Respiration In Plant 2h72u

Respiration In Plants

Energy requirement in plants • The 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 Respiration • Plants 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 light • When 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 dark • Respiration 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 / m

Aerobic @ Anaerobic ? C6H12O6



2C2H5OH + 2CO2 + Energy

210 kJ / m

Aerobic respiration in plants

Anaerobic respiration in plants • Yeast 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 & Photosynthesis • Respiration is the reverse of photosynthesis.

Compare & Contrast Respiration & Photosynthesis Respiration

Photosynthesis

Similarities • Both take place in living cells. • Both are metabolic process.

Differences

Respiration

Photosynthesis

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

Respiration

Photosynthesis

Uses glucose and oxygen

Uses carbon dioxide and water

Produces carbon dioxide and water

Produces glucose and oxygen

Respiration

Photosynthesis

Chemical energy is converted into heat and energy ATP.

Solar energy is converted into chemical energy

Cell loses weight

Cell gains weight

CO2 concentrations in air around plants throughout the day

CO2

Day

O2

O2

night

CO2

Compensation point

O2

Light intensity

CO2

All the CO2 produced during respiration is reused during photosynthesis

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.