Bioenergetics Flashcards
Define photosynthesis.
The process by which plants use carbon dioxide, water and light energy to produce oxygen and glucose for energy.
What is the word equation for photosynthesis?
Carbon dioxide + water–> oxygen + glucose
What is the symbol eqn for photosynthesis?
6CO2+6H2O→C6H12O6+6O2
Where does photosynthesis occur?
In the leaves in chloroplasts which contain chlorophyll.
What kind of reaction is photosynthesis?
Endothermic (requires light energy)
How do carbon dioxide and water enter the plant for photosynthesis?
CO2- Diffuses through the stomata
Water- Absorbed by the roots into the xylem cells
What are the 5 uses for glucose?
1- Cellular respiration
2- Makes cellulose
3- Makes starch
4- Makes amino acids
5- Makes oils and fats
Why is cellulose made by glucose?
Complex carb that strengthens the cell wall
Why is starch made by glucose?
Better form of glucose for storage because its more compact + insoluble.
How and why are amino acids made by glucose?
Glucose is used to make amino acids by combining with nitrate ions from the soil which make proteins.
Why are oils and fats made by glucose?
For long-term energy stores.
What factors affect the rate of photosynthesis?
Light intensity, carbon dioxide, temperature and amount of chlorophyll
What type of graphs are made when measuring light intensity, CO2 levels and temperature as factors?
Light intensity + CO2 levels: Positive correlation then plateaus
Temperature: Increases until optimum temperature then falls
Explain light intensity as a factor of photosynthesis.
As light intensity rises, ROP also rises because light energy is needed for photosynthesis. It plateaus eventually because something else is a limiting factor.
Explain CO2 as a factor of photosynthesis.
As CO2 levels rises, ROP also rises because CO2 is needed for photosynthesis. It plateaus eventually because something else is a limiting factor.
Explain temperature as a factor of photosynthesis.
As temperature rises, there is an initial rise in ROP until the optimum temperature because enzymes have more energy to work faster. Then, the ROP slows down after the optimum as enzymes denature.
Why does the amount of chlorophyll affect ROP?
More chlorophyll = more light energy being absorbed for photosynthesis.
What’s the method for measuring rate of photosynthesis as light intensity changes?
Place a boiling tube 10cm away from an LED light (LED doesn’t release a lot of heat), fill the tube with sodium hydrogen carbonate solution which releases CO2, and put a pondweed cut at the top in it, leave 10 mins to acclimatize, should produce bubbles. Start a stopwatch and measure volume in cylinder above.
What are the problems involved in the experiment of light intensity affecting photosynthesis?
No. of bubbles may be difficult to count (record)
Size of bubbles may be different but counted the same (measure volume)
Describe the inverse square law.
As distance from light source increases, the light intensity falls by a factor of 4 because 1/d^2.
Define respiration.
An exothermic reaction which is continuously occurring in living cells to break glucose down to release energy.
What are the 4 uses of energy?
1- Movement (muscle contraction)
2- Protein synthesis
3- Maintaining body temp
4- Chemical reactions
Describe aerobic respiration.
Requires oxygen and only takes place when there’s enough. Its the most efficient way to transfer energy from glucose, happens in the mitochondria.
What’s the word formula for aerobic respiration?
Glucose + oxygen–> CO2 + water
