KPK Board 12th class Chemistry Ch 21 Biochemistry questions answers

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Malakand Board 12th classes short questions Answer

Mardan Board 12th classes short questions Answer

Peshawar Board 12th classes short questions Answer

Swat Board 12th classes short questions Answer

Dera Ismail Khan Board 12th classes short questions Answer

Kohat Board 12th classes short questions Answer

Abbottabad  Board 12th classes short questions Answer

Bannu Board 12th classes short questions Answer

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Why vegetable oil is sensitive to rancidity?

When vegetable oil comes in contact with oxygen, it undergo partial hydrolysis or oxidation which develops sour test and unpleasant smell and the process is called rancidity. Naturally occurring fats and oil contain an active enzyme known as lipase due to which they are very sensitive to rancidity.

Give brief reason why melting point of saturated fatty acid is higher than unsaturated fatty acid.

The reason for this phenomenon can be found by a careful consideration molecular geometries. The tetrahedral bond angles on carbon results in a molecular geometry for saturated fatty acids that is relatively linear although with zigzags. This molecular structure allows many fatty acid molecules to be rather closely “stacked together. As a result, close intermolecular interactions result in relatively high melting points.

On the other hand, the introduction of one or more double bonds in the hydrocarbon chain in unsaturated fatty acids results in one or more “bends” in the molecule. The geometry of the double bond is almost always a cis configuration in natural fatty acids. These molecules do not “stack” very well. The intermolecular interactions are much weaker than saturated molecules. As a result, the melting points are much lower for unsaturated fatty acids.

Differentiation between Aldose and ketose

Aldose and ketose

Aldose Ketose
Polyhydroxy aldehydes are called aldose. Polyhydroxy ketones are called ketose.
In aldoses the carbonyl group is at position 1 In ketoses the carbonyl group is at position 2
Aldose gives Fehling solution test. Ketose donot give Fehling solution test.
Example: Glucose Example: Fractose

Differentiation between Homopoly-saccharides and heteropoly-saccharides

Homopoly saccharides  and Heteropoly saccharides

Homopoly saccharides Heteropoly saccharides
Polymers of carbohydrates of carbohydrate formed same sugar manomers Polymers formed by the combination of by combinin, carbohydrate with the carbohydrate.
In these carbohydrates same monosaccharides are present In these carbohydrate different units of monosaccharides combines.

Cellulose, Starch


Glycolipids, Glycoproteins

Differentiation between Sugar and non sugar-

Sugar and non sugar



Non Sugar


Sugar contains carbohydrates are soluble in water. Non sugar carbohydrates are in soluble in water they are amphorus solids.
They are crystalline solids. They are tasteless.
Sweet in taste.

Glucose, Sucrose, Fructose.


Starch, Cellulose.

Differentiation between Competitive and non-competitive inhibition.

Competitive and non-competitive inhibition.

Competitive Inhibition


Non-Competitive Inhibition


When inhibitor is in competition with substrate for active site is called competitive inhibition When inhibitor is not in competition with substrate for active site is called non-competitive inhibition.
In competitive in inhibition the inhibitor resemble with substrate. In non competitive inhibition  the substrate and inhibitor are different.
Bocking of active site of enzyme depends upon reactivity of substrate & inhibitor. No competition so inhibitor block the active site while substrate attach at another place.

Differentiation between DNA and RNA

Butterence between DNA RNA.

DNA is made of two strands of nucleotides. RNA is a single strand of nucleotides.
The bases of DNA are: Adenine, Thymine, Cytosine, and Guanine. The bases of RNA are: Adenine, Uracil. Cytosine, and Guanine
DNA does not have Uracil. RNA does not have Thymine.
In DNA. Adenine pairs with Thymine while Cytosine pairs with Guanine. In RNA, Adenine pairs with Uracil instead, while Cytosine pairs with Guanine.
DNA is found only in the nucleus. RNA can be found in the nucleus or cytoplasm of a cell.
DNA’s main function is to control cell activities, like telling each organelle what to make and what to do. RNA’s main function is to make proteins.

What is meant by the term fuel of life

Carbohydrates, proteins, lipids vitamins etc. are known to be the fuel of life specially the carbohydrates because they provides energy for the different functions of the body. That’s why they are known to be the fuel of life.

What happens when protein is denatured?

Most biological active substance loss their biological function when denatured. A common examples of denaturing of protein is comes from egg white.

What are chemical entities that compose the nucleic acid?

A nucleic acid consists of a polynucleotides which contains purines and pyrimidine as nitrogenous bases, along with nitrogenous bases, along with nitrogenous bases a sugar molecule (deoxyribose and ribose sugar) and a phosphoric acid constituents the chemical ententities of nucleic acid.

What is the importance of protein in our daily life?
  1. Protein take an essential part in the formation of protoplasm which is the essence of all forms of life.
  2. The nucleoprotein act as carrier of genetic formation or characters from one generation to other generations.
  3. Enzymes which are biological catalyst are protein in nature.
  4. Hormones are also protein in nature.
  5. Some proteins contributes in tissue structure formation.
Why zinc is important for human being?

Deficiency of zinc caused the delaying in wound healing and important of acuity taste.

State the medical problem that may relate to calcium and phosphorus.

Deficiency of Calcium: The deficiency of calcium is body results in hypocalcaemia.

Deficiency of Phosphorus: Its deficiency results in kidney dysfunction & Renal Rickets.

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