Answer:
Populations have variation in traits due to random mutation, crossing over and environmental conditions.
Antibodies to common microorganisms have been developed by infancy. <span>An </span>antibody<span> (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein produced mainly by plasma cells that is used by the immune system to identify and neutralize pathogens such as bacteria and viruses.</span>
Answer: True.
Spleen framework is created by reticular fibres from reticular cells.
Explanation:
Spleen is an organ found mostly in vertebrates. It develop from mesenchymal cells within the dorsal of mesogastrium near the greater curvature stomach. The mesencymal cells then divide and differentied to form framework of connective tissues of spleen. The framework of spleen is created by reticular fibres of the reticular cells. Reticular fibres are fibres in the connective tissue that is composed of type iii collagen secreted by reticular cells. Spleen function in filtering of blood. It plays a major role in red blood cells and immune system.
A cell can only respond to signals from other cells, not from the physical environment. receptor activation. The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on: the presence of the appropriate receptors on the cells of the target tissue or organ.
