Energy and Ecosystems Flashcards
What is a producer?
Producers are photosynthetic organisms. They are green plants.
What is a consumer?
Consumers are organisms that obtain energy by feeding on other organisms rather than using the energy of sunlight.
Animals are consumers.
What is a decomposer?
Organisms that use the energy from producers and consumers when they die. They break down complex materials that into simple components again. By doing this they release all sorts of valuable minerals that plants absorb. Decomposers are FUNGI and BACTERIA.
What is a detritivore?
An organism that breaks down some of the dead matter.
What is a food chain?
A feeding relationship where the producers are eaten by the primary consumers and they are eaten by secondary consumers and they are eaten by tertiary consumers and so on…
Each of these are trophic levels.
In a food chain with grass, sheep, human. Which direction is the energy going?
Grass –> Sheep –> Human
Energy transfer is represented by the arrows
What is a food web?
Many food chains all linked in together in a single habitat. This is made up of a lot of animals that eat more than one thing. For example African wild dogs eat: wildebeest, antelope, impala and other things.
How come plants only convert 1-3% of the Sun’s energy available to them into organic material?
90% of Sun’s energy is reflected back into space or absorbed by the atmosphere.
Not all wavelengths of light can be absorbed for photosynthesis.
Light might pass through the leaf without hitting a chloroplast.
Limiting factor like CO2 or temperature
What is gross production?
The total quantity of energy that the plants in a community convert to organic matter.
How is energy lost in the food chain?
Some of the organism isn’t eaten.
Some parts of the organism cannot be digested and therefore energy is lost in faeces.
Energy lost through excretion.
Endothermic organisms transfer body heat to the environment.
Why are food chains limited to only 4 or 5 trophic levels?
The food chains are too inefficient to support more levels because too much energy is lost.
What happens to the total amount of energy stored at each level as you move up the food chain?
The total amount of energy stored is less as you go up the food chain.
How do you calculate energy transfer?
(Energy available after the transfer)/ (energy available before the transfer) x 100
What are the issues with pyramids of numbers?
They don’t take into account the size of the organism. e.g: 1 oak tree is only 1 but the same amount of grass is 1 000 000s
An effective pesticide should be…
Specific
Biodegradable
Cost effective
Not accumulate
