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Test: Entrance exam for PG Biochemisty

Category: Biology

Description: Students who are preparing for the entrance examinations for various PG courses related to lifesciences will be benifited by this test.

Keywords: GATE, Lifesciences, Biology, CSIR, PG entrance

Relevant Website: http://www.purnasrinivas.weebly.com

Phosphofructokinase is allosterically inhibited by

ATP ADP Insulin Fructose-6-phosphate

The pH - value of a mixture of l00 ml of 0.1 N-acetic acid (of pKa = 4.7) and 100 ml of 0.1 N sodium acetate is

According to Handerson-Hasselbalch equation pH = pKa + log [Salt]/ [Acid] pH = 4.7 + log .1/.1 pH = 4.7 + 0 = 4.7 4.7 5.0 5.7 7.0

Saponification of a triglyceride forms

Soap is produced by the saponification (hydrolysis) of a triglyceride (fat or oil). In this process the triglyceride is reacted with a strong base such as sodium or potassium hydroxide to produce glycerol and fatty acid salts. The salt of the fatty acid is called soap. free fatty acid free glycerol solid fat phosphatidic acid

A molecule of DNA of 1000 base - pairs has guanine as 30% of its bases. The number of adenine bases in it is

Chargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. In this particular case guanine is 30% hence cytosine will be 30% making together 60%. The rest 40% is adenine (20%) and thymine (20%). 20% of 1000 = 200. 600 400 300 200

Coenzyme A is derived from

Coenzyme A is synthesized from Pantothenate (vitamin B5) and cysteine in a five-step process. vitamin A L-ascorbic acid pantothenic acid nicotinamide

In presence of a competitive inhibitor, the Michaelis constant (Km) of an enzyme is

During competitive inhibitor the inhibitor has no effect on Vmax but increases KM. reduced to half unaffected increased decreased slightly

The total number of carbon atoms in cholesterol is

Cholesterol has a molecular formula of C27H45OH. 25 27 28 30

Inactive precursors of enzymes are called

A zymogen (or proenzyme) is an inactive enzyme precursor. isoenzymes zymogens coenzymes ribozymes

The vitamin whose coenzyme form is required for carboxylation reactions is –

Thiamine derivate is a coenzyme for pyruvate dehydrogenase complex and is involved in the carboxylation reactions. L-ascorbic acid biotin nicotinamide thiamine

Alpha particles consist of

Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus, The alpha particle can be written as He2+. electrons electromagnetic rays hydrogen nuclei helium nuclei

The predominant form of Alanine at its isoelectric pH is

anionic form zwitterionic form cationic form denatured form

Which one of the following amino acids does not have an aromatic group?

Phenyl alanine Tyrosine Threonine Tryptophan

The absorbance of a solution exhibiting 50% transmittance is

0.17 0.30 0.50 1.70

Larger molecules are eluted out earlier than smaller molecules in

During gel filtration the support medium (gel) consists of porous beads whose pore size can be controlled. Macromolecules smaller than the pores get entrapped in the pores, while those bigger than the pores travel unhindered through the column and get eluted out first. adsorption chromatography reversed phase chromatography HPLC gel Filtration

Glycogen phosphorylase acts on glycogen to form directly -

Glycogen phosphorylase catalyses the rate-limiting step in the degradation of glycogen in animals by releasing glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond. free glucose glucose-6-phosphate glucose-1-phosphate maltose

The hormones serotonin and melatonin are synthesized from the amino acids -

Glutamic acid tyrosine Aspartic acid Tryptophan

Beta-oxidation of fatty acids yields all of the following except

Beta-oxidation of fatty acids is represented as fatty acid CoA + NAD+ + FAD ---> acetyl CoA + NADH + H+ + FADH2 Acetyl coenzyme A NADH Malonyl coenzyme A FADH2

Which hormone is synthesized from the amino acid - Glutamic acid?

T4 Seretonin T3 histamine

Which of the following is not used as a criterion for the identification of an osazone?

Osazones are crystals formed when the sugars react with a compound known as phenylhydrazine at boiling point. The study of crystals along with the time of formation helps us to distinguish between various sugars. time of formation crystalline shape colour melting point

Similarity between Methionine and Lysine is that both are

An essential amino acid or indispensable amino acid is an amino acid that cannot be synthesized de novo by humans and therefore must be supplied in the diet. The amino acids regarded as essential for humans are phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine, lysine, and histidine. aromatic amino acids basic amino acids essential amino acids sulphur containing amino acids