do we need to know about gregor mendel in much detail
1820-1880 (exact dates not required)
studied patterns of inheritance in pea plants (flower colour, pea colour, pea shape etc)
developed his 2 laws (segregation and randon assortment)
that's about it.
The application of his laws must be known also. A great example of this being the 2015 Q7 (b) (iii) in the agricultural science paper.