The carbon cycle
- Nutrient taken up by producer, which incorporates it into organic matter
- Consumer eats producer and nutrient is passed on
- When producers and consumers die, complex molecules are broken down by decomposers which release the nutrient in its simple form. They do this by releasing enzymes which break down complex molecules into simple ones which they then absorb and CO2 is relased in respiration.
- If decomposition is prevented, the organism is fossilised.
Why the carbon conc in the air fluctuates
- The rate of respiration and photosynthesis varies. During the day when photsynthesis is at its highest, the conc of CO2 is lower. On a summers day, the rate of photosynthesis is higher than on a winters day so conc of CO2 is lower.
- Deforestation and burning of fossil fuels increases conc of CO2 as there are less trees to absorb CO2 and carbon that was previously locked up in fuels is released.
- When conc of CO2 is too high, it dissolves in the ocean
- When conc of CO2 is too low, phyplankton in ocean absorb this CO2 and use it to form macromolecules
Greenhouse effect and global warming
Greenhouse gases trap sun's radiation, keeping the sun warm
CO2 is the most important greenhouse gas, due to its increasing conc, the temp of the earth is increasing
CH4 is another important greenhouse gas which is contributing to the greenhouse effect due to the large population cows which release CH4 when microorganims in their intestine digest food
- Changes to temp and precipitation could affect niches, some species may migrate to new areas and outcompete native species
- Melting of ice caps will cause sea levels to rise and polar bears to become extinct
- A rise in sea levels will cause the destruction of low lying land and salt water will travel up rivers making crops difficult…