Part A: Explain what substances would need to enter and exit the cell and what processes would these substances use to enter and exit the cell.

All living organisms are made up of cells. Cells may be eukaryotic (in animals and plants) or prokaryotic (bacterial cells). They:

absorb or produce food
reproduce
are sensitive to and respond to changes in their environment
control the chemical reactions taking place inside them
In this way they have the properties that characterise life.

All eukaryotic cells have a cell surface membrane (also known as a plasma membrane). It is very fragile and its role is to hold the cell together and to help control what substances can get in and out. It is partially permeable, allowing only some substances to pass through it. The membrane has a complex structure consisting of a phospholipid bi-layer and different types of proteins.