Biology · Chemistry

Carbohydrates and Biomolecules

986 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

Invert sugar is:

  1. a type of cane sugar

  2. optically inactive form of sugar

  3. mixture of glucose and galactose

  4. mixture of glucose and fructose in equimolar quantities
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Sucrose which is an equimolar mixture of glucose and fructose on hydrolysis brings about a change in the sign of rotation from dextro (+) to laevo (-) and the product is named as invert sugar.
Hence, invert sugar is a mixture of glucose and fructose in equimolar quantities.
Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

Which of the following compounds is found in abundance in nature?

  1. Fructose

  2. Glucose

  3. Starch

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

Cellulose is a type of carbohydrate, containing chains of glucose rings. The cell walls, which are responsible for providing support and rigidity to the plants are made of cellulose. 


It is also the primary constituent of wood, making it the most abundant organic compound found in nature.

Hence, the correct answer is option $\text{D}$.

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

Molisch reagent is used to identify following compound?

  1. Glucose

  2. Raffinose

  3. D-oxribose

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

Carbohydrates undergo dehydration in the presence of sulphuric acid, giving aldehyde as a product which undergoes condensation in the presence of Molisch reagent ($\alpha-napthanol $ dissolved in ethanol) to give a purple colored compound. This forms the basis of Molisch test to detect carbohydrates. Since glucose, raffinose, and deoxyribose are all carbohydrates, they can be identified using Molisch reagent

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

The reagent which may be used to distinguish between cane sugar and glucose solution is

  1. Molusch's reagent

  2. Iodine solution

  3. Baeyer's reagent

  4. Fehling's solution
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Fehling's solution is used to distinguish between reducing sugars (like glucose) and non-reducing sugars (like sucrose/cane sugar). Glucose will give a positive test (red precipitate), while sucrose will not.

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

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.