Question

1, whuxh of the folowing carbohydrates contain ketohexoses?

a. Sucrose

b. Lactose

c. Cellulose

d. Starch

e. Fructose

2.Which of the following functional groups in a carbohydrates are able to be oxidized to carboxylic acids?

a. Kentones that are rearranged in solution

b. Ketones that are rearranged in solution

c. Alcohols

d. Aldehydes

3. Which of the follwoing crbohydrates were reducing sugars?(select all that apply)

a. Cellulose

b.STArch

c. Sucrose

c. lactose

e. Fructose

4. Why does lactose give a positive result in Benedicts's test while sucrose gives a negative result?

a.Lactose contains a free anomeric carbon which can be oxidized when the ring is opened; sucrose does not.

b. Sucrose has an α-1,2 glycosidic link between the two monosaccharides which allows the rings to break apart and oxidize; lactose does not.

c.Lactose has a β-1,4-glycosidic link between the two monosaccharides which allows the rings to break apart and oxidize; sucrose does not.

d. Sucrose contains a free anomeric carbon which can be oxidized when the ring is opened; lactose does not

5.

Which of the following carbohydrates shoudl be able to be broken down into smaller pieces in a hydrolysis reaction? ( Select all that apply).

a.Cellulose

b. Starch

c. Fructose

d.Sucrose

e. Lactose

Answer 1

1.Sucrose = glu + fruc

Lactose = glu + galac

cellulose = glu

starch = glu

Fructose= ketohexose

hence sucrose and fructose contains ketohexose.

2. Glucose (alde) and fructose (ketone) both able to oxidise into acid with mild ox.agent

therefore

b and d both are correct

3.

cellulose, starch, lactose and fructose are redu. sugars.

4.

Lactose has beta 1,4- link and one anomeric will be free therefore it is red. sugar

correct will be a

5.

starch (poly)

cellulose(polu)

lactose(di) and sucrose(disacch) break down into smaller pieces upon hydrolysis