Question
Biology Question on Transport of water and minerals in plants
The major constituent of phloem sap is
A
Fructose
B
Starch
C
Galactose
D
Sucrose
Answer
Sucrose
Explanation
Solution
Chemicalanalysis of the sieve tube sap to study translocated photosynthates, have revealed the presence of the food substances like sugars (mostly sucrose; also sometimes glucose and fructose-but in traces only) among carbohydrates, and mostly amino acids as well as amines and some soluble proteins-among the nitrogenous materials. Sucrose is most suitable form of carbohydrate translocation as it is non-reducing and chemically stable