seegongsik
Grade 6 (age 11-12)

grade 6 Photosynthesis

Plants do not eat other living things; they make their own food. Using sunlight, the leaves make food from water brought up from the roots and carbon dioxide from the air. This is photosynthesis. Photosynthesis also gives off the oxygen we need to breathe, so plants hand out both food and oxygen to many other living things. Change the amount of light to see how the oxygen bubbles from the leaf change, then look at a cut-through leaf to find where photosynthesis happens.

How do plants make food?

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🌱 What is photosynthesis?
①It is the process in which a plant uses light energy to make its own food.
②Ingredients: carbon dioxide from the air, water from the roots, and light.
③Products: food (glucose) and oxygen.
④Stronger light makes photosynthesis faster, but only up to a point.
⑤The food made is turned into starch, stored in the leaf for a while, then carried to other parts through the stem.

The parts of a leaf and their jobs

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🔬 The structure of a leaf
①Chloroplasts: green bodies inside leaf cells, where photosynthesis happens.
②Palisade layer: tightly packed cells near the top of the leaf, full of chloroplasts, where photosynthesis is busiest.
③Spongy layer: cells with lots of space between them, so gases move easily.
④Stomata: tiny holes, mostly on the underside, that let carbon dioxide in and oxygen and water vapor out.

Photosynthesis and respiration compared

Photosynthesis
Carbon dioxide + water + light → glucose + oxygen
It happens in the chloroplasts of leaves when there is light.
Respiration
Glucose + oxygen → carbon dioxide + water + energy
It happens in every living cell, day and night.
💡 Photosynthesis and respiration
①Photosynthesis: uses light to make food; it happens in chloroplasts when there is light.
②Respiration: breaks food down to get the energy needed to live; it happens in every cell, day and night.
③Photosynthesis uses carbon dioxide and gives off oxygen; respiration uses oxygen and gives off carbon dioxide.
④In the daytime photosynthesis outpaces respiration, so plants give off more oxygen than they use.

Summary

Photosynthesis in one line
Carbon dioxide + water + light energy → glucose + oxygen
The process by which plants make their own food.
🎯 Key points
①Photosynthesis: carbon dioxide + water + light → glucose + oxygen
②Where: in chloroplasts, the green bodies inside leaf cells
③Stomata: holes where carbon dioxide comes in and oxygen goes out
④Respiration breaks food down for energy, and it happens day and night.
⑤The food and oxygen that plants make are used by many other living things too.

Examples and Unit Test

Example 1
What three ingredients does photosynthesis need, and what two things does it make?
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Photosynthesis needs carbon dioxide, water and light energy.
2
It makes food (glucose) and oxygen.
▸ Ingredients: carbon dioxide, water, light / Products: glucose, oxygen
Turn the light down in the first picture and the oxygen bubbles get fewer.
Example 2
Where in the leaf does photosynthesis happen, and what are the tiny holes where carbon dioxide and oxygen pass in and out called?
1
Photosynthesis happens in chloroplasts, the green bodies inside leaf cells.
2
The tiny holes where carbon dioxide comes in and oxygen goes out are called stomata.
▸ Chloroplasts / stomata
In the second picture, chloroplasts are drawn in the palisade layer near the top and stomata on the underside.
Unit-test style
Which statement about photosynthesis is correct?
①Photosynthesis uses oxygen and gives off carbon dioxide.
②Photosynthesis uses light energy to make glucose.
③Photosynthesis happens mainly in the roots.
④The products of photosynthesis are carbon dioxide and water.
⑤Stomata are where the food made by photosynthesis is stored.
▸ ② Photosynthesis uses light energy to make glucose.
1
Photosynthesis uses light energy to turn carbon dioxide and water into glucose and oxygen.
2
Using oxygen and giving off carbon dioxide is respiration (①), photosynthesis happens in leaf chloroplasts (③), its products are glucose and oxygen (④), and stomata are holes for gases (⑤).
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