Chapter 9 Biomolecules Solutions
Question - 11 : - Draw the structure of the amino acid, alanine.
Answer - 11 : -
Structure of alanine
Question - 12 : - What are gums made of? Is Fevicol different?
Answer - 12 : -
Gums are hetero-polysaccharides. They are made from two or more different types of monosaccharides. On the other hand, fevicol is polyvinyl alcohol (PVA) glue. It is not a polysaccharide.
Question - 13 : - Find out a qualitative test for proteins, fats and oils, amino acids and test any fruit juice, saliva, sweat and urine for them.
Answer - 13 : -
(a) Test for protein
Biuret’s test – If Biuret’s reagent is added to protein, then the colour of the reagent changes from light blue to purple.
(b) Test for fats and oils
Grease or solubility test
(c) Test for amino acid
Ninhydrin test – If Ninhydrin reagent is added to the solution, then the colourless solution changes to pink, blue, or purple, depending on the amino acid.
| Test | Name of item | Procedure | Result | Conclusion |
| Biuret’s test | Fruit juice | Juice + biuret’s reagent | Change of color from light blue to purple | Presence of protein |
| Saliva | Saliva + biuret’s reagent | Change of color from light blue to purple | Presence of protein |
| Sweat | Sweat + biuret’s reagent | Colour does not change | Absence of protein |
| Urine | Drops of urine + biuret’s reagent | Change of color from light blue to purple | Presence of protein |
| Grease test | Fruit juice | Few drops of juice on brown paper | Translucent spot not observed | Absence of oils and fats |
| Saliva | Few drops of saliva on brown paper | Translucent spot not observed | Absence of oils and fats |
| Solubility test | Sweat | Water added with sweat | Oil presence | Fats or oils can be present |
| Urine | Water added to a few drops of urine | Slight oily presence | Fats may or may not be present |
| Ninhydrin test | Fruit juice | Juice+ninhydrin reagent (boil for few minutes) | Change of color from no color to purple, pink or blue | Presence of amino acids |
| Saliva | saliva+ninhydrin reagent (boil for few minutes) | Change of color from no color to purple, pink or blue | Presence of amino acids |
| Sweat | sweat+ninhydrin reagent (boil for few minutes) | No color change | Absence of amino acids |
| Urine | urine+ninhydrin reagent (boil for few minutes) | Depending upon type of amino acid, colourless solution changes to purple, pink or blue color | Presence of amino acids |
Find out how much cellulose is made by all the plants in the biosphere and compare it with how much of paper is manufactured by man and hence what is the consumption of plant material by man annually. What a loss of vegetation!
Answer - 14 : -
Approximately, 100 billion tonnes of cellulose are made per year by all the plants in the biosphere and it takes 17 full grown trees to make one ton of paper. Trees are also used to fulfil the other requirements of man such as for timber, food, medicines, etc. Hence, it is difficult to calculate the annual consumption of plant material by man.
Question - 15 : - Describe the important properties of enzymes.
Answer - 15 : -
Properties of enzymes
(1) Enzymes are complex macromolecules with high molecular weight.
(2) They catalyze biochemical reactions in a cell. They help in the breakdown of large molecules into smaller molecules or bring together two smaller molecules to form a larger molecule.
(3) Enzymes do not start a reaction. However, they help in accelerating it.
(4) Enzymes affect the rate of biochemical reaction and not the direction.
(5) Most of the enzymes have high turnover number. Turnover number of an enzyme is the number of molecules of a substance that is acted upon by an enzyme per minute. High turnover number of enzymes increases the efficiency of reaction.
(6) Enzymes are specific in action.
(7) Enzymatic activity decreases with increase in temperature.
(8) They show maximum activity at an optimum pH of 6 – 8.
(9) The velocity of enzyme increases with increase in substrate concentration and then, ultimately reaches maximum velocity.