Transgenic organisms can be scientifically or commercially useful only if

Transgenic organisms are those that have had their genomes altered by external means. These organisms are found in applications of genetic engineering, but they are only useful if the inserted gene is expressed in the organism.

An example of a transgenic organism may be a rat with the gene for hemoglobin from a rabbit. This rat is only useful if it indeed does produce rabbit hemoglobin in its blood due to the inserted gene.

Called for cell.

answer: - b cells

explanation: -

there are many types of white blood cells present in our body. one such class of white blood cells are the lymphocytes. the b cells belong to the lymphocyte class of wbcs. the b cells perform their action against the pathogen by producing specialised proteins called as antibodies. these antibodies are produced as and when the b cells encounter pathogens in response to the antigens present on the surface of the pathogen. these antibodies bind to the antigens present on the pathogen and then, target them for destruction by other cells of the immune system.

so, the b cells mediate their action by identifying the antigens present on the surface of the pathogens and then producing antibodies in return to mediate its effect.