I think the best medium is agar. It is a jelly-like substance that is obtained from algae, and is used to culture small organisms such as microorganisms and bacteria.
Hope this helps. :)
Well, biotic factors are living things in an ecosystem such as animals or insects. Abiotic factors are non living things in an ecosystem such as sunlight or temperature. I would say biotic factors would be more harmful since this includes bacteria or other diseases, not many abiotic factors would pose a great threat to the entire human species. Hope this helped.
A 'red' apple does not emit red light. Rather, it simply absorbs all the frequencies of visible light shining on it EXCEPT for a group of frequencies that is perceived as red, which are REFLECTED. An apple looks red to us because it REFLECTS infrared waves.