Biology Exam Question Papers

Biochemistry Ph.D Entrance Exam Question Paper 2013 (Kerala University)


Biochemistry PhD Entrance Paper

KERALA UNIVERSITY Ph.D. ENTRANCE EXAMINATION – 2013
FACULTY OF SCIENCES

BIOCHEMISTRY

Time: 140 Minutes                                                  Maximum Marks: 160

Note: Answer any twelve questions from Section B and one question from Section C in the subject concerned. In Section B, each question carries 10 marks. Section C carries 40 marks. In Section B an answer should not exceed 100 words. In Section C, an answer should not exceed 500 words.

SECTION – B

(1). Explain the term Chromatography. How are proteins separated by :

a. Affinity Chromatography

b. Ion-exchange chromatography.

(2). Given a mixture of proteins which contains a recombinant insulin among other proteins which of the above two chromatographic technique will you employ for purification of the insulin molecule. Why?

(3). Explain Beer Lamberts’s law. Describe an experiment to verify this law. Given that the Molar extinction coefficient of a compound in water is 25,000 at 550 nm and a solution of this compound in water gave an absorbance of 0.552 at 550 nm calculate the concentration of the compound.

(4). Explain the importance of-SH functional groups in stabilizing structure of proteins.

(5). Explain the principle of density gradient centrifugation and describe how this technique can be used in purification of cell organelles.

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Biology Exam Question Papers

Biochemistry Ph.D Entrance Test 2015 Question Paper (Kerala University – Download PDF)


Biochemistry PhD Entrance Paper

KERALA UNIVERSITY Ph.D. ENTRANCE EXAMINATION
OCTOBER – 2015 
FACULTY OF APPLIED SCIENCES

BIOCHEMISTRY

Time: 140 Minutes                                                  Maximum Marks: 160

Note: Answer any twelve questions from Section B and one question from Section C in the subject concerned. In Section B, each question carries 10 marks. Section C carries 40 marks. In Section B an answer should not exceed 100 words. In Section C, an answer should not exceed 500 words.

SECTION – B

(1). Outline the principle behind the functioning of a Spectrophotometer.

(2). What is a zwitterion? Explain zwitterion with two examples.

(3). How is the functioning of an enzyme regulated? Explain with suitable examples.

(4). Elaborate the importance of isoelectric point in protein purification.

(5). What is sedimentation coefficient? Explain its importance in centrifugation.

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Biology Exam Question Papers

Kerala University Biochemistry Ph.D Entrance Examination 2009 Question Paper (Download PDF)


Biochemistry PhD Entrance Paper

KERALA UNIVERSITY Ph.D. ENTRANCE EXAMINATION
NOVEMBER 2009
FACULTY OF APPLIED SCIENCES

BIOCHEMISTRY

Time: 140 Minutes                                                  Maximum Marks: 160

Note: Answer any twelve questions from Section B and one question from Section C in the subject concerned. In Section B, each question carries 10 marks. Section C carries 40 marks. In Section B an answer should not exceed 100 words. In Section C, an answer should not exceed 500 words.

SECTION – B

(1). What are ribozymes? Explain their characteristic activities.

(2). What are Telomeres? What are their characteristics? How are they synthesized?

(3). Briefly describe how X-ray diffraction technique has been employed to elucidate the structure function relation of ribosomes.

(4). Dietary deficiency of vitamin B1 leads to the disease beriberi. This is characterized by increased levels of pyruvate and alpha ketoglutarate in the blood. How does vitamin B1 deficiency account for this?

(5). Explain why familial hypercholesterolemia results in elevated levels of blood cholesterol.

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biological chemistry

Titration Curve of a Weak Acid and its pKa (Biochemistry Notes)


Acetic Acid titration Curve

Titration Curve of a Weak Acid and its pKa
(Titration, Titration Curve, Titration Curve of Acetic Acid and its Significance)

What is Titration?

Titration is a method to determine the concentration of a dissolved substance (analyte or titrand) in a known volume by reacting it with another substance of known concentration and volume (titrant). The volume of the reactants plays a crucial role in the titration and thus the titration is better called as ‘volumetric analysis’.

There are different types of titrations in which the Acid-Base Titration is the most common one. The acid-base titration is used to determine the amount (concentration) of an acid in a given solution. In an acid-base titration, a known volume of acid (of unknown concentration) is titrated against a solution of strong base (usually NaOH) of known concentration in the presence of an indicator. After the titration, the concentration of the acid in the sample is calculated using the concept N1V1 = N2V2.

Where,

N1 – Normality of the unknown acid

N2 – Normality of the known base

V1 – Volume of unknown acid

V2 – Volume of the known base

What is Titration Curve?

The titration curve is a graphical representation of a titration in which the volume of titrant is plotted on X-axis (as the independent variable) and the pH of the solution is plotted on the Y-axis (as the dependent variable).

In simple terms, the titration curve is the plot of pH of the analyte (titrand) versus the volume of the titrant added as the titration progresses.

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biological chemistry

Proton Hopping in Water (Grotthuss Mechanism)


What is Proton Hopping

Proton Hopping in Water
(The Grotthuss Mechanism)

Proton Hopping is the process of diffusion of protons (H⁺ ions) through the network of hydrogen-bonded water molecules in the liquid water. Proton hopping is also called as Grotthuss mechanism, named after the discoverer Theodor Grotthuss. The net result of proton hopping is the fast movement of H⁺ ions in water than any other dissolved cations such as Na⁺ or K⁺. Let’s see how proton hopping occurs in water.

Water has a slight tendency of ionization. The H2O molecules can ionize into H⁺ and OH¯ ions as in the equation (1).

ions in water

The ionization reaction of water can be described by its equilibrium constant. The equilibrium constant (Keq) of the ionization of water at 25°C is calculated as 1.8 X 10¯16 M. The equilibrium constant and the concentration of H⁺ and OH¯ ions formed as a result of the ionization of H2O molecules are responsible for the pH of water.

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