PhotosynthesisL.O: To know the limiting factors for photosynthesisand explain how they affect the rate of photosynthesis.Be able to draw sketch graphs to show effect of limiting factors.

Photosythesis song

Watch the video. Click on www.vimeo.com/35073724

1.Write down the word equation.

2.Write down the symbol equation.

Weight Gain

• Plants make their own food via photosynthesis (chlorophyll in the leaves) with the energy coming from the Sun

Oxygen (given out)

Glucose (used by the plant)

carbon dioxide (from the air)

water (from the soil)

light energy

chlorophyll

Photosynthesis

• This is the process of food production for the plant (producing biomass) and requires the leaves to take place…

carbon dioxide + water glucose + oxygen

6CO2 + 6H2O C6H12O6 + 6O2

chlorophyll light energy

Limiting factors• List 4 factors that affect the rate of

photosynthesis? Explain why.

1.Light intensity2.Temperature - Click on the video link to find out

morehttp://espresso/espresso/clipbank/servlet/asset?assetID=4729

3. Amount of carbon-dioxide4. Amount of water

Sketch graph 1 A sketch graph includes title and a line of best fit ( no need to worry about units and scale).

Task 1 : Draw the graph (in pencil) then describe the graph (it’s pattern or shape) at stages 1, 2 and 3.

Suggest what limiting factors cause the graph to level off (stage 3)

1

2 3

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Photosynthesis and light – limiting factors

How does the amount of light affect the rate of photosynthesis on this labelled graph?

As the amount of light increases, the rate increases quickly . The limiting factor is light.

light intensity

rate

of

ph

oto

syn

thes

is

Here, increasing the amount of light has no affect on the rate. The limiting factor is now carbon dioxide or temperature.

What must be increased for the rate to increase?

1

2

1

2

Sketch graph 2 Task 2 : Draw the graph (in pencil) then describe the graph (it’s pattern or shape) in as much detail as you can.

Suggest what limiting factors cause the graph to level off (stage 3)

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Photosynthesis and carbon dioxide – limiting factors

How does the amount of carbon dioxide affect the rate of photosynthesis on this labelled graph?

As the amount of carbon dioxide goes up, so does the rate. The limiting factor is carbon dioxide.

concentration of carbon dioxide

rate

of

ph

oto

syn

thes

is

Here, increasing the amount of carbon dioxide has no affect on the rate. Light or warmth is now the limiting factor.

What must be increased for the rate to increase?

1

2

1

2

Sketch graph 3Task 3: Draw the graph (in pencil) then describe the graph (it’s pattern or shape) in as much detail as you can.

Suggest why this graph is a different shape.

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Photosynthesis and temperature – limiting factors

How does temperature affect the rate of photosynthesis on this labelled graph?

1. As temperature increases, so does the rate because photosynthetic enzymes work best in the warmth. Here, the limiting factor is temperature.

temperature

rate

of

ph

oto

syn

thes

is

0oC 45oC

Most plant enzymes are denatured (change shape) at about 45°C. Here, photosynthesis stops and the rate falls to zero.What is the limiting factor?

1

2

1

2

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Limiting factors activity

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Limiting factors in the greenhouse

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Anagrams