Question

why are flowering plants more efficient at pollinating than gymnosperms?

Answer 1

bees can get in and out, carrying pollen with them from flower to flower pollinating as they go. On the the other hand, Gymnosperms have to let their seeds somehow travel away and plant itself, or with the help of nature, they plant themselfs
But it is easier for those flowering plants to pollinate. 
=)

Answer 2

Gymnosperms usually have their seeds enclosed in cones. The cones have to either fall to the ground or be eaten by an animal for the seeds to be released. It is amore protective covering than the fruity covering of Angiosperms. Angiosperms seeds may be carried by wind and pollinators, like insects, birds, animals.