Cells that are a structured material.
Oxygen, neccessary for cellular respiration, is the answer. As oxygen becomes scarce, your cells begin to aerobically produce very little ATP, in effect fermenting and producing lactic acid.
Explanation:
Immunity is the ability of an animal to resist infection.
There are two types of immunity in the body; INNATE OR INHERITED IMMUNITY AND ACQUIRED IMMUNITY. Inherited immunity it is the type of immunity that one is born with. It is passed from parent to offspring.
Acquired immunity is immunity to particular infections that is not inherited but has developed in the animal's life as it interacts with its environment. Acquired immunity can develop naturally in which case it is called NATURAL ACQUIRED IMMUNITY OR ARTIFICALLY.
ACTIVE IMMUNITY is the form of acquired immunity in which the body produces its OWN antibodies against infections. While PASSIVE IMMUNITY is the form of acquired immunity in which an individual is PROTECTED AGAINST INFECTION BY RECEIVING ANTIBODIES.
NATURAL ACQUIRED IMMUNITY
when attacked by the same pathogens again, they don't became seriously ill. this is because memory cells are able to recognise the antigens and stimulate the immune system to produce antibodies against the pathogens. This is known as NATURAL ACTIVE ACQUIRED IMMUNITY. It develops when one recovers from an infection.
During pregnancy, the mother passes antibodies across the placenta to the foetus. At birth the baby gets antibodies from the mother through breast milk. This is natural passive acquired immunity.
Near the surface or the shallow water. Hope I helped
