Free Food chains, webs & energy flow questions for IGCSE Biology (0610), part of Ecology & human influence. Each question has the answer and the marking points an examiner would look for.
Generate a full Food Chains, Webs & Energy Flow worksheet →All Ecology & human influence questionsA single oak tree supports thousands of caterpillars, which are eaten by a few birds.
What are the shapes of the pyramid of numbers and the pyramid of biomass?
| pyramid of numbers | pyramid of biomass | |
|---|---|---|
| A | narrow base, wide middle | pyramid shape (wide base) |
| B | pyramid shape (wide base) | pyramid shape (wide base) |
| C | narrow base, wide middle | narrow base, wide middle |
| D | pyramid shape (wide base) | narrow base, wide middle |
Answer: A
The diagram shows a food web. Which organism is a secondary consumer?
Answer: C
In a grassland ecosystem, grass captures 80000 kJ/m² of energy per year. Rabbits obtain 12000 kJ/m² per year from the grass and foxes obtain 1200 kJ/m² per year from the rabbits.
Calculate the percentage efficiency of energy transfer from rabbits to foxes.
Explain why so little of the energy in the rabbits is passed on to the foxes.
Use the data to explain why food chains rarely have more than five trophic levels.
Explain why it is more efficient, in terms of energy, for humans to eat crop plants than to eat animals that have been fed on crops.
A farmer adds too much nitrate fertiliser to a field next to a pond. Describe the effects on the pond.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 10% 1200 ÷ 12000 × 100 M1 10 A1 | 2 |
| (b) | Energy lost as heat in respiration; not all parts eaten (bones, fur); some not digested and lost in faeces; energy in urine/excretion; movement heat lost from respiration B1 not all of the rabbit eaten / indigestible parts B1 egested in faeces / excretion B1 | 3 |
| (c) | Energy decreases at each level, so not enough energy left to support another level energy lost at each transfer B1 too little energy remains for a further population B1 | 2 |
| (d) | Fewer trophic levels so less energy lost; more people can be fed from the same area shorter food chain / fewer trophic levels B1 less energy lost, so more energy available to humans B1 | 2 |
| (e) | Algae grow rapidly (algal bloom); block light; plants die; decomposers (bacteria) increase and respire aerobically using oxygen; fish/animals die algal bloom B1 light blocked, plants die B1 decomposers increase and use up oxygen B1 fish die from lack of oxygen B1 | 4 |
In a field, the energy in the grass is 20000 kJ per m² per year. The energy in the rabbits feeding on the grass is 2400 kJ per m² per year, and the energy in the foxes that eat the rabbits is 240 kJ per m² per year.
Calculate the percentage of the energy in the grass that is transferred to the rabbits.
Calculate the percentage efficiency of energy transfer from rabbits to foxes.
Describe three ways in which energy is lost between the rabbits and the foxes.
Explain why food chains rarely have more than five trophic levels.
Explain why it is more energy-efficient for humans to eat crops than to eat animals that have been fed on crops.
Some of the energy in the grass is never eaten. Suggest what happens to it.
Draw and label a pyramid of energy for this food chain.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 12.0 % 2400 ÷ 20000 × 100 C1 12.0 % A1 | 2 |
| (b) | 10.0 % 240 ÷ 2400 × 100 = 10.0 % B1 | 1 |
| (c) | respiration (heat); faeces / undigested; parts not eaten (bones, fur) Any 3 of: energy released in respiration and lost as heat; movement; excreted in urine / faeces (egested); not all of the rabbit is eaten, e.g. bones, fur B3 | 3 |
| (d) | energy lost at each level; too little left to support another population energy is lost at each trophic level B1 so too little energy remains to support a population at a higher level B1 | 2 |
| (e) | fewer trophic levels; less energy lost eating crops is one trophic level shorter B1 so less energy is lost and more is available to humans / more people can be fed from the same area B1 | 2 |
| (f) | dead material to decomposers; released by respiration of decomposers dead leaves / roots are broken down by decomposers B1 the energy is released (as heat) in the decomposers’ respiration B1 | 2 |
| (g) | three bars decreasing; labelled grass, rabbits, foxes three horizontal bars, widest at the bottom, decreasing in width B1 labelled grass / producer, rabbits, foxes in order B1 | 2 |
This question is about a food chain: oak tree → caterpillars → blue tits.
State the meaning of the arrows in a food chain.
Identify the producer, the herbivore and the secondary consumer in this food chain.
Explain why a food web is more stable than a single food chain.
Draw and explain the shape of a pyramid of numbers for this food chain.
Predict and explain the effect on the oak tree if the blue tits were removed.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | direction of energy flow show the transfer of energy from one organism to the next B1 | 1 |
| (b) | oak tree; caterpillars; blue tits producer oak tree and herbivore caterpillars B1 secondary consumer blue tits B1 | 2 |
| (c) | consumers have alternative food sources; loss of one species has less effect animals can feed on more than one species B1 so if one population falls the others are less affected B1 | 2 |
| (d) | inverted base: one tree supports many caterpillars correct shape with a narrow base (one tree), wide middle (many caterpillars), narrower top B1 one large producer supports many small consumers B1 energy still decreases at each level B1 | 3 |
| (e) | caterpillars increase; oak tree decrease; later caterpillars decline due to less food the caterpillars population would increase (fewer predators) B1 so more oak tree would be eaten and decrease B1 eventually the caterpillars population would fall from lack of food B1 | 3 |
In a food chain, energy is transferred from one trophic level to the next.
Explain why food chains rarely have more than five trophic levels.
Define a consumer and a producer.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | energy lost at each level energy is lost at each level B1 through respiration, movement, heat, excretion and uneaten parts B1 too little energy is left for higher levels B1 | 3 |
| (b) | organism that eats; organism that makes food by photosynthesis producer: makes its own organic nutrients (photosynthesis) B1 consumer: gets energy by feeding on other organisms B1 | 2 |
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Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in