14. which group experienced a significant decline in the biodiversity at the end of the mesozoic era? 15. during which period did archosaurs diverge (branch off) from a common vertebrate ancestor?

1. Marine life experienced the greatest decline in biodiversity.

2. The Triassic era was the time in which Archosaurs diverged from a vertebrate ancestor.

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.