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Chemistry 10th Class Chemistry

 10th Class Chemistry Chapter 13  Biochemistry Notes

 10th Class Chemistry Chapter 13  Biochemistry Notes

Question#1) Define Biochemistry and carbohydrates? How monosaccharides are prepared? Give characteristics of carbohydrates?

Biochemistry: The branch of chemistry that deals with the study of biomolecules and all types of chemical reactions that takes place in the body of living organisms.

CARBOHYDRATES:

Carbohydrates are macromolecules defined as polyhydroxy aldehydes or ketones or their derivatives.

General formula: general formula for carbohydrates is Cn(H2O)n. In the formula ‘n’ is a whole number from three to many.

 

Sources of Carbohydrates OR Preparation of monosaccharides : Carbohydrates are synthesized by plants through photosynthesis process from carbon dioxide and water in the presence of sunlight and green pigment chlorophyll.

The glucose is further polymerized to form starch and cellulose. Animals obtain carbohydrates from plants.

 

Classification of Carbohydrates: Carbohydrates are classified as:

  1. Monosaccharides
  2. Oligosaccharides
  3. Polysaccharides

Monosaccharides: Mono means one and saccharon means sugar.

Monosaccharides are the simplest sugars which cannot be hydrolyzed. They consist of 3 to 9 carbon atoms. Therefore, they are classified according to the number of carbon atoms in their molecules as trioses, tetroses, pentoses, hexoses, and so on. The important monosaccharides are hexoses like glucose and fructose, etc. Glucose is a pentahydroxy aldehyde while fructose is pentahydroxy ketone having the open chain structures as follows and general formula C6H12O6

 

Properties of Monosaccharides: (1) They are white crystalline solids.

  • They are soluble in water.
  • They have sweet taste.
  • They cannot be hydrolyzed. They are reducing in nature, therefore, these are called reducing sugars.

 

Oligosaccharides : Oligo means few and saccharon means sugar units. These Carbohydrates composed of few sugar units ranges from 2 to 9. These can be hydrolysed. Therefore, they are classified as disaccharides, trisaccharides, tetrasaccharides, etc., depending upon the number of units they produce on hydrolysis. The most important oligosaccharides are disaccharides like sucrose. On hydrolysis, sucrose produces one unit of glucose and one unit of fructose.

 

Polysaccharides: poly means many and saccharon means sugar unit.

Polysaccharides are macromolecular carbohydrates consisting of hundreds to thousands of monosaccharides. Examples of polysaccharides are starch and cellulose.

Properties : (1)They are amorphous solids.

  • They are tasteless.
  • They are insoluble in water.
  • They are non-reducing in nature.

 

Sources of Carbohydrates:

Carbohydrates range from simple to complex ones. They have varied sources and uses. Sources of simple sugars e.g. glucose, fructose and galactose are fruits, vegetables, honey and cereals.

Disaccharides are sucrose, lactose and maltose. Sucrose is found in sugar beet, sugar cane and fruits.

Lactose consisting of glucose and galactose is the main sugar in milk and dairy products.

Maltose, a disaccharide of two glucose molecules is found in cereals.

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

 

Uses of Carbohydrates:

Our body uses carbohydrates in the form of glucose. Glucose is the only form of carbohydrates that is used directly by muscles for energy. It is important to note that brain needs glucose as an energy source, because it cannot use fat for this purpose.

Besides, the energy providing materials, carbohydrates also provide the following usage to our body.

  1. They regulate the amount of sugar level in our body. Low sugar level in body results in hypoglycemia.
  2. They provide essential nutrients for bacteria in intestinal tract that helps in digestion.
  3. Dietary fibre helps to keep the bowel functioning properly.
  4. Fibre helps in lowering of cholesterol level and regulates blood pressure.
  5. Carbohydrates protect our muscles from cramping.

Carbohydrates as source of energy:

Carbohydrates provide 17 kilojoules of energy per gram. We take carbohydrates as food. Long chains of starch (carbohydrates) are broken down into simple sugars (glucose) by digestive enzymes. The glucose is absorbed directly by small intestine into the blood stream. Blood stream transports the glucose to its place of use, e.g., muscles.

 

 

For your information: The use of dextrose in drips:

Dextrose is crystallized glucose (natural sugar found in starchy foods). It provides simple carbohydrates to the body that can be easily broken down and processed. Dextrose solution is available in several concentrations. For example, five percent dextrose solution (D5W) consists of 5 grams of dextrose in each 100 mL of solution. It is used to provide fluid replacement and energy to the body. It contains approximately 170 calories of energy, but does not contain electrolytes. Therefore, electrolytes are added according to requirements in solution. Dextrose is given to patients directly into vein called intravenous (IV) therapy. It is commonly called drip system. It is the fastest way to deliver fluids, electrolytes and medications throughout the body. It prevents air entering into blood stream.

 

 

 

 

Fig. Showing carbohydrates as a source of energy.

 

 

 

Some monosaccharide molecules can rotate the plane of polarized light to right (clockwise). They are called dextro-rotatory or dextrose sugars. Glucose, manose, galactose are dextrose sugars.

 

 

 

Question#2) What are proteins? Explain the uses and sources of proteins? Explain that amino acids are the building blocks of proteins?

PROTEIN: Proteins are highly complicated nitrogenous compounds made up of amino acids.  They are polymers of amino acids.

Chemical composition: Proteins consist of carbon, hydrogen, oxygen, nitrogen and sulphur.

Peptide Linkage: Amino acids are linked with each other through peptide linkage .

Hydrolysis of Proteins: Protein has more than 10,000 amino acids. All proteins yield amino acids upon hydrolysis.

Amino acids: Amino acids are organic compounds consisting of both amino and carboxyl groups. They have the general formula.

 

Side chain ‘R’ is different for different amino acids. There are 20 amino acids. Ten out of twenty amino acids can be synthesized by human body. These amino acids are called non-essential amino acids. While the other ten which cannot be synthesized by our bodies are called essential amino acids. Essential amino acids are required by our bodies and must be supplied through diet.

 

Amino acids are Building Blocks of Proteins:

Two amino acids link through peptide linkage. Peptide linkage (bond) is formed by the elimination of water molecule between the amino group of one amino acid and carboxyl acid group of another, such as:

 

 

When thousands of amino acids polymerize they form protein.

 

 

Sources and Uses of Proteins:

Proteins make up more than 50% of the dry weight of animals. Each protein has its source and carries out a specific function. Sources and uses of protein are as follows:

  1. Sources of animal’s proteins are meat, mutton, chicken, fish, eggs. These are used as food by human beings as they are essential for the formation of protoplasm.
  2. Enzymes are proteins that are produced by the living cells. They catalyze the chemical reactions taking place in the bodies. They are highly specific and have extraordinary efficiency. Many enzymes are used as drugs. They control the bleeding and treat blood cancer.
  3. Hides are proteins. These are used to make leather by tanning. Leather is used to make shoes, jackets, sports items, etc.
  4. Proteins are found in bones. When bones are heated they give gelatin. Gelatin is used to make bakery items.
  5. Plants also synthesize proteins, such as pulses, beans, etc. These are used as food.

Question#3) Define lipids? What are the types, sources and uses of lipids?

 Answr:  Lipids:

Lipids are macromolecules made up of fatty acids. Lipids include oils and fats. Oils and fats are esters of long chain carboxylic (fatty) acids with glycerol. These esters are made of three fatty acids, therefore, they are called triglycerides. General formula of triglycerides is as under.

 

Formation of Triglyceride:

 

Fatty Acids:

Fatty acids are building blocks of lipids. They are long chain saturated or unsaturated carboxylic acids. Examples are:

 

C17H32COOH à Oleic acid.

 

Palmitic acid and stearic acids are saturated lipids while oleic acid is unsaturated lipid.

 

Sources and Uses of Lipids:

Fats and oils are high energy foods. They are source of vitamins A, D and E. They are used to build brain cells, nerve cells and cell membranes. They are insoluble in water but soluble in organic solvents. The fats stored in the body insulate it as they are poor conductor of heat and electricity.

Fats and oils are synthesized naturally by animals, plants and marine organisms.

  1. Animal fats are found in adipose tissue cells. Animals secrete milk from which butter and ghee is obtained. Butter and ghee are used for cooking and frying of food, for preparing bakery products and sweets.
  2. Animal fats are used in soap industry.
  3. Plants synthesize oils and store them in seeds, such as sunflower oil, coconut oil, groundnut oil and corn oil. These oils are used
    as vegetable oils or ghee for cooking and other purposes.
  4. Marine animals like salmon and whales are also source of oils. These oils are used as medicines, e.g. cod liver oil.

 

Science, Society and Technology;

Hydrogenation of vegetable oil:

Vegetable oils are triester of glycerol and fatty acids of unsaturated long chains. These oils are hydrogenated in the presence of nickel catalyst at 250 to 300 °C to form vegetable ghee.

 

 

 

 

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

This reaction is used to make margarine or vegetable ghee. Fatty acid component of vegetable oil contains carbon-careen double bonds. When hydrogen is added to these oils, they become saturated and harder.

 

Question#4) Define Nucleic acid? What are the types of nucleic acids?

Answer: Nucleic acids:

They are generally long chain molecules made up of nucleotides. Nucleic acids are essential components of every living cell. Nucleotide is the building blocks of nucleic acids.

Components of nucleotide: Each nucleotide consists of three components; nitrogenous base, a pentose sugar and a phosphate group.

Types of Nucleic acid:

There are two types of nucleic acids:

Deoxyribonucleic Acid (DNA):

DNA consists of deoxyribose sugar. Its structure was discovered by J. Watson and F. Crick in 1953. It is long double stranded molecule consisting of two chains. Each chain is made up of sugar, phosphate and a base. The sugar and phosphate groups make the backbone of the chains and two chains are linked through bases. The chains are wrapped around each other in a double helix form as shown in figure below.

DNA is the permanent storage place for genetic information in the nucleus of a cell. It carries and stores all genetic informations of the cell. It passes these informations as instructions from generation to generation how to synthesize particular proteins from amino acids. These instructions are ‘genetic code of life’. They determine whether an organism is a man or a tree or a donkey and whether a cell is a nerve cell or a muscle cell.

The sequence of nitrogenous bases in DNA determines the protein development in new cells. The function of the double helix formation of DNA is to ensure that no disorder takes place. DNA carries genes that controls the synthesis of RNA. Errors introduced into the genes synthesize faulty RNA. It synthesizes faulty proteins that do not function the way they are supposed to. This disorder causes genetic diseases.

Ribonucleic acid (RNA):

It consists of ribose sugar. It is a single stranded molecule. It is responsible for putting the genetic information to work in the cell to build proteins. Its role is like a messenger.

RNA is synthesized by DNA to transmit the genetic information. RNA receives, reads, decodes and uses the given information to synthesize new proteins. Thus RNA is responsible for directing the synthesis of new proteins.

 

 

 

Question#5) What are vitamins? Describe the sources , uses, and deficiency symptoms of water soluble and fat soluble vitamins?

Answer: Vitamins:

In 1912 Hopkins noticed that in addition to carbohydrates, proteins and fats there are other substances needed for normal growth. Although these substances were needed in small quantity, yet these substances were called Accessory Growth Factors. Later Funk proposed the name Vitamin for these substances. He discovered Vitamin B (Thiamin).

Types of Vitamins:

Vitamins are divided into two types:

(i) Fat Soluble Vitamins: The vitamins which dissolve in fats are called fat soluble vitamins. These are vitamin A, D, E and K. If these vitamins are taken in large quantity, they accumulate in the body and cause diseases. For example, accumulation of vitamin D in the body causes bone-pain and bone-like deposits in the kidney. However, their deficiency also causes diseases.

Vitamin A:

Sources of vitamin A: Dairy products, eggs, oils and fats, fish. It can also be obtained from the beta-carotene found in green vegetables, carrots and liver.

Uses of Vitamin A: Maintain the health of the epithelium and acts on the retina’s dark adaptation mechanism.

Disease due to deficiency of vitamin A: Deficiency of vitamin A causes Night blindness and eye inflammation. Night blindness (also called nyctalopia) is the inability to see well at night or in poor light. It is not a disease, but rather a symptom of an underlying disorder or problem, especially untreated nearsightedness.

 

Vitamin D:

Sources of Vitamin D: Fish liver, dairy products, oils and fats, Vitamin D is formed in the skin when it is exposed to sunlight.

Uses of vitamin D: vitamin D has a role in the absorption of calcium, which is essential for the maintenance of healthy bones.

Diseases due to deficiency of Vitamin D: Deficiency of vitamin causes Rickets and Dementia. Rickets is the softening of the bone while dementia is a decline in thinking, behavior, and memory that negatively affects daily life.

Vitamin E:

Sources: It is found in many foods including vegetable oils, fish, cereals, meat, poultry, eggs, milk, fruits and vegetables. It is also available as a supplement.

Uses of Vitamin E: Vitamin E an antioxidant and it slows down the aging process. It is helpful in skin treatment. If you want to be young,healthy,energetic and good skin texture with no wrinkles you must add vitamin E in your diet. Maintenance of cell membrane,normal function of muscular and vascular system are also due to vitamin E.

Diseases due to deficiency of vitamin E: Deficiency of vitamin E leads to skin problems and respiratory diseases.

Vitamin K:

  Sources: Green leafy vegetables, vegetable oils, meat, liver, milk, cabbage and onion.

  Uses: Its main function is to coagulate blood.

Deficiency: Failure in blood clotting.

 

 

(ii) Water Soluble Vitamins:

The vitamins that dissolve in water are called water soluble vitamins. These vitamins are B complex (this include 10 vitamins) and vitamin C (ascorbic acid). Water soluble vitamins are rapidly excreted from the body. Hence, these vitamins are not toxic even if taken in large quantity. However, their deficiency causes disease.

  • Vitamin B1 (Thiamine) :

Sources: sunflower seeds, Liver, kidney, cereal, peanuts, beans, eggs-yolk, legumes (pulses), fish, meat, milk, yeast, wheat germ, nuts and read meat.

Uses: It helps body cells to convert carbohydrates into energy (helps in carbohydrates metabolism). Vitamin B1 plays an important role in energy metabolism. It is essential for growth. Protect us from digestive disturbance. Healthy heart function. Healthy nerve cells. Protect us from herpes zoster. Helpful in healthy brain functioning. Useful in anemia.

Deficiency symptoms: Deficiency causes cardiac failure, Loss of weight, loss of appetite digestive disturbance, weakness, fatigue, irritability , nerve damage, constipation. Severe deficiency can lead to beri beri.

 

Vitamin B2 (Riboflavin) :

Sources: Milk, eggs, liver, fish, yeast, fruits, green leafy vegetables, wheat , pea, soybean.

Uses: Vitamin B2 is essential for intracellular metabolism and normal body growth, red cell production, prevents us from rheumatoid arthritis, migraine, skin disorders, Cataract prevention and it is a helper for other B- vitamins.

Deficiency symptoms: Dry & cracked skin, inflammation on mouth (stomatitis), inflamation of tongue (glossitis), anemia, eye diseases, slow wound healing ,poor general health, scales on nails, cracks at corners of mouth, sickle cell anemia.

Vitamin B3 (Niacin):

Sources: Red meat, chicken, liver, yeast, Milk,peanut, fish, eggs, Legumes,coffee etc.

Uses: Vitamin  B3 a metabolizer for amino acids and carbohydrates. It is required in the synthesis of fats. Essential for healthy skin. Helps in cell respiration and proper functioning of nervous system. Used to control cholestrol level and control diabetes. Mental alertness. Significant decrease in health diseases.

Deficiency diseases: A deficiency of vitamin B3 is rare, due to the widespread enrichment of flours with niacin. However, a deficiency can occur if a person consumes a diet too low in protein.  Mental disturbances, Diarrhea, Pellagra ,Skin lesions, Decreased appetite, vomiting and nausea.

 

Vitamin B5 ( Pantothenic Acid) : Pantos means easily available.

Sources: Yeast, chicken, fish, Kidneys, beef, liver ,Peanuts, mushrooms, soybean , eggs , sunflower seeds , lentils,cashews ,fresh vegetables,wheat, milk, etc. It is also synthesized by bacterial flora in the small intestine.

Uses: VITAMIN B5 is very important in metabolic system and stress resistance. It is also helpful in the synthesis of antibodies, fats, proteins and hemoglobin. Vitamin B 5 plays very important role in the secretion of hormones. It slows down aging process. Prevents from arthritis and helpful against wrinkles.
Vitamin B5 is also known as anti-stress vitamin because it relieves physical and emotional stress.

Deficiency symptoms of vitamin B5: Fatige, cardiovascular disorders, digestive disorders, low blood cholesterol level and general weakness.

 

 

 

Vitamin B6:

          Sources : Milk, liver, yeast, green leafy vegetables , cereals, kidney, fish, chicken, eggs, nuts, banana, wheat germs, etc.

 

Uses:Vitamin B6 is Protein , fatty acids and glucose metabolizer. It helps to synthesize RBC and antibodies. It helps in healthy brain functions. Also helps in gene expressions.

Deficiency: Due to deficiency of vitamin B6 following disorder occurs.

** Skin disorders, Anemia, Memory problems, low absorption of glucose, fats and proteins.

 

 

Vitamin B12:

Sources: Liver , fish , red Meat, Eggs, yeast , Kidney , Dairy products.

 

Uses: Helps in formation of RBC and genetic materials, maintains normal growth, prevents from anemia, allergies, asthma and skin disorders.

Deficiency problems: Deficiency leads to retarded growth, anemia, fatigue, memory loss, depression and confusion.

Vitamin C:

Sources: vegetables like cabbage and tomato. Citrus fruits like orange, lemon, guava, strawberry, grapes, pine apples are the main sources.

Uses: Helps in synthesis of collagen that is basic part of the connective tissues and form bones, healing of wounds, maintenance of teeth and gums, production of haemoglobin and so helps in absorption and transport of iron, prevents from scurvy.

Deficiency symptoms: Main symptoms are bleeding of the teeth, scurvy, anemia, painful joints, poor wound healing, softness of gums.

Importance of Vitamins

  1. Each vitamin plays an important role in the healthy development of our body.
  2. Natural vitamins are organic food substances found only in plants and animals. Our body is unable to synthesize vitamins.
    Because of this, they must be supplied either directly in the diet or by way of dietary supplements. They are absolutely necessary for our normal growth.
  3. Vitamins cannot be assimilated without ingesting food. This is why, it is suggested that vitamins must be taken with meal. They help to regulate our body’s metabolism.

 

Commercial uses of enzymes.

Enzymes are used on commercial scale for different purposes.

Common types of enzymes and their role in industry is described as:

  1. Enzymes present in the yeast are commercially used for the fermentation of molasses and starch to produce alcohol (Ethanol). These enzymes are diastase, invertase and zymase.
  2. Microbial enzymes are used in detergents (powder or liquid). Lipases decompose fats into more water soluble compounds. Amylase removes starch based stains. Cellulase degrades cellulose to glucose, a water soluble compound. Bacterial proteases break down protein stains on the clothes. Thus, enzymes containing detergents clean effectively and remove all
    stains and dirt.
  3. Enzymes are used for the purification of fruit juices. They are added to fruit that has been crushed like grapes. This increases the yield of the juice extracted by removing suspended particles. It also improves the colour derived from the fruit skins.
  4. Amylase enzymes are used in bread making because they can yield more starch of the flour. Even they are efficient enough to convert starch to sweet glucose syrup. This can be used as sweetner in the food as well as bread making.
  5. Lactase enzyme is used to increase sweetness in ice cream. As lactose in milk is broken down to galactose and glucose,
    which are sweeter than lactose.
  6. In the dairy industry, some enzymes are used for the production of cheeses, yogurt and other dairy products while others are used to improve texture or flavours of the product.

 

Short Questions

  1. How plants synthesize carbohydrates?

Answer: Carbohydrates are synthesized by plants through photosynthesis process from carbon dioxide and water in the presence of sunlight and green pigment chlorophyll.

The glucose is further polymerized to form starch and cellulose.

 

Sunlight
6H2O + 6CO2——————–> C6H12O6 + 6O2
Chlorophyll

 

 

 

  1. Give the characteristics of monosaccharides.

Answer: Properties of Monosaccharides: (1) They are white crystalline solids.

  • They are soluble in water.
  • They have sweet taste.
  • They cannot be hydrolyzed. They are reducing in nature, therefore, these are called reducing sugars.

 

 

  1. What is difference between glucose and fructose?

Answer: Glucose is a pentahydroxy aldehyde while fructose is a pentahydroxy ketone. Glucose has six headed cyclic structure while fructose has five headed cyclic structure.

 

  1. Give an example of a disaccharide. How is it hydrolyzed into monosaccharides?

Answer: Example of diasaccharide is sucrose. With the addition of a molecule of water, it is hydrolyzed to glucose and fructose.

C12H22O11 (Sucrose) + H2O C6H12O6 (Glucose) + C6H12O6 (Fructose)

 

  1. Give the characteristics of polysaccharides.

Answer: Properties : (1)They are amorphous solids.

  • They are tasteless.
  • They are insoluble in water.
  • They are non-reducing in nature.

 

  1. Where are the proteins found?

Answer: Proteins are present in all living organisms. They make up bulk of the non-bony structure of the animal bodies. They are major component of all cells and tissues of animals. About 50% of the dry weight of cell is made up of proteins. They are found in muscles, skin, hair, nails, wool, feathers, etc.

 

 

  1. Describe the uses of carbohydrates.

Answer: Uses of Carbohydrates:

Our body uses carbohydrates in the form of glucose. Glucose is the only form of carbohydrates that is used directly by muscles for energy. It is important to note that brain needs glucose as an energy source, because it cannot use fat for this purpose.

Besides, the energy providing materials, carbohydrates also provide the following usage to our body.

  1. They regulate the amount of sugar level in our body. Low sugar level in body results in hypoglycemia.
  2. They provide essential nutrients for bacteria in intestinal tract that helps in digestion.
  3. Dietary fibre helps to keep the bowel functioning properly.
  4. Fibre helps in lowering of cholesterol level and regulates blood pressure.
  5. Carbohydrates protect our muscles from cramping.

 

 

 

  1. Lactose is disaccharide; which monosaccharides are present in it?

Answer: Lactose consists of glucose and galactose.

 

  1. Why are the ten amino acids essential for us?

Answer: Ten out of 20 amino acids that can not be synthesized by our body are called essential amino acids. These amino acids must be supplied to the body through diets.

 

  1. How are proteins formed?

Answer: Amino acids are Building Blocks of Proteins:

Two amino acids link through peptide linkage. Peptide linkage (bond) is formed by the elimination of water molecule between the amino group of one amino acid and carboxyl acid group of another, such as:

 

 

When thousands of amino acids polymerize they form protein.

 

 

  1. How is gelatin obtained?

Answer: Proteins are found in bones. When bones are heated they give gelatin. Gelatin is used to make bakery items.

 

  1. Give the general formula of the lipids.

Answer: General formula of lipids is as follows:

 

 

  1. Name two fatty acids with their formulae.

Answer:

 

C17H32COOH                      Oleic acid

Palmitic acid and stearic acids are saturated lipids while oleic acid is unsaturated lipid.

  1. Give the types of vitamins.

Answer: Vitamins are divided into two types.

1) Fat soluble vitamins: The vitamins that easily dissolved in water are called water soluble vitamins. These include vitamin A, D, E and K.

  • Water soluble vitamins: Vitamins that easily dissolved in water are called water soluble vitamins. These include Vitamin B complex and vitamin C.

 

  1. What is the significance of vitamins?

Answer: Importance of Vitamins:

  1. Each vitamin plays an important role in the healthy development of our body.
  2. Natural vitamins are organic food substances found only in plants and animals. Our body is unable to synthesize vitamins.
    Because of this, they must be supplied either directly in the diet or by way of dietary supplements. They are absolutely necessary for our normal growth.
  3. Vitamins cannot be assimilated without ingesting food. This is why, it is suggested that vitamins must be taken with meal. They help to regulate our body’s metabolism

 

  1. Describe the sources and uses of vitamin A.

Answer: Sources of vitamin A: Dairy products, eggs, oils and fats, fish. It can also be obtained from the beta-carotene found in green vegetables, carrots and liver.

Uses of Vitamin A: Maintain the health of the epithelium and acts on the retina’s dark adaptation mechanism.

 

  1. Justify water soluble vitamins are not injurious to health.

Answer: Water soluble vitamins are rapidly excreted from the body. Hence, these vitamins are not toxic even if taken in large quantity.

 

  1. What do you mean by genetic code of life?

Answer: DNA is the permanent storage place for genetic information in the nucleus of a cell. It carries and stores all genetic informations of the cell. It passes these informations as instructions from generation to generation how to synthesize particular proteins from amino acids. These instructions are ‘genetic code of life’. They determine whether an organism is a man or a tree or a donkey and whether a cell is a nerve cell or a muscle cell.

 

 

  1. What is the function of DNA?

Answer: DNA is the permanent storage place for genetic information in the nucleus of a cell. DNA synthesize RNA, that helps in the formation of proteins. DNA controls all the characteristics of living organisms.

  1. How you justify RNA works like a messenger?

Answer: DNA pass genetic information to RNA. RNA carries this information to ribosome in cytoplasm to produce particular proteins. As RNA carries messages of DNA to ribosome , so work like a messenger.

 

Long Answer Questions:

  1. What are carbohydrates? How monosaccharides are prepared? Give their characteristics.

Answer: See answer of question number 1.

 

  1. Explain oligosaccharides.

Answer: Please see answer of question number 1.

 

  1. What are polysaccharides? Give their properties.

Answer: Please see answer of question number 1.

 

  1. Explain the sources and uses of proteins.

Answer: Please see answer of question number 2.

 

  1. Explain that amino acids are building blocks of proteins.

Answer: Please see answer of question number 2.

 

 

  1. Explain the sources and uses of lipids.

Answer: Please see answer of question number 3.

 

Question#7) Give the importance of vitamins.

Answer: Please see answer of question number 5.

 

Question#8) Describe the sources, uses and deficiency symptoms of water soluble vitamins.

Answer: Please see answer of question number 5.

 

SOLVED TEST YOURSELVES

 

Test Yourself 13.1.

  1. Define carbohydrates.

Answer: polyhydroxy aldehydes or polyhydroxy ketones or their derivatives are called carbohydrates.

 

  1. Give the characteristics of disaccharides.

Answer: Disaccharides consists of two sugar units. These are easily soluble in water.

 

  1. Give the balanced equation for the formation of glucose.

Answer:

 

 

  1. Draw the structure of glucose.

Answer:

 

 

5.Give the balanced equation for the hydrolysis of sucrose.

Answer: C12H22011 + H2O C6H12O6 + C6H12O6

 

 

Test Yourself 13.2

 

  1. Which elements are found in proteins?

Answer: Protein consists of carbon, hydrogen, Oxygen, nitrogen and sulphur.

 

 

  1. How are amino acids bonded with each other?

Answer: Amino acids are bonded with each other through peptide bond.

 

  1. Give the general formula of amino acid?

Answer:

 

 

4.What do you mean by non-essential amino acids?

Answer: Amino acids that are synthesized by our body are called non essential amino acids.

Test yourself 13.3

  1. What is difference between ghee and oil?

Answer:

        Ghee         Oil
1) Ghee are solids at room temperature.1) Oils are liquid at room temperature.
2) These are saturated lipids.2) These are unsaturated lipids.

 

  1. Give the characteristics of fats.

Answer: 1) Fats exists as solid at room temperature.

2) Fats are saturated lipids.

3) Fats are obtained from animals.

4) Fats are insoluble in water.

iii. Give the sources and uses of animal fats.

Answer: Animal fats are found in adipose tissue cells. Animals secrete milk from which butter and ghee is obtained. Butter and ghee are used for cooking and frying of food, for preparing bakery products and sweets. Animal fats are used in soap industry.

  1. Plants are source of oils, justify.

Answer: Plants synthesize oil and store them in seeds, such as sunflower oil, coconut oil, and corn oil. These oils are used as vegetables oils or ghee for cooking and other purposes.

 

Test yourself 13.4

  1. What are the disadvantages of fats soluble vitamins?

Answer: Fat soluble vitamins cannot be easily excreted from the body. So they accumulate in the body and cause various diseases. Example: accumulation of vitamin D causes bone pains.

 

  1. What are advantages of water soluble vitamins?

Answer: Water soluble can rapidly be excreted from the body and so if they are in excess amount can be rapidly excreted from the body and does not harm the body.

 

  1. Give examples of fats soluble vitamins.

Answer: Examples of fats soluble vitamins are vitamin A, D, E and K.

 

  1. What are the components of nucleotide?

Answer: A nucleotide consists of following three components.

  1. A Nitrogenous base (Adenine, Guanine, cytosine, Thymine or Uracil)
  2. A pentose sugar (Ribose or deoxyribose).
  3. A phosphate group.

          

  1. What is the function of DNA ?

Answer: ◎ DNA is the permanent storage place for genetic information.

◎ DNA controls the synthesis of RNA and in return play a role in synthesis of proteins.

  1. Why is RNA called a messenger?

Answer: The DNA pass genetic information to RNA. Which carries these information to ribosome to   synthesize various proteins. So RNA works like a messenger.

 

 

 

 

 

 

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