Bacteria In a Petri Dish half of the dish has food

Hi please help

You take a very large petri dish that contains a population of bacteria. The bacteria live in the petri dish and you periodically add food to the dish. You decide to test what happens when you manipulate some of the abiotic (non living) factors of an environment. You decide to decrease the amount of food added to the plate and you place food only on half the petri plate instead of spreading it all over the plate.

a) What happens to the distribution, range and population size of the bacteria.?

b) If you introduce a second type of bacteria (that consumes the same type of food), what do you think will happen to the population of both these bacteria over the course of a few days?