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

The minimum number of carbon atoms that should be present in a monosaccharide is :

  1. 2

  2. 3

  3. 4

  4. 6
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Monosaccharide is single polyhydroxy aldehyde (aldose) or ketone (ketose) units. Glucose is a single polyhydroxy aldehyde, while fructose is a single polyhydroxy ketone. A monosaccharide contains a skeleton, of carbon atoms. The minimum number of carbon atoms is three and it can go up to seven.

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

Carbohydrates that, on attempted hydrolysis, are not cleaved to smaller carbohydrates are called :

  1. oligosaccharides

  2. polysaccharides

  3. disaccharides

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

A carbohydrate that cannot be hydrolysed further to give simpler unit of polyhydroxy aldehyde or ketone is called a monosaccharide. Some common examples are glucose, fructose, ribose, etc.
Carbohydrates that yield two to ten monosaccharide units, on hydrolysis, are called oligosaccharides. They are further classified as disaccharides, trisaccharides, tetrasaccharides, etc., depending upon the number of monosaccharides, they provide on hydrolysis. Amongst these the most common are disaccharides. The two monosaccharide units obtained on hydrolysis of a disaccharide may be same or different.

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

Carbohydrates mix directly with blood and supply energy to the cells.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
As we take carbohydrates, our body breaks them simple sugars (glucose, fructose, and galactose) which are absorbed into the bloodstream. Any glucose not needed right away gets stored in the muscles and liver in the form of glycogen.
Therefore, the given statement is wrong
Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

From the following substances, which carbohydrates has the maximum sweetness?

  1. Sucrolose

  2. Saccharin

  3. Aspartme

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

All sugars are compared relative to sucrose on the basis of sweetness. Hence, sucrose is rated one in terms of sweetness. 

Alitame is the sweetest among the following with a sweetness rating of 2000, while saccharin, aspartame, and sucralose have a rating of 400, 180, and 600 respectively

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

Carbohydrates are ___________.

  1. used to make a paper

  2. produced as an intermediate in the synthesis of proteins

  3. the polyhydroxy aldehyde or polyhydroxy ketone

  4. all of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Carbohydrates are polyhydroxy aldehydes or polyhydroxy ketone. Cellulose is a carbohydrate used to make a paper. Carbohydrates are also produced as an intermediate in the synthesis of protein.

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

D-glucose & D-fructose can be differentiated by :

  1. Fehling solution

  2. Tollens reagent

  3. Benedict test
  4. $Br _2/H _2O$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Br _2/H _2O$ being a mild oxidising agent can only oxidise aldose to carboxylic acids but cannot oxidise ketose.


As glucose contains aldehyde group it gets oxidised and converted into a carboxylic acid and is differentiate from fructose which has ketone group.

Therefore, the correct option is D.

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

Free aldehyde group can be produced on hydrolysis of which of the following compound(s)?

  1. Maltose

  2. Sucrose
  3. $\alpha$-D Glucose

  4. Lactose
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

 $\alpha$-D glucose has cyclic hemiacetal structure. Hemiacetal on hydrolysis gives free aldehyde group.
Maltose, sucrose and lactose are are disacharides which on hydrolysis gives monosaccharides in which aldehyde group becomes free.
Maltose  $\displaystyle \xrightarrow { \text { hydrolysis} }$ Glucose $\displaystyle + $ glucose.
Sucrose  $\displaystyle \xrightarrow { \text { hydrolysis} }$ Glucose $\displaystyle + $ fructose.
Lactose  $\displaystyle \xrightarrow { \text { hydrolysis} }$ Glucose $\displaystyle + $ galactose.

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

Which of the following is a physical property of sugar?

  1. It is a white crystalline solid.

  2. Carbon, hydrogen, and oxygen are its constituents.
  3. It turns black when concentrated $\displaystyle { H } _{ 2 }{ SO } _{ 4 } $ reacts with it.

  4. When heated it decomposes.

  5. It decomposes readily.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Colour and appearance are physical properties.
The remaining are chemical properties which include its composition, reaction with sulphuric acid and decomposition.