Weeds affect the crop plants by

Write the modes by which insects affect the crop yield.

Freshwater resources include canals,ponds,reservoirs and rivers.

$(i)$ State three ways by which pests attack plants.
$(ii)$ Name the chemicals used to control pests.
$(iii)$ Explain why excessive use of such chemicals should be avoided.

While selecting a breed of crop,which characteristics of the crop are to be taken into account by the farmers?

Find out the correct sentence:
$(i)$ Hybridisation means crossing between genetically dissimilar plants.
$(ii)$ Cross between two varieties is called as interspecific hybridisation.
$(iii)$ Introducing genes of desired character into a plant gives genetically modified crop.
$(iv)$ Cross between plants of two species is called as inter-varietal hybridisation.