You should spend about 20 minutes on this task.

Write at least 150 words.

MODEL ANSWER>>

The process of photosynthesis, in which energy is produced and stored in plants, is illustrated in the given diagram.

Overall, it is clear that sunlight, water and carbon-di-oxide are the crucial factors behind the whole process.

As per the diagram, energy from the Sun is trapped in the leaves of plants, and this is done by a unique factor, which is called chlorophyll. This makes leaves appear green.

Stomata, an opening in each leaf’s epidermis and cuticle, absorb carbon-di-oxide from the atmosphere, and this happens simultaneously with the solar energy absorption.

Water, which is the third key factor, moves up through the roots and acts with the first two factors in the leaves to produce sugar, which is essential for the growth of the plants.

When excess sugar is stored as starch in the roots for future use, the by-products of photosynthesis: water vapour and oxygen, escape through the stomata, by a process called transpiration.

Word count: 155