Organisms and their Environment

Worked examples (12)extended set

• 1Tracing energy from the Sun through a meadow food chain
• 2Which statement describes energy flow correctly (multiple choice)
• 3Percentage of energy transferred and lost in a grassland pyramid
• 4Energy lost between producers and secondary consumers (multiple choice)
• 5Energy budget of a grazing bullock
• 6How much energy reaches the fifth trophic level
• 7Feeding people with soya beans or with chicken
• 8A floating weed shades a fishing lake
• 9Why there are so few lions on the savanna
• 10Comparing the efficiency of energy transfer in a stream
• 11Measuring energy transfer from cabbage to caterpillars
• 12Following energy to decomposers in a woodland

Model answers (6)

• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) extended-response style

Worked examples (12)extended set

• 1Producers, consumers and decomposers in a kelp forest
• 2Reading a rocky shore food web
• 3Counting secondary and tertiary consumers (multiple choice)
• 4Trophic levels and a five-organism chain in a lake food web
• 5Choosing pyramids for an apple tree food chain (multiple choice)
• 6What a pyramid of energy shows
• 7Drawing a pyramid of biomass for a hedgerow
• 8Krill fishing and a penguin colony
• 9Stoats introduced to an island
• 10An inverted pyramid of biomass in the open sea
• 11Sampling a nettle patch to build a pyramid of numbers
• 12Anglers overharvest the perch in a lake

Model answers (6)

• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) extended-response style

Worked examples (12)extended set

• 1Naming the processes on a carbon cycle diagram
• 2Processes that release carbon dioxide (multiple choice)
• 3How carbon in an ancient swamp forest returns to the air
• 4The yearly rise and fall of carbon dioxide in the air
• 5Which arrows are carried out by bacteria (multiple choice)
• 6From protein in a dead leaf to protein in a cow
• 7Why a farmer ploughs clover into the soil
• 8Heating soil and the conversion of ammonium ions
• 9Draining a waterlogged field
• 10Balancing the global carbon budget
• 11Decomposers in both cycles, and a body in a peat bog
• 12A soil chemical that stops nitrification

Model answers (6)

• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) extended-response style

Worked examples (12)extended set

• 1Population, community or ecosystem in a pond
• 2Finding the stationary phase on a growth curve (multiple choice)
• 3Birth rate and death rate in each phase (multiple choice)
• 4Describing and explaining the growth of goats on an island
• 5Rate of growth of a yeast population
• 6Voles and owls: a predator and its prey
• 7Investigating a duckweed population
• 8Two species competing in the same culture
• 9Counting barnacles at different heights on a shore
• 10Bacteria in a closed flask and in a renewed flask
• 11Reindeer on an island with no predators
• 12Why one introduced population took longer to take off

Model answers (6)

• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 short-answer style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) structured style
• ✓Model answer — Paper 4 (Extended) extended-response style