Without having any knowledge of your syllabus, I would suggest thinking about it a bit like this:
1. List the different roles that proteins play in organisms;
- enzymes catalyse reactions and cellular chemistry - including enzymes in DNA replication
– structural proteins which give form and shape to biological structures
- proteins that act as hormones (such as insulin and glucagon) to regulate specific processes
- membrane transport proteins
– haemoglobin and myoglobin to facilitate oxygen transport
- antibodies to fight infection
– rhodopsin and iodopsin - visual pigments
- rubisco - the enzyme catalysing carbon fixation
2. Decide and explain which of these comes under the heading of "controlling processes and responses" . Most (if not all) of them could - this is what makes the question rather poor, imho - but your syllabus might have a particular take on what this phrase is intended to refer to.
3. Write the essay describing how each of these functions contributes to the "control of processes and responses", making sure you invest most time in the most relevant ones, and giving examples of how specific proteins (you could describe a particular enzyme; a particular hormone; a particular membrane transport protein etc) work to control a given process and/or response
Obviously, how much detail you go into will be determined by how long the essay has to be.
Does that help?