Energy in ecosystems Flashcards
What do food chains show?
The feeding relationships that exist in an ecosystem
What do arrows in a food chain represent?
The energy flow
How much energy is lost when transferred from one level to the next?
Around 90%
Why is this energy lost?
Lost because of things such as heat, movement and egestion of undigested waste (faeces)
What happens with the remaining 10%?
It’s used for growth
In a pyramid of numbers, what happens to the numbers of organisms as you go along the food chain?
The organisms get bigger and fewer in number as you go along the food chain
Why do organisms get bigger but fewer in numbers?
Energy loss between levels limits the quantity of living material at the next level.
Does a pyramid of numbers have the same shape for every ecosystem?
No
What happens to the pyramid of numbers if you start it with a tree?
It has a tree shape
How do we show the energy content of each level of a food chain?
By using the pyramid of energy
What is the unit of energy in the pyramid of energy?
Joules (J)
What does productivity describe?
The energy used in an area in a unit of time.
KJ/m2/year
What is there not in a pyramid of energy?
Exception. There is always loss from one level to the next
What is the 10% rule based on?
A whole feeding (trophic) level - all the producers and consumers, not just one food chain
What is a producer?
An organism which makes it’s own food (by photosynthesis)
