In some traditional agricultural systems, farmers introduce ducks into flooded rice paddy fields as a form of biological control.
The ducks help the rice plants to grow by feeding on insect pests and weeds.
Suggest how the ducks eating insect pests helps the rice plants to grow.
Explain how the ducks eating weeds helps the rice plants to grow.
Explain why droppings (faeces) from the ducks help the rice plants to grow.
As the ducks swim through the paddies, their webbed feet stir up the mud and loosen the waterlogged soil, which increases the dissolved oxygen content of the water surrounding the roots. Suggest how increasing the oxygen content of the soil and water helps the rice plant roots to grow.
Using ducks as a method of biological control allows the farmers to produce rice without using chemical sprays.
Suggest what is meant by the term herbicide.
Give three advantages of using biological control rather than using chemical pesticides.
44 exam-style questions on Edexcel IGCSE Biology Human influences on the environment. Each one has a worked solution and a mark scheme showing where the marks go.