Poultry fowl are susceptible to the following pathogens:

Discuss various methods for weed control.

$(a)$ What is composite fish culture system?
$(b)$ Mention one merit and one demerit of this system.

Which one of the following fish variety is a surface feeder?

Fill in the blanks:
$(a)$ Photoperiod affects the . . . . . . .
$(b)$ Kharif crops are cultivated from . . . . . . to . . . . . . .
$(c)$ Rabi crops are cultivated from . . . . . . to . . . . . . .
$(d)$ Paddy,maize,green gram,and black gram are . . . . . . crops.
$(e)$ Wheat,gram,pea,and mustard are . . . . . . crops.

The milkman in our society started carrying a lactometer. His move was well appreciated by the society members.
$(a)$ What is the use of a lactometer? On what principle does it work?
$(b)$ What values of the milkman are shown by this move?