3.7.4 AO1 Qs

Question 1

Succession occurs in natural ecosystems. Describe and explain how succession occurs (5 marks)

Answer 1

-colonisation by pioneer species
-change in environment
-enables other species to colonise and survive
-change in diversity/ biodiversity
-stability increases (environment is less hostile)
-climax community (e.g. formation of hummus/ increase in nutrients/ organic matter)

Question 2

A weed plant is growing where it is not wanted. Fat hen is a weed which grows in some crop fields. Describe how you could estimate the number of fat hen plants in a field. (5 marks)

Answer 2

1. Use a grid/ divide area into squares
2. Use a random number generator to obtain a random coordinate
3. Count number in quadrat
4. Repeat at least 30 times and calculate mean per quadrat
5. Multiply mean number of plants per m2 by area of field (scale up)

Question 3

Explain the features of an ecological succession. (6 marks)

Answer 3

1. colonisation/ pioneering
2. microscopic plants at start
3. death/ decomposition
4. increase in organic matter in soil (change in environment)
5. new species colonise once there is a change
6. increase in number of species/ diversity/ more niches/ more stability/ increase in available nutrients