Tag: carbohydrates - definition and classification

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

Which of the following compounds will not undergo decomposition on passing electricity through aqueous solution?

  1. Sugar

  2. Sodium chloride

  3. Sodium bromide

  4. Sodium acetate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sodium chloride, sodium bromide, and sodium acetate are all ionic compounds and hence, they dissociate into their respective ions in an aqueous solution. On the contrary, sugar is a covalent compound and hence does not dissociate into ions

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

The two functional groups present in a typical carbohydrate are :

  1. $-CHO$ and $-COOH$
  2. $-CO$ and $-OH$
  3. $-OH$ and $-CHO$
  4. $-OH$ and $-COOH$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carbohydrates are polyhydroxy aldehydes or polyhydroxy ketones OR compounds which give aldehydic as well as ketonic groups on hydrolysis. Therefore the major functional groups are (carbonyl) Aldehyde, Ketone, and hydroxy groups. 

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

Out of $1$M glucose and $2$M glucose. 2M glucose has  a higher boiling point.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

2 M glucose has a higher boiling point than 1 M of glucose.

Since on increasing the no of moles the molality also increases which is directly proportional to an elevation in boiling point.
Thus, the boiling point of the 2M of glucose will be greater than 1M glucose.

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.