What is a difference between starch and glycogen?

A major difference between starch and glycogen is that starch is the form plants primarily use to store excess glucose, while glycogen is the form in which excess glucose in animals is stored.

Starch is a carbohydrate produced by all green plants and has a large number of glucose units used to store energy. Plants such as wheat, rice and potatoes are all rich with carbohydrates.

Glycogen is made by the liver and  muscle cells and plays an important role in the glucose cycle. It helps cells store glucose  energy  and thus ensures a steady supply of energy to cells when needed.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products

idk what the options are but

these is a strong electrostatic attraction between the ions hence a lot of energy is needed to overcome this attraction

this is why the boiling points are so high