Root cells do not contain chloroplasts because in most plants the roots are underground and not exposed to light. Chloroplasts are needed for photosynthesis, which needs light to occur.
Chloroplasts are small bodies, or organelles, that are found in the cells of green plants. They are not attached to the cell walls but float in the cytoplasm. Chloroplasts contain chlorophyll, which is a green pigment that can change the light energy of the sun into fuel. Plants take carbon dioxide from the air and water from the soil and change them into sugars.
When light strikes a molecule of chlorophyll, it excites the molecule and causes it to give up an electron. In turn, the chlorophyll molecule grabs an electron from water, which makes the water molecule unstable. This makes it decompose and release oxygen and hydrogen. The oxygen is released into the air, but the hydrogen is used to make simple sugars for the plant.
The function of the roots is to absorb and store water and nutrients from the soil and to support the plant. In many plants, the roots are also used for reproduction. The roots of some plants can be cut up and replanted to grow new plants.