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Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

Which among the following is not the example of carbohydrate ?

  1. Glucose

  2. fractose

  3. Maltose

  4. Nylon
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$\rightarrow$ Carbohydrates are important source of instant energy in our body system.
$\rightarrow$ Honey has been used as instant source of enrgy in ayurvedic medicines.
$\rightarrow$ Carbohydrates are used as storage starch in plants and glycogen
$\rightarrow$ carbohydrates are also used in textile industry.

So, the correct answer is NYLON (It is a synthetic polymer)

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

For 'invert sugar', the correct statement(s) is (are)
(Given : specific rotations of (+) -sucrose, (+) -maltose, L-(-)-glucose and L-(+)-fructose in aqueous solution are $+66^0, +140^0, -52^0$ and $92^0$, respectively)

  1. 'invert sugar' is prepared by acid catalyzed hydrolysis of maltose

  2. 'invert sugar' is an eqimolar mixture of D-(+)-glucose and D-(-)-fructose
  3. specific rotation of 'invert sugar' is $-20^0$
  4. on reaction with $Br _2$ water, 'invert sugar' forms saccharic acid as one of the products
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Invert sugar is a sucrose, partially or totally cleaved into fructose and glucose. Sucrose is converted into  invert sugar by chemical reaction called hydrolysis by heating a mixture or solution of table sugar.

Also, breakdown of sucrose may happen in a reaction catalyzed by enzymes such as sucrose, invertase etc or by acid catalyzed hydrolysis of maltose.

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

In fructose and glucose the possible optical isomers are:

  1. 12, 12

  2. 8, 16

  3. 16, 8

  4. 4, 12
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Fructose contains three chiral carbon atom and glucose contain 4 chiral carbon atoms.
The Number of possible Optical isomers for Fructose are ${2}^{3} = 8$
The Number of possible Optical isomers for Glucose are ${2}^{4} = 16$
8, 16 is the Answer
Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

The $\alpha$- D glucose and $\beta$- D glucose differ from each other due to difference in carbon atom with respect to its

  1. Number of $OH$ groups

  2. Size of hemiacetal ring

  3. Conformation

  4. Configuration
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Alpha and beta D-glucose are anomers, which are a type of stereoisomer that differ specifically in the configuration at the anomeric carbon (C-1).

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

What is the nature of glucose-glucose linkage in starch that males its so susceptible to acid hydrolysis?

  1. Starch is hemiacetal

  2. Starch is acetal

  3. Starch is polymer

  4. Starch contain only few molecules of glucose
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Starch contains acetal linkages (glycosidic bonds) between glucose units. Acetals are acid-labile and readily hydrolyze by acid. Hemiacetals are more reactive but acetals are stable to base but hydrolyzed by acid, making starch susceptible to acid hydrolysis.

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

${ C } _{ 12 }{ H } _{ 22 }{ O } _{ 11 }\longrightarrow 12C+{ 11H } _{ 2 }{ O }$ in presence of concentrated ${ H } _{ 2 }{ SO } _{ 4 }$.

Which of the following is obtained in the above reaction?

  1. Animal charcoal

  2. Sugar charcoal

  3. Coke

  4. Wood charcoal
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The dehydration of sucrose (C12H22O11) by concentrated sulfuric acid leaves behind a porous black mass of carbon known as sugar charcoal.