What are the 3 environmental factors that affect the rate of photosynthesis?

1Temperature.


2Light intensity.


3Carbon dioxide concentration.

Answer in your head, out loud, or on paper, then tap the card to flip.

With reference to photosynthesis, what is a limiting factor?

A limiting factor is anything that constrains (limits) the rate of reaction.

Answer in your head, out loud, or on paper, then tap the card to flip.

Describe and explain how the rate of photosynthesis varies with temperature. 

The rate initially increases with temperature because the particles have more energy and move faster, so they react more frequently.


The highest rate occurs at the optimum temperature for the enzymes.


At higher temperatures, the rate decreases as bonds holding the enzymes together begin to break, so the enzymes change shape, meaning they're no longer as complementary to the substrates.


The rate falls to zero as the enzymes denature.

Answer in your head, out loud, or on paper, then tap the card to flip.

Why do farmers use greenhouses?

  1. Greenhouses help trap the heat energy from sunlight, and so increase the temperature.


  1. They keep out pests which could otherwise damage the plants.


  1. They make it easier to control the conditions, such as levels of carbon dioxide, fertiliser, water etc. 

Answer in your head, out loud, or on paper, then tap the card to flip.

What are paraffin heaters, and why are they used in greenhouses?

Paraffin heaters burn a fossil fuel called paraffin.


This produces carbon dioxide and heat energy, both of which help plants to grow.

Answer in your head, out loud, or on paper, then tap the card to flip.

The graph above should show how the rate of photosynthesis is affected by temperature.


What should the shape of the line be? 

Answer in your head, out loud, or on paper, then tap the card to flip.

The graph above should show how the rate of photosynthesis is affected by concentration of CO2.


What shape should the line be? 

Answer in your head, out loud, or on paper, then tap the card to flip.

The graph above should show how the rate of photosynthesis is affected by light intensity.


What shape should the line be? 

Answer in your head, out loud, or on paper, then tap the card to flip.

Which part of the above graph indicates that light is a limiting factor for photosynthesis?

Answer in your head, out loud, or on paper, then tap the card to flip.