Because their bodies tell them that they need more oxygen and so breathe faster, and try and get the oxygen their body requires and depends on.
I believe that both flatworms and roundworms have a body type called Bilateral symmetry. Animals that are bilaterally symmetric have mirror symmetry in the sagittal plane, which divides the body vertically into left and right halves, with one of each sense organ and limb pair on either side.
RNA nucleotides form complimentary base pairs with DNA bases. Hydrogen and sugar-phosphate bonds form and the mRNA is synthesized.
Explanation:
The process of mRNA formed by DNA is called transcription. The genes coding for the protein is present on DNA as a nitrogenous base or nucleotides.
Transcription takes place inside the nucleus with the assistance of major enzyme RNA polymerase. In transcription 5'to3' single strand of RNA is synthesized which is complementary to the 3'to5' strand of DNA. The sequence of DNA has promoter sites which will be recognized and DNA will unzip to form transcription bubble. Several transcription factors and enzyme will be required to synthesize mRNA.
This mRNA after some modification would become primary transcript and pass on to the cytoplasm where protein synthesis will take place.
