Rate of Photosynthesis

Rate of Photosynthesis

Learning Objectives:

- List the 4 factors that can limit photosynthesis

- Recognise the limiting factor in different environments

- Be able to draw and interpret graphs in relation to limiting factors

Make sure to take notes for your records.

Attempt all questions included in this lesson

Multiple Choice

What is Photosynthesis?

• The reaction where plants convert carbon dioxide and water into glucose and oxygen

• The reaction where plants convert glucose and oxygen into carbon dioxide and water

• The reaction where animals convert glucose and oxygen into carbon dioxide and water

• The reaction where plants use heat as the energy to convert carbon dioxide and water into glucose and oxygen

Multiple Choice

What is the name of the main pigment found in Chloroplasts.

• Chlorophyll

• Carotene

• Chlorofil

• Chlorophyle

Multiple Select

Which of these are the reactants for the photosynthesis reaction?

• Carbon Dioxide

• Water

• Glucose

• Oxygen

Multiple Select

Which of these are the two products of the Photosynthesis reaction?

• Glucose

• Oxygen

• Chlorophyll

• Water

Open Ended

What is the word equation for Photosynthesis?

Multiple Choice

What is the chemical formula for glucose?

• C₆H₁₂O₆
• C₆H₆O₁₂
• C₁₂H₆O₁₂
• C₆O₂H₆

Open Ended

What is the balanced symbol equation for Photosynthesis?

What does rate of reaction mean?

• The rate of reaction is a measure of how quickly reactants are converted into products.

• The rate of reaction is dependent on many different factors - we call these limiting factors.

• When a limiting factor is present it means the reaction can't happen any quicker.

Limiting factors in Photosynthesis

• There are 4 limiting factors for the reaction of Photosynthesis

• They are not always a limiting factor however. It is dependent on the environment around the plant as to which one is limiting at the time

• The four factors are: Light Intensity, Temperature, Carbon Dioxide and Chlorophyll

Poll

Before we discuss these in detail...

Which factor do you think could be the limiting factor at night?

• Light Intensity

• Temperature

• Chlorophyll

• Carbon Dioxide

Poll

In the winter which factor do you reckon would be the limiting factor?

• Light Intensity

• Carbon Dioxide

• Temperature

• Chlorophyll

Light Intensity

• Light is important to photosynthesis because it provides the energy needed for the reaction

• When Light intensity is low, it is the limiting factor, so if we increase the amount of light we will increase the rate of photosynthesis

Light Intensity

• This graph helps show the relation ship between Light and Rate.

• At point A = light is too low and limiting photosynthesis

• Point B = As light increases so does the rate of Photosynthesis

• Point C = Increasing the light no longer affects the rate, it is no longer a limiting factor

Carbon Dioxide

• Carbon Dioxide is one of the reactants for Photosynthesis

• When the levels of Carbon Dioxide is too low it will affect the rate of Photosynthesis

• As you increase the concentration of Carbon dioxide the rate of Photosynthesis also increases

• Until a point...

Carbon Dioxide

• This graph shows the relationship between the rate of reaction and concentration of Carbon Dioxide

• At point A = concentration of Carbon Dioxide is too low and the limiting factor

• Point B = Concentration increases and so does the rate of reaction

• Point C = Increasing the amount of Carbon Dioxide no longer increases the rate, therefore it stops being the limiting factor

Multiple Choice

Why is light needed for photosynthesis?

• Provides the energy needed for the reaction

• Creates the heat needed for the reaction

• Ensures that the plant can see the reactants

• Is one of the reactants

Multiple Choice

What happens when we increase the concentration of Carbon Dioxide?

• The rate of reaction increases

• The rate of reaction decreases

Open Ended

Do you have any questions?

Temperature

• Temperature affects photosynthesis because of the enzymes involved

• Enzymes are catalysts that decrease the amount of energy needed to get a reaction started

• Unlike the other two factors if the temperature is too high the whole reaction will stop.

• This is because the enzymes become denatured

Temperature

• When the temperature is too low the enzymes work slowly causing the rate of reaction to be low

• As you increase the temperature the rate begins to increase

• If it increases too high however the enzymes become damaged and the reaction slows

• The maximum temperature for enzymes varies in each plant but is always around 45^oC

Chlorophyll

• Chlorophyll is needed to convert the energy from sunlight needed for Photosynthesis.

• When the amount of Chloroplasts is depleted this causes not enough Chlorophyll to be made

• This lack of Chlorophyl is the limiting factor

• Disease, Lack of minerals and environmental stress all cause a lack of chlorophyll

Multiple Choice

Which one of these is not a limiting factor?

• Light Intensity

• Temperature

• Water

• Carbon Dioxide

Multiple Choice

Which factor, if too high, cause the reaction to stop completely?

• Light Intensity

• Temperature

• Carbon Dioxide

• Chlorophyll

Multiple Choice

It's a rainy day, there is a high level of cloud in the sky. Which factor is most likely limiting Photosynthesis today?

• Light Intensity

• Temperature

• Carbon Dioxide

• Chlorophyll

Multiple Choice

My plant has started to have black spots appear on its leaves.

Which factor is most likely the current limiting factor?

• Light Intensity

• Temperature

• Chlorophyll

• Carbon Dioxide

Multiple Choice

It is a sunny day, about 33^oC, blue sky. What factor would most likely be the limiting factor?

• Light Intensity

• Temperature

• Carbon Dioxide

• Chlorophyll

Multiple Choice

True or False: Limiting factors change all the time and are dependent on the environment

• True

• False

Open Ended

Checkout Question:

What are the four limiting factors that can affect the rate of photosynthesis?

Pick one and describe the relation of the factor and photosynthesis.

Include: 1) When the factor is too low 2) When the factor is increasing 3) When the factor is high

Poll

How confident are you on Photosynthesis and it's limiting factors? (Out of 5)

• 1

• 2

• 3

• 4

• 5