Carbohydrates - Classification, Mono, Di, Polysaccharides - UNSOLVED PRACTICE SET

Q7. Define carbohydrates. Classify them into monosaccharides, oligosaccharides, and polysaccharides with one example of each.

Q8. What is the difference between reducing and non-reducing sugars? Give one example of each.

Q9. Why is cellulose not digested by humans even though it is also made of glucose units? Explain the structural difference between starch and cellulose.

Q10. Your grandmother makes delicious laddoos using besan (gram flour) and sugar. Which type of carbohydrate is present in besan and which in sugar? Classify each.

Q11. What are polysaccharides? Name two homopolysaccharides and two heteropolysaccharides

Q.12. Why does a patient receive glucose solution intravenously in a hospital instead of sucrose solution? Explain based on the nature of these carbohydrates.

Q13. Describe the classification of carbohydrates with examples. Explain how monosaccharides, disaccharides, and polysaccharides differ in terms of:

(a) Number of sugar units

(b) Hydrolysis products

(c) Solubility in water

(d) Sweetness

Q14. (a) What are reducing sugars? Explain why glucose is a reducing sugar while sucrose is not.

(b) Describe the Molisch test for carbohydrates. What is the significance of this test?

(c) Why does sucrose not give a positive Fehling's test or Tollens' test?

Q15. (a) Compare the structures and functions of starch and glycogen. Why is starch called 'plant starch' and glycogen called 'animal starch'?

(b) A student eats a plate of rice (rich in starch) before a football match. Explain the journey of starch from digestion to energy release during the match, mentioning the enzymes involved at each stage.

Q16. A carbohydrate has the molecular formula C₁₂H₂₂O₁₁.

(a) To which class of carbohydrates does it belong? Give reason.

(b) On hydrolysis, it gives two different monosaccharides in equal amounts. Identify the possible disaccharide.

(c) Is this carbohydrate a reducing sugar or non-reducing sugar? How would you test this in the laboratory?

(d) Draw the Haworth projection of the two monosaccharide units formed on hydrolysis (name them only, no need to draw actual structures—just describe the components).

(e) Why does this disaccharide not have a free aldehyde or ketone group?

Q17. The following data was obtained for hydrolysis of a polysaccharide:

Initial mass of polysaccharide = 16.2 g

After complete hydrolysis, mass of glucose obtained = 18.0 g

Molecular mass of glucose unit = 180 g/mol

(a) Calculate the number of glucose units in the polysaccharide molecule.

(b) If this polysaccharide is starch, what type of glycosidic linkage connects the glucose units?

(c) During the hydrolysis, 1.8 g of water was consumed. Verify this using stoichiometry.

(d) If a person consumes 50 g of this polysaccharide, how many grams of glucose will be produced upon complete digestion?

Q18. In a school science project, students compare the carbohydrate content of different Indian foods:

Food A: White bread (contains starch)

Food B: Jaggery (contains sucrose)

Food C: Honey (contains fructose and glucose)

Food D: Apple (contains cellulose and fructose)

(a) Classify the carbohydrates present in each food as monosaccharide, disaccharide, or polysaccharide.

(b) Which food would give a positive Benedict's test? Explain why.

(c) Which food contains a carbohydrate that humans cannot digest? What is the role of this carbohydrate in the human body?

(d) A diabetic patient is advised to avoid Food B but can eat Food D in moderation. Explain the scientific reason behind this advice.

(e) During a marathon, athletes often consume glucose gels (Food C type) rather than starchy foods (Food A type). Why?