Positive selection of thymocytes is necessary to produce a T-cell repertoire capable of interacting with self-MHC molecules. Thus the correct option is A.
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What is the purpose of positive selection during T cell development?</h3>
To address the necessity that T cells be capable of binding MHC complexes, T cells undergo positive selection. In this process, cells in the thymus present short pieces of proteins known as peptides, on their own MHC class I and class II molecules, allowing immature T cells to bind.
Further the this positive selection process also measures if a T cell will become a CD8+ T cell or a CD4+ T cell. Specifically, if a TCR (T-cell receptor) complex binds strongly to MHC class II, the complex send intracellular signals to induce the expression of a protein called ThPOK. This protein reduces the expression of another key protein, called Runx3, responsible for driving CD8 expression.
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Answer: A.
Explanation:
Proteins are the things that determine what functions will play out. They are the reason we are able to digest foods, transfer oxygen throughout the body. Proteins MAKE these functions happen. Without proteins, we wouldn't be able to do anything
Answer:
C) carbon dioxide is incorporated into PGA.
Explanation:
Light reactions of photosynthesis include splitting of the water molecule in presence of sunlight and release of electrons and oxygen gas, generation of electrochemical gradient during electron transfer from PSII to NADP+ via PSI and synthesis of ATP and NADPH.
The ATP and NADPH are used in the light-independent phase of photosynthesis which includes the Calvin cycle.
The first stage of the Calvin cycle is carbon fixation during which carbon dioxide is fixed into 3-PGA (3-phosphoglyceraldehyde). Carbon fixation is followed by reduction and regeneration of RuBP.
Answer:
All of these choices are correct
Answer:
The correct answer is C.The pesticide is traveling through the food chain.
Explanation:
The pesticide is used to kill pests that harm our crops but these pesticides have harmful effects on animals live there. These pesticides get into herbivores body when they eat crops on which pesticides are used.
Then when these primary consumers are eaten by carnivores the pesticide gets transferred to them and like this, they travel in the food chain. So by this pesticide can be found in carnivores that live far from the land.
The level of pesticide gets increased in animals present at a higher level which is called biomagnification. So the right answer is C.