This set of Biology Quiz for Medical Entrance Exams focuses on “Biomolecules-3”.
1. Enzymes are biocatalysts i.e. they increase the rate of reaction of metabolic reactions.
a) True
b) False
View Answer
Explanation: Enzymes are biocatalysts i.e. they increase the rate of reaction of metabolic reactions. The reactant that takes part in metabolic reaction is called substrate. Rate of reaction = (dx/dt). Here, x = concentration of substrate and t refers to the time.
2. Which among the following is incorrect about enzymes?
a) Pepsin helps in breaking of proteins
b) Lipase breaks lipids
c) Amylase breaks vitamins
d) Enzymes have a three dimensional structure and this structure has active sites
View Answer
Explanation: Pepsin helps in breaking of proteins. Lipase breaks lipids. Amylase breaks starch into sugars. Enzymes have a three dimensional structure and this structure has active sites in them.
3. Which among the following is incorrect about amino acids?
a) Enzymes are named after compounds/ class on which they act and their names end with “-ase”
b) Oxidoreductase reduces few substrates whereas oxidizes few other substrates
c) Enzyme kinetics is governed by Michael-Menden equation
d) Enzymes take part in the reaction and increase the rate of reaction
View Answer
Explanation: Enzymes are named after compounds/ class on which they act and their names end with “-ase”. Oxidoreductase reduces few substrates whereas oxidizes few other substrates. Enzyme kinetics is governed by Michael-Menden equation. Enzymes don’t take part in the reaction but increase the rate of reaction.
4. Which among the following does not affect the activity of the enzyme after a particular point?
a) Temperature
b) PH
c) Concentration of substrates
d) Competitive inhibitor
View Answer
Explanation: Temperature, pH, competitive inhibitor, concentration of substrates and enzymes are the factors that affect the activity of enzyme. Rate of reaction increases with the concentration of enzyme and substrate but remains unaffected after a particular rate.
5. Transferase catalyzes oxidation and reduction between 2 substrates.
a) True
b) False
View Answer
Explanation: Oxidoreductase catalyses oxidation and reduction between 2 substrates. Transferase is an enzyme catalyses the transfer of specific functional groups from one molecule to another.
6. Enzymes that link covalent bond between substrates to form a large molecule are called _______
a) Isomerases
b) Lyases
c) Ligases
d) Transferases
View Answer
Explanation: Enzymes that link covalent bond between substrates to form a large molecule are called ligases. Lyases are enzymes that break covalent bonds of large molecules. Isomerases are the enzymes that isomerize a specified compound.
7. Which among the following nucleotide is not present in DNA?
a) Adenine
b) Thymine
c) Cytosine
d) Uracil
View Answer
Explanation: The four nucleotides that are present in DNA are Adenine, Thymine, Cytosine and Guanine. Uracil is absent in DNA but not present in RNA. Adenine binds with Thymine and Guanine binds with Cytosine in DNA.
8. Which among the following is incorrect about RNA?
a) RNA is always less stable than DNA because of the two –OH on 1’ and 2’ carbons of oxy ribose
b) RNA has uracil whereas DNA has thymine
c) RNA is single stranded whereas DNA is double-stranded
d) RNA on hydrolysis gives ribose sugar
View Answer
Explanation: RNA is always less stable than DNA because of the two –OH on 2’ and 3’ carbons of oxy ribose. RNA has uracil whereas DNA has thymine. RNA is single stranded whereas DNA is double-stranded. RNA on hydrolysis gives ribose sugar.
9. Which among the following is incorrect about RNA?
a) RNA is of 3 types i.e. r-RNA, m-RNA and t-RNA
b) m-RNA carries the code for protein synthesis in terms of three nucleotide bases called codons
c) Each codon will represent a unique amino acid and an amino acid is represented by a unique codon
d) r-RNA synthesis the proteins and t-RNA will recognize the codons
View Answer
Explanation: RNA is of 3 types i.e. r-RNA, m-RNA and t-RNA. m-RNA carries the code for protein synthesis in terms of three nucleotide bases called codons. Each codon will represent a unique amino acid and amino acids can be represented redundantly. r-RNA synthesis the proteins and t-RNA will recognize the codons.
10. Which among the following is incorrect about lipids?
a) These are heterogeneous organic compounds comprising of C, H and O
b) These are water insoluble and release more energy as compared to carbohydrates
c) These also act as water barrier and messenger and are constituents of plant
d) Phospholipids are an example of simple fatty acids
View Answer
Explanation: Lipids are heterogeneous organic compounds comprising of C, H and O. These are water insoluble and release more energy as compared to carbohydrates. These also act as water barrier and messenger and are constituents of plant. Phospholipids are an example of compound fatty acids.
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