Three reasons why dichotomous keys would be subject to changes over time

The dichotomous key refers to a tool that determines the unfamiliar organism by comparing its features with the arranged set of mutually exclusive features of distinct species. The dichotomous keys modify with time due to the following reasons:  

1. The keys are framed on the basis of the features of the previously known organisms. If one finds novel features in the newly invented organisms, the keys get modify.  

2. The organisms can modify their features because of evolution.  

3. The dichotomous keys are totally dependent upon history. The scientists may not witness the present evolutionary variations taking place. This signifies that this characteristic will be determined later in the coming time, therefore, the keys modify.  

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.