Biology · Chemistry

Carbohydrates and Biomolecules

1,073 Questions

Carbohydrates and biomolecules questions test your understanding of sugars, monosaccharides, and metabolic substrates. The topic covers food transportation in plants and the biochemical properties of sweeteners. Practicing these questions builds a strong foundation for exam preparation.

Disaccharides and monosaccharidesArtificial sweetenersGlycogen storagePlant food transportGlycoprotein hormones

Carbohydrates and Biomolecules Questions

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

Which of the following is not a sugar?

  1. Sucrose

  2. Glucose

  3. Fructose

  4. All are sugars
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sucrose, glucose and fructose all are sugars. Glucose and fructose are monosaccharides and sucrose is a disaccharide of the two combined with a bond. Glucose and fructose have the same molecular formula $(C _6H _{12}O _6)$ but glucose has a six member ring and fructose has a five member ring structure. Fructose is known as the fruit sugar as its source in the diet is fruits and vegetables. Honey is also a good source. Glucose is known as grape sugar, blood sugar or corn sugar as these are its richest sources. Sucrose is the sugar we know as sugar or table sugar. Typically extracted as cane or beet sugar. If sucrose is treated with acid or heat, it hydrolyses to form glucose and fructose. This mixture of sucrose, glucose and fructose is also called invert sugar.

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

The products formed when a pinch of sugar is strongly heated for fifteen minutes in a test tube are:

  1. carbon and water vapour

  2. carbon, hydrogen and oxygen

  3. carbon dioxide and water vapour

  4. carbon dioxide and hydrogen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Any carbohydrate will give water and $CO _2$ after combustion.

Example: Combustion of Glucose,
$C _6H _{12}O _6 + 6O _2 \xrightarrow{heat} 6CO _2 +6 H _2O$

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

When sugar is treated with sulphuric acid, we get a very pure form of:

  1. carbon

  2. oxygen

  3. water

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

(A) carbon

Concentrated sulphuric acid is a strong dehydrating agent. Sulphuric acid removes water from organic compounds; it is evident by its charring action on carbohydrates.
${C} _{12}{H} _{22}{O} _{11} \xrightarrow{\text{ conc. } {H} _{2}S{O} _{4}} 12C + 11{H} _{2}O$

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

Formula of glucose is :

  1. $C _{5}H _{12}O _{6}$
  2. $C _{6}H _{12}O _{16}$
  3. $C _{6}H _{12}O _{7}$
  4. $C _{6}H _{12}O _{6}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Formula of glucose is $C _6H _{12}O _6$ it is derived from the reaction of photosynthesis that is :


$6CO _2 + 6H _2O \overset{Sunlight}\longrightarrow C _6H _{12}O _6 + 6O _2$

Hence, the correct option is D.

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

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