2101 - Photosynthesis & Respiration Flashcards
Photosynthesis equation
Carbon Dioxide + Water + Light Energy = Sugar + Oxygen
Respiration equation
Sugar + Oxygen = Carbon Dioxide +. Water + Energy
Respiration definition
Respiration is the process of releasing stored energy (from Photosynthesis) within the cell for growth and cell regulation.
occurs day and night
Aerobic respiration
- Conversion of Sugars and Oxygen into Carbon Dioxide and Water.
- Releases of a lot of energy.
- occurs in the mitochondria
- requires a source of oxygen, usually atmospheric
Anaerobic respiration
- Does not require Oxygen
- Conversion of Sugars to Ethanol and Carbon Dioxide.
- Release a small amount of energy.
- Occurs in the Cytoplasm
Anaerobic respiration occurs when…
There is not enough available Oxygen.
- Waterlogged soils
- Seeds stored in airtight storage
- Fruit in airtight storage
Short term ‘fix’ that enables energy production to continue in adverse conditions. Small energy release, also Ethanol build up which can cause tissue damage and lead to death.
Factors affecting Aerobic respiration
Respiration is at its highest in actively growing cells, during seed germination or cutting producing new roots.
- Oxygen Levels, As Oxygen levels fall the rate of respiration decreases. Increase will increase in Rate of Respiration, up to a point where it will flatten.
- Temperature, Respiration is enzyme driven, therefore rates increases with temperature. Increasing past the optimum temperature will decrease the Rate of Respiration and therefore the plant will be less productive and growth slows.
- Respiration rate below 5c is very slow. Increases rapidly to an optimum around 25/30c, then decreases again due to enzyme de-activation and stops at 40c.
Respiration in Horticultural situations
Reducing the Rate of Respiration in stored crops, fruit, seed and bulbs. Will keep fresh for longer.
Storage facilities may reduce temperature and replace oxygen with Nitrogen to limit the rate of respiration.
Photosynthesis
Co2 + H2o + Light Energy = Sugar + o2
Occurs in the chloroplasts of plants. Typically in the leaves.
Converts co2, h2o and light into high energy sugars easily transported around the plant.
Can be efficiently converted to starch for storage (and back again when needed).
Factors affecting Photosynthesis
Light Carbon Dioxide concentration Temperature Water Availability of Chlorophyll
Law of limiting Factor
The factor is least supply will limit the rate of Photosynthesis.
This factor must be raised in order to increase rate of Photosynthesis. Irrespective of the availability of other limiting variables.
Horticulturalists try to optimise levels of the limiting factors to maximise production.
Sub-Optimal, Optimal, Super-Optimal levels
Sub-Optimal levels, will reduce the rate of growth/productivity
Optimal levels, will allow for optimal growth
Super-Optimal levels, will typically damage the plant and reduce growth/productivity
Factors affecting Photosynthesis - Light
- Low Levels have insufficient energy to drive photosynthetic reactions.
- Too little will cause Stomata to close reducing co2 exchange limiting photosynthesis
- After optimum levels are reached rate of photosynthesis flattens off.
- Too much light, can lead to bleaching/scorching and the breakdown of chlorophyll. Resulting in less growth.
Species and situation dependant (eg desert plants or shade plants).
Factors affecting Photosynthesis - Quality of Light
- Photosynthetically active radiation to harness light energy. Blue and Red end of the spectrum are most absorbed.
(artificial lighting systems)
Factors affecting Photosynthesis - co2
- too little will affect rate of photosynthesis and slow growth.
- Can increase but flattens off quickly
- Too much results in an inability to respire, so growth is slowed but not directly because of photosynthesis
- add gas burner to green-house, or pump in co2