B4g - Decay

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GCSE BIOLOGY (B4) Mind Map on B4g - Decay, created by Chloe.Sharland on 06/11/2014.
Chloe.Sharland
Mind Map by Chloe.Sharland, updated more than 1 year ago
Chloe.Sharland
Created by Chloe.Sharland over 10 years ago
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Resource summary

B4g - Decay
  1. Decay
    1. Decay is a process involving the breakdown of complex substances into simpler ones by microorganisms.
      1. Decay is important for plant growth because it releases minerals into the soil for their healthy growth.
        1. The ideal conditions for the microorganisms that cause decay are those that increases their respiration, growth and reproduction rates.
          1. Temperature - as temperature is increased, the microorganisms' rate of respiration and growth increase until it reaches 40 degrees, which is the optimum temperature. Above this the enzymes are denatured, so decay stops.
            1. Oxygen - increasing amount of oxygen in the air increases the microorganisms' rate of respiration, which means they release more energy enabling them to grow and reproduce more quickly. The re is no optimum.
              1. Water - microorganisms grow quickest in moist conditions, which increases the rate of decay. Having too much or too little water present slows down their growth and, therefore, the rate of decay.
              2. Bacteria and fungi and saprophytes - they feed on dead organic material by secreting enzymes externally onto their food and then absorbing the digested products. This is called extra-cellular digestion. Saprophytes are essential for decay.
            2. Food Preservation
              1. Microorganisms will feed on any source of food and cause it to decay if the conditions are right. Food can be preserved by removing one of the conditions needed.
                1. Canning - food can be heated to destroy and sealed to prevent microorganisms from getting any oxygen
                  1. Refrigeration and freezing - food can be kept at low temperatures to slow down the growth and reproduction
                    1. Pickling - low pH slows the growth of microorganisms by denaturing the microorganisms' enzymes
                      1. Adding sugar or salt - conditions to concentrated for the
                        1. Drying - reduces the moisture available, preventing growth
                      2. Decomposers
                        1. When dead organisms or waste material decay, minerals are released which can then be re-used by other living organisms, particularly plants.
                          1. Various soil organisms, including bacteria, fungi, earth worms, maggots and woodlice, help with the process of decay.
                            1. Earthworms, woodlice and maggots are known as detritivores; they feed on dead organisms and the waste produced by living organisms.
                              1. Detritivores speed up the process of decay because they break down detritus into small particles which have a large surface area, making it easier for decomposers to feed on.
                                1. The faeces of detritvores also provide food for decomposers like bacteria and fungi.
                                  1. Decomposer organisms are used by humans to break down waste: they feed on human waste in sewage treatment works and they break down waste in compost heaps.
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