of decomposers in the nitrogen cycle?

Answer 4

• break down proteins in rotting organisms and urea and turn them into ammonia.
• this forms ammonium ions in the soil.

Question 5

what is the role of nitrifying bacteria in the nitrogen cycle?

Answer 5

turn ammonium ions in decaying matter into nitrates (nitrification)

Question 6

what is the role of denitrifying bacteria in the nitrogen cycle?

Answer 6

turns nitrates back into N2 gas. this is of no benefit to living organisms.