Topic 6 - 6.1 To 6.6 Photosynthesis Flashcards
(20 cards)
What is photosynthesis?
A chemical reaction that takes place inside photosynthesis organisms (eg plants, algae) converting light energy into chemical energy
Write the word equation for photosynthesis
Carbon dioxide + water - arrow - glucose + oxygen
Write the symbol equation for photosynthesis
6CO(2) + 6H(2)O - C(6)H(12)O(6)+6O(2)
() numbers in brackets are subscript
Why is photosynthesis important?
It produces glucose which has a wide range of uses:
Used in respiration to release energy
Converted to starch and stored - broken down to glucose when the plant requires energy
Used to make complex organic molecules which are used for growth, making up an organism’s biomass (transferred through food chains)
Where does photosynthesis take place?
Within chloroplasts
What type of reaction is photosynthesis?
An endothermic reaction that takes in energy (in the form of light)
What is chlorophyll?
A pigment found in chloroplasts that absorbs light
Describe the 2 main stage of photosynthesis
Chlorophyll absorbs light energy which is used to split water into oxygen gas (waste product) and hydrogen ions
Carbon dioxide combines with hydrogen ions to form glucose
What factors affect the rate of photosynthesis
Temperature
Light intensity
Carbon dioxide concentration
What is a limiting factor?
A variable that limits the rate of a particular reaction.
Explain how temperature affects the rate of photosynthesis
Higher temperatures provide more KE for enzymes involved in photosynthesis so the rate increases as temperature rises
The optimum temperature is usually 25oC
If the temperature becomes too high (around 45oC) enzymes become denatured and the rate of photosynthesis decreases
Draw a graph to show the effect of increasing temperature on the rate of photosynthesis
Explain how light intensity affects the rate of photosynthesis.
Rate of photosynthesis is directly proportional to light intensity, therefore as light intensity increases, the rate of photosynthesis increases.
Why does the rate of photosynthesis eventually plateau even if light intensity continues to increase? (Higher)
Another factor (temperature or Co2 concentration) becomes limiting.
Draw a graph to show the effect of light intensity on the rate of photosynthesis
How can the effect of light intensity on the rate of photosynthesis be measured in the lab (2)? Higher
Using a light meter
Using the inverse square law where:
Light intensity x (funny squiggal) 1 over distance 2 (superscript)
Why does the rate of photosynthesis decrease as the distance from a light source increases (higher)?
Light intensity is inversely proportional to the square of the distance from the light source. Thus, as the distance increases, light intensity decreases and the rate of photosynthesis decreases.
Explain how carbon dioxide concentration affects the rate of photosynthesis
As carbon dioxide concentration increases, the rate of photosynthesis increases
Why does the rate of photosynthesis eventually plateau even if CO2 concentration continues to increase? (Higher)
Another factor (temperature or light intensity) becomes limiting.
Draw a graph to show the effect of carbon dioxide concentration on the rate of photosynthesis.
