B7- Biology across the Ecosystem

Interdependence

• All life depends on the solar energy absorbed during photosythesis, it is stored in plant chemicals such as starch.
• Autotrophs create their own food and energy.
• Hetrotrophs is an organism that must eat other organisms for food and energy.
• Chlorophyll in plant cells absorbs light for the process of photosynthesis. The word equation is;

Carbon Dioxide + Water ---------> Glucose + Oxygen

• Glucose is used for different things, making cellulose, proteins, starch and chlorophyll.
• Nitrates are absorbed from the soil and added to glucose to form proteins.
• They are absorbed by the roots by 'active transport'.
• Starch has little effect on the osmotic balance of the cell, so it is used for energy storage.
• Photosynthesis can be affected by low temperatures, low carbon dioxide or different lights levels.
• Human activity is incresing atmoshperic carbon dioxide levels.
• Compenstaion points points occur when respiration makes as much carbon dioxide as phosynthesis uses.
• Energy is transferred when living things are eaten or broken down by decomposers.
• Pyramids of biomass show the food available to the herbivores and carnivores in an ecosystem.
• Only about 10% of the energy in biomass is passed on at each stage in the food chain. The rest is lost to decomposers or waste heat.
• Soil contains living organisms, decaying material, sand, clay, air, water and dissolved minerals.