Tag: carbohydrates - definition and classification

Questions Related to carbohydrates - definition and classification

Which of the following is correct for Lactose

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. It is nonreducing sugar

  2. Glycosidic bond $[1,4]$ between glucose and galactose

  3. Glycosidic bond $[1,4]$ between glucose and fructose

  4. Glycosidic bond $[1,2]$ between glucose and galactose

Show answer
Correct Option: B
Explanation:

Lactose $=$ Glycosidic bond $[1,4]$ between glucose and galactose 

Carbohydrates are used by body mainly:

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. for obtaining vitamins

  2. as a source of energy

  3. for building muscles

  4. for all its development needs

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Correct Option: B
Explanation:

Carbohydrates are used by body mainly as a source of energy. 


Carbohydrates represent the most important source of energy for the body, and are vital for a varied and balanced diet. 

The building blocks of all carbohydrates are sugars and they can be classified according to how many sugar units are combined in one molecule. Various forms of sugar, such as glucose and sucrose (table sugar), are simple carbohydrates. 

They are small molecules, so they can be broken down and absorbed by the body quickly and are the quickest source of energy. They quickly increase the level of blood glucose (blood sugar).

Option B is correct.

Which of the following is not a sugar?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Sucrose

  2. Glucose

  3. Fructose

  4. All are sugars

Show answer
Correct Option: D
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.

Which of the following is a source of instant energy?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Salt

  2. Glucose

  3. Water

  4. Starch

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Correct Option: B
Explanation:

Glucose is a source of instant energy because it is quick to act to create energy along with oxygen so our body does not need to convert the glucose to anything else. It also can be absorbed through the lining of the stomach.

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

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. carbon and water vapour

  2. carbon, hydrogen and oxygen

  3. carbon dioxide and water vapour

  4. carbon dioxide and hydrogen

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Correct Option: C
Explanation:

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

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

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

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. carbon

  2. oxygen

  3. water

  4. hydrogen

Show answer
Correct Option: A
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.
${C} _{12}{H} _{22}{O} _{11} \xrightarrow{\text{ conc. } {H} _{2}S{O} _{4}} 12C + 11{H} _{2}O$

Transition state structure of the substate formed during an enzymatic reaction is

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Transient but stable

  2. Permanent but unstable

  3. Transient and unstable

  4. Permanent and stable

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Correct Option: C
Explanation:

Transition state is intermediate state produced during enzymatic biochemical reaction which is transition state and unstable state

Which enzyme converts glucose to ethanol?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Diesterase

  2. Invertase

  3. Zymase

  4. Both (2) and (3)

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Correct Option: C
Explanation:

$Glucose\underrightarrow { Zymase } Ethanal$
Zymase converts glucose to ethanal

The light coming from the sun is stored as energy in plants by the process of photosynthesis. This happens by converting carbon dioxide and water into:

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. green leaves

  2. carbohydrates

  3. fats

  4. plants hormones

Show answer
Correct Option: B
Explanation:

Photosynthesis is the process by which plants utilize the energy from the sunlight in order to convert carbon dioxide and water into carbohydrates.

Formula of glucose is :

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. $C _{5}H _{12}O _{6}$

  2. $C _{6}H _{12}O _{16}$

  3. $C _{6}H _{12}O _{7}$

  4. $C _{6}H _{12}O _{6}$

Show answer
Correct Option: D
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.