In the cell shown below, which lettered structure is responsible for the excretion of most cellular wastes?

B.

Explanation:

The lettered structure B, is a cell membrane.

The cell membrane, also known as plasma membrane is the outer thin enclosure that surrounds a cell. It serves a s physical barrier that separates the cell structures from the surrounding environment of the cell.

This cell membrane is permeable, and performs one of the important function of the cell which is the excretion of most of the wastes from the cell.

The cell member is the medium fro exchange of substances between the cell and the its environment.

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.