Mafni, of Ridgway School, asks :-

Why are tree tops green?

David Jackson, a Horticulturalist at Lincoln University, responded.

Because their leaves contain the green pigment Chlorophyll.

Cells in the plant contain discrete sections which are called Chloroplasts. It is these which contain the pigment chlorophyll and they are possibly the most important cells in the whole of the animal and plant kingdom.

Photosynthesis is the process that occurs in green plants and combines the gas carbon dioxide from the air with water from the soil, using the energy in light to form carbohydrates such as sugars and starch. Photosynthesis occurs in chloroplast and involves the chlorophyll molecule.

The chlorophyll molecule absorbs red and blue light but reflects green light hence leaves, the parts of a plant involved in photosynthesis, are green.

Without photosynthesis life as we know it would not exist. The carbohydrates can be converted into the structure of the plant - roots, shoots, leaves etc - and by respiration they can release energy which enables all plant processes to occur. Indirectly animals, including humans, gain the same advantages by consuming the plants themselves or eating other animals which have eaten plants.