Chapter 5 Flashcards
(19 cards)
Plants and photosynthesis
Autotrophs
Create energy via photosynthesis
Light energy is harnessed to produce glucose
Producers
Photosynthesis equation
6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂. + 6H₂O
Light + carbon dioxide + water = (light and chlorophyll) glucose + oxygen
Grana
Optimal surface area to volume ratio
Stacks of disks
Stroma
The fluid filled space
Thykaloid membrane
Form stacks called grana
Light independent location
Thykaloid membrane
Light independent/ Calvin cycle location
Stroma
Light independent input and output
Inputs: light and water
Output: oxygen
Light dependent input and output
Input: carbon dioxide
Output : glucose
Light dependent steps
- Light energy excites electrons in chlorophyll
- Oxygen is released from the chloroplast
- Hydrogen and electrons generate atp and nadph
- ATP and nadph coenzymes
- Move to light independent stage
Light independent steps Calvin cycle
- Carbon fixation
- Reduction
- Regeneration
Rubisco
Rubisco
Enzyme
Controls first reaction ( carbon fixation) in light independent stage
Initial changes to carbon dioxide at the start of the Calvin cycle
Photo respiration
Occurs when rubisco binds to oxygen instead of carbon dioxide
Process is wasteful
Less photosynthesis therefore less glucose and energy
Factors affecting rubisco and photo respiration
Substrate concentration
Temp
Why does stomata open
Allow carbon dioxide to enter
Oxygen and water vapour diffuse out
Because rubisco needs carbon dioxide
C3 plants
85% of plants. Normal plants
Normal photosynthesis
No adaptations to reduce photorespiration
C4 plants
Light dependent stage is same as C3
Light independent occurs in bundle sheath
Photorespiration minimised and photosynthesis maximised
Good in hot climates
CAM plants
Adaptation to decrease photorespiration
Light dependent stage same as C3 and C4
Open stomata at night to let carbon dioxide in because photosynthesis during the day
Don’t open stomata during day to prevent water loss
High concentration of carbon dioxide near rubisco decreasing photorespiration
Water conservation
Requires more atp
Agricultural application of CRISPR CAs 9
Can edit genomes of agricultural crops potentially improving photosynthesis
Maximise crop productivity
1. Target rubisco function directly
2. Edit the function of chloroplasts to make them more efficient
3. Target stomata to reduce the impacts of water stress
