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Respiration
• Free Energy Is Released
and Incorporated into a
Form (ATP) that can Be
Readily Used for the
Maintenance and
Development of the
Plant cell
Definition
• Oxidation of Carbohydrates Carried out by
Enzymes and Living Systems
• Net Reaction Appears as the Reverse of PS
• The individual reactions that occur to achieve
the net effect are entirely different
Cells Net Chemical Reaction
C 6H 12 O 6 + 6 O 2+ 40 ADP + 40
Phosphates
6 CO 2+ 6 H2 O
+ 40 ATP
• Respiration Means to Turn Carbohydrates into
Usable Chemical energy (ATP) for many other Plant
Reactions including Photosynthesis
• All Living Plant and Animal Cells Carry out
Respiration
Respiration Occurs
• At same Time as Photosynthesis
• During the Night
• In Developing and Ripening Fruit
• In Dormant Seeds
Where does it occure ?
• Occurs in Mitochondria
of Cells
• Mitochondria are
membrane-enclosed
organelles distributed
through the cytosol of
most eukaryotic cells.
• Their main function is
the conversion of the
potential energy of food
molecules into ATP
Aerobic respiration
• Requires Oxygen
• Main Type of Respiration that Occurs in most
Situations in Plants and Animals
• Involves Complete Breakdown of Glucose
back to CO2 and Water
Main steps of respiration
Glucose
Glycolysis
ATP
NADH
Pyruvate
Acetyl Co A
Glycolysis
Acetyl Co A
TCA cycle
Citric
Acid
cycle
Co A
8 eOxidative
phosphorylation
ATP
2 CO2
Anaerobic respiration
• Fermentation
• Occurs in Low-Oxygen
Environments
• Wet or Compacted Soils for
Plants
• After Strong Exertion for
Animals
• ATP Is still Produced from
Glucose but not as
Efficiently as with Aerobic
Respiration
• Glucose + Oxygen →2
Ethanol + 2 Water + 2 ATP
Factors Affecting Respiration
Kind of Cell or Tissue
• Young and Developing Cells (Meristematic
Areas) usually Have Higher Respiration Rates
• Developing and Ripening Fruit and Seeds, too
• Older Cells and Structural Cells Respire at
Lower Rates
Temperature
• Respiration generally Has Higher Optimum and
Maximum Temps than PS
• Can Have Net Dry Matter Loss at High Temps
where Respiration Exceeds PS
• Temp Refers to Temp Inside Plant or Animal
Cell, not Air Temp
• Using Irrigation to Help Cool the Plant Can
Keep the Plant in Net Gain Range
Oxygen
• Low O2 Can Reduce Aerobic Respiration and
Increase Anaerobic Respiration
• Low O2 Can Reduce Photorespiration
Light
• Can Enhance Rate of Photorespiration
• Does not Directly Affect other Forms of
Respiration
Glucose
• Adequate Glucose Needed to Carry out
Respiration
CO2
• Higher CO2 Levels Reduce Rate of Respiration
• Feedback Inhibition
ATP
• Higher [ATP] Reduces Rate of Respiration
• Feedback Inhibition
Plant Injury
• Injury will Increase respiration, Plant’s Growth Rate
Increases in Attempt to Recover
• Plant Synthesizes Compounds to Fight Pests
• Diseases
• Some Herbicides Kill Plants by Disrupting or
Affecting Respiration