Summary - IAL Edexcel Biology Unit 4: Climate Change

Week 5: Lead Lessons

Climate Change



Nutrient cycles

Chemical components if life [carbon/nitrogen] continually cycled through ecosystems.



2 phases:

- BIOTIC PHASE => inorganic ions/molecules incorporated into tissues of living things
e.g. CO2 taken up by plants [photosynthesis] and incorporated into carbs, proteins, lipids
that make up tissues

- ABIOTIC PHASE => inorganic molecules/ions returned to non-living parts of ecosystem

e.g. release of CO2 in respiration



Carbon cycle




Carbon => essential part of all organic molecules

Cycled as carbon containing compounds



Carbon sinks

Anything that absorbs more carbon than it releases (as carbon-containing compounds)

- Locked up as both organic and inorganic molecules

, Atlantic ocean

 Absorbs up to 23% of carbon produced by humans/year
 Influenced by WATER TEMP AND OCEAN CURRENTS

 Calcium carbonate shells produced by marine organisms REDUCES CONC OF
DISSOLVED CO2 – allows ocean to absorb even more


Balancing the carbon cycle

 PHOTOSYNTHESIS removes carbon from atmosphere into bodies of living organisms
 RESPIRATION/DECOMPOSITION releases back into atmosphere from bodies of living
organisms

NATURAL BALANCE = SELF-REGULATING CYCLE