A molted external skeleton.
<span>The gene sequence containing an operator, promoter and repressor is known as an operon. These genes are called as structural genes. the operon is regulated by the presence/absence of the inducer such as glucose/lactose. It may also be a constitutive operon, which works all the time.</span>
<span>The lymph is moved through the lymphatic vessels by contractions of the lymphatic vessels and the surrounding skeletal muscles.</span>