<span>They do not possess any skeleton at al</span>
<u>Smoking</u> causes respiratory disorders such as bronchitis, pneumonia and lung cancer.
<u>Explanation:</u>
Respiratory disorders such as bronchitis, pneumonia and lung cancers are caused by smoking tobacco, air pollution and by infection. Smoking is the predominant cause of this respiratory order it also raises the level of air pollution which becomes hazardous to all the living organisms.
Infection in the lungs which is identified as pus in air sacs and found as inflamed lungs is usually life threatening. Severe shortness of breathe called the bronchitis is due to airborne chemicals.
EDTA inhibits the activity of DNase during DNA isolation process.
DNase is an enzyme which degrades DNA using divalent metal ions like Mg^{2+} . These metal ions act as cofactor for the proper functioning of DNase.
EDTA chelates the divalent metal ions and thus does not allow DNase to access them.
Therefore in this way DNA is prevented from degradation during its isolation.
