Mutualism - This relationship happens when two different species benefit from one another. For example is the deer and the bird, The birds eat the flee and ticks off the deer.
Commensalism - This relationship happens between 2 organisms where 1 benefits and 1 doesnt get affected. For example is the antelope and the birds, the birds eat the insects.
Parasitism - This relationship happens when parasites benefits from an organism with it being hurt. For example is deer and ticks, The ticks benefit from the deer but the deer is getting hurt.
Competition - This relationship happens when 2 organisms fight for something. For example is a Lion fighting a tiger
Predation - This happens when the predator injures of kills its prey for food. For example is Lions kill zebras for them to have food
If the grass were to disappear in the forest there will be no place for the other animals to hide from they're predator. And if the grass were to disappear the animals that are herbivore will run out of food and eventually die.. Some animals will go extinct if it happens.