organising an ecosystem (required practical) Flashcards
what are the stages of a food chain?
producer → primary consumer → secondary consumer → tertiary consumer → apex predator.
what do the arrows show in a food chain?
direction of energy flow.
what is a predator prey cycle?
the link between the populations of predators and prey.
what is the distribution of an organism?
where the organism is found.
how can you study the distribution of small organisms with a quadrat? (practical)
- place a 1m x 1m quadrat on a random point in a sample area.
- count all the organisms within the quadrat.
- recount at different points in the area as many times as possible.
- work out the mean organisms within the sample area.
- repeat this test in a different sample area.
- compare the distributions in the 2 areas.
what environmental changes affect the distribution of organisms? (3)
- availability of water.
- change in temperature.
- composition of atmospheric gas.
how can you study the distribution of small organisms with a transect? (practical)
transects can be used to find the distribution of organisms along a line.
1. mark out a line in a sample area.
2. count the organisms touching the line.
what are the steps of the water cycle?
- the sun makes sea water evaporate.
- water vapour rises and condenses to form clouds.
- water falls as precipitation.
- the water drains into the sea.
what are the steps of the carbon cycle?
- carbon enters the atmosphere from respiration and combustion.
- carbon dioxide is absorbed by produces in photosynthesis.
- animals eat plants passing carbon along the food chain then die.
- decomposers eat bodies and carbon returns to the atmosphere.
what is compost?
decomposed organic matter.
what affects the rate of decay?
temperature - warm temperature increases enzyme rate.
oxygen availability - some microorganisms need oxygen to respire.
water availability - microorganisms need water.
number of decay organisms - more microorganisms can decay faster.
how is biogas made?
microorganisms decaying waste anaerobically. (in a digestor or generator)
what is the difference between a batch and continuous biogas generator?
batch generators produce in small amounts.
continuous generators produce constantly.
how do you investigate the effect of temperature on the rate of decay?
you can observe the action of lipase in milk.
1. add 5cm³ of lipase solution to a test tube. (label L)
2. add 5cm³ of milk to a test tube.
3. add 5 drops of phenolphthalein to the milk.
4. add 7cm³ sodium carbonate to the milk. (the tube will turn pink because it’s alkaline)
5. put both tubes in a 30°c water bath.
6. add 1cm³ lipase solution to the milk and start a stopwatch.
7. stir the contents.
8. as soon as the test tube stops being pink stop the timer and record the time and water bath temperature.
9. repeat the experiment at different temperatures.
10. rate of decay = 1000 ÷ time.
