Define the term limiting factor in the context of photosynthesis.

A limiting factor is a factor that limits the rate of photosynthesis .

What are the three factors that limit the rate of photosynthesis?

The three limiting factors for photosynthesis are: temperature light intensity carbon dioxide concentration

Why does the rate of photosynthesis slow down at low temperatures ?

Photosynthesis occurs slowly at low temperatures because molecules (such as enzymes involved in photosynthesis) have little kinetic energy . This means that fewer successful collisions take place.

Why do very high temperatures cause photosynthesis to stop?

At very high temperatures the enzymes that control photosynthesis denature , meaning that the reaction can no longer take place.

What is the effect of increasing light intensity on the rate of photosynthesis?

The higher the light intensity , the faster the rate of photosynthesis. This continues until another factor becomes limiting. ( Higher Tier Only )

True or False? In a graph of light intensity against the rate of photosynthesis, the part of the graph where the line is horizontal could indicate a point at which temperature is the limiting factor. ( Higher Tier Only )

True. In a graph of light intensity against rate of photosynthesis, the part of the graph where the line is horizontal is a point at which a factor other than light intensity is limiting. This factor could be temperature or carbon dioxide concentration .

True or False? The rate of photosynthesis increases consistently as temperature increases. ( Higher Tier Only )

False. The rate of photosynthesis only increases with temperature up to a certain point , after which higher temperatures lead to a decrease in the rate of photosynthesis. This is because high temperatures denature enzymes involved in the reactions of photosynthesis.

True or False? The rate of photosynthesis is inversely proportional to light intensity. ( Higher Tier Only )

False. The rate of photosynthesis is directly proportional to light intensity.

GCSEBiologyEdexcelFlashcards6. Plant Structures & their FunctionsPhotosynthesis

Photosynthesis (Edexcel GCSE Biology)

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FrontLimiting Factors
Define the term limiting factor in the context of photosynthesis.
FrontLimiting Factors
What are the three factors that limit the rate of photosynthesis?
BackLimiting Factors
The three limiting factors for photosynthesis are:
temperature
light intensity
carbon dioxide concentration

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Cards in this collection (17)

Define the term limiting factor in the context of photosynthesis.
A limiting factor is a factor that limits the rate of photosynthesis.
What are the three factors that limit the rate of photosynthesis?
The three limiting factors for photosynthesis are:
- temperature
- light intensity
- carbon dioxide concentration
Why does the rate of photosynthesis slow down at low temperatures?
Photosynthesis occurs slowly at low temperatures because molecules (such as enzymes involved in photosynthesis) have little kinetic energy. This means that fewer successful collisions take place.
Why do very high temperatures cause photosynthesis to stop?
At very high temperatures the enzymes that control photosynthesis denature, meaning that the reaction can no longer take place.
What is the effect of increasing light intensity on the rate of photosynthesis?
The higher the light intensity, the faster the rate of photosynthesis.
This continues until another factor becomes limiting. (Higher Tier Only)
True or False?
In a graph of light intensity against the rate of photosynthesis, the part of the graph where the line is horizontal could indicate a point at which temperature is the limiting factor. (Higher Tier Only)
True.
In a graph of light intensity against rate of photosynthesis, the part of the graph where the line is horizontal is a point at which a factor other than light intensityis limiting. This factor could be temperature or carbon dioxide concentration .
True or False?
The rate of photosynthesis increases consistently as temperature increases. (Higher Tier Only)
False.
The rate of photosynthesis only increases with temperature up to a certain point, after which higher temperatures lead to a decrease in the rate of photosynthesis. This is because high temperatures denature enzymes involved in the reactions of photosynthesis.
What is happening at point B on the graph? (Higher Tier Only)
At point B the graph has levelled off, indicating that a factor other than carbon dioxide concentration is limiting, e.g. temperature or light intensity.
True or False?
The rate of photosynthesis is inversely proportional to light intensity. (Higher Tier Only)
False.
The rate of photosynthesis is directly proportional to light intensity.
Why does bubble production decrease as distance between the light source and the aquatic plant increases in the graph shown? (Higher Tier Only)
The number of bubbles produced decreases as the light moves further away from the pondweed because the rate of photosynthesis is inversely proportional to the distance from a light source.
Light intensity decreases with distance; this means that rate of photosynthesis decreases and so less oxygen is produced.
What is the name of the law represented by the equation below? (Higher Tier Only)
$l i g h t i n t e n s i t y \propto \frac{1}{d i s t a n c e^{2}}$
The equation $l i g h t i n t e n s i t y \propto \frac{1}{d i s t a n c e^{2}}$ represents the inverse square law.
True or False?
Doubling the distance between the lamp and a plant will result in a quarter of the light intensity. (Higher Tier Only)
True.
Doubling the distance will result in a light intensity that is a quarter of what it was previously. This is due to the inverse square law, e.g.
At a distance of 10 cm = $l i g h t i n t e n s i t y \propto \frac{1}{10^{2}} = 0.01$
At a distance of 20 cm = $l i g h t i n t e n s i t y \propto \frac{1}{20^{2}} = 0.0025$
0.01 x 1/4 = 0.0025
What investigation can be carried out using the practical equipment below?
The equipment shown in the image can be used to investigate the effect of light intensity on the rate of photosynthesis.
What information is required to measure the rate of photosynthesis using the equipment below?
To measure the rate of photosynthesis we need to know the volume of gas collected and time period during which it has been collected.
What would the independent variable be in the investigation shown?
The independent variable is light intensity, which is controlled by altering the distance between the lamp and the beaker.
What would the dependent variable be in the investigation shown?
The dependent variable in this investigation is the rate of photosynthesis, which is measured by recording the volume of oxygen produced within a set time period.
Give two control variables for the investigation shown.
Control variables for this investigation would include:
- maintaining the same environmental temperature
- using the same species, length and age of plant in each repeat
- dissolving sodium hydrogen carbonate (NaHCO₃) in the water to maintain carbon dioxide levels

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