Biology · Chemistry

Carbohydrates and Biomolecules

1,073 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 $\alpha$- 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.

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

Consider the given statements:


I. Maltose is also known as malt sugar.
II. Sucrose is also known as cane sugar.
III. Lactose is also known as grape sugar.
IV. Starch is also known as amylum.

The correct statement(s) is/are:

  1. I, II and IV

  2. I, II and III

  3. II, III and IV

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

(I) Maltose is also known as malt sugar.


(II) Sucrose is also known as cane sugar.

(III) Lactose is also known as milk sugar.

(IV) Starch is also known as amylum.

Hence, option A is correct.

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

Consider the statements about mono, di and oligo saccharides:


I. These are crystalline solids.
II. These are soluble in cold water.
III. These are tasteless.

The incorrect statement(s) is/are:

  1. only III

  2. I, II and III

  3. I and II only

  4. I and III only
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Monosaccharides, disaccharides and oligo saccharides are crystalline solids, water soluble and sweet in taste. They are called sugar.
Thus only statement III is incorrect.

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

A carbohydrate which cannot be hydrolysed to simpler compounds is called:

  1. monosaccharide

  2. disaccharide

  3. polysaccharide

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

Monosaccharide cannot be hydrolyzed to simpler compounds as it is itself the simplest unit.
Disaccharides, polysaccharides and oligosaccharides can be hydrolyzed to monosaccharides.