It is commonly believed that only roots develop below the ground. how would prove that potato tuber is a stem and not root?

Potatoes  are from the grounds but they are considered as modified stem because they are capable of photosynthesis as what other stem plants do and they also  develop as thickened portions of stolons. these stolons are stem tissue, as they arise from stem tissue and they contain the vascular architecture of stem tissue buds, which are a characteristic of stem tissue and not the roots. moreover, the roots are incapable of photosynthesis. therefore, potato tuber is indeed a stem and not a root.

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.

It is used to during sexual reproduction between humans