b17 Flashcards
what are food chains
they describe and show what is eaten by what.
what are producers
they start the food chain, and make their own food using the sun’s energy. eg plants or algae
what is biomass
the amount of energy stored. the mass of living material. as you go up the food chain, amount of biomass decreases
what environmental changes affect the distribution of organisms
temperature, availability of water, composition of atmospheric gases
describe the water cycle
- energy from sun makes water evaporate from land and sea as water vapor. transpiration from plants also causes water to evaporate
- water vapor rises, and condenses at cooler temperatures higher up to form clouds
- water falls from clouds as precipitation, providing fresh water for plants and animals
- then it drains into the sea and the process starts again
describe carbon cycle
- carbon dioxide is taken in from plants by photosynthesis
- when plants and algae respire, some carbon dioxide is released back into the atmosphere. when it is eaten, some carbon becomes part of the fats and proteins in the animals bodies. the carbon moves through the food chain
- most of the carbon is then returned to the environment when animals also respire
- when the plants and animals die, detritus feeders and microorganisms feed on their remains. when they respire, more carbon dioxide is released back to atmosphere
- combustion of wood and burning fossil fuels also release carbon dioxide back to air
- this cycle repeats.
why is decay used for
farmers use it to produce compost which acts as a natural fertiliser for crops. they find the ideal conditions for rapid decay.
anaerobic decay produces methane gas which is useful as a fuel.
factors affecting rate of decay
temperature, water, amount of oxygen, number of decay organisms
how does temperature affect rate of decay
warmer temperatures mean faster decay as they increase the rate at which the enzymes involved work at. too hot temperatures means enzymes are denatured so decay slows down if stops. if it’s too cold, it can slow rate of decay as well.
how does water availability affect the rate of decay
decay happens faster in moist environments as the organisms involved in decay require water to carry out the biological processes
oxygen and rate of decay
the organisms involved in decay need oxygen to respire so that they can survive. however, some that respire anaerobically do not.
why is decay needed
it puts the stuff that plants need to grow, like mineral ions, back into the soil.
what is biogas and how is it produced
it is made of methane which can be burned as fuel.
- it is produced when microorganisms respire and cause plant and animals to decay anaerobically
what are batch generators
they make biogas in small batches.
- manually loaded up with waste and left to digest. the by products are cleared away at the end of each session
what are continuous generators
- they make biogas all the time.
- waste is continuously fed in and biogas is produced at a steady rate.
- these are more suited for large scale biogas projects
