Biotechnology is a growing field of applied biology. Many crops, such as corn, have been engineered to be resistant to herbicides. Therefore, farmers can spray these chemicals to kill weeds growing near the crops without worries of killing the crop itself.

How does this type of biotechnology work?

Corn crop is resistant to herbicides because they are genetically modified through genetic engineering. There are some bacteria which are resistant to herbicides i. e. no effect of chemicals on that bacteria. So the biotechnologist take a gene from this resistant bacteria and induced it in the corn plant which becomes the part of their genetic makeup. So when we apply herbicide, the gene produces some enzymes which cancel the adverse affect of herbicide and only weeds are affected.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.