Abiotic component - physical and chemical factors:
- wavelength of water
- air currents / wind
Biotic factors - factors determined by organisms:
A primary sucession starts in newly formed habitats where there has neber been a community before
Pioneer species - the first organisms to colonise their habitat. These are the only species that can cope with the extremes of temperature and lack of soil, water and nutrients
Climax community - a community usually dominated by trees is reached. Often remains unchanged unless conditions unless conditions in the habitat change.
Secondary succession - where an existing community has been cleared.
Deflected sucession - A community that remains stable only because human activity prevents succession from running its course.
Producers and productivity
Primary productivity - rate at which wnergy is incorporated into organic molecules in an ecosystem
Producers - organisms that can make their own organic compounds from inorganic compounds.
When light falls on producers, some energy is trasnferred to a chemical energy store by producing organic fuels such as glucose
CO2 is reduced as hydrogen and electrons from water are added to it, creating a carbohydrate.
Releasing hydrogen from water:
Photosynthesis uses energy from sunlight to split water. Process called the photolysis of water
Storing hydrogen in carbohydrates
The hydrogen reacts with carbon dioxide in order to store the hydrogen.
Using the glucose:
Fuel releases large amount of energy when the H stored in the carbohydrate reacts with oxygen during respiration.
Light Independent reaction
Light independent reactions - use energy from light and hydrogen from photolysis of water to produce reduced NADP + ATP, and waste product oxygen.
Occurs in the thylakoid membranes:
- Light energy raises electrons in each chlorophyll molecule to a higher energy level
- The electrons leave the excited C molecules, and pass along a series of electron carrier molecules
- Electrons pass from one carrier to the next in a series of oxidation and reuction reacts, losing energy in the process. The energy used in the synthesis of ATP - photophosphorylation
- Electrons lost from the chlorophyll must be replaced if the flow of electrons along the ecltron transport chain is to continue
- Within the thylakoid space, an enzyme catalyses the splitting of water to Oxygen. hydrogen ions and electrons. The [H+] is raises as a result of photolysis.