DECOMPOERS AND DETRIVORES Flashcards
What is the major food chain in most ecosystems?
Saprotrophic
What are detrivores?
Invertebrates that eat detritus (Dead organisms or waste material)
Give examples of detrivores
Earthworm, millipede and woodlouse
How is detritus digested by detrivores?
Internally using enzymes secreted into the gut
What happens to undigested detritus?
It becomes fragmented into smaller pieces as it is passed through the digestive system. This passes out as faeces and forms humus
What is the result of fragmentation?
It increases the surface area of the material available for decomposers to work on.
What is decomposition?
The chemical breakdown of organic matter in detritus
Which organisms are decomposers?
Bacteria and fungi
What are the major decomposers of plant material?
Fungi
Where do fungi get their energy from?
By breaking down organic matter such as cellulose in dead plants or herbivore droppings.
What are the major decomposers of dead animals?
Bacteria
What type of digestion do decomposers use?
External
What do the secreted enzymes break the complex organic molecules into?
Smaller molecules and nutrient ions which can then be absorbed into the cell.
What are the nutrient ions also available to?
Plants
What is the result of the decomposition of the decomposers?
All the nutrients are recycled into the soil
What is another word for decomposition and why?
Mineralisation because nutrients are released into the soil
Why are soil decomposers essential for an ecosystem?
They are the only organisms able to make mineral nutrients available again for use by plants.
What would be the result of no soil decomposers?
A build up of dead material and plant growth would cease due to lack of nutrient availability
Where else can nutrients become available?
The very slow erosion of weathering rocks
What are two limiting factors for decomposition?
Low temperature (enzymes work slower) Nitrogen availability (microbes need nitrogen to make enzymes and other cell proteins)
What is the cycle of a nutrient?
Nutrients are fixed into organisms , transformed into various compounds as they pass along the food chain, and are then broken down into simple forms that can be fixed again
How is the CO2 fixed by photosynthesis recycled back into the atmosphere?
Respiration
How do other nutrient elements become available to the community again?
Compounds have to be broken down be decomposer organisms in the soil
What are the three basic stages of a nutrient cycle?
Fixation
Transformation
Loss
Describe fixation
The nutrient is taken from the abiotic environment and is fixed into a food web as an organic compound
Describe transformation
The organic compound can be changed into other organic molecules
Describe loss
The organic compounds are lost from the food web; they are broken down to release simple organic units back to the abiotic environment
