Biomolecules quiz

Glucose on prolonged heating with HI gives:

Which of the following is a non-reducing sugar?

Amylose is a:

Lactose on hydrolysis gives:

The bond that links amino acids in a protein is the:

Deficiency of vitamin C causes:

Which base is present in RNA but not in DNA?

Glucose is oxidised by bromine water to:

Which of the following is a fat-soluble vitamin?

The helical structure of a protein is stabilised mainly by:

Why is glucose called an aldohexose? Write its open-chain formula. (2 marks)

What is a zwitterion? Write the zwitterionic form of glycine. (2 marks)

Distinguish between fibrous and globular proteins with one example each. (2 marks)

What is denaturation of proteins? Give one example. (2 marks)

Name the products of hydrolysis of maltose and the linkage present. (2 marks)

Why must vitamin C be supplied regularly in the diet? (2 marks)

Name the sugar present in DNA and in RNA. How do they differ? (2 marks)

What are essential amino acids? Give two examples. (2 marks)

Why does glucose pentaacetate not react with hydroxylamine? (2 marks)

State two biological functions of nucleic acids. (2 marks)

Calculate the molar mass of the dipeptide glycylglycine formed from two glycine molecules (glycine = 75) and the percentage of nitrogen in it (N = 14). (3 marks)

Calculate the mass of glucose and fructose formed by complete hydrolysis of 34.2 g of sucrose (C12H22O11 = 342, C6H12O6 = 180). (3 marks)

A polysaccharide sample has a molar mass of 1,62,000 g/mol. Calculate the approximate number of glucose units in it if each unit contributes 162 g/mol (C6H10O5). (3 marks)

A double-stranded DNA segment has 2,000 nucleotides, of which 600 are guanine. Calculate the number of adenine, thymine and cytosine nucleotides. (3 marks)

A protein of molar mass 66,000 g/mol is made of amino acid residues with an average molar mass of 110 g/mol. Estimate the number of amino acid residues and the number of peptide bonds (assuming a single chain). (3 marks)

Read the passage and answer the questions. Sucrose, the common table sugar, rotates plane-polarised light to the right. When boiled with dilute acid or treated with the enzyme invertase, the solution rotates light to the left. (i) Why does the direction of rotation change? (ii) What is the product called? (iii) Write the equation for the hydrolysis. (5 marks)

Read the passage and answer the questions. When glucose is heated with nitric acid, it gives a dicarboxylic acid. With hydroxylamine it forms an oxime, and with HCN it forms a cyanohydrin. However, it does not give Schiff's test or form a hydrogensulphite addition product. (i) Name the dicarboxylic acid formed. (ii) What do the oxime and cyanohydrin reactions indicate? (iii) Why does glucose not give Schiff's test? (5 marks)

Read the passage and answer the questions. A student boiled an egg and noticed that the clear egg white turned opaque and solid. He also observed that milk turned sour and curdled when kept for a long time. (i) Name the process occurring in both. (ii) Which structures of proteins are affected? (iii) Name the acid responsible for curdling of milk. (5 marks)

Read the passage and answer the questions. A child living in a region with little sunlight developed soft, bent bones. Another person who ate polished rice only for months developed weakness and nerve problems. (i) Name the deficiency diseases and the vitamins. (ii) Why is sunlight important for one of them? (iii) Give one food source for each vitamin. (5 marks)

Read the passage and answer the questions. Starch is stored in plants and glycogen in animals. Cellulose forms plant cell walls. Cattle can digest cellulose, but humans cannot. (i) Name the monomer and linkage in cellulose. (ii) Why is glycogen called animal starch? (iii) Why can cattle digest cellulose? (5 marks)

Describe the structure of glucose. Draw its open-chain and cyclic structures, and explain the reactions that support each. (6 marks)

Describe the structures of sucrose, maltose and lactose with Haworth diagrams, and explain which are reducing sugars. (6 marks)

Explain the classification of amino acids and proteins. Draw the four levels of protein structure with labelled diagrams. (6 marks)

Describe the structure of DNA and RNA. Draw a labelled diagram of the DNA double helix and a nucleotide. (6 marks)

Classify vitamins as fat soluble and water soluble. Draw a chart listing each vitamin, its source and its deficiency disease. (6 marks)