Scientists repeat the experiment to further prove it being correct, and they can replicate is with data, models, and other forms of proof of a correct hypothesis
Answer: To know if a document is a primary source, check to see when the document is published, if it is an autobiography of a person, a diary, a letter, or the documents happen at the time of the event.
The competition between two organisms can be seen if there is only 1 source of food or habitat space and they're competing against each other for the food or habitat.
There is cooperation between two organisms if they are helping each other with resources or alarming each other if there is danger.
Predation between two organisms happen when one organism hunts the other organism for food.
The natural spreading of particles through a liquid or gas is called diffusion