Question

Why do frogs produce large number of gamates

Answer 1

There can be two possible reasons for this:

1. Like Truman Sharp said, frogs are placed lower in the food chain, and a lot of them need to hopping around to sustain the life above them.

2. This seems more likely though: 
     Amphibians like frogs reproduce by external fertilization. That is, the female and male gametes fuse outside the frog's body. This usually happens in water, thus there is a possibility that the male gametes never make it to the eggs, unless there are lots of them. This could be one of the reasons that frogs release so many gametes.

Answer 2

This happens because their mode of fertilization is external. They lay eggs in the water and if they are in less quantity,there is a chance of destruction of these gametes by water current.And because of this, they lay more and more eggs in order to rule out the possibility of destruction of all eggs.So at least some eggs are fertilized by sperm and produce zygote

Hope this helps u......................^_^