Alveolar macrophages are phagocytes found in the human gas exchange system. They produce hydrolytic enzymes, such as lysozyme, to digest pathogens entering the alveolus.

1. (a)(i)State the term used to describe the sequence of nucleotides in the DNA of the alveolar macrophage that codes for a protein, such as lysozyme.[1]
2. (a)(ii)Synthesis of lysozyme occurs in two stages. The first stage occurs in the nucleus using one strand of DNA to synthesise mRNA. State the name of the strand of DNA that is used to synthesise mRNA.[1]
3. (a)(iii)Name the organelle where the translation of mRNA takes place to produce lysozyme.[1]
4. (a)(iv)Lysozyme destroys bacterial cells by hydrolysing bonds in peptidoglycan. Explain how the hydrolysis of bonds in peptidoglycan leads to the destruction of bacterial cells.[2]
5. (b)(i)Alveolar macrophages are found in contact with squamous epithelial cells in the walls of alveoli. Explain how the cells lining the alveoli are adapted for gas exchange.[2]
6. (b)(ii)Describe the role of elastic fibres in the wall of an alveolus.[2]