Biological molecules | Exit Quiz | Oak National Academy

What three elements do carbohydrates contain?

• carbon

• nitrogen

• hydrogen

• oxygen

• sulfur

Answer explanation

Carbohydrates are made of carbon, hydrogen and oxygen.

Which of the following are polysaccharides?

• maltose

• cellulose

• glycogen

• starch

• glucose

Answer explanation

Many sugar molecules joined together make polysaccharides. Some examples are starch, which plants store, glycogen which animals store and cellulose which is what plant cell walls are made of.

Which statements about proteins are not true?

• The order of amino acids is coded for by DNA.

• Proteins are polymers.

• Proteins are monomers.

• Proteins are made from amino acids.

• Antibodies are proteins.

Answer explanation

Proteins are polymers, not monomers. They are made from a chain of amino acid monomers.

Which of these is a use for lipids in an organism?

• preventing disease

• making cell walls

• making cell membranes

• carrying oxygen

• making enzymes

Answer explanation

Cell membranes are made from lipids that contain one glycerol molecule attached to three fatty acid chains.

Organisms are made of carbohydrates, proteins, lipids, (a)   and minerals.

Answer explanation

Water is needed for chemical reactions to take place inside cells and makes up a large part of living organisms.

Match the word to its description.

• sugar

• one of two units used to build lipid molecules

• polymer

• a molecule made of one unit

• amino acids

• the units used to build large carbohydrate molecules

• glycerol

• the units used to build protein molecules

• monomer

• a molecule made of many repeated units

Answer explanation

Monomers can be joined together to create polymers. Examples are sugars joined together to make carbohydrates and amino acids joined together to make proteins. Glycerol is joined to fatty acids to create lipid molecules.