Organisation of an ecosystem .2

what are decomposers

bacteria and fungi, which break down dead organisms in a process called decomposition or rotting

how do bacteria and fungi, break down dead organisms

release enzymes onto dead matter and then consume the broken down substances

When organisms die and decompose plants….

absorb the broken down nutrients through their roots.

what 3 things does the graph show

1. the number of predators increases because there is more prey

2. the number of prey reduces because there are more predators

3. the number of predators reduces because there is less prey

how can you catch smaller animals if you want to do an investigation on how many mammals live in an area

• Pitfall 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 the mammals escaping.

example of another method

use large nets to sweep through grasses or leaves of trees in a process called sweep netting

what can you use when sampling

pooters which are small devicies used to suck up small insects safetly without them going to your mouth

example of method for catching aquatic organism

• nets are often held downstream of an area of river bed

• The small animals float into the net.

• This is called kick-sampling.

what are quadrants + size

• placed on ground to look at plants / animals in them

• sqaure frames of wire usually 0.25 m²

When looking at plants in a quadrant the following sampling can be used:

• Number of an individual species

• Species richness

• Percentage cover

Required practical - measuring population size in a habitat - method

1. choose a starting point on the school field in an area where the grass is often cut

2. use random numbers to generate a set of coordinates to place your first quadrat

3. count the number of different plant species within this quadrat (the species richness)

4. return to your starting position and repeat steps two and three a further 14 times using different random numbers

5. repeat steps one to four for a part of the school field which the grass is infrequently cut

6. compare your results by calculating a mean for each location

How materials are cycled in an ecosystem (4)

• rocks can cycle between igneous, sedimentary and metamorphic

• carbon and water can exist in different forms at different times.

• humans eat meat which is broken down in body for growth + repair + when we die these building blocks are returned to environment and used for other living organism

• Decomposing bacteria and fungi help dead organisms break down and rot. They help recycle minerals and nutrients to the environment, which can then be used by other organisms

what does the carbon cycle show

how atoms of this element (carbon) can exist within different compounds at different times

the 4 carbon cycle stages

• stage 1 : carbon enters atmosphere as carbon dioxide from respiration + combustion

• stage 2 : co2 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.

if the process is photosynthesis:

• what does carbon start as

• what does carbon end as

• carbon dioxide

• glucose

if the process is respiration:

• what does carbon start as

• what does carbon end as

• glucose

• carbon dioixde

if the process is combustion (burning):

• what does carbon start as

• what does carbon end as

• fuel (eg. methane/wood)

• carbon dioxide

water cycle process

• evaporation

• condensation

• transportation

• precipitation

• surface runoff

• infiltration

• transpiration

evaporation

• water goes from liquid → gas when it evaporates

• energy from sun can make this happen to places like puddles, ponds, lakes and oceans

condensation

• after evaporation water cools + converts from gas → liquid

• forms cloud often

transport

• water in clouds is blown + transported to other areas by wind

precipitation

occurs when rain, snow ,hail and sleet falls from sky

surface runoff

• water absorbed into group after precipitation

• if lots falls + ground is wet, water runs along surface of ground

infiltration

• occurs when water fallen as precipitation is absorbed into ground

• can be stored within underground rocks called aquifers

transpiration

• plants need constant stream of water to leaves for transport + support

• so they allow some water to evaporate as water vapour from their leaves to mean that more is continually ‘pulled’ to their leaves from the soil.