winter 14 examination subject code: 0808 model answer...

MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION (Autonomous)

(ISO/IEC - 27001 - 2005 Certified)

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WINTER– 14 EXAMINATION

Subject Code: 0808 Model Answer Page No: 1/ 41

Important Instructions to examiners:

1) The answers should be examined by key words and not as word-to-word as given in the

model answer scheme.

2) The model answer and the answer written by candidate may vary but the examiner may try

to assess the understanding level of the candidate.

3) The language errors such as grammatical, spelling errors should not be given more

Importance (Not applicable for subject English and Communication Skills.

4) While assessing figures, examiner may give credit for principal components indicated in the

figure. The figures drawn by candidate and model answer may vary. The examiner may give

credit for any

equivalent figure drawn.

5) Credits may be given step wise for numerical problems. In some cases, the assumed constant

values may vary and there may be some difference in the candidate’s answers and model answer.

6) In case of some questions credit may be given by judgement on part of examiner of relevant

answer based on candidate’s understanding.

7) For programming language papers, credit may be given to any other program based on

equivalent concept.



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WINTER – 14 EXAMINATION


1. Attempt any five of the following

a) Define the following( 1 m each)

I) Ketosis: Presence of ketone bodies (acetone, aceto acetic acid and beta

hydroxybutyric acid) in urine is called as ketosis.

II) Glycosuria: Presence of sugar in urine is called as glycosuria.

III) Polyuria: It is a condition of excessive urination.

IV) Purpura: It’s a condition of less platelet count. Or There are red or purple

discolorations on the skin that do not blanch on applying pressure. They are

caused by bleeding underneath the skin usually secondary to vasculitis or dietary

deficiency of vitamin C

b) Explain the role of following members of cell( 1 m each)

i) Cell nucleus: It is involved in the synthesis of RNA and in the biogenesis of

ribosomes.

ii) Cell membrane:

It holds cell together.

It serves as selective barrier to the outside.

It secretes waste products.

It keeps out toxic materials.

iii) Mitochondria: Mitochondria are engaged in oxidative metabolism, and are

responsible for the transportation of chemical energy into biological energy, in

the form of ATP compounds. All enzymes involved in Kreb’s cycle are present

in mitochondria.

iv) Endoplasm reticulum:

Give mechanical support, by forming skeletal network.

Involves in the intracellular transport.

Involves in the cellular metabolism.

Carries protein synthesis, ATP synthesis, etc.

http://en.wikipedia.org/wiki/Skin

http://en.wikipedia.org/wiki/Blanch_(medical)

http://en.wikipedia.org/wiki/Bleeding

http://en.wikipedia.org/wiki/Vasculitis



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c) Rancidification of Fats and Oils. ( 2 marks, 1 mark for rancidity and 1 mark for

explaination.).

1. When fats and oils are exposed to light, air, heat, moisture for a longer time,

develops disagreeable and objectionable odour. Such oil or fat is said to be

rancid, and the phenomenon is called as rancidification.

2. The bad and objectionable odour is because of liberation of volatile fatty acids

like butyric acid, caproic acid, caprylic acid.

3. The rancid oils or fats shows acidic reaction due to decomposition of glyceride

resulting into more amount of free acid.

4. Rancid oil shows high acid values.

5. Rancidification can be prevented by antioxidants Vitamin E, BHT.

d) Give the structures of the following( 1 m each)

I)



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ii) D – fructose

iii) Menadione



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iv) Ascorbic acid

e) What are the reducing and non-reducing sugar? Give examples (Exp 3 M and Eg. 1M)

Sr no. Reducing sugars Non reducing sugars

1 Carbohydrates having free&

potential carbonyl function are

called reducing sugars

Carbohydrate without free & potential

carbonyl function are called non reducing

sugars

2 They give Fehlings Benedicts

And Tommers test positive

They give Fehlings Benedicts And

Tommers test negative

3 Osazone test is positive Osazone test is negative

4 Eg. Glucose, lactose, maltose,

fructose

Eg, Sucrose



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f) Define coenzymes. Give coenzymes of (Definition 1 M and 1 M each coenzyme)

Co enzyme : (Definition 1 marks and 3 marks for names of co enzyme)

Co enzymes are the organic molecules often derived from vitamin B complex group that

participate directly in enzymatic reaction. Many enzymes catalyze the reactions only in presence

of specific non protein organic molecules called the co enzyme.

Folic acid : Tetra hydrofolate (THF)

Pyridoxin : Pyridoxal phosphate (PP)

Cyancobalamine: Deoxyadenosyl cobalamine

g) Explain the structure of starch ( 2m for structure and 2 m for explanation)

Structure



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Explanation: Starch is homopolysaccharide of D-glucose, it is widely distributed throughout the

vegetable kingdom occurring in grains, fruits and tubers. On complete hydrolysis yields glucose.

The two major constituents of starch granule, amylose and amylopectin differ in molecular

structure. Amylose is linear or unbranched chain of d –glucose molecules, while amylopectin is

branched.in partial structure. The glucose units are joined by the alpha 1- 4 linkages. Only the

alpha 1- 4 linkages are present in amylose whereas in addition to the alpha 1- 4 linkages, the

alpha 1- 6 linkages are also seen in amylopectin. (Partial structure can also considered for few

marks). Amyloses are water soluble and amylopectin are water insoluble.

2. Attempt any three of the following:

a) Lipids: Definition (1 mark, Classification 3 marks)

The lipids are a large and diverse group of naturally occurring organic compounds that are

related by their solubility in nonpolar organic solvents (e.g. ether, chloroform, acetone &

benzene) and general insolubility in water. They are esters of fatty acids.

Classification:

• Simple

• Compound

• Derived

• Miscellaneous

Neutral

Simple lipids:

Esters of fatty acids with alcohol.

• Fats & oils : Castor oil

• Waxes : Bees wax

Compound Lipid

• Glycerophospholipids., Sphingophospholipids, Glycolipids:.

• Lipoprotiens: Contain protiens

• Sulpholipids

• Aminolipids



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• Lipoprotiens: Contain protiens

• Sulpholipids:

• Aminolipids:

Derived Lipids:

• Eg: Alcohols, Glycerol, Fatty acids etc

Miscellaneous Lipids:

• Eg : Carotenoids, Squalene.

Neutral Lipids:

• They are mono, di, triacyl glycerols, cholesterol, cholesteryl esters.

B) Denaturation of proteins (Defination 1 M, Agents 1 M and changes 2 M)

Denaturation of proteins involves the disruption and possible destruction of both the secondary

and tertiary structures. Since denaturation reactions are not strong enough to break the peptide

bonds, the primary structure remains the same after a denaturation process.

Agents causing denaturation

Physical agents: Temperature, Cooling

Chemical agents: Acetic acid, Sulfosalicyclic acid, X ray.

Changes after denaturation

Loss of biological activity

Change in surface tension

Changes in solubility

Destruction of secondary and tertiary structures

E.g . Boiled eggs become hard, skin formed on curdled milk



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c) Give the reactions of amino acids with their significance:

( 1 M reaction and 1 M significance of each)

i) ) Ninhydrin reaction:

In acidic condition amino acid reacts with ninhydrin to give blue to violet colour, at 60-70 0C.

(Reaction is optional )

Ninhydrin Amino acid

A deep blue or purple colour known as Ruhemann's purple is evolved. It’s an identification test

for amino acids

Ninhydrin is most commonly used to detect fingerprints.

ii) Reaction with Dansyl chloride: This reagent is used to determine the N- terminal amino acid

residue of polypeptides. The amino group of free amino acid reacts with dansyl chloride.

http://en.wikipedia.org/wiki/Fingerprint



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d) Explain Epimers and Anomers with suitable examples

( 1 m definition and examples of each)

Epimers: Epimer refers to one of a pair of stereoisomers. They are very closely related

structures. The two isomers differ in configuration at only one carbon other than

anomeric carbon

Anomers: It is one of two stereoisomers of a cyclic saccharide that differs only in its

configuration at the hemiacetal or hemiketal carbon, also called the anomeric carbon.

http://en.wikipedia.org/wiki/Stereoisomerism

http://en.wikipedia.org/wiki/Stereoisomer

http://en.wikipedia.org/wiki/Saccharide

http://en.wikipedia.org/wiki/Hemiacetal



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e) Give structure and two tests of cholesterol.( stru. 1 marks, any 2 tests 3marks)

1)Liebermann-Burchard test:

When chloroform solution of cholesterol is treated with acetic anhydride & concentrated

sulphuric acid, green colour is formed.

2)Salkowaski test:

When chloroform solution of cholesterol is treated with concentrated sulphuric acid, upper layer

gives red colour and H2$O4 layer gives green colour.

3) Formaldehyde-H2SO4 Test:

To a solution of cholesterol in chloroform in dry test tube if formaldehyde- sulphuric acid

solution is added, cherry colour develops.



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Q 3: Attempt any three of the following:

a. Explain secondary structure of protein.(2 M Structure and 2 M Explanation)

Secondary structure of protein: Secondary structure deals with the shape of peptide chain i.e.

linear, cyclic, branched or arranged in the form of helix.

In protein molecule polypeptide is present in different geometric arrangement called

folding. It is essential for the functional activity of the protein.

The folding of the chain is mainly due to the presence of hydrogen bond between amino groups

and carboxyl groups of the peptide bond, this is called as secondary structure of proteins.

Based on nature of hydrogen bonding there are two types:

(i) α- helix (α- helical)

(ii) β-pleated sheet

i) α- helix (α- helical)

The α helical is the most common spiral structure of protein. It has a rigid arrangement of

polypeptide chain. The α - helical structure depends on the intramolecular hydrogen bonding

between NH and C=0group of peptide bond, in the α - helix the polypeptide is folded in such a

way that the C=O of each amino acid residue is hydrogen bonded to the NH of 4th

amino acid

residue along the chain.



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(ii) β-pleated sheet: It is another form of secondary structure, this result from hydrogen bonding

between two peptide chains.

It may occur in two types

a) Parallel pleated sheet:

In this type of structure the polypeptide chain is side by side and in the same direction so that N-

terminal residues are on the same end. This pleated sheet confirmation is stabilized by hydrogen

bonding, here bonds are formed between NH group of a peptide in one chain and C=O group of

a neighboring chain.

b) anti- parallel pleated sheet-

In this type of structure the polypeptide chain lie in opposite direction so that N-terminal end of

one and C- terminal of the other, face each other. In this structure the polypeptide chains are held

together by hydrogen bonds, so as to give a sheet like structure and hence are called as β –

pleated sheet confirmation.



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b. What is an active site of an enzyme? Explain ‘lock and key model’ and ‘induced fit

model’(1 M Definition 1.5 M for each explanation)

Active site of an enzyme: It is a region or area of an enzyme on which the substrate binds.

Lock & Key model:

It is the first model proposed by” Emil Fisher” to explain enzyme action mechanism.

It is like a Lock & Key.

In this case the shape of active site of an enzyme and that of substrate is complementary to each

other.

The substrate molecule fits into the active site of enzyme just as key fits into a lock. Hence

called Lock & Key model.

The shape of active site is rigid and complementary to the shape of substrate complex.



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Induced fit model:

In this case the shape of active site of an enzyme is flexible so as to accommodate wide variety

of substrate molecules.

The shape of active site of enzyme is made complementary to the substrate molecule.

c. Explain biological importance and absorption of iron. (2 M for imp and 2 M for absorption)

Iron helps in,

1. Formation of RBC.

2. Oxygen transportation to the tissues.

3. Process of cellular respiration

4. Formation of myoglobin.

5. It is involved in DNA synthesis.

6. Acts as electron carrier.

Absorption of iron:

Iron is absorbed as Fe++ by active transport system in upper tract. The 25% iron is stored in

liver, spleen, bone marrow, bound with proteins. Under normal condition, very little dietary iron

is absorbed and the amount excreted by urine is minimal. Infants and children absorb a higher

percentage of iron from food than adults.

Red blood cells are destroyed which leads to release of about 20-25mg iron per day. This

released iron is reused for the formation of new blood cells.



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d. Explain the following reactions :( 1 M each)

(i) Biuret test : principle –this test is positive for all compounds containing more than one

peptide linkage. The peptide linkage of protein reacts with copper ions to form a complex of

violet colour.

Procedure : Biuret Test: General test for proteins: 3 ml of protein solution + 3 ml of 5% Sodium

hydroxide + 3 to 4 drops of 1% Copper sulphate Purple or pinkish purple colour is developed.

Proteins are present.

(i.e. presence of peptide bond)

(ii) Xanthoproteic test:

Principle: It is based on nitration of aromatic ring which shows color change

when treated with NAOH.

Procedure: test solution + conc. HNO3+ boil test tube add NAOH to make alkaline drop by

drop. Yellow color appear which changes to orange on addition of NAOH.

(iii) Seliwanoff’s test :

Principle : sugar solution reacts with HCL to form a derivative of Furfuraldehyde which gives a

red color when react with resorcinol. (This is present in Seliwanoff Reagent)

Procedure: Seliwanoff reagent + sugar solution, boil for 2 min. red color or ppt indicates

presence of fructose or sucrose.

(iv) Molish’s test

Step I : Formation of furfural compound

STEP II: Furfural compound reacts with alpha napthol present in molish reagent to give violet

ring at junction of two liquids and Conc H2SO4 acts as a dehydrating agent.

Molisch test: - Sugar solution + Molisch reagent + Conc H2SO4 from the side of test tube – gives

Violet ring at the junction of two liquids.(1 mark)

Either Principle or Procedure Can be considered



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e.) Enumerate the factors that affect the rate of enzyme catalyzed reaction. Describe the

effect of temperature and pH (2 m for enlist and 1 m for each factor)

Factors that affect the rate of enzyme catalyzed reaction.

• Hydrogen ion concentration

• Concentration of enzymes

• Concentration of substrate

• Temperature

• Time

• Products of reaction

• Effect of light & other physical factors

• Allosteric factors

• Effect of hormones & other biochemical agents

Effect of temperature:

• Optimum temperature is usually reached at around 37oC—45

oC for animal enzymes.

• Velocity of reaction is increased from 1.1 to 3 times for every 10o rise in temperature.

• Above the optimum temperature, rate decreases.

• The enzyme gets denatured at a rate faster than the increase in reaction.

• Most of the enzymes get denatured above 60oC.

• The time of exposure is also important factor. An enzyme may withstand higher

temperatures for short periods of time.

• Optimum temperature has meaning only if the time of reaction is also stipulated. Enzyme

activity is maximum at optimum temperature.



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Effect of pH:

• Enzyme reactions are influenced by varying H ion concentration.

• The optimum pH is that pH at which a certain enzyme causes a reaction to progress most

rapidly.

• On either side of the optimum, the rate of reaction is lower & at certain pH enzyme may

be inactivated or even destroyed.

• Buffers are used to keep enzyme at an optimum or at least a favorable H ion

concentration.

• Optimum pH is dependent on kind of buffer, particular substrate, source of enzyme.

• Eg.: optimum pH of sucrase is 6.2

pepsin is 1.5- 2.5



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Q 4: Attempt any three of the following:

a) Discuss the following reactions of protein catabolism:

i) Oxidative deamination: An amino acid is converted into the corresponding keto acid by

the removal of the amine functional group as ammonia and the amine functional group is

replaced by the ketone group. The ammonia eventually goes into the urea cycle. The main sites

for this reaction are liver and kidney. The reaction is catalysed by amino acid oxidase enzymes.

Reaction:

ii) Transamination In transamination, the NH2 group on one molecule is exchanged with

theC =O group on the other molecule. The amino acid becomes a keto acid, and the keto acid

becomes an aminoacid

In this example alpha keto glutaric acid becomes glutamic acid, amino acid becomes keto acid.

This reaction is reversible.



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b) Define and classify minerals. Give functions of minerals.

(Definition and classification 2 m and function 2 m)

MINERALS: these are inorganic homogeneous substances which must be supplied by the diet to

perform various physiological functions.

Major minerals : Calcium ,magnesium, sodium, potassium, phosphorus, sulphur, chlorine.

Trace minerals : Iron, Iodine, zinc, copper ,Manganese, cobalt, selenium.

Physiological functions :

Maintenance of osmotic pressure of cell

Oxygen transportation

Growth and maintenance of tissues and bones

Proper working of nervous system

Muscular contraction

Maintenance of electrolyte balance

Maintenance of acid- base balance

Activation of enzymes.

c) Define ‘physiological and pathological’ urine. Write various abnormal constituents of urine

with their related diseases.

Physiological urine: Urine that contains normal organic and inorganic substances is called as

physiological urine or normal urine.

Pathological urine: Urine that contains substances essential to the body or tissues (like sugar,

bile salts, albumin etc.), in addition to normal organic & inorganic substances, is called as

pathological or abnormal urine.



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Abnormal constituents Associated ailment

Sugar (glucose) Glycosuria- Diabetes mellitus

Ketone bodies Ketonuria- Diabetes mellitus, Pregnancy,

Carbohydrate starvation

Albumin Proteinuria- Pregnancy, severe exercise, high

protein meal, Nephritis

Bile pigments / salts Jaundice /Hepatitis

Blood Hematuria- Acute inflammation of urinary

organs, T.B., Cancer, Haemolytic jaundice etc.

Pus Pyuria- Inflammation of urinary bladder,

urethra, kidney

d) Explain (2 m each)

i) Microcytic anemia:

It is also called as iron deficiency anemia or hypo chromic anemia. In this deficiency

of iron is due to inadequate absorption of iron, excessive loss of iron, increased iron

requirement or insufficient intake of iron, hemoglobin content of red cell decreased.

The size of red cells is below average. Women are at higher risk, due to menstrual

blood loss and increased demand during pregnancy.

Symptoms :

retarded growth

Loss of appetite.

weakness



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ii) Diabetes mellitus: It is metabolic disorder in which body is unable to utilize glucose. It is

of two types

i) Insulin dependent DM

ii) Non-insulin dependent DM.

It is characterized by following symptoms

Hyperglycemia

Glycosuria

Polyuria

Polydipsia

Polyphagia

Ketosis

Marked loss of weight

Light color of urine.

Treatment: DM can be treated by antidiabetic drugs. Or by administering insulin SC.

II) Patient is advised to take high protein diet and low carbohydrate diet and exercise.

f) Protein deficiency diseases

Kwashiorkor

Marasmus

Nutritional edema



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Kwashiorkor

It is predominantly found in children between 1-5 yrs.

It is due to insufficient intake of proteins as the diet of a weaning child consists of carbohydrate

Symptoms:

Stunted growth, Edema on legs & hands, Diarrhea , Discoloration of hair skin, Anemia , Apathy,

Moon face, Decreased plasma albumin concentration

Treatment

Protein rich food

Marasmus

Occurs in children below 1 yr age.

Symptoms:

Growth retardation, Muscle wasting, Anaemia , Weakness, No edema ,No decreased

concentration of plasma albumin

Treatment:

Mother’s milk

Nutritional Edema:

Results from long continued deprivation of proteins & usually occurs in famine areas. This

Protein deficiency in adults is very rare.

Symptoms:

Weight loss, General lethargy, Frequent loose stools, Delay in wound healing, Edema

Treatment:

Food items like soyabean, milk, eggs.



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Q.5. Attempt any three of the following

a) Define the following (1 m each)

i )Anabolism:

It’s a biosynthetic phase, uses energy to construct components of cells such as proteins and

nucleic acids.

ii) Acetyl number

It is number of milligrams of KOH required to neutralize the acetic acid obtained by

saponification of 1gm of fat after it has been acetylated.

iii) Isoenzymes

The multiple forms of same enzyme that differ in amino acid sequence but catalyze the same

chemical reaction are called as isoenzymes. E.g. lactate dehydrogenase exist in the blood in five

different isoenzyme forms i.e. LDH1, LDH2, LDH3, LDH4, LDH5.

iv) Anuria

It is the pathological condition in which there is absence of urine production or a urinary output

of less than 100 mL per day.

b) Define enzyme. Give classification of enzyme: (Defn 1 mark, Classification 3 marks)

Highly specific proteinous substances that are synthesized in a living cell & catalyze or speed up

the thermodynamically possible reactions necessary for their existence.

Classification Of Enzymes: On the basis of site of action:

Exoenzymes / Extracellular enzymes:

• Secreted outside the cell

• Decompose complex organic matter like proteins ,fats, cellulose .E.g..: proteoses, lipases.

http://en.wikipedia.org/wiki/Protein

http://en.wikipedia.org/wiki/Nucleic_acid



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Subject Code: 0808 Model Answer Page No: 25/41

Endoenzymes / Intracellular enzymes:

• Present inside the cell

• E.g..: synthetases, phosphorylases

Constitutive Enzymes:

• Produced in absence of substrate. Eg.: Enzymes of glycolytic series.

Induced Enzymes:

• Produced in presence of substrate. Eg.: hepatic microsomal enzymes.

Zymogens / Proenzymes:

• Produced naturally in an inactive form which can be activated when required. Enzymes

like pepsin are created in the form of pepsinogen, an inactive zymogen. Pepsinogen is

activated when Chief cells release it into HCl which partially activates it.

OR

Classification of Enzymes on the basis of reactions they catalyze:

• Oxidoreductases :

They bring about biological oxidation & reduction between two substrates.

e.g ; Dehydrogenases, Oxidases, Hydroperoxidases, Oxygenases, Hydroxylases

• Transferases :

Catalyse transfer of some group or radical from one molecule to another.

http://en.wikipedia.org/wiki/Pepsin

http://en.wikipedia.org/wiki/Pepsinogen



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E.g.Transaminases, Transphosphorylases, Transglycosidases

• Hydrolases:

Bring about hydrolysis or condensation of substrate by addition or removal of water.

Eg. Esterases, Peptidases

Lysases:

• Catalyse removal of groups from larger substrates by mechanisms other than hydrolysis,

leaving double bonds.

e.g. Carboxylysases, Aldehydelysases

Isomerases:

Catalyze interconversion of isomers. eg. Dextrose isomerase

Ligases/ Synthatases:

• Catalyse the linking or synthesizing together of 2 compounds. Forming C-S bonds, C-N

bonds, C-C bonds. E.g: Lysases, Isomerases, Ligases / Synthatases .

c) Explain biochemical role of calcium & factors affecting rate of absorption of calcium in

body. (Role: 2 M, Factors 2 M)

Functions

It is required for formation and development of bones and teeth

It is required for blood coagulation process

It is required for regulation of muscle contraction

Deficiency of calcium causes tetany, rickets or osteoporosis



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Factors affecting calcium absorption: Any 4

1. Vitamin D - induces the synthesis of calbindin (carrier protein for Ca) in the intestinal

epithelial cells, thus increasing Ca absorption.

2. Parathyroid hormone - it increases Ca transport across the membrane of intestinal cells.

3 Acidity - Ca is more soluble and absorbed in acidic medium.

4. Lactose - it favors calcium absorption in infants.

5. Need for calcium efficiency of calcium absorption increases according to body demands.

During pregnancy, lactation and adolescence calcium absorption efficiency increases by

50%.

6. Phosphate when present in high amount it causes precipitation of calcium in the form of

calcium phosphate.

Ideal ratio of Ca: P is 1:2 to 2:1.

7. Laxatives decrease the transit time for passage of food through intestinal tract. Thus

reducing time for absorption.

8. Caffeine , drugs like anticoagulants, cortisone and thyroxine reduce calcium absorption.

d).What are phospholipids? Give biological importance& structure of any one phospholipid.

(Definition 1 M, Imp 2 M and Any one Structure 1 M)

Phospholipids are compound or complex lipids that are esters of fatty acid with alcohol &

contain additional group phosphoric acid

Glycerophospholipids: contain glycerol as alcohol.Eg. Lecithin, Cephalin.

Sphingophospholipids: contain sphingosine as alcohol.Eg. Sphingomyelin.

Biological importance: Any 4

Phospholipids form structural components of membrane& regulate membrane permeability.



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Phospholipids are responsible for maintaining conformation of electron transport chain

components & so cellular respiration

Phospholipids participate in absorption of fat from intestine & also transport of lipids

Phospholipids act as surfactants

They are involved in signal transmission across membranes.

Cephalins participate in blood clotting.

Any one of the following structure or any correct structure be considered



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e) Discuss in brief any two of the following:( 2 M for any TWO)

i) Egg white injury;

It’s a deficiency disease of biotin which is rare and generally observed when large quantities

of raw eggs are consumed. Egg white contains large amount of protein avidin which binds to

biotin very tightly and prevents its absorption in the intestine. The avidin in egg white may

be a defense mechanism inhibiting growth of bacteria. When eggs are cooked avidin gets

denatured along with other egg white proteins

ii) Scurvy is an avitaminosis resulting from lack of vitamin C, since without this vitamin, the

synthesised collagen is too unstable to perform its function.

• Scurvy leads to the formation of spots on the skin, spongy gums, and bleeding from

all mucous membranes.

• The spots are most abundant on the thighs and legs, and a person with the ailment

looks pale, feels depressed, and is partially immobilized.

• In advanced scurvy there are open, suppurating wounds and loss of teeth, sluggish

hormonal function of adrenal cortex, swollen joints, osteoporosis.

The human body can store only a certain amount of vitamin C and so the body soon depletes

it if fresh supplies are not consumed. It can be given orally.

iii)Pellagra

• Pellagra is a vitamin deficiency disease caused by dietary lack of niacin (B3) and

protein, especially proteins containing the essential amino acid tryptophan. Because

tryptophan can be converted into niacin, foods with tryptophan but without niacin,

such as milk, prevent pellagra.

http://en.wikipedia.org/wiki/Scurvy

http://en.wikipedia.org/wiki/Avitaminosis

http://en.wikipedia.org/wiki/Collagen

http://en.wikipedia.org/wiki/Mucous_membrane

http://en.wikipedia.org/wiki/Suppuration

http://en.wikipedia.org/wiki/Teeth

http://en.wikipedia.org/wiki/Vitamin

http://en.wikipedia.org/wiki/Deficiency_disease

http://en.wikipedia.org/wiki/Niacin

http://en.wikipedia.org/wiki/Protein

http://en.wikipedia.org/wiki/Essential_amino_acid

http://en.wikipedia.org/wiki/Tryptophan

http://en.wikipedia.org/wiki/Niacin

http://en.wikipedia.org/wiki/Milk



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The symptoms of pellagra include:

• High sensitivity to sunlight

• Dermatitis, alopecia, oedema

• Red skin lesions

• Mental confusion

• Diarrhea

• Eventually dementia

The main results of pellagra can easily be remembered as "the four D's": diarrhea, dermatitis,

dementia, and death.

Pellagra can be treated with niacin (usually as niacinamide). The frequency and amount of

niacinamide administered depends on the degree to which the condition has progressed.

http://en.wikipedia.org/wiki/Photodermatitis

http://en.wikipedia.org/wiki/Dermatitis

http://en.wikipedia.org/wiki/Alopecia

http://en.wikipedia.org/wiki/Oedema

http://en.wikipedia.org/wiki/Skin_lesion

http://en.wikipedia.org/wiki/Mental_confusion

http://en.wikipedia.org/wiki/Diarrhea

http://en.wikipedia.org/wiki/Dementia



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Q.6 Attempt any three of the following

(Detailed diagramatic representation can be considered for full marks)

a) Discuss the reactions involved in urea cycle.



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1) Molecule of ammonia, CO2 & phosphate are condensed to form ‘Carbamoyl phosphate’

in presence of enzyme ‘carbamoyl-phosphate synthetase.

2) Carbamoyl phosphate transferred to ornithine forms citrulline in presence of an enzyme

ornithine transcarbamoylase. This reaction takes place in mitochondria. The citruline formed

in this reaction enters in cytoplasm & the next reactions take place in cytoplasm

3) Citrulline condenses with Aspartate to form argininosuccinate. The reaction is catalysed

by an enzyme Arginosuccinate synthetase.

4) Argininosuccinate is now cleaved into ‘arginine’ & ‘fumarate’ by the enzyme

‘arginosuccinase’. Fumarate formed may be converted to oxaloacetate via the actions of

enzymes ‘fumerase’& malate dehydrogenase & then transmitted to regenerate aspartate.

5) Finally arginine is cleaved into ornithine & urea by the enzyme arginase. With this

reaction cycle is completed & ornithine molecule accepts molecule of carbamoyl phosphate

to repeat the cycle.

The overall equation of the urea cycle is:

NH3 + CO2 + aspartate + 3 ATP + 2 H2O → urea + fumarate + 2 ADP + 2 Pi + AMP +

PPi

https://en.wikipedia.org/wiki/Ammonia

https://en.wikipedia.org/wiki/Carbon_dioxide

https://en.wikipedia.org/wiki/Aspartate

https://en.wikipedia.org/wiki/Adenosine_triphosphate

https://en.wikipedia.org/wiki/Water

https://en.wikipedia.org/wiki/Urea

https://en.wikipedia.org/wiki/Fumarate

https://en.wikipedia.org/wiki/Adenosine_diphosphate

https://en.wikipedia.org/wiki/Phosphate

https://en.wikipedia.org/wiki/Adenosine_monophosphate

https://en.wikipedia.org/wiki/Pyrophosphate



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b ) Explain all steps involved in glycolysis



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Glycolysis: ( Detailed diagramatic representation can be considered for full marks)

It’s a main pathway for glucose oxidation

1. Phosphorylation of glucose to glucose 6 phospate in presece ofenzyme hexokinase &

ATP & Mg

2. Isomerisation of Glucose 6 phosphate to fructose 6 phosphate in presence of

phosphohexo isomerase

3. Phosphorylation of fructose 6 phosphate to fructose 1,6 diphosphate in presence of

phosphofructokinase,ATP & Mg

4. Cleavage of fructose 1,6 diphosphate to dihydroxy acetone phosphate & glyceraldehyde 3

phosphate in presence of aldolase. These 2 products are interconvertible in presence of

triose phosphate isomerase

5. Glyceraldehyde 3 phosphate further undergoes oxidation to 1,3 diphosphoglycerate in

presence of

glyceraldehyde 3 phosphate dehydrogenase & NAD+

6. Transformation of 1,3 diphosphoglycerate to 3- phosphoglycerate in presence of

phosphoglycerate kinase, Mg & ADP

7. 3- phosphoglycerate changes to 2-phosphoglycerate in presence of phosphoglycerate

mutase

8. Loss of water molecule from 2-phosphoglycerate results into formation of phosphoenol

pyruvic acid in presence of enolase

9. Loss of phosphate from phosphoenol pyruvic acid results into formation of Enol pyruvic

acid in presence of pyruvate kinase, Mg & ADP



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10. Enol pyruvic acid gets converted to keto form of pyruvic acid in presence of pyruvate

kinase

11. Keto pyruvic acid under aerobic conditions enter TCA cycle in mitochondria. Pyruvic

acid forms main end product of glycolysis in those tissues which are supplied with

sufficient Oxygen

12. But tissues where oxygen is not supplied ,lactic acid is formed as an end product of

glycolysis by reduction in presence of lactate dehydrogenase & NADH

Net reaction for glycolysis is:

Glucose + 2NAD+ + 2 ADP + 2 Pi → 2 Pyruvate + 2 ATP + 2 NADH + 2 H2O



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c) Give the reactions involved in Kreb’s cycle ( Detailed diagramatic representation can be

considered for full marks)



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Kreb’s cycle:

It’s a central pathway for release of energy from acetyl CoA whch is produced from

glycolysis, catabolism of fatty acids or amino acids

Steps:

1. Condensation of acetylCoA obtained from pyruvic acid with oxaloacetate to form

citric acid in presence of citrate synthatase

2. Conversion of citric acid to cis aconitate in presence of aconitase &fe2+

3. Cis aconitate accepts water to give isocitric acid in presence of aconitase & Fe2+

4. Isocitric acid undergoes oxidation in presence of isocitric dehydrogenase &

NAD+ to give Oxalosuccinic acid

5. Decarboxylation of oxalosucccinic acid to alpha ketoglutaric acid in presence of

isocitri dehydrogenase, Mg/ Mn

6. Oxidative decarboxylation of alpha ketoglutaric acid to succinyl CoA in presence

of alpha keto glutarate dehydrogenase, CoA-SH, NAD+, Mg

7. Succinyl Coa gets converted to succinic acid in presence of succinate thiokinase,

GDP, Mg

8. Succinic acid undergoes dehydrogenation in presence of succcinate

dehydrogenase, FAD+ to form fumaric acid

9. Fumaric acid takes up water molecule in presence of fumarase to form maleic

acid

10. Maleic acid undergoes oxidation in presence of malate dehydrogenase, NAD+ to

form oxaloacetic acid.

11. Cycle gets repeated again by entrance of another molecule of Acetyl CoA



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d) Define & classify amino acid with examples. Write structure of any one sulphur containing

amino acid

( definition 1mark,classification 2.5marks , any one structure 0.5 marks; classification

based on polarity or on nutritional requirement can also be considered))

Amino acids- these are a group of organic compounds containing two functional groups,

amino group and carboxyl group. Amino group is basic while the carboxyl group is

acidic in nature.

Classification of amino acids:

1) Neutral amino acid.

2) Acidic amino acid.

3) Basic amino acid.

1) Neutral:

(a) Aliphatic amino acids:

e .g. Glycine, Alanine

(b) Aromatic amino acids:

e. g. Phenyl alanine, tyrosine

(c) Heterocyclic amino acids/Imino acids

e. g. Proline, Hydroxy proline

(d) Sulphur containing amino acids:

e.g. Cysteine, Methionine.

(e) Amino acid containing hydroxyl group:

e.g. Serine, Threonine

2) Acidic amino acids:

e.g. Aspartic acid, Aspargine.

3) Basic amino acids:

e.g. Arginine, Lysine



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e) Explain Beta oxidation of fatty acids



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( Detailed diagramatic representation can be considered for full marks)

Beta oxidation is the main pathway used to liberate energy by oxidation of fatty acid

It takes place in the beta carbon of fatty acid with removal of 2 carbons at a time from

the carboxyl end of the molecule. The process repeats itself until the fatty acid with

even number of carbon is completely converted to acetate molecules. fatty acid

containing even & odd number of carbon atoms as well as unsaturated fatty acids are

oxidised by beta oxidation. It takes place in 5 steps in mitochondria of liver.

1. Activation of fatty acid.

Long chain fatty acid gets activated to fatty acyl CoA in presence of CoASH,

thiokinase &ATP

2. Fatty acylCoA undergoes dehydrogenation in presence of acyl CoA dehydrogenase

&FAD to give alpha,beta unsaturated fatty acyl CoA

3. Addition of water molecule across the double bond results into formation of Beta

hydroxy acyl CoA in presence of Enoyl CoA dehydratase

4. Hydroxyl group of Beta hydroxy acyl CoA gets oxidised to keto group forming

Beta keto acyl CoA in presence of Beta hydroxy acyl CoA dehydrogenase & NAD+

5. Thiolytic cleavage of acyl CoA takes place in presence of Beta keto acyl CoA

Thiolase & CoASH. Acyl CoA thus formed contains 2 Carbons less than original acyl

CoA which undergoes further oxidation by Beta-oxidation. Acetyl CoA is also formed

which enters TCA cycle.



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winter 14 examination subject code: 0808 model answer...

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