4.2 Respiration Flashcards
What is respiration?
Process in which plants produce energy from oxygen and glucose.
Plants respire by way of gas exchange through the stomata in the leaves - oxygen in, carbon dioxide out.
Mitochondria cells are the site of respiration.
What is Aerobic respiration?
This is efficient respiration - the process of producing cellular energy using oxygen.
Occurs throughout whole plant.
Equation:
Oxygen + Sugars (glucose) = Carbon Dioxide + Water + Energy (high yield)
What is Anaerobic respiration?
This is respiration without oxygen.
The breakdown of glucose in the absence of oxygen, to produce a small amount of energy.
e.g. in waterlogged conditions normal respiration shuts down.
The sugars (without the O2) ferment and turn to alcohol.
Equation:
Sugars = Carbon Dioxide + Ethanol + Energy (low yield)
What factors affect the rate of respiration?
Oxygen
Temperature
How does Oxygen affect aerobic Respiration?
A good level of Oxygen is needed for efficient respiration.
Oxygen breaks down sugars to release their energy efficiently.
Where the level is low, normal respiration will shut down - this results in Anaerobic respiration.
How does Temperature affect aerobic Respiration
Lower: respiration slows down
Higher: respiration speeds up
Optimum temp for respiration is around 37 deg C.
At around 60 deg C, respiration will fail and the plant will die (varies between species).
Describe areas of significance of anaerobic and aerobic respiration in horticultural situations (4)
Waterlogging: causes plant to go into anaerobic respiration, which will damage roots - lawns or crops will go yellow, and death may occur.
Propagation: extra Oxygen and Heat help quick rooting of cuttings.
Produce storage: respiration continues after crops are harvested, so the atmosphere can be controlled to keep certain produce at its best and avoid over-ripening - Temperature and O2 is reduced.
Seed storage: Airtight packaging - reduces respiration - seed will store for longer and won’t germinate.
State TWO distinct environmental factors that can be controlled to extend the length of time seeds can be stored:
Temperature - reducing seed refrigeration temperature to 5 deg C (or much lower in a seed bank) will reduce respiration rate to increase the storage time of seeds.
Oxygen - reducing oxygen concentration will reduce the respiration rate to increase the storage time of seeds.
What are the products of aerobic respiration?
Carbon dioxide, water and energy
Where is the cellular site of aerobic respiration?
The mitochondria
How does the rate of aerobic respiration affect seed storage?
The higher the respiration rate, the shorter the storage time (or the reverse!)
Describe the significance of aerobic respiration for propagation
Respiration is essential for growth of the embryo in seed germination or new roots in cuttings.
Compost must be well aerated to ensure a good supply of oxygen.
Respiration can be reduced to increase the length of time seeds can be stored.
