4.1 Photosynthesis Flashcards
Equation for photosynthesis in words:
Carbon dioxide + Water + Light = Sugars + Oxygen + a little Water
State the necessity for Chlorophyll and Light in Photosynthesis
Chlorophyll absorbs or captures light of specific wavelengths (red and blue) known as PAR (Photosynthetically Active Radiation) which is used in photosynthesis.
Light provides the Energy for photosynthesis to take place
Environmental factors that affect the rate of Photosynthesis: (4)
Temperature
Light (intensity & quality/PAR, duration)
Carbon dioxide
Water & mineral nutrients
How does temperature affect photosynthesis? (3)
If temps too to high or too low, it will inhibit photosynthesis
Photosynthesis increases to a maximum of 35 deg C.
Wilting at high temperatures will decrease photosynthesis (less light interception)
Stomata will close at high temperatures which decreases photosynthesis
How does light INTENSITY affect photosynthesis? (3)
Higher intensity produces higher rates of photosynthesis, up to an optimum level
No photosynthesis takes place in the dark (stomata close and CO2 not taken in)
Very high light intensities can damage chlorophyll and reduce rate of photosynthesis
How does carbon dioxide supply affect photosynthesis?
If the level of CO2 is increased, the rate of photosynthesis will be increased.
How does water supply affect photosynthesis? (2)
Reduced water supply results in stomatal closure, depriving plant of CO2 and reducing rate of photosynthesis
Insufficient water causes leaves to wilt and reduces absorption of light, so reduces rate of photosynthesis.
How does the availability of mineral nutrients affect photosynthesis?
Deficiencies will reduce photosynthesis.
Magnesium is a key component of chlorophyll
Trace metals are components of vital enzymes
Nitrogen is vital for healthy vegetation
What is the Law of Limiting Factors? (+ example)
This is where a process has more than one input or starting material
The rate of the process will be limited by one factor that is least available (even though other factors may be plentiful)
Photosynthesis example - if light levels are low the rate of photosynthesis will be limited, even if levels carbon dioxide and the temperature are perfect!
How can a grower optimise the conditions for photosynthesis? (3)
Provide the correct light wavelength when light levels are low or days are short (e.g. high pressure sodium light)
Ventilating to replace CO2 used, or introduce a CO2 gas to increase levels
Space plants correctly to allow maximum light interception
Where in a plant cell does photosynthesis take place?
In the Chloroplast
How does light QUALITY affect photosynthesis?
Photosynthesis uses light mainly from red and blue portion of spectrum - this is called PAR (Photosynthetically Active Radiation) - if not enough PAR is present (e.g. indoors or greenhouses), PAR bulbs can be used.
