Photosynthesis

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  • Created by: Cristina
  • Created on: 09-02-11 18:43
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Photosynthesis
Photosynthesis
The process in which plants made glucose as food.
This happens in the leaves of all green plants.
Photosynthesis happens inside the chloroplasts, which are found in leaf cells and in other green parts of
a plant. Chloroplasts contain a substance called chlorophyll, which absorbs sunlight and uses its energy
to convert carbon dioxide and water into glucose. Oxygen is also produced.
What is needed for photosynthesis?
1. Light ­ Usually from the Sun.
2. Chlorophyll ­ The green substance found in chloroplasts that makes leaves look green. It absorbs the
energy in sunlight and uses it to combine carbon dioxide and water to make glucose. Oxygen is just a
byproduct of this product.
3. Carbon Dioxide ­ Enters the leaf from the air around.
4. Water ­ Comes from the soil, up the roots and stem and into the leaf.
The Leaf Structure
Adaptations of the Leaf for Photosynthesis
Adaptation Function
Supported by stem and petiole To expose as much of it as possible to sunlight and air.

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Large surface area To expose as much of it as possible to sunlight and air.
Thin To allow sunlight to penetrate to all cells to allow CO2 to
diffuse in and O2 to diffuse out as quickly as possible.
Stomata in lower epidermis To allow CO2 and O2 to diffuse in and out.
Air spaces in spongy mesophyll To allow CO2 and O2 to diffuse to and from all cells.
No chloroplasts in epidermis To allow sunlight to penetrate to mesophyll layer.…read more

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How Plants Use the Glucose
1. For Respiration
Plants manufacture glucose in their leaves.
They then use some of the glucose for respiration.
This releases energy which enables them to convert the rest of the glucose into various other useful
substances which they can use to build new cells and grow.
To produce some of these substances they also need to gather a few minerals from the soil.
2.…read more

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Nutrients and Minerals Needed for Healthy Growth
Plants need the carbohydrates they get from photosynthesis and various mineral salts to grow properly.
They get the mineral ions by absorbing them from the soil through their roots ­ active transport:
Nitrates
These are needed for making amino acids, which are then used to make proteins.
If the soil is deficient in nitrates, the plant starts to show stunted growth and won't reach its usual size.…read more

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