limiting factors Flashcards
What do plants need to photosynthesize (and grow as fast as they can)?
Light, warmth and carbon dioxide
How does light affect the rate of photosynthesis?
If there is plenty of light, lots of photosynthesis can take place; In low light, photosynthesis will stop
How does temperature affect the rate of photosynthesis?
As the temperature rises, the rate of photosynthesis increases as the reaction speeds up
What happens when the temperature gets too high during photosynthesis?
The enzymes controlling photosynthesis are denatured and the rate of photosynthesis will fall
Why does the rate of photosynthesis fall if the temperature get too high?
Most of the enzymes that control photosynthesis are denatured once the temperature rises to around 40–50ºC
Why do plants need carbon dioxide?
To make glucose
Why does carbon dioxide often limit the rate of photosynthesis?
Because the atmosphere is only about 0.04% carbon dioxide
How do carbon dioxide levels affect the rate of photosynthesis?
Increasing the carbon dioxide levels will increase the rate at which photosynthesis takes place
Why are carbon dioxide levels the most limiting factor for plants on a sunny day?
The carbon dioxide levels around a plant tend to rise at night, when the plant respires but does not photosynthesize
What happens to the carbon dioxide as light and temperature levels increase in the morning?
The carbon dioxide around the plant is used up
What occurs the more a plant photosynthesizes?
It produces more biomass and it grows faster
How can people artificially control the environment of their plants?
By using greenhouses or polytunnels
Why is artificially controlling the plants’ environment important?
The atmosphere is warmer inside than out, speeding up the rate of photosynthesis so the plants grow faster, flower and fruit earlier and produce higher yields
What do companies using big commercial greenhouses do to the carbon dioxide levels?
They are increased during the day when light levels are at their highest
What do companies using big commercial greenhouses do to the temperature?
They make sure the optimum temperature for enzyme activity is maintained all the time
What do companies using big commercial greenhouses do to the light?
Artificial lighting is used to prolong the hours of photosynthesis and to increase the light intensity
What can artificial lighting be used for?
It can be used to give year-round production by plants, and to grow plants out of their normal season or out of their normal habitat
What are some advantages of using greenhouses to control a plant’s environment?
= Turnover is fast, which means profits can be high
= The crops are clean and unspoilt
= There is no ploughing or preparing the land
= Crops can be grown where the land is poor
= Fewer staff are needed
What are some disadvantages of using greenhouses to control a plant’s environment?
= It costs a lot of money
= It takes a lot of energy to keep the conditions stable
