Tag: introduction to carbohydrates

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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.