Cells use the chemical reactions to change the chemical stored in food into forms needed to perform activities.

Cell use the chemical  reaction to the chemical ENERGY stored in food into other forms needed to perform activities.

Explanation:

ATP is the enengy currency of cell it is stored as chemical energy in foods.When we intake food the cell utilize the chemical energy by stimulating the hydrolysis of ATP stored in foods.

         The hydrolysis of ATP generate energy which is used by the cell to carry out various biological and physiological activities such as membrane transport,muscle contraction,synthesis of macromolecules such as protein,lipid,carbohydrates.

Homologous organs can be described as structures having the same internal organization.

The forelimbs of many vertebrates have the same arrangement of bones. Some of these vertebrates having similar organisation of forelimbs are bird wings, bat wings, flippers, and human arms and legs.

Although the function of these limbs yet they have similar internal organisation.

A bird's wing helps the bird in flying. Bat wing helps the bat to fly. Human arm and legs are used for movement. Flippers help in movement in water.