B 8 Waste materials from plants and animals Flashcards
(15 cards)
What is decay?
The breakdown of dead organisms and waste materials by microorganisms.
Which organisms are responsible for decay?
Microorganisms such as bacteria and fungi.
What conditions speed up the rate of decay?
Warm temperatures, moist conditions, and the presence of oxygen.
What is compost and how is it made?
Compost is decomposed organic material used as fertiliser. It is made by allowing plant and food waste to decay under warm, moist, and aerobic conditions.
What is anaerobic decay?
Decay that occurs in the absence of oxygen, producing methane gas.
What is biogas?
A mixture of gases (mainly methane) produced by anaerobic decay, used as a fuel.
How is biogas produced?
By anaerobic decay of plant and animal waste in a biogas generator.
What conditions are needed in a biogas generator?
A constant warm temperature and anaerobic (oxygen-free) conditions.
What is the role of decomposers in ecosystems?
They break down dead organisms and waste, recycling carbon and nutrients into the environment.
Why is decay important for ecosystems?
It recycles nutrients and returns carbon to the atmosphere, supporting plant growth and the carbon cycle.
Name three processes in the carbon cycle.
Photosynthesis, respiration, and decomposition.
How does carbon return to the atmosphere in the carbon cycle?
Through respiration by plants, animals, and decomposers, and combustion of fossil fuels.
How does carbon enter food chains?
Plants absorb carbon dioxide during photosynthesis to make glucose, which enters food chains when animals eat the plants.
What human activities disrupt the carbon cycle?
Burning fossil fuels and deforestation.
How can the rate of decay be investigated in a practical?
By using milk and lipase enzyme with a pH indicator to measure how fast the pH changes at different temperatures.
