Unit B1, B1.5 and 6 Energy and biomass in food chains
Waste materials from plants and animals
1.
A gardener pulled up weeds and used them to start a compost heap. The compost heap soon
became colonised by large numbers of earthworms and slugs. The gardener then noticed a
hedgehog rooting through the compost heap, eating the earthworms and slugs. Every so often the
hedgehog stopped to scratch itself. This was because it had large numbers of fleas which fed by
sucking the hedgehog’s blood.
(a)
Use only information from the passage to answer the following.
Construct and label a pyramid of biomass for your food chain.
(2)
(b)
Gardeners put plant material onto compost heaps so that it will decay. They then put the
decayed compost onto soil where they are growing their plants.
Give three conditions which are needed for plant material to decay rapidly.
1 .....................................................................
2 .....................................................................
3 .....................................................................
(3)
(Total 5 marks)
Page 1 of 6 Unit B1, B1.5 and 6 2.
2
The diagram shows the flow of energy through 1 m of an ecosystem.
2
The unit in each case is kJ per m per year.
96
D
24
120
1500
C
380
2000
E
8000
5000
B
F
15 000
52 000
23 000
A
Key
(a)
(i)
A Plants
D Mammals and birds
B Animals
E Heat transfer to environment
C Animals
F Detritus feeders and microorganisms
Name the process in which green plants transfer solar energy into chemical
compounds.
...........................................................................................................................
(1)
(ii)
Name the process in living organisms which eventually results in the transfer of heat
to the environment.
...........................................................................................................................
(1)
(b)
Give two ways in which energy is transferred from animals to detritus feeders.
1 ..................................................................................................................................
.....................................................................................................................................
2 ..................................................................................................................................
.....................................................................................................................................
(2)
Page 2 of 6 Unit B1, B1.5 and 6 (c)
(i)
Calculate the percentage of the energy intake of mammals and birds which is
transferred to the environment.
...........................................................................................................................
...........................................................................................................................
Percentage = .......................................
(2)
(ii)
Explain why mammals and birds lose a greater percentage of their energy intake to
the environment as heat, than other groups of animals.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(Total 8 marks)
3.
The diagram below shows the mass of carbon involved each year in some of the processes in the
carbon cycle.
Fossil fuels
5 billion
tonnes
Land plant
respiration
50 billion
tonnes
Land plant
Deforestation
photosynthesis by burning
100 billion
2 billion tonnes
tonnes
Decomposition
of dead
organisms
50 billion
tonnes
Biological
and
chemical
absorption
104 billion
tonnes
Biological
and
chemical
emissions
100 billion
tonnes
Oceans
(a)
Complete the equation for plant respiration.
+
oxygen
→
carbon dioxide
+
+
energy
(2)
(b)
(i)
Calculate the mass of carbon removed from the atmosphere each year.
(Show your working.)
Answer .......................... billion tonnes
Page 3 of 6 Unit B1, B1.5 and 6 (1)
(ii)
Calculate the percentage of this total which is removed by the photosynthesis of land
plants. (Show your working.)
Answer ...................................... %
(2)
(iii)
Calculate the net gain of carbon by the atmosphere in one year. (Show your working.)
Answer ........................... billion tonnes
(2)
(Total 7 marks)
4.
Gardeners often put waste materials onto compost heaps.
The graph shows how the conditions in a compost heap affect how quickly waste materials in the
heap decay.
(a)
(i)
Describe the effect of increasing the temperature from 15 °C to 25 °C on the rate of
decay at 20 % oxygen concentration.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
Page 4 of 6 Unit B1, B1.5 and 6 (ii)
Gardeners are advised to put waste materials into
special compost bins.
These bins have holes in their sides.
Holes in the sides of the compost bin help the waste
materials to decay faster.
Explain why.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(b)
A gardener noticed that some of his plants were growing poorly.
He put some decayed compost onto the soil, around the plants.
Six months later the plants were growing well.
Explain why.
.....................................................................................................................................
.....................................................................................................................................
(1)
(Total 5 marks)
5.
The diagram below shows a food web for a wood.
owls
voles
insects
herbs
Page 5 of 6 weasels
small birds
moths
trees and bushes
shrews
beetles
other leaf
eaters
earthworms
oak trees
leaf litter
Unit B1, B1.5 and 6 (a)
The diagrams below show a pyramid of the numbers and a pyramid of the biomass for 0.1
hectare of this wood.
Pyramid of Numbers
numbers/0.1 hectare
Pyramid of Biomass
biomass (grams per square metre)
2
120 000
1
X
2
150 000
5 139
200
Y
(i)
Name one organism from the level labelled X.
...........................................................................................................................
(1)
(ii)
Explain, as fully as you can, why the level labelled Y is such a different width in the
two pyramids.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
(b)
Explain, as fully as you can, what eventually happens to energy from the sun which is
captured by the plants in the wood.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(10)
(Total 14 marks)
Page 6 of 6