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Topic 4 Bioenergetics By Bethan Poole (4.1 Photosynthesis (Variegated…
Topic 4 Bioenergetics
By Bethan Poole
4.1 Photosynthesis
4.1.2 Rate of photosynthesis
Factors affecting photosynthesis
Light Intensity
As light intnsity increases rate of photosynthesis increses
Due to more energy being provided for the reaction
After a certain point , any increase in light intensity has no further effect
As light intensity no longer limiting factor
Chlorophyll Concentration
Amount of chlorophyll directly proportionate to amount of photosyntheis
CO2 Concentration
As conc. of CO2 increases rate of photosynthesis increases
Due to CO2 being needed for the reaction
After reaching a certain point , an increase in CO2 has no further effect
As CO2 is no longer limiting factor
Temperature
As temp. increases rate of photosynthesis increases
Due to more energy being provided for the reaction
As temp. reaches 45°C rate of photosynthesis to zero- enzymes controlling photosynthesis have been destroyed
Limiting Factor
- The factor that stops the reaction going any faster
Inverse Square Law
When light intensity is studied, doubling the distance between the lamp and the pondweed will reduce the light intensity by a quarter.
You square the amount the light has moved away
4.1.3 Uses of glucose from photosynthesis
Glucose used for
Produce fat or oil for storage
Produce cellulose- Strengthens cell wall
Converted into insoluble starch for storage
Produce amino acid- protein synthesis
Respiration
4.1.1. Photosynthesis reaction
Carbon Dioxide + Water -> Glucose + Oxygen
-
6CO2 + 6H2O-> (light energy) C6H12O6 + 6O2
Reaction-
Endothermic
Energy supplied by
Sunlight
Sunlight
trapped in
Chlorophyll
- found in
Chloroplasts
Variegated leaves
No chlorophyll
White patches
Don't photosynthesis
Grow slower
Starch Test
Plant in light will turn black with iodine as glucose produced- starch present
Plant in dark won't turn black as it won't have photosynthesised. As no glucose stored as starch uses glucose to respire
4.2 Respiration
4.2.2 Response to exercise
During exercise the body demands more energy so the rate of respiration needs to increase
Heart Rate, Breathing Rate and Breath Volume
all increase
Supply the muscles with more oxygen and glucose for the increase in aerobic respiration
Muscles may not get supplied with enough oxygen- Anaerobic respiration begins to take place
Causes lactic acid build up, creates oxyen debt
Lactic acid causes muscles to hurt- stops them contracting efficiently. Lactic acid= Poison, needs to got rid of quickly
Once exercise has finished oxygen debt must be "repaid"
Lactic Acid + Oxygen -> Carbon Dioxide + Water
4.2.1 Aerobic and Anaerobic respiration
Aerobic
(With oxygen)
Glucose+Oxygen-> Carbon Dioxide + Water
C6H12O6 + 6O2 → 6CO2 + 6H2O
A chemical reaction that releases a lot of energy for glucose using oxygen
Anaerobic
(Without oxygen)
In muscles
Glucose-> Lactic Acid
A chemical reaction that releases a little bit of energy from glucose without using oxygen
Plants, yeast and alcohol
Glucose-> Ethanol + Carbon Dioxide
In yeast it is called
fermentation
It is important in the manufacture of bread and alcoholic drinks
Respiration is
exothermic
Realeases energy from glucose molecules
Organisms need this energy for:
Chemical reactions to build larger molecules
Movement
Maintain body temperature
Continuously occuring in all cells
4.2.3 Metabolism
Sum of all chemical reaction in a cell or body
All reactions controlled by enzymes and many need a transfer of energy
This energy is transferred by respiration and used to make new molecules
Including:
Formation of lipid molecules from a molecule of glycerol and 3 molecules of fatty acids
Use of glucose and nitrate ions to form amino acids, which are use to synthesis proteins
Conversion of glucose to starch, glycegon and cellulose
Breakdown of excess proteins into urea for excreation
