How to prepare for kvpy especially for biology? As well as which subject is given more preference?

@kumkum 
for biology focus on the below chapters 
1- respiratory tract of human being 
2- mechanism of respiration and importance of diff terms like respiratory quotent , etc . 
3- mechanism of digestion and som,e fact about digestive glands like brunners gland , crypts of liberkuhn . 
4- neural controll and mechanism . 
5- process of photosynthesis and c3 and c4 cycle . 
6- examples of difrent phyla . 
go beyond ncert and read BIOLOGY BYTE by mtg publication . 
and arihant also have 1 magazines , take that 
and u will crack kvpy 
all the best