1. Do now! Can you stick the target sheets in please?
Can you then fill out the first column of the target sheet?
YouTube - Human ' Treeman ' begs for help as he turns into a tree.

2. 9c – Plants and photosynthesis

3. Plants use photosynthesis to make their own food
Water + carbon dioxide (+ light energy) glucose + oxygen
Reactants Products
Chlorophyll absorbs light energy to make photosynthesis happen
Most of the glucose is then turned into starch by the plant
Starch is an insoluble storage material
Photosynthesis only happens when it is light
YouTube - Photosynthesis Song
Plants use photosynthesis to make their own food

4. Plants respire too! glucose + oxygen Water + carbon dioxide (+ energy)
Reactants Products
Aerobic respiration (uses oxygen)
Happens all the time
Overall plants produce more oxygen by photosynthesis than they use by respiration
YouTube - Plant Physiology: Respiration (Britannica.com)

5. Leaves Waterproof layer protects leaf
Most photosynthesis occurs here (lots of chloroplasts)
Carry water
vein
Carry food
Controls size of stoma (plural = stomata)
Hole that lets carbon dioxide in and oxygen out by diffusion

6. Leaves Thin so that CO2 does not have to travel far to palisade cells
Photosynthesis faster in more light
Photosynthesis faster by increasing CO2 concentration
Less light = need for bigger leaves

7. Use of glucose by plants
Glucose molecules can be joined together (polymerisation) to make starch (a food store) or cellulose (cell walls) or fats
Glucose molecule

8. Use of glucose by plants
Glucose can also be turned into amino acids by combining with Nitrogen from nitrates.
Amino acids can be joined together to make proteins

9. Roots
Root hair cells have a large surface area to absorb more water

10. Xylem The water travels up xylem tubes to the leaves.
The water also contains minerals salts.

11. Phloem tubes
These transport dissolved glucose around the plant

12. Mineral salts
Nitrates needed to make proteins – too little = poor growth
Phosphates needed to make cell membranes and for root growth
Potassium needed to help enzymes for photosynthesis and respiration – too little = yellow leaves

13. Changing atmosphere
When the earth formed (around 4600 million years ago) the atmosphere was mainly carbon dioxide (produced by volcanoes)

14. Changing atmosphere
Around 3800 million years ago, algae evolved, which used photosynthesis to turn CO2 into glucose and oxygen.
The oxygen would have been poisonous to other organisms living at the time.

15. Changing atmosphere Today the atmosphere is 78% Nitrogen 21% oxygen
0.9% Argon
About 0.04 % CO2
Variable amounts of water vapour

16. Changing atmosphere
The composition of the atmosphere continues to change……WHY?

17. Homework
Read pages 26 to 35 of your book AT LEAST TWICE, due Friday 15th April
I wonder why he’s asked us to do that?
He must have a very good reason.