Organisations of an ecosystem

Question 1

What is the base of almost every food chain

Answer 1

a producer

Question 2

How do decomposers break down dead organisms

Answer 2

in a process called decomposition. They do this by releasing enzymes onto the dead matter and afterwards, consume the broken down substances.

Question 3

How do plants benefit from decomposers

Answer 3

When organisms die and decompose plants absorb the broken down nutrients through their roots.

Question 4

What is a healthy balanced ecoystem

Answer 4

one where the number of predators and the number of prey remain fairly constant

Question 5

What could effect the cycle of predators and prey to increase or decrease and change their healthy constant

Answer 5

Abiotic factors like water or sunlight, or biotic factors, like a new predator or pathogen.

Question 6

https://bam.files.bbci.co.uk/bam/live/content/zr46yrd/medium

3 patterns you can deduce from this image

Answer 6

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

Question 7

Why is it important to estimate the number of species of an organisms population

Answer 7

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

Question 8

Two methods of sampling a population

Answer 8

Pitfall traps

Using large nets called sweep netting

quadrats

Question 9

How does a pitfall trap work

Answer 9

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

Question 10

sweep netting

Answer 10

Use large nets to sweep through grasses or leaves of trees

Question 11

Kick sampling

Answer 11

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

Question 12

species richness

Answer 12

the number of different plant or animal species is recorded but not the number of individuals within a species

Question 13

percentage cover

Answer 13

the percentage of the quadrat area that is covered by one species.

Question 14

systematic sampling

Answer 14

can be used if there is a trend or pattern across the habitat

Question 15

How could we use systematic sampling to link changes in species

Answer 15

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.

Question 16

Required practical - measuring population size in a habitat

Answer 16

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
   compare your results by

6.calculating a mean for each location

Question 17

How do decomposers contribute to the carbon cycle

Answer 17

they respire

Question 18

Carbon cycle

Answer 18

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.

Question 19

Water cycle

Answer 19

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.

Question 20

infiltration

Answer 20

This occurs when water that has fallen as precipitation is absorbed into the ground. This can then be stored within underground rocks called aquifers.