Answer. Carbohydrates are defined as polyhydroxy aldehydes or ketone. They have general formula Cn (H2O)n. They are macromolecules.
Carbohydrates are synthesized by plants through 1 photosynthesis process from carbon dioxide and water in the presence of sunlight and green pigment chlorophyll.
sunlight
6CO2 + 6H2O C6H12O6+6O2
chlorophyll
Monosaccharide’s are the simplest sugars which cannot be hydrolyzed. They consist of 3 to 9 carbon atoms. Therefore, they are classified according to the number of carbon atoms in their molecules; as trioses, tetroses, pentoses, hexoses, and so on. The important monosaccharide’s are hexoses like glucose and fructose, etc. Glucose is a pentahydroxy aldehyde while fructose is pentahydroxy ketone having the open chain structures as follow
CHO CH2OH
H-C-OH C=O
HO-C H HO-C-H
H-C-OH H-C-OH
H-C-OH H-C-OH
CH2OH CH2OH
Glucose Fructose
Characteristics of monosaccharide’s
Monosaccharide’s are white crystalline solids. They are soluble in water and have sweet taste. They cannot be hydrolyzed. They are reducing in nature, therefore, these are called reducing sugars.