Question

Do they flower during the same
month year after year? Why do you think the availability of fruits like
mango apple. jackfruit, etc. is se asonal? Are there some plants that flowe
the year and some oth that show seasonal flowering?

Answer 1

On observing the trees, it has been found that trees belonging to a particular species flower in the same month year after year. If trees around you are of the same species, they will flower in the same month but if not, then they will flower in different months of the year as they depend on nature and changes in the environment. 
   
The availability of fruits like mango, apple, jack fruit, etc is seasonal because they flower based on temperatures, humidity and several other factors found in a particular season.

Every season has a considerable influence on the overall fruit quality. 

Yes, there are some plants that flower throughout the year and there are some plants that show seasonal flowering, too depending on the length of the days required for their growth and the conditions that spur their flowering