Three statements about malarial parasites are listed. 1 Insecticides are used to kill the vectors. 2 Netting is used to keep the vectors away from people. 3 People take drugs that stop the malarial pathogen developing. Which of these methods can be used to control malaria?

Why is it important to control the amount of nitrate fertiliser used on farm land?

On decomposition, which substance in decaying plants is the major source of carbon for carbon dioxide production by t…

If high levels of nitrates are washed into rivers, the following changes may occur, causing fish to die. 1 Water plan…

Bacteria can be genetically engineered to produce human insulin by adding a human insulin gene to the bacterial DNA. …

A person has blood group A. Which statement about his genotype is correct?

In fruit flies, the allele for an ebony coloured body is recessive to the allele for a grey coloured body. In an inve…