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Biochemistry: Solved Exercise and Think-Tank

 Question 2: Give short answers.

I. Decide, whether sucrose is a disaccharide or monosaccharide. Give reason.

Answer.

Since, sucrose on hydrolysis gives two molecules of  monosaccharaides or simple sugars (glucose and fructose), so it a disaccharide. e.g.

Question: What is a dextrose sugar?

Answer.

The sugar  that rotates plan of plan polarized light in right direction (clockwise) is called dextrose sugar. It is also known as common name of  D-glucose . It is abundant in nature and mainly obtained from starch.

iii. Write the formula of an amino acid and identify the functional groups in it.

Answer. 

NH2-C(R)H-COOH 

Functional groups: i. Amino group (-NH2) ii. Carboxyl group (-COOH)

iv. What is peptide bond?

A chemical bond between amino group of one amino acid and carboxylic group of an other amino acid molecule is called peptide bond. 

OR 

A chemical bond which joins two amino acids molecules together is calleda peptide bond. 

For example, 

NH2C(R)H---CO----NH---C(R)H-COOH 

v. Which compounds are included lipids?

vi. What is the function of DNA?

Answer.

DNA replicates itself during cell growth. The main function of DNA  is to store genetic information and to transmit it from generation to generation. It synthesis RNA which reads, decodes and genetic information from DNA to synthesis new protein. 

Question: Distinguish between mono. di- and tri-saccharide. Give example.

Answer.

Monosaccharaides

Monosaccharide are simple sugars which can not be further hydrolyzed. 

These carbohydrates are water soluble.

They are reducing sugar.

They are sweet in taste.

Examples. Glucose, fructose etc.

Disaccharides

Disaccharides can be hydrolyzed to two monosaccharide units.

They are water soluble.

Some disaccharide are reducing sugars (i.e. lactose )and some are non reducing sugars (i.e. sucrose ) 

They are sweet in taste.

Examples.  Sucrose, lactose etc.

Polysaccharides

Polysaccharide can be hydrolyzed to many monosaccharaides units 

These carbohydrates are insoluble in water.

They are non-reducing sugars.

They are not sweet in taste.

Examples. cellulose, starch etc.

Question 4: Describe bonding in protein molecules.

Answer.

Sources of Proteins 

Most of proteins obtained from animal sources contain all the essential amino acids in adequate amounts. For example, meat, fish, eggs, milk and cheese are important sources of Proteins. 

Plants also provide us proteins. For example, pulses, beans,etc are rich sources of Proteins.

Uses

We require in our diet, to provide amino acids to make muscles, hair, enzymes and repair the body tissues.

Proteins are essential for the formation of protoplasm and components of cells.

Proteins are essential for physical and mental growth especially in children.

A proteins knows as gelatin is obtained by heating bones and tendons in water. It is used in bakery products.

Enzymes are proteins that catalyse specific biological reactions without which life be not possible.

Antibodies are also proteins that help us to fight against the diseases.

Question 5: Explain sources and uses of lipids.

Answer.

Sources 

Animals, 🐃 🦌, 🐐 plants 🪴, and marine 🐟 🐠 🐋 organism such as salmon and whale 🐋 are rich source of lipids. Cod liver oil is obtained from salmon and whale.

Milk is an importan source of animal fats from which butter, ghee, chees etc are obtained.

Seeds of many plants such as sunflower 🌻, corn 🌽, cotton, ground nuts, coconut 🥥, olive 🫒 are good source of vegetables oils.

   Usese

Butter ki and vegetable oils are used for cooking and flying a food prepareing Bakery products and sweets.

In mammals a layer of fat is present under the skin this layer as a thermal insulator.

Fats protect delicate organ from shocks earlier of ADS around our heart and kidney protectors are gone from injury.

Leopards provide some vitamin such as a d and e which are essential for health these vitamin are insoluble and water and soluble in lipids.

Fats and oils are important food store in living organism they provide about twice as much energy per gram as do carbohydrates.

Vegetable oils are converted into vegetable ghee by catalytic hydrogenation.

Fats and oils are also used for manufacture of materials like soaps and determines cosmetics colleges Paints and warishes.

Cholesterol is essential in our bodies for censes of several hormones Vitamin D and bye lesson

Question 6: Give sources and uses of proteins.

Question 7: Give sources and uses of carbohydrates. 

Answer.

Sources and Uses of Carbohydrates 

Carbohydrates are the most abundant class of carbon containing compounds. There are various sources and uses. 

Sources of monosaccharaides or simple sugars: 

 Glucose, fructose and galactose are found in fruits, vegetables, honey and cereals. 


Sources of Disaccharides 

Sucrose is found in sugar beet, sugar cane, and fruits. .Lactose is present in milk and dairy products. Maltose, is found in cereals. 

Sources of Polysaccharides 

Starch is found in cereal crops; wheat, barley, maize, rice, etc. Cotton is pure cellulose. 

Uses 

1.Carbohydrates in form of glucose transport energy both in plants and animal. In human body, 1 g of glucose produces 15.6 KJ/mole energy.

2. Carbohydrates are source of food for most of organism. 

3. Carbohydrates are structural material of plants 

4. Cellulose (fibers) is found bran, whole meal bread, vegetable and fruits etc, 

5. Cellulose absorbs toxic material in food that can harm the human body. 

6. It lowers the cholesterol level and control the blood pressure. 

7. Sucrose is used as table sugar. 

8. Glucose is stored in animal in muscles and liver in the form of glycogen which serves as source of energy for long time. 

9. Glucose is sstored in plant in the form of starch, 

10. Starch is used in preparation of rectified spirits. 

11.Sarch is used as adhesives.

Question 8: Differentiate between fats and oil 🛢.

Question 9: Define snd Explain vitamins.

Question 10: Why are vitamins important for us?

Question 11: Describe the importance of nucleic acids.

Question 12: Explain why agricultural and nutritional sources are vital?

Question 13: Explain the hydrogenation of vegetable oil. 

Answer.

Addition of hydrogen to an alkene is called hydrogenation. This reaction takes place in the presence of Ni, Pt or Pd catalyst. 

     CH2=CH2     +     H2  ---------Pt/Ni--------->  CH3-CH3

This reaction is used to make margarine and vegetable ghee. Fatty acid components of vegetable oil 🛢 contains carbon-carbon double bonds. When hydrogen is added to these oils, they became saturated and hard.


Question 14: List commercial uses of enzymes.

Answer. 

Enzymes are commercially important. They are used in:

i. Production of sweatners 

ii. Chocolate 🍫 syrup 

iii. Bakery  products 

iv. Infants 🚼  food 😋 

v. Detergents to remove stains 

vi. Making chees

vii. In papers and pulp industries to remove sticky materials 

viii. preparation of  fabric for clothes 

ix. Furniture and other house 🏠 items

Question 15: Explain the uses of dextrose in drips.

Answer.

5% m/v aqueous solution of  dextrose is used in drips. 5% m/v aqueous solution means 5g of dextrose is dissolved in water to form 100 cm3 of solution. It is intravenously injected to the patient who is severely dehydrated or unable to eat or is unable to eat.

Question 16: Separate water soluble vitamins from the following;

Vitamin A, Vitamins C,Vitamins B, Vitamins E.

Answer.

Vitamin  A, Vitamin C, Vitamin E

Think Tank 

Question 17: Compare components in both proteins and carbohydrates. 

Question 18: what is the name of the bond that forms between two amino acids in building a protein?

Answer.

Peptide bond.

Question 19: how many molecules of water are needed to allow a disaccharide to form monosaccharides.  Illustrate with chemical equation. 

Answer.

Only one molecule of water is required for complete hydrolysis of a disaccharide to form monosaccharides. For example, 

C12H22O11   +  H2O   ------------->   C6H1206        +     C6H1206 

sucre                                                    glucose                fructose 

f

Question 20: Draw the structure of each the following molecules. 

a. An amino acid having CH3 as R group 

b. A protein containing two amino acid 

Question 21: Distinguish between DNA and RNA.

Answer.

State the differences between chemical structure of DNA and RNA.

Main differences between structures of DNA and RNA are:
1.DNA is a double stranded while RNA is a single stranded.
2.DNA has deoxyribose sugar and phosphate backbone while RNA has ribose sugar and phosphate backbone.
3.DNA has four different bases: adenine, guanine, cytosine and thiamine while RNA has four different bases:adenine, guanine, cytosine and uracil.

4.DNA has unique helix geometry of beta form while RNA has unique helix geometry of alpha form.

 22: Hydrogenation is an importan reaction on food industry. Interpret statement.

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