N order for the immune system to protect the body against attack by foreign organisms, it must be able to distinguish between the body's own <span>proteins </span><span>(autoantigens) and proteins from foreign cells (foreign </span><span>antigens </span>). When the immune system turns against autoantigens, thus attacking its own tissues, the resulting condition is an autoimmune disease.<span>
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An oxygen atom of a polar water molecule is negative.
Answer:
True
Explanation:
The Devonian Period comprises the years between 416 million and 354 million and is subdivided by periods: Lower (the oldest), Middle and Upper (the most recent).
During this period, the main transformations occurred in the flora, with the exponential growth of small terrestrial plants through the development of spores. With this process, plants will become more similar with modern plants. During this period the plants were able to fertilize themselves with the seeds and reach the height of trees. They formed the first forests to be recorded, with the appearance of licopodia, ferns and progimosperms.
The right answer to this question is option A. O2 in the atmosphere.
The main reason why it's a true that organisms would grow larger than we have today with more oxygen available is pretty simple to understand, their respiratory systems were smaller than we have today, and even though it was a small one, it was enough because of the higher presence and concentration of O2 in the atmosphere.
Some studies were held nowadays to check this possibility, to see if the O2 was the real main reason for this, and the animals used in it really grew bigger than usual, so by that, they confirmed their hypothesis by testing it.
