Organisation of the ecosystem

Question 1

What is an ecosytem

Answer 1

A system where all of the organisms are interdependent.

Question 2

Explain the use of sampling to discover more about organisms in a habitat

Answer 2

Scientists sample a part of a habitat and use that information to draw conclusions about the whole. It enables them to make judgements without surveying everything which would be inefficient.

Question 3

Describe how quadrats are used for sampling.

Answer 3

A quadrat is a square usually 0.25 square metres.
It is placed on the ground and the organisms within it are recorded in one of 3 ways. It is most useful for collecting information on plants or slow moving animals!
1 the number of individual organisms are recorded
2 the number of different species are recorded
3 the approximate percentage cover of plants can be recorded

Question 4

Describe the method of random sampling using quadrats to estimate the number of daisies in a field

Answer 4

1. Choose a fixed location to start- usually the corner.
2. Use a random number generator or table to tell you how far to walk in each direction to place the quadrat.
3. Count/record the number of daisies in the quadrat.
4. Go back to the fixed point and repeat.
5. The more samples you take the more accurate your results. Usually about 30.
6. Measure the field and calculate the number of quadrats which fit into it
7. Find the mean number of daisies per quadrat from your sampling.
8. Multiply the mean (step 7) by the number of quadrats (step 6) to estimate the number of daisies.

If you are asked to compare two parts of one field you would carry out this method as if the two areas were separate fields

You could be asked to outline this method in a long question, it is important that you are precise and detailed. Marks are given for logical sequencing.

Question 5

Describe the method of systematic sampling using quadrats to look at the distribution of seaweed on the shore.

Answer 5

1. Place a line called a transect from the top to the bottom of the shore.
2. Place the quadrat at regular intervals eg every metre along the transect and estimate the percentage coverage of seaweed in each quadrat.

Question 6

What type of sampling method would you use to estimate the population of a species in a given area?

Answer 6

Random sampling using a quadrat

Question 7

What type of sampling method would you use to compare the populations of a species in two different areas?

Answer 7

Random sampling using a quadrat in one area, then random sampling in the second and compare the two results

Question 8

What type of sampling method would you use to check the distribution of a species in a given area?

Answer 8

Use a transect to draw a line across the area. Calculate the distribution from quadrats placed at exact intervals along the transect.

Question 9

What is meant by the term producer

Answer 9

Any organism which photosythesises (plant or algae)
They produce biomass from inorganic compounds
Plants produce about 30% of the oxygen produced each day by photosynthesis, algae a surprising 70%

Question 10

What is biomass?

Answer 10

A resource made from living or recently living material.

Question 11

What is meant by the term inorganic

Answer 11

Inorganic substances are not or have never been living.

Question 12

What is consumer

Answer 12

An organism which eats other organisms for food.

Question 13

Describe the different types of consumers using examples

Answer 13

1. Primary consumer- feeds on producers eg aphid feeds on plants
2. Secondary consumer, feeds on primary consumer eg ladybird feeds on aphids
3. Tertiary consumer feeds on secondary consumer eg bird feeds on ladybirds

Question 14

Identify and describe the four processes of the carbon cycle.

Answer 14

1. Photosynthesis- glucose is produced from carbon dioxide and water
2. Respiration - carbon dioxide is produced from the carbon in glucose
3. Combustion - carbon dioxide is released from burning fuels such as wood, coal, methane and other gases.
4. Decay - microorganisms such as fungi and bacteria respire during decomposition releasing the carbon from the plant or animal back into the atmosphere.

Question 15

Identify the processes in the water cycle

Answer 15

1. Evaporation- water evaporates from oceans, lakes, rivers and puddles. Energy from the sun cause the water to change state from a liquid to a gas.
2. Transpiration - water taken in through the roots of plants evaporates from the leaves as a gas. 90% of the water a plant takes in is lost this way.
3. Condensation - water vapour condenses as it becomes colder high in the atmosphere and forms clouds.
4. Precipitation - condensed water vapour from clouds falls back to the ground as rain, hail, sleet and snow.