Not sure about the second, but the first is easy. You simply identify the variables in the question first. Then based on the variables, draw up a correlation. That forms the basis of the experiment.

For the second, I'm guessing it's related to the fact that seeds are not digestible. Why? Not too sure. Maybe it's the covering? I only know nature has it designed like that so that the seeds can be transported by animals, but I doubt that's the answer they want!

(a) The more you chew, the smaller food bits become. The results show that smaller pieces get digested faster, therefore the more you chew the food, the faster you can digest the food.

(b) Not sure what's the model answer, but i guess digestive juices are unable to digest seeds. It passed out as motion, if animals were to eat the seeds. It helps in spreading of apple seeds.