The function of ribosomes in cells is protein synthesis. Ribosomes are the cellular structures that are responsible for making proteins. They do this by reading the instructions encoded in messenger RNA molecules and assembling the appropriate sequence of amino acids to form a protein. This process is called translation and is a crucial step in the overall process of protein synthesis.
Starch synthesis, transport of material, and lipid storage are not functions of ribosomes. These processes are carried out by different cellular structures and enzymes. Starch synthesis, for example, is carried out by specialized enzymes in the cytoplasm. Transport of material is carried out by specialized structures such as the endoplasmic reticulum, Golgi apparatus, and vesicles. Lipid storage is carried out by structures such as lipid droplets.