A1. Molecules of Life

Question 1

Monomers and polymers
Most carbohydrates, proteins and nucleic acids are polymers. Polymers are large, complex molecules composed of long chains of monomers joined together.

Monomers are small, basic molecular units that can form a polymer. Examples of monomers include ________________, ______ _____ and _____________.

Answer 1

Most carbohydrates, proteins and nucleic acids are polymers. Polymers are large, complex molecules composed of long chains of monomers joined together.

Monomers are small, basic molecular units that can form a polymer. Examples of monomers include monosaccharides, amino acids and nucleotides.

Question 2

Making polymers
Most biological polymers are formed from their monomers by _____________ reactions. A ______________ reaction forms a chemical bond between monomers, releasing a molecule of water-see Figure 2.

Answer 2

Most biological polymers are formed from their monomers by condensation reactions. A condensation reaction forms a chemical bond between monomers, releasing a molecule of water-see Figure 2.

Question 3

Figure 2: An example of the formation of a polymer.

Answer 3

Question 4

Exam Tip
If you’re asked to show a condensation reaction, don’t forget to put the _____ __________ in as a _________.

Answer 4

Exam Tip
If you’re asked to show a condensation reaction, don’t forget to put the water molecule in as a product.

Question 5

Breaking down polymers
Biological polymers can be broken down into ________ by __________ reactions. A hydrolysis reaction breaks the chemical bond between monomers using a _____ _________. It’s basically the opposite of a condensation reaction.

Answer 5

Biological polymers can be broken down into monomers by hydrolysis reactions. A hydrolysis reaction breaks the chemical bond between monomers using a water molecule. It’s basically the opposite of a condensation reaction.

Question 6

Figure 3: Hydrolysis of a polymer.

Answer 6

Question 7

Tip: A condensation reaction ________ one molecule of water, but a hydrolysis reaction _____ a molecule of water.

Answer 7

Tip: A condensation reaction removes one molecule of water, but a hydrolysis reaction adds a molecule of water.