Photosynthesis and ATP Flashcards
ATP is the immediate source of energy inside a cell. Describe how the synthesis and breakdown of ATP meets the energy needs of a cell. 6marks
In the cell, ATP is synthesised from ADP and Pi.
using energy from an energy-releasing reaction e.g. respiration.
The energy is stored as chemical energy in the phosphate bond.
ATP synthase catalyses this reaction,
ATP then diffuses to the part of the cell that needs phosphate.
which is catalysed by ATPase.
Chemical energy is released from the phosphate bond and used by the cell.
Where does the light-dependent stage occur?
Thylakoid membrane of chloroplast
Where does the light-independent stage occur?
Stroma of chloroplasts
What is the photolysis of water and explain its purpose?
Light energy splits water.
H20 –> 2H+ + 0.5 O2
Replaces lost electrons.
Describe how triose phosphate is produced in the calvin cycle. 6marks
RuBP and CO2 join together to form an unstable 6-carbon compound.
This reaction is catalysed by enzyme rubisco.
The compound breaks down into 2 molecules of G3P.
2 molecules of G3P are then converted to 2 molecules of TP.
The energy for this reaction comes from ATP
and the H+ ions come from rNADP
Explain briefly how ribulose bisphosphate (RuBP) is regenerated in the calvin cycle. 2marks
RuBP is regenerated from TP molecules.
ATP provides the energy for this.
Rubisco is an enzyme that catalyses the first reaction of the calvin cycle. CA1P is an inhibitor of rubisco. Explain the effect that CA1P would have on glucose production. 3marks
No G3P would be produced
so no TP would be produced
This means there would be no glucose produced.
Name the factors that could limit plant growth.
Temperature, light intensity, CO2 concentration.
How do commercial growers create optimum conditions in a glasshouse.
CO2 is added to the air by burning a small amount of propane in a CO2 generator.
Light can get in through the glass or lamps can provide light at night.
Glasshouses trap heat energy from sunlight, which warms the air. Heaters and cooling systems can also be used to keep a constant temperature, and air circulation systems make sure the temperature is even throughout the glasshouse.
