Most animals can survive without food and water for a longer time than they can survive without water. why is water so important to animals? why can an animal survive without food for longer?

Water has many uses in animals. For example, it is used to transport materials, removing waste from body, act as solvents and much more. So we might heard of doctors suggesting human to drink 6 to 8 cups of water each day, or else we may suffer form dehydration.
However, if animals don't take in food for a short time, they wouldn't die immediately. It is because inside animal body there is food storage, of carbohydrates (glucose) and fat. The body will break down these food store.

The basic building blocks of dna and rna are nucleotides