Biology · Chemistry

Carbohydrates and Biomolecules

986 Questions

Carbohydrates and biomolecules questions test your understanding of sugars, monosaccharides, and metabolic substrates. The topic covers food transportation in plants and the biochemical properties of sweeteners. Practicing these questions builds a strong foundation for exam preparation.

Disaccharides and monosaccharidesArtificial sweetenersGlycogen storagePlant food transportGlycoprotein hormones

Carbohydrates and Biomolecules Questions

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

The two functional groups present in a typical carbohydrate are :

  1. $-CHO$ and $-COOH$
  2. $-CO$ and $-OH$
  3. $-OH$ and $-CHO$
  4. $-OH$ and $-COOH$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carbohydrates are polyhydroxy aldehydes or polyhydroxy ketones OR compounds which give aldehydic as well as ketonic groups on hydrolysis. Therefore the major functional groups are (carbonyl) Aldehyde, Ketone, and hydroxy groups. 

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

Which among the following is not the example of carbohydrate ?

  1. Glucose

  2. fractose

  3. Maltose

  4. Nylon
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$\rightarrow$ Carbohydrates are important source of instant energy in our body system.
$\rightarrow$ Honey has been used as instant source of enrgy in ayurvedic medicines.
$\rightarrow$ Carbohydrates are used as storage starch in plants and glycogen
$\rightarrow$ carbohydrates are also used in textile industry.

So, the correct answer is NYLON (It is a synthetic polymer)

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

For 'invert sugar', the correct statement(s) is (are)
(Given : specific rotations of (+) -sucrose, (+) -maltose, L-(-)-glucose and L-(+)-fructose in aqueous solution are $+66^0, +140^0, -52^0$ and $92^0$, respectively)

  1. 'invert sugar' is prepared by acid catalyzed hydrolysis of maltose

  2. 'invert sugar' is an eqimolar mixture of D-(+)-glucose and D-(-)-fructose
  3. specific rotation of 'invert sugar' is $-20^0$
  4. on reaction with $Br _2$ water, 'invert sugar' forms saccharic acid as one of the products
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Invert sugar is a sucrose, partially or totally cleaved into fructose and glucose. Sucrose is converted into  invert sugar by chemical reaction called hydrolysis by heating a mixture or solution of table sugar.

Also, breakdown of sucrose may happen in a reaction catalyzed by enzymes such as sucrose, invertase etc or by acid catalyzed hydrolysis of maltose.

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

In fructose and glucose the possible optical isomers are:

  1. 12, 12

  2. 8, 16

  3. 16, 8

  4. 4, 12
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Fructose contains three chiral carbon atom and glucose contain 4 chiral carbon atoms.
The Number of possible Optical isomers for Fructose are ${2}^{3} = 8$
The Number of possible Optical isomers for Glucose are ${2}^{4} = 16$
8, 16 is the Answer
Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

The $\alpha$- D glucose and $\beta$- D glucose differ from each other due to difference in carbon atom with respect to its

  1. Number of $OH$ groups

  2. Size of hemiacetal ring

  3. Conformation

  4. Configuration
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Alpha and beta D-glucose are anomers, which are a type of stereoisomer that differ specifically in the configuration at the anomeric carbon (C-1).

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

What is the nature of glucose-glucose linkage in starch that males its so susceptible to acid hydrolysis?

  1. Starch is hemiacetal

  2. Starch is acetal

  3. Starch is polymer

  4. Starch contain only few molecules of glucose
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Starch contains acetal linkages (glycosidic bonds) between glucose units. Acetals are acid-labile and readily hydrolyze by acid. Hemiacetals are more reactive but acetals are stable to base but hydrolyzed by acid, making starch susceptible to acid hydrolysis.

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

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.

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

Which of the following is synthetic sweetener?

  1. Saccharin

  2. Aspartame

  3. Dulcin

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Saccharin, aspartame, dulcin all are synthetic sweetener. They have a sugar-like taste but with less food energy.

Artificial sweeteners are used in one of two ways. They may be used directly in commercially processed foods, or they are mixed with one or more starch-based sweeteners before sale to consumers.


$\therefore$ Option D is the correct answer.

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

Which of the following is incorrect?

  1. Fructose is reducing sugar
  2. Cellulose has $\beta$-D Glucose units

  3. DNA has D-ribose

  4. Amylopectin is insoluble in water
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Fructose is reducing sugar.
 
Cellulose is a polysaccharide composed of a linear chain of  $\beta $ 1,4 linked d glucose unit.with a degree of polymerization ranged from several hundreds to over ten thousands.

Amylopectin is a highly branched polymer of glucose found in plants. It is one of the two components of starch, the other being amylose.

As the name suggest DNA is deoxyribonucleic acid hence it has deoxyribose sugar not ribose sugar.

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

Consider the given statements.
I. Dextrin and glycogen are polysaccharides
II. Lactose and glucose are disaccharides
III.Sucrose and maltose are disaccharides
IV. Raffinose is oligosaccharide
The incorrect statements is/are:

  1. only II

  2. I and II

  3. I, II and III

  4. IV only
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Option (A) is right. The incorrect statement is (II).
(II) Lactose is a disaccharide while glucose is an aldosic monosaccharide.