Answer:
a) 粒 -> 童 -> 野 -> 預
粒 RYUU, tsubu - a grain
童 DOU, warabe - child
野 YA, no - field, plain
預 YO, azu(keru), azu(karu) - entrust
b) 章 -> 古 -> 員 -> 贈
章 SHOU - chapter, badge, mark
古 KO, furu(i) - old
員 IN - member
贈 ZOU, SOU, oku(ru) - give, present, bestow