Question

Why there is a difference in test of sugar when we taste it with our nose closed???????

Answer 1

there is a difference because when we eat something because the nose first detects the smell and activates gustatory receptors in tongue. this helps in tasting the food completely. there is even a connection between the nasal cavity and buccal cavity.
Hope this will be helpful :)

Answer 2

actually we taste with the help of nose  and flavour=taste +smell

when ur nose blocked  u r not able to smell it and thus not give any flavour

eg: sometime you eat your medicine by closing your nose because your olfactory lobe is enclosed