B17: Organising an ecosystem Flashcards
What is the producer?
Every food chain starts with a producer - in most food chains the producer is a green plant.
The source of all biomass in a community.
Why are producers important in food chains?
They synthesise complex molecules and produce all the biomass in a community.
What is biomass?
e.g. glucose.
Molecules that pass down the food chain into other organisms
What are primary consumers?
Organisms that eat the producers.
What are secondary consumers?
The animal that eats the primary consumer.
What is a predator?
Consumers that kill and eat other animals
What is a prey?
The animal that is being eaten by the predator
What would the predator-prey graph look like for 2 animals?
Put population against time.
Wavy - prey is generally higher, with more fluctuation, whereas predators are generally lower, with less fluctuation in numbers. The numbers of predators and prey rise and fall in cycles - only true in a STABLE COMMUNITY.
When there are more foxes, it means more rabbits are eaten, so population of rabbits falls. Now less rabbits are available, so fox population falls. Now rabbits can grow in population and rinse and repeat
What are the two sampling techniques?
Random sampling
Sampling along a transect
Describe the process of random sampling
Used to compare the numbers of organisms in different areas. This is done using a quadrat (a wooden or plastic square). A quadrat is placed on the ground and the number of organisms inside the quadrat are then counted - can be used to sample plants or slow-moving animals. The quadrat is placed at random locations across the area (can use random numbers to select the different locations), the count the numbers of each organism in the quadrat. Do this a few times until you have sampled a large number of random locations, which produces more valid results.
What is the equation to find the total population size in an area?
Total population size = (total area /area sampled) *number of organisms of that species counted in the sample
Describe the process of sampling along a transect
Used when we want to investigate whether the numbers of species change across a habitat e.g. a sand dune. Place transect so it runs across the habitat we are looking at. Then use a quadrant to count the number of organisms at intervals on the transect.
Investigation should be carried out a number of times to get valid results.
What is a transect?
A line e.g. a rope or tape measure
Where does the carbon cycle start?
With CO2 in the atmosphere - the only way that carbon can enter the carbon cycle is through photosynthesis.
How does CO2 return back to the atmosphere?
Aerobic respiration, carried out by every living organism.