Tuesday PAP Biology

Carbon and Nitrogen Cycles Biology 12(E)

Learning Objectives Describe the flow of matter through the carbon and nitrogen cycles Explain the consequences of disrupting the carbon and nitrogen cycles Carbon and Nitrogen Cycles

Nitrogen – essential element for life Nitrogen gas (N 2 ) – 78% of atmosphere, not usable by most organisms Within living organisms (biomolecules) – Proteins Nitrogen cycle – means by which nitrogen gas converted to usable form then cycled through ecosystem Nitrogen Cycle

Processes that contribute to nitrogen cycle: Ammonification – when plants and animals excrete wastes or die, decomposers convert their nitrogen compounds to ammonia (NH 4 ) Nitrification – nitrifying bacteria in soil convert ammonia to nitrites (NO 2 – ) Nitrogen Cycle

Processes contributing to nitrogen cycle: Nitrogen fixation – bacteria found in roots of legumes (beans and peas) N 2  Nitrates (NO 3 – ) – Plants use nitrates to synthesize proteins, stored in plant tissues – Animals eat plants, acquire usable nitrogen – Nitrogen passed through food chain Nitrogen Cycle

Processes that contribute to nitrogen cycle: Nitrates assimilated by plants into tissues Eaten by animals Denitrification – bacteria convert compounds into nitrogen gas Nitrogen Cycle

Disruptions to nitrogen cycle: Burning of fossil fuels (fire!) – releases excess nitrogen into atmosphere Consequence: Greenhouse effect Acid rain – emissions form nitric acid in atmosphere – Affects soil and water quality – Can kill plants Disruptions to Nitrogen Cycle

Disruptions to nitrogen cycle: Excessive irrigation and erosion – washes away nitrogen Consequence: Plant growth fails Disruptions to Nitrogen Cycle

Disruptions to nitrogen cycle: Fertilizing crops – excess nitrogen enters soil and water Consequences: Adverse effect on marine life – Algal blooms – causes oxygen deficiency in aquatic ecosystems Disruptions to Nitrogen Cycle

Disruptions to nitrogen cycle: Ranching – livestock waste releases ammonia into soil and water supplies Consequences: Poor water quality – health risk Poor plant growth Disruptions to Nitrogen Cycle

Carbon – key element in organic matter In the environment – Carbon dioxide (CO 2 ) gas in atmosphere and sea water – Long carbon chains in fuels Inside living organisms – all of our biomolecules Carbon cycle – means by which carbon is cycled between the environment and living tissues Carbon Cycle

Processes contributing to carbon cycle: How C Leaves the environment – Photosynthesis – transform CO 2 into glucose (C 6 H 12 O 6 ) Stored in cells and tissues of plants Passed through food chain as one organism eats another How C is Returned to the environment from organisms – Cellular respiration – organisms break down complex compounds and release CO 2 – Decomposition – microorganisms and some fungi break down dead organisms and release CO 2 Carbon Cycle

Disruption to carbon cycle: Burning fossil fuels Deforestation Additional humans and animals Consequence: Increases greenhouse effect Disruptions to Carbon Cycle

Greenhouse effect – the trapping of heat by greenhouse gasses such as carbon dioxide Increase in gasses increases amount of heat trapped Impacts of increasing greenhouse effect on all ecosystems Raises temperature Changes atmospheric moisture patterns Melts polar ice caps, raising water levels Greenhouse Effect

Disruption to carbon cycle: Deforestation – removal of forests – Often by burning – Releases CO 2 into atmosphere Consequences: Contributes to greenhouse effect Reduces ecosystem’s ability to remove CO 2 through photosynthesis Disruptions to Carbon Cycle

Learning Objectives Describe the flow of matter through the carbon and nitrogen cycles Explain the consequences of disrupting the carbon and nitrogen cycles Carbon and Nitrogen Cycles

Describe the impact of the following on the environment with regards to BOTH the carbon and nitrogen cycles: – A forest fire – Burning coal in a factory – Automobile emissions Essay using your notes and your own paper!!! Turn into box when finished…