The responses observed in type IV hypersensitivities result from the action of T cells and phagocytes.
Hypersensitivity IV type, also called delayed-type hypersensitivity (DTH), involves T cell-antigen interactions that cause activation and secretion of cytokines. This type of hypersensitivity requires sensitized lymphocytes that respond 24–48 hours after exposure to soluble antigens. A type IV hypersensitivity reaction is a cell-mediated reaction that can occur in response to contact with certain allergens, resulting in what is called contact dermatitis, or in response to certain diagnostic procedures such as the tuberculin skin test. Certain allergens need to be avoided to treat this condition. Type IV hypersensitivity response is observed results from the action of T cells and macrophages while other types are mediated by antibodies. This reaction occurs at least 1–3 days after the initial exposure. Type IV hypersensitivity is the mechanism of many autoimmune disorders.
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Answer:
3. the absence of a cell wall in human cells
Explanation:
Animal cells do not have cell walls. Cell membranes separate the cytoplasm of the animal cells from the surroundings and maintain their interior. Plant cells have cellulosic cell walls. A cell wall surrounds the cell membrane of a plant cell. Cell walls serve to provide structural support and protect plant cells from pathogens. Cell walls also help keep excess water out of cells so they do not burst. Therefore, human cheek cells would not have cell walls while the onion cells would have cell walls made up of cellulose.
Answer:
A Scientific Hypothesis Must Be Testable
For a hypothesis to be testable means that it is possible to make observations that agree or disagree with it. If a hypothesis cannot be tested by making observations, it is not scientific.19-Feb-2021
Explanation:
Answer:
40%
Explanation:
Remember that guanine always pairs with cytosine, and thymine always pairs with adenine. That means that any time there is a guanine, there is always a cytosine.
If there are 10% guanines, then there are 10% cytosines. That means the total of guanines and cytosines is 20%.
The other 2 bases (thymine and adenine) have to make up the rest of the bases. That means they have to make up 100-20 = 80%.
Again, there will be equal amounts of thymine and adenine, so 80%/2 = 40%.
