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12th Grade > Biology

BIOMOLECULES MCQs

Total Questions : 58 | Page 2 of 6 pages
Question 11. Which model of enzyme action is represented in the given image?
Which Model Of Enzyme Action Is Represented In The Given Ima...
  1.    Lock and key 
  2.    Induced fit 
  3.    Michaelis-Menton 
  4.    None of the above
 Discuss Question
Answer: Option B. -> Induced fit 
:
B
In the image given here the substrates do not fit into the enzyme active site like a lock and key, instead the substrates induces a change in the enzyme active site on binding the enzyme, thereby enabling the interaction between the substrates and formation of products. Therefore the representation shown here is the induced fit model of enzyme action.
In the lock and key model the substrate structure has to be the right fit for the enzyme active site, like that of a key and its lock. Similar to how akeyhas to be the correct one for alock, no reaction takes place if an incorrect substrate tries to bind the enzyme.
Question 12. Protein in silk thread is ___.
  1.    Fibroin          
  2.    Keratin
  3.    Albumin  
  4.    Globulin
 Discuss Question
Answer: Option A. -> Fibroin          
:
A
Given here is the list of substances where the proteins mentioned here are found.
F
ibroin - Silk
Albumin- Egg, Blood plasma
Keratin- Hair, Skin
Globulin- Blood plasma
Question 13. The function of ligases is
  1.    Oxidation 
  2.    Reduction
  3.    Synthesis by condensation 
  4.    Group transfer reaction
 Discuss Question
Answer: Option C. -> Synthesis by condensation 
:
C
A ligaseis an enzyme that can catalyze the joining of two large molecules by forming a new chemical bond.
Oxidation and reduction are carried out by oxidoreductases and group transfer reactions are carried out by transferases.
Question 14. Which of the following statement(s) is false, regarding Proteins ?
I. A protein is a heteropolymer but not a homopolymer.
II. Collagen is the most abundant protein in the animal world.
III. RUBISCO is the most abundant protein in the biosphere.
IV The first amino acid in a polypeptide chain is C- terminal amino acid and the last is N- terminal amino acid.
  1.    I only
  2.    II only
  3.    ll & lll
  4.    IV
 Discuss Question
Answer: Option D. -> IV
:
D
Statement IV is incorrect because,proteinsare naturallysynthesizedstarting from theN-terminusand ending at theC-terminus. Therefore conventionally,the first amino acid in a polypeptide chain is N- terminal amino acid and the last is the C- terminal amino acid.
Question 15. Which one of the following is a structural protein?
  1.    Keratin
  2.    Hemoglobin      
  3.    Amino acid
  4.    Gelatin
 Discuss Question
Answer: Option A. -> Keratin
:
A
Keratin is a structural protein found in hair and nails etc.
Hemoglobin is a protein in blood, that carries oxygen from the lungs to the tissues. It is a functional protein.
Amino acid is the monomer unit of a protein and gelatin is a form of irreversibly hydrolyzed collagen.
Question 16. Substances, which obstruct enzyme activity are called ___.
 Discuss Question

:
Substances, which obstruct enzyme activity are called inhibitors.
Question 17. The deficiency of vitamin-C causes___.
  1.    Scurvy
  2.    Rickets
  3.    Pyrrohea
  4.    Pernicious Anaemia
 Discuss Question
Answer: Option A. -> Scurvy
:
A
The deficiency of vitamin-Ccausesscurvy”, characterized byweakness, tiredness, gum disease etc.
Ricketsis defective mineralization or calcification of bones in immature mammals due to deficiency of vitamin D.
Pyrrohea orPeriodontitis,is an advanced stage of gum disease in which the gums and bones that provide support to the teeth become inflamed.
PerniciousAnaemiaoccurs when your body can’t absorb enough vitamin B-12, which is needed to make healthy red blood cells.
Question 18. In an enzymatic reaction, when will the substrate concentration be equal to the Michaelis constant, Km?
  1.    When the velocity of the reaction is halved 
  2.    When the velocity of the reaction is doubled 
  3.    When the velocity of the reaction is half the maximum velocity
  4.    When the substrate concentration is doubled
 Discuss Question
Answer: Option C. -> When the velocity of the reaction is half the maximum velocity
:
C
In an enzymatic reaction, the rate of the reaction increases as we increase the substrate concentration, till a point where the reaction reaches the maximum velocity Vmax. Once this upper limit has been attained, further increase in substrate concentration will not increase the rate of the reaction, as all the substrate binding sites on the enzyme will be saturated. The substrate concentration at half the maximum velocity is defined as the Michaelis constant, Km.
In An Enzymatic Reaction, When Will The Substrate Concentrat...
Question 19. A compound of similar sugars, linked with glycosidic bonds, is __(i)__ and a compound of 2 or more different sugars, is __(ii)__.
  1.    (i) Heteropolymer (ii) Homopolymer
  2.    (i) Homopolymer  (ii) Heteropolymer
  3.    (i) Isopolymer (ii) Anisopolymer
  4.    (i) Anisopolymer (ii) Isopolymer
 Discuss Question
Answer: Option B. -> (i) Homopolymer  (ii) Heteropolymer
:
B
Polysaccharides can be homopolymers (contain only one sugar residue) like Cellulose (glucose in beta 1-4 linkages) or heteropolymers (contain more than one sugar residue) like Hemicellulose which contain xylose, mannose, galactose, rhamnose, and arabinose; which are different monomers of sugar.
Question 20. The difference between a ribonucleotide and a deoxyribonucleotide is_____.
  1.    Deoxyribonucleotide has an -- H instead of an --OH at C-2.
  2.    Deoxyribonucleotide has an α configuration; ribonucleotide has the β configuration; at C-1.
  3.    Ribonucleotide has an extra --OH at C-4.
  4.    Ribonucleotide has more structural flexibility than deoxyribonucleotide.
 Discuss Question
Answer: Option A. -> Deoxyribonucleotide has an -- H instead of an --OH at C-2.
:
A
A deoxyribonucleotide and a ribonucleotide are both formed by a sugar moiety, attached to a nitrogenous base and one or more phosphate groups. If the sugar present in the nucleotide is ribose sugar, it is a ribonucleotide. Whereas if the sugar present is derived from ribose by deoxygenation of the the -OH on the C-2, it is called a deoxyribose sugar and this moiety combines with the nitrogenous base and phosphate groups to form the deoxyribonucleotide.
The Difference Between A Ribonucleotide And A Deoxyribonucle...

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