Answer:
a) 昆 -> 皆 -> 皇 -> 珠
昆 KON - elder brother, later, insect
皆 KAI, mina - all
皇 KOU, OU - emperor
珠 SHU - pearl
b) 畑 -> 男 -> 加 -> 味
畑 hatake - cultivated field
男 DAN, NAN, otoko - male, man
加 KA, kuwa(eru), kuwa(waru) - add, append, join, take part
味 MI, aji , aji(wau) - taste