In which part of a flower is pollen produced

Pollen is produced in the stamen.

Stamen is the male reproductive part of a flower that produces pollen. The stamen is composed of a slender filament and a compact body called anther. The anther within the stamen is where pollen is produced. The anther is supported by the filament. Hundreds of stamens or only few stamens may be found in a flower.

b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.