MYP Biology sample question: Food chains and energy transfer

Consider this food chain: grass → rabbit → fox. A disease greatly reduces the rabbit population.

1. (a)Predict and explain the effect on the amount of grass.[2]
   Show the mark scheme for (a)

   • • Grass will increase (1)
   • • because fewer rabbits are eating it (1)
2. (b)Predict and explain the effect on the fox population.[2]
   Show the mark scheme for (b)

   • • The fox population will decrease (1)
   • • because there is less food, so more starve or move away (1)
3. (c)Give two reasons why only a small proportion of the energy in one trophic level reaches the next.[2]
   Show the mark scheme for (c)

   • • Any two: energy is lost as heat in respiration; some parts of the organism are not eaten; waste such as faeces and urine contains energy

Follow the change step by step along the chain. Show a link such as less food, so fewer foxes.