Questions - Answers

4 Marks

1. Give the sources and deficiency diseases of vitamins.
     (a) A         (b) D        (c) E          (d) K
A:

 2. What are Vitamins? Give one source and deficiency disease of vitamin C.
A: Naturally occurring organic compounds, which are required in small amounts for the maintenance of normal health of organism.
Sources: Orange, amla
Deficiency diseases: Scurvy, Pyorrhea.

3. Explain 'Heredity' and 'Genetic Code'.
A: Heredity: Nucleic acids controls the heredity. The genetic information contains 23 pairs of chromosomes. Each chromosome contains thousands of DNA Units.
Genetic Code: The message carried by m-RNA is in coded language. Specification of amino acid by 3 base sequence is known as genetic code. eg: Leucine code is CUU.
 

4. What is DNA finger printing?
A: As the sequence of bases in DNA in a person is Unique, their finger prints also unique. It is used for the identification of racial groups, identification of criminals & dead bodies and determination of paternity.
 

5. Write a brief note on the structure of glucose.
A: The molecular formula of glucose is C₆H₁₂O₆.
* The formation of n - Hexane with HI & Red P indicates straight chain for glucose.
OHC − (CHOH)₄ − CH₂OH    CH₃ − CH₂ − CH₂ − CH₂ − CH₂ − CH₃
* The formation of oxime with NH₂OH & the formation of cyanohydrin with
    HCN indicates presence of  

* The formation of gluconic acid with Br₂ water indicates presence of − CHO group.

                 
* The formation of saccharic acid with HNO₃ indicates presence of one primary −OH group.

                    
* The formation of pentaacetate with acetic anhydride indicates presence of five -OH groups.

* From these facts, open chain structure of glucose is

2 Marks 
1. What are Anomers?
A: Anomers are the stereoisomers which differ in their configuration at C₁.
e.g.: α − D − Glucopyranose & β − D − Glucopyranose.

2. What is "Zwitter ion"? Give an example.
A: A dipolar neutral ion formed when the carboxyl group loses a proton and this proton is gained by amino group in aqueous solution of amino acid is called "Zwitter ion".

      
                                           (Zwitter ion)

3. What is "Glycosidic Linkage"?
A: The linkage between two monosaccharide units through Oxygen atom is called "glycosidic linkage".
e.g.: In sucrose, glycosidic linkage is present between C − 1 of α − glucose and C − 2 of β − fructose.
 

4. What is "denaturation of protein"?
A: The lose of biological activity of a native protein due to physical or chemical change or change in pH or temperature is called "denaturation of protein".
Denaturation of protein is due to disturbed Hydrogen bonds and destroyed 2° and 3° structures of proteins.

e.g.: Coagulation of egg white on boiling.
 

5. Why cannot vitamin C be stored in our body?
A: As vitamin C is water soluble and readily excreted in urine and cannot be stored in our body. So it must be supplied regularly in diet.

6. What are nucleic acids? Mention their 2 important functions.
A: Nucleic acids are long chain biopolymers of nucleotides having polyphosphate ester chain.
Functions: * DNA is the chemical basis of heredity.
                   * Protein synthesis in the cell. 
 

7. What is the difference between a nucleoside and a nucleotide.
A: Nucleoside: A unit formed by the attachment of a base to 1' position of sugar is called nucleoside.
Nucleotide: A unit formed by the attachment of phosphoric acid at 5' position of sugar present in nucleoside is called nucleotide.
 

8. What are essential and non-essential amino acids? Give one example for each.
A: The amino acids, which cannot be synthesised in the body and obtained through diet, are called "essential amino acids".
e.g.: Leucine, Isoleucine.
The amino acids, which can be synthesised in the body are called "Non essential amino acids".
e.g.: Glycine, Alanine.
 

9. What are proteins? Give an example.
A: A polypeptide with more than 100 amino acid residues, having molecular mass higher than 10,000 U is called a protein.
e.g.: "Keratin" in hair.