A level sugars ppq

Lactose, galactose and monosaccharide X are all reducing sugars.
After the lactose has been broken down there is a higher concentration of
reducing sugar. Explain why

the mark scheme answer is Because there are 2 sugars produced but I don't understand why this would make the actual concentration higher? Surely there can't be more sugar produced 2 sugars just means more TYPES of reducing sugar???

Well, you see, Lactose is a disaccharide, meaning that Galactose and Glucose were joined by a condensation reaction to make it.

Monosccharide x is one molecule only, and Galactose is a type of monosaccharide. So if you break down Lactose, there would be two monosaccharides in the mixture, which would increase the concentration, because there was one before, and now there's two, replacing that one.

Hi sorry on two counts:-
1. That you are confused.com
2. That you are the devil.

Your answer is not incorrect, but I think we need to explain to OP that the MOLAR CONC e.g. in units M [or moles/L] will increase because each lactose molecules will give one molecule of glucose AND one molecule of galactose.

Actually the concentration by mass e.g. mg/L will increase by a miniscule amount ONLY cos each molecule of lactose breaking down will lead to uptake of one H and one OH [hydrolysis reaction].

I hope you get promoted from hell to heaven in due course!

PS: I think this Q is quite unfair and stupid - I bet it is an Edexcel one!

M