The level of protein X in these patients will be low due to degradation in the proteasome. Ubiquitnation process occur when ubiquitin is attached to a particular protein and the protein become deactivated. Ubiquitin is a small biochemical molecule which marks out proteins for destruction. Any protein that have ubiquitin attached to it will be transported to the proteasome for destruction by degradation.
The correct answer is (c) discover antigens in body fluids.
B lymphocytes act as antigen presenting cells that recognizes and displays the antigen to the white blood cells. These cells process the antigens that are present in body fluids. Professional antigen presenting cells includes B-lymphocytes, macrophages, dendritic cells, etc.
These animals were living in an environment with a warm climate that results in changing sea levels. These conditions create a lot of shallow inland seas allowing these animals to thrive. The Cretaceous period is the last period of the Mesozoic area where new groups of mammals, birds, and flowering plants appeared on Earth.