Tag: carbohydrates - definition and classification

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

${ C } _{ 12 }{ H } _{ 22 }{ O } _{ 11 }\longrightarrow 12C+{ 11H } _{ 2 }{ O }$ in presence of concentrated ${ H } _{ 2 }{ SO } _{ 4 }$.

Which of the following is obtained in the above reaction?

  1. Animal charcoal

  2. Sugar charcoal

  3. Coke

  4. Wood charcoal
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The dehydration of sucrose (C12H22O11) by concentrated sulfuric acid leaves behind a porous black mass of carbon known as sugar charcoal.

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

Which of the following does not reduce Benedict's solution?

  1. Sucrose

  2. Aldehyde

  3. Glucose

  4. Fructose
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
 Sucrose.. 
Because Sucrose (table sugar) contains two sugars (fructose and glucose) joined by their glycosidic bond in such a way as to prevent the glucose isomerizing to aldehyde, or the fructose to alpha-hydroxy-ketone form. Sucrose is thus a non-reducing sugar which does not react with Benedict's reagent.
Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

In plant glycolipids, the sugar is normally.

  1. oil

  2. wax

  3. glycolipid

  4. phospholipid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Glycolipids yeild fatty acids, glycerol and carbohydrates on hydrolysis. Monogalactosyldiglycerides are glycolipids which are commonly found in plant leaves and algae. They contain a high proportion of poly unsaturated fatty acids and appear to play a role in photosynthesis.

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

Carbohydrates may be:

  1. sugars

  2. starch

  3. polyhydroxy aldehyde/ketones

  4. compounds that can be hydrolyzed to sugar
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

Carbohydrates are primarily produced by plants and form a very large group of naturally occurring organic compounds. Some common examples are cane sugar, glucose, starch, etc.
The carbohydrates may be defined as optically active polyhydroxy aldehydes or ketones or the compounds which produce such units on hydrolysis.

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

Which of the following is true regarding monosaccharides?

  1. Always have six carbon atoms

  2. Always have five carbon atoms

  3. Always have four carbon atoms

  4. May contain 3 to 7 carbon atoms
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Monosaccharides may contain 3 to 7 carbon atoms. They have chemical formula $(CH _2O) _{n}$, where conventionally $n=3$. Monosaccharides can be classified by the number of carbon atoms they contain: diose(2), triose(3), tetrose(4), pentose(5), hexose(6), heptose(7) and so on.