starch

• found in plants
• storage form of alpha glucose
• mixture of two polysaccharides of alpha glucose, amylose and amylopectin
• amylose - long, unbranched chain of alpha glucose. has a coiled structure, so compact and good for storage
• amylopectin - branched chain of glucose with 1,4 and 1,6 glycosidic bonds. side branches allow glucose to be released quickly as glycosidic bonds are accessible
• iodine test for presence of starch - add iodine in dissolved potassium iodide solution to sample. if positive, will turn from brown-orange, to blue-black colour
• insoluble in water so won't affect water potential or diffuse out the cell