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
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
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
The total number of carbon atoms in cholesterol is
Cholesterol has a molecular formula of C27H45OH.
25
27
28
30
Which hormone is synthesized from the amino acid - Glutamic acid?
T4
Seretonin
T3
histamine
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
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
The predominant form of Alanine at its isoelectric pH is
anionic form
zwitterionic form
cationic form
denatured form
The absorbance of a solution exhibiting 50% transmittance is
0.17
0.30
0.50
1.70
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
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
Which one of the following amino acids does not have an aromatic group?
Phenyl alanine
Tyrosine
Threonine
Tryptophan
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
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
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
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
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
Inactive precursors of enzymes are called
A zymogen (or proenzyme) is an inactive enzyme precursor.
isoenzymes
zymogens
coenzymes
ribozymes
The hormones serotonin and melatonin are synthesized from the amino acids -
Glutamic acid
tyrosine
Aspartic acid
Tryptophan
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