Poultry farming is undertaken to raise which of the following?
$(i)$ Egg production
$(ii)$ Feather production
$(iii)$ Chicken meat
$(iv)$ Milk production

Sahil's grandfather had a prostate problem. The doctor advised him to go in for an ultrasound. Sahil accompanied his grandfather to a diagnostic centre. His grandfather went through the process and was given a photograph.
$(a)$ What is the principle of ultrasound? What waves are used for this purpose?
$(b)$ Name four other areas in which the ultrasound is used as a diagnostic tool.
$(c)$ What value did Sahil imbibe about ultrasound?

Define the terms hybridization and photoperiod.

What do you mean by:
$(a)$ Blue revolution?
$(b)$ Yellow revolution?

For what reasons are improved poultry breeds developed?

$(i)$ List three factors on which cultivation practices and crop yield depend.
$(ii)$ Name three stages involved in farming practices.