Answer:
a complex series of feeding relationships with many organisms interacting and depending on each other
Explanation:
Positive selection of t cells occur in .the thymus
Answer:
Acid is a kind of chemical compound that when dissolved in water gives a solution with H+ ion activity more than purified water. A base is an aqueous substance that donates electrons, accept protons or release hydroxide (OH-) ions. An acid is a proton donor. While a base is a proton acceptor.
