Discuss why pesticides are used in very accurate concentration and in a very appropriate manner.

Which of the following are Indian cattle?
$(i)$ Bos indicus
$(ii)$ Bos domestica
$(iii)$ Bos bubalis
$(iv)$ Bos vulgaris

Kanchan purchased gold from a jeweller. She was,however,very apprehensive about the purity of the gold purchased by her. Ultimately,she approached a person who claimed he could test its purity by making certain measurements of weight of the gold in air and water.
$(a)$ What principle was he making use of for testing purity?
$(b)$ Write the relation by which he found the relevant quantity.
$(c)$ What value did Kanchan imbibe?

What do you understand by composite fish culture?

How can you identify a healthy animal?

Find out the correct sentence:
$(i)$ Hybridisation means crossing between genetically dissimilar plants.
$(ii)$ Cross between two varieties is called as inter-varietal 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-specific hybridisation.