Respiration In Plants

Energy requirement in plantsThe energy requirement for living processes of plants is lower compared to animals. Why?

Because plants are less active than animals. Plants do not move about like animal do.

The Intake Of Oxygen By Plants For RespirationPlants do not have specialised breathing mechanisms for gaseous exchange.

Gaseous exchange between plants cells and the environment occurs by diffusion through stomata and lenticels.

stomata

lenticels

Gaseous exchange in the lightWhen the leaf is photosynthesising,

CO2 concentration in the air spaces of the spongy layer. (what will happen?)

O2 diffuses from the atmosphere through stomata into the leaf for cell respiration.

Gaseous exchange in the darkRespiration alone is taking place.

< O2 in the air spaces than atm. O2 diffuses inward though lenticels. Stomata are normally closed at night.

CO2 will diffuse outwards.

Aerobic & Anaerobic Respiration in Plants.C6H12O6 + 6O2 6CO2 + 6H2O + Energy 2880 kJ / mC6H12O6 2C2H5OH + 2CO2 + Energy 210 kJ / mAerobic @ Anaerobic ?

Aerobic respiration in plantsNeed O2, waste products are CO2 and water.

In the light, photosynthesis is faster than respiration. The CO2 produced is quickly used up by photosynthesis.

In the dark, respiration continues.

Anaerobic respiration in plantsYeast respires anaerobically to produce alcohol (alcoholic fermentation).During flooding, plants can survive for several days completely submerged in water.Young rice plants are planted in fields that are muddy and flooded.During initial stages of germination, embryo is completely enclosed within an airtight seed coat.

Respiration & PhotosynthesisRespiration is the reverse of photosynthesis.

Compare & Contrast Respiration & Photosynthesis

RespirationPhotosynthesisSimilaritiesBoth take place in living cells. Both are metabolic process.

Differences

RespirationPhotosynthesisA process of catabolism (breaking down of organic materials)A process of anabolism (synthesis of organic materials)Occurs in all living cellsOccurs in cells containing chlorophyll.Take place in the presence / absence of lightTakes place only in the presence of light

RespirationPhotosynthesisUses glucose and oxygenUses carbon dioxide and waterProduces carbon dioxide and waterProduces glucose and oxygen

RespirationPhotosynthesisChemical energy is converted into heat and energy ATP.Solar energy is converted into chemical energyCell loses weightCell gains weight

Light Intensity & The Compensation Point

CO2 concentrations in air around plants throughout the day

CO2O2Day

O2CO2night

O2CO2All the CO2 produced during respiration is reused during photosynthesisCompensation pointLight intensity

The Compensation Point The light intensity at which the rate of carbon dioxide production during respiration is equal to that of carbon dioxide consumption during photosynthesis.

If the rate of photosynthesis and the rate of respiration remained at compensation point:The plant would not be able to store food.

There would be no growth and development in green plants.

No oxygen released into the atmosphere to sustain living things.