Tag: biomolecules

Questions Related to biomolecules

Which enzyme converts glucose to ethanol?

  1. Diesterase

  2. Invertase

  3. Zymase

  4. Both (2) and (3)


Correct Option: C
Explanation:

$Glucose\rightarrow Ethanol$
Zymase enzymes can do above conversion.
(catalyzes fermentation of sugar into ethanol & $CO _2$).

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

  1. Sucrolose

  2. Saccharin

  3. Aspartme

  4. Alitame


Correct Option: D
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

Carbohydrates contains carbon, hydrogen, and oxygen molecules.

  1. True

  2. False


Correct Option: A
Explanation:

Carbohydrates are the biomolecules containing carbon, hydrogen, and oxygen respectively. They are also called hydrates of carbon.

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


Correct Option: D
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.

Which of the following is not the example of carbohydrate?

  1. Glucose

  2. Maltose

  3. Glycine

  4. Fructose


Correct Option: C
Explanation:

Here Glucose, Maltose, and Fructose are carbohydrate. Glycine is not a carbohydrate. It is a protein.

The polyhydroxy aldehydes are called:

  1. proteins

  2. fats

  3. carbohydrates

  4. vitamins


Correct Option: C
Explanation:
  • Polyhydroxy aldehydes or ketones are molecules with more than one hydroxyl group $(−OH)$, and a carbonyl group $(C=O)$ either at the terminal carbon atom (aldose) or at the second carbon atom (ketose) are called carbohydrates.
  • Monosaccharides are polyhydroxy aldehydes and are called Simple Sugar, any of the basic compounds that serve as the building blocks of carbohydrates. 

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

  1. Fehling solution

  2. Tollens reagent

  3. Benedict test

  4. $Br _2/H _2O$


Correct Option: D
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.

Carbohydrates Contains:

  1. $-CHO$ group

  2. $-OH$ group

  3. $> C=O$ group

  4. All


Correct Option: D

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


Correct Option: A,B,C,D
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.

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.


Correct Option: A
Explanation:

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