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KS3 Biology. 9C Plants and Photosynthesis. Contents. 9C Plants and Photosynthesis. What is photosynthesis?. Leaves and glucose. Roots and water. Summary activities. How do plants grow?. Many years ago people thought that plants ate soil and that made them grow.
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KS3 Biology 9C Plants and Photosynthesis
Contents 9C Plants and Photosynthesis What is photosynthesis? Leaves and glucose Roots and water Summary activities
How do plants grow? Many years ago people thought that plants ate soil and that made them grow. Think about it, if that really happened then there wouldn’t be any soil left! Plants actually grow by making their own food, not by eating soil! So where does the stuff that plants are made of come from?
How do plants make their own food? One of the raw materials that plants need to make food does come from the soil, the other comes from the air. What are these two raw materials called? carbon dioxide (from the air) water (from the soil) Plants use carbon dioxide and water to make their own food in a chemical reaction. What is the name of this reaction?
How do plants make their own food? Plants make their food from carbon dioxide and water in a chemical reaction called... photosynthesis. carbon dioxide (from the air) glucose oxygen water (from the soil) The food made by photosynthesis is the sugar glucose. Oxygen gas is also made as a by-product of photosynthesis.
How do plants grow? Plants need energy for photosynthesis to take place. Where does this energy come from? light energy carbon dioxide (from the air) glucose oxygen water (from the soil) The energy for photosynthesis comes from the Sun. Where in a plant does photosynthesis take place?
How do plants grow? Plant cells in the upper surface of leaves have chloroplasts which contain the green pigment called chlorophyll. light energy chlorophyll carbon dioxide (from the air) glucose oxygen water (from the soil) It is chlorophyll that absorbs light energy from the Sun to make photosynthesis happen.
Photosynthesis summary Plants make their own food by the process of photosynthesis. In this chemical reaction, chlorophyll in plant cells absorbs light energy to change carbon dioxide and water into glucose and the by-product oxygen. What is the word equation for photosynthesis? light energy carbon dioxide water glucose oxygen chlorophyll This equation can be read as: “carbon dioxide and water, in the presence of light energy and chlorophyll, produces glucose and oxygen”.
Contents 9C Plants and Photosynthesis What is photosynthesis? Leaves and glucose Roots and water Summary activities
How are leaves adapted? Leaves are small ‘factories’ that produce food for plants by photosynthesis. Leaves are adapted so that photosynthesis can take place. Plants need carbon dioxide, water, sunlight and chlorophyll to carry out this important process. What features of leaves make them suitable for photosynthesis?
How are leaves adapted? The features of leaf that make it suitable for photosynthesis are: • A leaf is broad and flat to capture lots of sunlight. • carry water to the leaf and take food from the leaf to the rest of the plant. Veins also help to support the leaf. • Certain plant cells contain chloroplasts with chlorophyll. • Small holes called stomatain the underside of a leaf allow gases in and out. • Veins
What do plants use glucose for? glucose What do plants with the glucose made by photosynthesis? Some glucose is used straight away in respiration. Plants also carry out respiration to release the energy they need for life processes. Some glucose is converted into starch and other substances for storage. These stores of energy can be used later when the plant needs them. Some glucose is used to make new chemicals such as proteins, sugars and fatsthat the plant also needs to function properly.
Contents 9C Plants and Photosynthesis What is photosynthesis? Leaves and glucose Roots and water Summary activities
How does water enter a plant? Water is one of the raw materials needed for plants to carry out photosynthesis. How does water enter a plant? Water from the soilenters a plant through the roots. You can’t normally see them but roots are a very important part of a plant. Why are roots branched and spread out through the soil?
How are roots adapted? water • Roots are branched and spread out • for two reasons: • to absorb water (and mineral salts) from a large amount of soil. • to anchor the plant in the soil. • Taking a closer look, roots are • covered in root hair cells. • Root hair cells have thin walls • and a large surface area to help • them absorb lots of water. • How are roots adapted to their job?
Why do plants need water? Water is needed by plants for photosynthesis but this importantliquid is also used in many other ways: • to provide dissolved minerals that keep the plants healthy; • to transport substances around the plant; • to keep the plant rigid and upright; • to keep the plant cool; • to allow other chemical reactions to occur in plant cells. What happens to a plant if it does not get enough water?
Contents 9C Plants and Photosynthesis What is photosynthesis? Leaves and glucose Roots and water Summary activities
Glossary • chlorophyll –The green pigment inside chloroplasts that plants need for photosynthesis to take place. • chloroplast –The part of a plant cell where photosynthesis occurs. • glucose –The sugar plants make during photosynthesis. • palisade cell –A type leaf cell with lots of chloroplasts. • photosynthesis –The process by which plants use carbon dioxide and water to produce glucose and oxygen in the presence of light and chlorophyll. • starch – Extra glucose from photosynthesis is stored as this substance which can be tested for with iodine. • stomata –Small holes in the lower surface of a leaf that allow gases in and out. • xylem –Tubes in veins that carry water around a plant.
