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How do plants make their food

 

By PHOTOSYNTHESIS - making food by using light.

 

A diagram shows a green plant growing above dark soil, with its roots spreading downwards. At the top left, a bright yellow sun shines, and a labelled arrow points from the sun to the plant with the words “Light energy”. Arrows around the plant illustrate the main inputs and outputs of photosynthesis. A blue arrow near the upper leaves points outward with the label “Oxygen given out”. A red arrow points towards the leaves from the right with the label “Carbon dioxide in from air”. At the bottom, a blue arrow points into the roots with the label “Water taken in from soil by roots”. A white caption near the stem states “Glucose turned into starch and stored in all parts of plant”. The background shows a soft blue sky above a horizon of blurred green vegetation.

 

PHOTO = LIGHT, SYNTHESIS = MAKE.

 

Plants produce their own food by PHOTOSYNTHESIS.   The food they produce is GLUCOSE.  To make this, plants use LIGHT ENERGY from the Sun, WATER from roots and CARBON DIOXIDE from the air.  Photosynthesis take place in the LEAVES of all green plants.

Leaves are like little food factories.  They are specially adapted to carry out photosynthesis as efficiently and as quickly as possible. 

 

Structure of a leaf cell.

A diagram of a plant cell

 

 

The main adaptations are:

 

  • Leaves provide a large surface area to trap lots of sunlight, as they are flat and thin.

  • The positioning of the PALISADE cells nearer to the top of leaf.

  • Many CHLOROPLASTS in the Palisade cell.

  • The location of GUARD cells on the surface of the leaf, which control the exchange of gases through the STOMATA.

The process of Photosynthesis can be represented in the form of a chemical equation:

CARBON DIOXIDE

+

WATER

 SUNLIGHT

GLUCOSE

+

OXYGEN
arrow
CHLOROPHYLL

Remember:

6CO2

+

6H2O

 SUNLIGHT

C6H12O6

+

6O2
arrow
CHLOROPHYLL

 

Four conditions are necessary for photosynthesis to happen:

 

  • Light - provided by the Sun onto the leaves.

  • Water - comes from the soil, absorbed by root hairs, up the stem and into the leaves.

  • Chlorophyll - 'green stuff' found in the chloroplasts which makes the leaves look green and absorbs sunlight.

  • Carbon Dioxide - enter the leaves from the surrounding air.

    •  


    Conditions affecting the rate of Photosynthesis

     

     

    Why is photosythesis important?

     

    Why is Photosynthesis Important?

    Photosynthesis is effectively the engine room of our planet. Without these green machines working overtime, Earth would be a very quiet, very hungry, and very breathless place.

    Here is a breakdown of why this process is the ultimate VIP of biology:

     

    1. The Oxygen Factor

    Every time you take a deep breath, you should probably thank a plant. Photosynthesis is the primary source of the world’s oxygen.

    • Respiration: Most living organisms (including us!) need oxygen to perform cellular respiration, which is how we release energy to keep our hearts beating and brains thinking.
    • The Cycle: While we breathe in oxygen and exhale carbon dioxide, plants do the heavy lifting of flipping that cycle back around.

     

    2. The Foundation of the Food Web

    If you enjoy eating, you enjoy photosynthesis. Plants, algae, and phytoplankton are producers—the only organisms capable of making their own "food" from sunlight.

    • Directly: Herbivores eat the plants.
    • Indirectly: Carnivores eat the herbivores that ate the plants.

    Without that initial energy conversion, every food chain on Earth would collapse.

     

    3. Atmospheric Thermostat

    Photosynthesis acts as a natural "carbon sink." By pulling carbon dioxide (CO2) out of the air, it helps regulate the global climate.

    • The Balance: It works alongside respiration and combustion to keep O2 and CO2 levels stable.
    • The Formula: In scientific terms, plants take 6CO2 + 6H2O and, with light, turn it into C6H12O6 (glucose) and 6O2.

     

    4. Ancient Energy & Modern Materials

    Even things that seem "dead" often owe their existence to photosynthesis:

    • Fossil Fuels: Coal, petroleum, and natural gas are essentially "bottled sunlight." They are the remains of ancient plants and organisms that lived millions of years ago.
    • Raw Materials: From the timber in your furniture to the rubber in your tires and the oils in your kitchen, these products are all biological results of photosynthetic processes.

     

    The Bottom Line: Photosynthesis is the bridge between the sun’s raw energy and the complex life we see today. It feeds us, lets us breathe, and keeps the planet’s chemistry in check.

     

     

     

    🔬 Knowledge Check: KS3 Photosynthesis

    Test your understanding of how plants produce food and the factors that affect this process.

    1. Which of the following is a waste product of photosynthesis that the plant releases into the air?

    2. In which specific part of a plant cell does photosynthesis occur?

    3. Through which tiny pores does carbon dioxide enter the leaf?

    4. What does a plant convert glucose into so it can be safely stored without affecting the cell's water balance?

    5. Which of the following is NOT considered a 'limiting factor' for the rate of photosynthesis?

    Click to Reveal Answers
    1. Oxygen (A byproduct released into the atmosphere).
    2. Chloroplasts (These organelles contain the chlorophyll needed to absorb light).
    3. Stomata (Tiny pores on the leaf surface that allow gas exchange).
    4. Insoluble starch (Starch is used for storage because it does not wash away).
    5. Amount of oxygen (The main limiting factors are light, carbon dioxide, and temperature).
    Tags:Chlorophyll, Light, Water, Carbon dioxide, Photosynthesis

     

     

     

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