Abiotic factors
Non living
- climate
- oxygen conc.
- endaphic
Biotic factors
Living
- competition
- relationships btwn organisms
Succession - process
The change of a community over time
- pioneer species colonise - start to break up rock surface allowing organic material to accumulate e.g. soil
- conditions begin to change - suitable for other organisms e.g. moss
- mosses build up more organic matter - more water held
- soil develops, enables shallow rooted plants to grow
- larger plants colonise + outcompete other plants
- climax community reached
Primary Productivity - definition
The rate at which energy is incorporated into organic molecules in an ecosystem
Light Dependant Reaction
what and where?
Uses energy from light + hydrogen from photolysis to produce NADPH, ATP + O2
Thylakoid membrane
Light Dependant Reaction - process
- light absorbed by PSI and PSII in chlorophyll
- chlorophyll molecule excited, e- raised energy level
- e- leave molecule + pass along electron carrier molecules - form ETC
- A series of oxidisation and reduction reactions occur -losing energy in the process - energy used for photophosphorylation
- e- from PSII replace those lost from PSI
- PSII electrons then replaced - from photolysis
- e- passed along ETC combine w/ co-enzyme NADP and H ions from water to from NAHPH
Light Independant Reaction
what and where?
Use NADPH and ATP from LDR to reduce CO2 to carbohydrates
Stroma
Light Dependant Reaction - process
- CO2 combines w/ RuBP (catalysed by RuBISCO)
- unstable 6 carbon compound forms - breaks down to 2GP
- GP reduced to GALP
- 2/12 GALP involved in making hexose
- 10/12 GALP involved in recreation of RuBP
- the 10 GALP’s rearranged to 6 5cc which are phosphorylated to form RuBP
Phosphorylation
Making ATP
ADP+ Pi = ATP
Photolysis
Splitting of water
H2O = 1/2(O2) + 2e- + 2H+
Thylakoid Membrane
System of interconnected flattened fluid filled sacs
- proteins are embedded in the membrane
- LDR takes place here
Stroma
Fluid surrounding TM containing all enzymes needed for LIR
Starch Grain
Stores product of photosynthesis
Granum
Stack of thylakoids joined together
Inner Membrane
Contains transporter molecules
- regulate the passage of substances in/out of chloroplasts e.g. sugars, proteins
Outer Membrane
Freely permeable to CO2 and H2O
Thylakoid Space
Fluid within TM sacs
- contain enzyme for photolysis
Evidence for climate change
- peat bogs and pollen
- dendrochronology
- temperature records
Speciation - types
- ALLOPATRIC
- populations geographically isolated - SYMPATRIC
- isolated due to other isolating mechanisms
- eg behavioural (dont respond to others worship bhvrs), temporal (reproduce at different times), physical incompatibility.
