Comprehension STOP Use your dictionary to find out the meaning of the bold words below.


! How Does a Plant Make Food?


The answer … photosynthesis! Humans and animals get the energy to learn, run and do everyday tasks from the food that we eat. Plants don’t take in food in the way that we do. They make their own through a process called photosynthesis.


What does a plant need to make food?


ƒ Carbon dioxide in the air is absorbed through pores in the leaves called stoma. ƒ Water is absorbed through the roots and travels through vessels in the stem to the leaves. ƒ Sunlight (light energy) is absorbed by a green chemical in the leaves’ cells called chlorophyll.


Carbon dioxide


Sunlight energy Oxygen


Chlorophyll Stoma Stem Water Roots Leaf Vessel What does photosynthesis mean for us?


ƒ The glucose that plants store is the energy that humans and animals absorb when they eat vegetables and fruit. Even when we eat meat, we get plant energy.


ƒ Plants release oxygen, which we need to breathe. We couldn’t exist without photosynthesis!


ƒ When humans breathe, we breathe out carbon dioxide. This chemical is harmful to the environment. Plants help to balance the oxygen and carbon dioxide levels in the atmosphere.


ƒ Most of the energy that we use to heat our homes or power our cars comes from fossil fuels such as natural gas, oil and coal. These fossil fuels are the remains of dead plants and animals stored in the earth for millions of years. They got their energy from photosynthesis. Burning these fuels releases carbon dioxide, which plants absorb.


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What happens in the process of photosynthesis?


1. Chlorophyll absorbs the sun’s energy.


2. This energy splits water (H2 O)


molecules into hydrogen (H) and oxygen (O).


3. The leaves release oxygen into the atmosphere.


4. Hydrogen and carbon dioxide combine to make glucose or sugar.


5. Some of the glucose is used as food energy to help the plant to grow. The rest is stored in leaves, fruit or roots for later use.


What does photosynthesis mean?


‘Photo’ is a Greek word meaning ‘light’. ‘Synthesis’ is a Greek word meaning ‘putting together’.


Imagine being able to eat without going to the shop or even touching a saucepan. Well this is exactly what plants do in the fascinating process of photosynthesis. However, photosynthesis does much more than provide food for plants. It provides food, energy and clean air for humans too.


Unit 13 | Explanatory Text 2


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