This set of Life Sciences Multiple Choice Questions & Answers (MCQs) focuses on “Carbohydrate”.
1. Carbohydrates are also known as___________
a) Hydrates of carbon
Explanation: Basically, carbohydrates are polyhydroxy aldehyde or ketones, or compounds that can be break down to them. Mostly carbohydrates contain hydrogen and oxygen in the same ratio as in water, hence it is also called as hydrates of carbon.
2. Class of carbohydrate which cannot be hydrolyzed further, is known as?
Explanation: Monosaccharides are single polyhydroxy aldehyde or ketone unit with general formula CnH2nOn. These are simple sugars which cannot be hydrolyzed further in a simpler form.
3. Which class of carbohydrates is considered as non-sugar?
Explanation: When hundreds or thousands of monosaccharides condense together, it will form polysaccharides. These are not sweet in taste hence they are called non-sugars.
4. Sugars which differs from each other only around single carbon atom is called epimer.
Explanation: Mostly common sugars are similar, the basic difference among them is at a single carbon atom i.e. differing by stereochemistry, these types of sugars which differ from each other only at a single carbon atom are called epimers. For e.g. D-glucose and D-mannose differ only at second carbon position.
5. A molecule of amylopectin which contains 1500 glucose residues and is branched after every 30 residues. How many reducing ends are there?
Explanation: Correct answer is 1 as no matter how many residues are there but a molecule of amylopectin has only one reducing end.
6. What is the name of the drug which inhibits Na+/K+ pump across the cell membrane?
Explanation: Ouabain is a common glycoside which inhibits the action of enzymes that pump Na+/k+ ions across cell membranes. Glycosides are formed by condensation between monosaccharides.
7. Mark the INCORRECT statement about sugar alcohol?
a) Addition of -itol as a suffix
b) A linear molecule that cannot cyclize
c) Carbonyl groups reduced to a hydroxyl group
d) Terminal -OH group oxidizes
Explanation: Sugar alcohol or alditols are formed by reduction of the carbonyl group in aldoses and ketoses to a hydroxyl group. These are designated by the addition of -itol and are linear molecules. So, terminal -OH group oxidizes is incorrect.
8. Which of the following amino sugar are present in the bacterial cell wall?
a) N-acetylmuramic acid
b) Sialic acid
Explanation: N-acetylmuramic acid is a derivative of glucosamine in which lactic acid is linked to oxygen at C-3 of N-acetylglucosamine which is a part of many structural polymers.
9. Which of the following glycosidic linkage found in maltose?
a) Glucose (α-1 – 2β) Fructose
b) Glucose (α1 – 4) Glucose
c) Galactose (β1 – 4) Glucose
d) Glucose (β1 – 4) Glucose
Explanation: In maltose, α- anomeric form of C-1 on one sugar and hydroxyl oxygen atom on C-4 of other sugar are joined by glycosidic linkage. Such linkage is also called the α-1, 4-glycosidic bond.
10. Which of the following is also known as invert sugar?
Explanation: Sucrose is also known as invert sugar as during hydrolysis of sucrose with hot dilute acid it produces an equimolar combination of D-glucose and D-fructose. This phenomenon is also called inversion of sucrose or invertose.
11. Name the major storage form of carbohydrates in animals?
Explanation: Glycogen is a carbohydrate which found mostly in liver and muscle of animals and considered as major storage form. It is highly branched form of amylopectin where branching occurs after every 10 glucose residues.
Sanfoundry Global Education & Learning Series – Life Sciences.
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