We only know about extinct groups like dinosaurs, ammonites and trilobites through fossils. Some animals and plant are only known to us as fossils. By studying the fossil record we can tell how long life has existed on Earth, and how different plants and animals are related to each other.
An effective way to teach children the difference between acceptable and unacceptable behavior is redirection. Redirection focuses on the desired behavior by helping children forget about the undesired behavior. so the answer is A.
Answer:
The correct option is : <u>C. prevent the immune system from responding to self-antigens</u> and <u>D. prevent excessive response to foreign antigens </u>
Explanation:
<u>Immune tolerance</u>, also known as the immunotolerance, of the immune system, is a state of unresponsiveness to the cells or tissues that are capable of eliciting an immune response in an organism.
Tolerance is classified into <u>central and peripheral. </u>The central tolerance is induced in the thymus and bone marrow. Whereas, the peripheral tolerance is induced in the other tissues and the lymph nodes.
<u>Central tolerance of the immune system is responsible for discriminating the self cells from the non-self cells of the body and thus prevents the body from responding to self-antigens.</u>
<u>Peripheral tolerance of the immune system is responsible for preventing excessive response of the immune system to foreign antigens like allergens.</u>
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The answer is D, because eventually we will be run out of all of those things.