Photosynthesis Flashcards
What is another optimum condition for photosynthesis
Constant supply of water, too little and photosynthesis stops, too much the soil becomes waterlogged (reducing the uptake of minerals such as magnesium which is needed to make chlorophyll a)
What are the 3 main optimum conditions for photosynthesis
High light intensity of a certain wavelength
Temperature at around 25c
Carbon dioxide at 0.4%
Explain what is meant by a high intensity of light as an optimum condition for photosynthesis
Light is needed to provide energy for light-dependent reactions (higher the light intensity, the more energy)
Only certain wavelengths of light used for photosynthesis. The photosynthetic pigments chlorophyll a, b and carotene only absorb the red and blue light in sunlight (green reflected)
Explain what is meant by temperature around 25c as an optimum condition for photosynthesis
Photosynthesis involves enzymes (eg ATP synthase, rubisco) if the temp falls below 10c the enzymes become inactive, but if temp is more than 45c they start to denature.
At high temps, stomata close to avoid losing too much water, photosynthesis slows down as less CO2 enters leaf when stomata are closed
Explain what is meant by carbon dioxide at 0.4% as an optimum condition for photosynthesis
CO2 makes up 0.04% of gases in atmosphere, increasing this to 0.4% gives a higher rate of photosynthesis, any higher and stomata start to close
What is the saturation point
Where a factor is no longer limiting the reaction, something else has become the limiting factor
How is the carbon dioxide concentration managed in a glasshouse
CO2 is added to the air eg by burning a small amount of propane in a CO2 generator
How is light managed in a glasshouse
Light can get through the glass
Lamps provide light at night time
How is temperature managed in a glasshouse
They trap heat energy from sunlight which warms air, heater and cooling systems used to keep constant optimum temperature, air circulation systems make sure temp is even throughout glasshouse
Describe 4 ways in which conditions can be controlled in glasshouses to increase yields
Burning propane to increase air CO2 conc, adding heaters to increases temp, adding coolers to decrease temp, adding lamps to provide light at night
Examples of things that plants need energy for
Photosynthesis, active transport, DNA replication, cell division, protein synthesis
Examples of things that animals need energy for
Muscle contraction, maintenance of body temp, active transport, DNA replication, cell division and protein synthesis
ATP is the immediate sourced of energy in a cell. Describe how the synthesis and breakdown of ATP meets the energy needs of the cell
- A cell can’t directly get its energy from glucose
- In respiration, the energy released from glucose is used to make ATP
- It carries energy around the cell to where it is needed
- ATP is synthesised from ADP and inorganic phosphate using energy from an energy-releasing reaction, e.g. respiration. The energy is stored as chemical energy in the phosphate bond. The enzyme ATP synthase catalysed the reaction
- ATP diffuses to the part of the cell that needs energy
- It is then broken down back into ADP and inorganic phosphate. Chemical energy is released from the phosphate bond and used by the cell. ATPase catalysed this reaction
- The ADP and inorganic phosphate are recycled and the process starts again
Where do light dependent reactions take place
In thylakoid membranes
Where do light independent reactions take place
In the stroma
