Tag: carbohydrates - definition and classification

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

Carbohydrates are used by body mainly:

  1. for obtaining vitamins

  2. as a source of energy

  3. for building muscles

  4. for all its development needs
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

  1. carbon

  2. oxygen

  3. water

  4. hydrogen
Reveal answer Fill a bubble to check yourself
A Correct answer
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.
${C} _{12}{H} _{22}{O} _{11} \xrightarrow{\text{ conc. } {H} _{2}S{O} _{4}} 12C + 11{H} _{2}O$

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

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:

  1. green leaves

  2. carbohydrates

  3. fats

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

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

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.