Many biological substances are polymers. Complete the details to state the type of monomer which forms each of the biological polymers:

• Starch: $\dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots$
• Enzyme: $\dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots$
• RNA: $\dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots$

Look at the structure of the polymer called poly(propene):

$${\begin{array}{ccc}H& & H\\ |& & |\\ -C& -& C-\\ |& & |\\ H& & {CH}_3\end{array}}_n$$

This polymer is made from a monomer. Draw or represent the structure of this monomer.

Polyesters are also polymers.

Look at the structure of a polyester:

$${\left[-C(=O)-\square -C(=O)-O-◯-O-\right]}_n$$

This polymer is made from two different monomers.

Draw or write the chemical formulas of each different monomer (use $\square$ and $◯$ to represent the central carbon chains).

Kevlar is a high-strength polyamide. It can be prepared in a laboratory by reacting terephthaloyl chloride with 1,4-phenylenediamine.

• Terephthaloyl chloride is corrosive and reacts with moisture in the air to release toxic acidic fumes ($HCl$ gas).
• The solvent used (dichloromethane) is highly volatile and is a toxic inhalation hazard.

Describe and explain two precautions a chemist should take to carry out this experiment safely.