Name any one method of incorporating desirable characters into a crop variety.

Ram's teacher was showing the structure of a cell under a compound microscope,highlighting different parts like the cell wall,cell membrane,and nucleus. The teacher explained the difference between plant and animal cells,noting that the cell wall is found only in plant cells. Everyone observed the structure carefully and understood its structural importance.
$(a)$ What kind of qualities are shown by Ram?
$(b)$ Why is the cell called the structural and functional unit of life?

Bakut has a poultry farm. He feeds his birds with a protein and fat-rich diet in large amounts. The birds are in good health,but their egg quality is not good.
$(a)$ What should he do to get good production of eggs?
$(b)$ What should he add in the feed to make the shells of the eggs strong?

The kind of flowers available determines the taste of honey.

The number of dengue cases has increased in Sana's village in the last one year. She read in her textbook that diseases like dengue spread through mosquitoes which breed in stagnant water. She immediately suggested to her friends that they should kill the mosquitoes in water bodies in the locality. They also took the help of the nearest municipal office.
$(a)$ Which preventive measures do you suggest for the prevention of such diseases caused by mosquitoes? Mention any two measures.
$(b)$ Which values are displayed by Sana in taking this initiative?
$(c)$ Suggest one school activity to promote such values in school students.

Why is excess use of fertilizers detrimental for the environment?