This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “Biochemistry Tricky Questions and Answers”.
1. Which of the following is a hypertonic solution?
b) Freshwater habitats
c) 0.45% sodium chloride
d) Red blood cells placed in fresh water
Explanation: The sea water or oceans are hypertonic to the extracellular fluid of many of the marine organisms. These marine organisms overcome the problem of hyper tonicity by expelling the salt water continuously.
2. If pH of solution of NaOH is 12.0 the pH of H2SO4 solution of same molarity will be ____________
Explanation: pH = 12 then pOH = 2
[OH–] = 10-2
Molarity of NaOH = 10-2
For H2SO4, molarity = 10-2
[H+] = 2 × 10-2
pH = 2 – log2 = 1.7.
3. 1M NaCl and 1M HCl are present in an aqueous solution. What is the solution?
a) Not a buffer solution with pH < 7
b) Not a buffer solution with pH > 7
c) A buffer solution with pH < 7
d) A buffer solution with pH > 7
Explanation: It is a neutral solution and its pH = 7.
4. What does it mean when we say that water acts as a “heat buffer”?
a) It keeps the temperature of an organism relatively constant as the temperature of the surroundings fluctuates
b) It increases the temperature of an organism as the temperature of the surroundings increases
c) It decreases the temperature of an organism as the temperature of the surroundings increases
d) It increases the temperature of an organism as the temperature of the surroundings decreases
Explanation: Water has a high specific heat capacity, it is hard to increase or decrease the water temperature which requires a lot of heat energy and therefore water acts as a heat buffer.
5. What trend does the reactivity of group II elements follow with water?
a) Increases down the group
b) Decreases down the group
c) Does not follow any particular trend
d) No reaction
Explanation: As we descend down the group, losing of electrons from the outer orbit of an atom becomes easy.
6. Which of the following is not the classified form of conjugated proteins?
d) Complete proteins
Explanation: On the basis of the chemical nature of their prosthetic groups conjugated proteins are classified into lipoproteins, glycoproteins and metalloproteins.
7. Tertiary conformation of proteins is maintained by 3 types of bonds namely ionic, hydrogen and ____________
Explanation: Ionic interactions, hydrogen and disulfide linkages stabilizes the tertiary structure of a protein.
8. Which of the following is true?
a) The disulfide bridges formed by reduction of the sulfhydryl groups on cysteine stabilizes protein tertiary structure
b) The disulfide bridges formed by oxidation of the sulfhydryl groups on cysteine destabilize protein tertiary structure
c) The disulfide bridges formed by oxidation of the sulfhydryl groups on cysteine stabilizes protein tertiary structure
d) The disulfide bridges formed by reduction of the sulfhydryl groups on cysteine destabilize protein tertiary structure
Explanation: The disulfide bridge formed by oxidation of the sulfhydryl groups on cysteine stabilizes protein tertiary structure, allowing different parts of the protein chain to be held together covalently.
9. In 3° structure of proteins, folding and shaping is done by ____________
a) Hydrophobic interactions
b) Polar interactions
c) Hydrogen bonding
d) None of the mentioned
Explanation: Globular proteins have a tertiary structure with hydrophobic amino acid residues and a surface region of hydrophilic residues; these hydrophobic interactions are responsible for the folding and shaping of 3° structure of proteins.
10. Which of the following does not affect the stability of an α-helix?
a) Electrostatic repulsion
c) Interaction between R groups spaced three residues apart
d) Occurrence of alanine and glycine residues
Explanation: The occurrence of Proline and Glycine residues affects the stability of an α-helix.
Sanfoundry Global Education & Learning Series – Biochemistry.
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