Note about the question:
You will find the image in the attached files
Answer:
Protection
Step-by-step explanation:
The red arrow seems to be pointing to the membrane of bacteria cells. Probably the green structure also includes the cell wall.
Bacteria are a wide group of unicellular prokaryotic microorganisms with a simple structure and sized between 1 to 10 micrometers. These organisms lack a nucleus, nuclear membrane, and organelles. They only present plasmids and ribosomes. They have a cell membrane and a cell wall that protects the cell. Some of them can also show a capsule.
Membranes and cell walls delimitate and protect the cells from different extracellular factors that might damage them. The membrane constitutes a selectively permeable barrier that allows the free pass of only a few substances while it blocks others.