The most frequently used portal of entry for pathogens is the

Mucosal surfaces of respiratory and gastrointestinal tract

Explanation:

A portal of entry is an avenue through which pathogenic microbes can have access to its host tissue. Since the pathogens are from the external environment, the portal of entry must be a site connected to the external.

Surfaces of the mucous membranes like respiratory tract, gastrointestinal tract etc. links the external and internal environment, hence, they are the most employed portals of entry by pathogens.

Also, the respiratory and gastrointestinal tract are vulnerable portals of entry because particles comprising of microbes are constantly taken in via the nose and mouth respectively.

well we can't tell you because we cant see the time give a screen shot or something.

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.