Adipocytes may be much larger than other body cells because each cell contains a large lipid droplet. The largest adipocyte in Fig. 2.1 has a mean diameter of $35\,\mu\text{m}$. A person with good eyesight can see cells of $0.05\,\text{mm}$ or greater diameter without a magnifying glass or any other optical aid. State whether this adipocyte can be seen by the person without any optical aid. Show your working to justify your answer.
Only some organelles inside the adipocyte can be observed with a high quality light microscope at maximum magnification. Organelles such as rough endoplasmic reticulum, smooth endoplasmic reticulum and ribosomes are visible only with an electron microscope. Explain why these organelles cannot be seen with a light microscope.
Name the type of bond broken by active ATGL to produce fatty acids and glycerol.
Name and outline the process by which the fatty acids shown in Fig. 2.2 leave the cell.
Using Fig. 2.2, outline the process of cell signalling.
Suggest why red blood cells cannot metabolise fatty acids to synthesise ATP.