Which of the following is the type of cell largely responsible for type i hypersensitivity responses?
erythrocyte
mast cell
t lymphocyte
antibody

Mast cell

Explanation:

Type 1 hypersensitivity can be defined as an reaction( allergic) which is generated through the re-exposure of the same or specific kind of antigen which is known as allergen.

Type 1 hypersensitivity is different from type II, III, IV hypersensitivity. The exposure to the antigen may be by inhalation, injection and  infection.

In this case, the antibody released is IgE. During the time of sensitization, the TgE antibody binds to FCER1 receptors on the surface of mast cell and basophills.

On later exposure to the same allergen anaphylatic degranulation takes place with release of histamines and other chemicals.

b. the carbon cycle ensures living things have a source of hydrogen

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.