Quiz - Carbohydrates | Carbohydrates

1

What atoms are carbohydrates made of?

Carbon and hydrogen

Carbon and oxygen

Carbon, hydrogen and oxygen

Carbon, hydrogen, oxygen, nitrogen

A carbohydrate is a biomolecule consisting of carbon, hydrogen and oxygen atoms

2

What are monosaccharides?

Aldoses

Ketoses

Monomer of polysaccharides

All of the above

Monosaccharides, also called simple sugars, are the simplest form of sugar and the most basic units of carbohydrates: they are aldehydes (aldoses) or ketones (ketoses) that contain at least 2 additional hydroxy groups
Polysaccharides are polymers of monosaccharides

3

What is the most common configuration of sugars in nature?

In L-form

In D-form

In α anomer

All of the above

Sugars are classified as D when the highest-numbered stereocenter (= the one farthest from the carbonyl group) is R, L when it is S. Configuration D is the most common in nature

4

Which of the following synthesis conditions is used to oxidize sugars to monocarboxylic acid?

HNO3, H2O

HNO3, H2O, Δ

Br2, H2O

Na2Cr2O7, H2SO4, H2O

Oxidation to mono- or dicarboxylic acids:

5

What is the mechanism of etherification of sugars?

SN2

E2

Addition-elimination

Hemiacetal formation

Ag2O deprotonates each alcohols forming alkoxides RO- which reacts with CH3I in an SN2 reaction

6

What is the most common monomer of polysaccharides?

Glucose

Fructose

Cellulose

Amino acids

Nature is remarkably conservative in the construction of polysaccharides: the 3 most abundant natural polysaccharides (cellulose, starch and glycogen) are derived from the glucose