AQA GCSE Biology (8461), Higher tier · Ecology › Organisation of an ecosystem
Practise Levels of organisation. 20 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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A food chain in a woodland is shown. oak leaves → caterpillar → blue tit → sparrowhawk Which organism in the food chain is the producer?
Oak leaves (oak tree)
A student counted the snails in five quadrats. The numbers were: 5, 2, 8, 2, 6 Give the mode and the median of these numbers.
Mode 2; median 5
In the Southern Ocean:
phytoplankton are single-celled algae
krill are small animals that eat phytoplankton
Adélie penguins eat krill
leopard seals eat Adélie penguins.
Use the information to write a food chain.
phytoplankton → krill → Adélie penguin → leopard seal
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
A food chain in a woodland is shown. oak leaves → caterpillar → blue tit → sparrowhawk
(a) Which organism in the food chain is the producer?[1]
(b) Producers make glucose. Name the process they use.[1]
(c) Which organism is a secondary consumer? Tick (✓) one box.[1]
Oak leaves
Caterpillar
Blue tit
Sparrowhawk
(d) The sparrowhawk is a predator. What is a predator?[1]
(e) Explain why all food chains begin with a producer.[1]
Show the answer and mark scheme
(a)Answer: Oak leaves (oak tree)
oak leaves / oak tree
(b)Answer: Photosynthesis
photosynthesis
(c)Answer: Blue tit
(d)
an animal / consumer that kills and eats other animals
(e)
producers make their own food / synthesise molecules (by photosynthesis), so they are the source of biomass for all other organisms
Question 2Medium7 marks
A student wanted to compare the number of dandelions in two areas of a park. One area is mown every week. The other area is mown only once a year.
(a) Describe how the student could use quadrats to take samples at random positions in each area.[3]
(b) The student used 10 quadrats in each area. Explain why using more quadrats would improve the investigation.[1]
(c) The quadrats were 0.5 m × 0.5 m. The mean number of dandelions in the area mown every week was 2.4 per quadrat. Calculate the mean number of dandelions per m2 in this area.[2]
(d) There were more dandelions in the area mown every week. Suggest one reason why.[1]
Show the answer and mark scheme
(a)
lay out two tape measures at right angles along the edges of the area / divide the area into a grid
use random numbers (e.g. from a random number generator) as coordinates
place the quadrat at each pair of coordinates and count the dandelions inside it
(b)
the mean would be more representative / closer to the true mean / the effect of unusual quadrats would be reduced
(c)Answer: 9.6 per m2
area of quadrat = 0.25 m2
2.4 ÷ 0.25 = 9.6
(d)
dandelion leaves grow flat against the ground, so they are not cut by the mower (but taller plants are)
less competition for light from taller grasses / plants
more light reaches the dandelions
Question 3Hard7 marks
Limpets are small animals that live on rocks on the seashore. A student noticed that there seemed to be more limpets near the low tide line than near the high tide line.
(a) Plan an investigation to find out whether the distance from the low tide line affects the population density of limpets on a rocky shore.[6]
(b) Suggest one reason why there may be more limpets near the low tide line.[1]
Show the answer and mark scheme
(a)
at low tide, lay a tape measure (transect) from the low tide line up the shore to the high tide line
place a quadrat at regular intervals along the tape, e.g. every 2 m
count the number of limpets in each quadrat
use the same size of quadrat each time, e.g. 0.5 m × 0.5 m
repeat with several transects at different places along the shore and calculate a mean for each distance
calculate population density = mean number per quadrat ÷ area of quadrat
keep other variables the same where possible, e.g. same type of rock, same day
safety: check tide times; take care on slippery rocks
Marked with levels of response: the full level descriptors are in the app.
(b)
they are covered by water for longer, so are less likely to dry out