Organisations of an ecosystem Flashcards
What is the base of almost every food chain
a producer
How do decomposers break down dead organisms
in a process called decomposition. They do this by releasing enzymes onto the dead matter and afterwards, consume the broken down substances.
How do plants benefit from decomposers
When organisms die and decompose plants absorb the broken down nutrients through their roots.
What is a healthy balanced ecoystem
one where the number of predators and the number of prey remain fairly constant
What could effect the cycle of predators and prey to increase or decrease and change their healthy constant
Abiotic factors like water or sunlight, or biotic factors, like a new predator or pathogen.
https://bam.files.bbci.co.uk/bam/live/content/zr46yrd/medium
3 patterns you can deduce from this image
the number of predators increases because there is more prey
the number of prey reduces because there are more predators
the number of predators reduces because there is less prey
Why is it important to estimate the number of species of an organisms population
to better understand the relationships in a community.
This information is useful for monitoring the impact of conservation projects that aim to conserve endangered species or habitats
Two methods of sampling a population
Pitfall traps
Using large nets called sweep netting
quadrats
How does a pitfall trap work
Pitfalls traps are small traps dug into the ground, which often has food inside to attract small mammals. The sides of these traps are smooth to stop mammals escaping
sweep netting
Use large nets to sweep through grasses or leaves of trees
Kick sampling
To catch aquatic organisms nets are often held down stream of an area of river bed which is then gently disturbed by the person doing the sampling. The small animals float into the net. This is called kick-sampling
species richness
the number of different plant or animal species is recorded but not the number of individuals within a species
percentage cover
the percentage of the quadrat area that is covered by one species.
systematic sampling
can be used if there is a trend or pattern across the habitat
How could we use systematic sampling to link changes in species
A quadrat could be placed at regular distances, for example every five metres, along an imaginary line called a transect, which would run down the shore. Systematic sampling would be used along the transect to link changes in species to abiotic factors, such as immersion by water, temperature fluctuations, light intensity, all of which are influenced by the tide.
Required practical - measuring population size in a habitat
1.choose a starting point on the school field in an area where the grass is often cut
- use random numbers to generate a set of coordinates to place your first quadrat
- count the number of different plant species within this quadrat (the species richness)
- return to your starting position and repeat steps two and three a further 14 times using different random numbers
- repeat steps one to four for a part of the school field which the grass is infrequently cut
compare your results by
6.calculating a mean for each location
How do decomposers contribute to the carbon cycle
they respire
Carbon cycle
Stage 1. Carbon enters the atmosphere as carbon dioxide from respiration and combustion.
Stage 2. Carbon dioxide is absorbed by producers to make carbohydrates in photosynthesis.
Stage 3. Animals feed on plants, passing the carbon compounds along the food chain. Most carbon they consume is exhaled as carbon dioxide during respiration. The animals and plants eventually die.
Stage 4. Dead organisms are eaten by decomposers and carbon in their bodies is returned to the atmosphere as carbon dioxide. In some conditions decomposition is blocked. The plant and animal material may then be available as fossil fuel in the future for combustion.
Water cycle
Either it evaporates or transpires into the air
it condenses forming clouds
Water within clouds can be blown many miles by strong winds and so transported to other areas
precipitation occurs
Then the majority of the water will be absorbed into the ground reaching the ocean by percolation and some
others getting absorbed by the roots of plants and transpiration occurs. Some of the water will flow straight back to the ocean.
infiltration
This occurs when water that has fallen as precipitation is absorbed into the ground. This can then be stored within underground rocks called aquifers.
