(a) The clown is blowing / blowing up the balloon.
(b) The web can catch insects.
(c) The fruit of the banana treegrows in bunches.
(d) Peter's grandfather and his grandson are playing chess. -- ?? Do you mean Peter's grandfather and Peter's grandson? That's a lot of generations. Or do you mean Peter's grandfather and Peter's gran
(a) The fruit of the banana trees grows in bunches.
The fruits of the banana trees grow in bunches.
This is possible if you are referring to a specific group of banana trees. However, it seems more likely that you are talking about the habit of banana trees in general. In this case, the version I offered is better. Despite appearances, "the banana tr