In summer squash, white fruit color (w) is dominant over yellow fruit color (w) and disk-shaped fruit (d) is dominant over sphere-shaped fruit (d). if a squash plant pure breeding for white and pure breeding for disk-shaped fruit is crossed with a plant pure breeding for yellow, sphere-shaped fruit, what will the phenotypic and genotypic ratios be for: the f1 generation? the f2 generation?

P:    WWDD x wwdd
Formed gametes are WD and wd
F1 generation: WwDd all phenotypes are white and disc-shaped (dominant traits are expresed)
F2 generation: 9  :  3  :  3   :   1 are ratios of phenotypes (white and disc-shaped : white sphere-shaped : yellow disc-shaped : yellow sphere shaped).  

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.