Plants Flashcards
What is the problem with phytoliths?
The silicon makes plants less digestible and grinds down teeth
When are insectivorous plants found?
Where there is a lack of nitrogen
What factors determine plant distribution?
Water. Nutrients. Grazing. Seed spreading.
What is the main feature of moving from aquatic to land?
Coping with water loss
How do plants get what they need on land?
- Water, limiting, soil
- CO2, air, stomata
- Light, high UV, leaves
- Minerals, vary, soil
When did stomata and cuticles start to appear?
When mosses evolved
What are the features of the liverwort?
- Primitive, undifferentiated leaves
- Pores
- Thick, waxy cuticles
- No roots has rhizoids
- Lives in damp gloomy conditions
What are the features of Oleander?
- Thick cuticle
- Multi layer epidermis
- Gas exchange happens at the bottom
- Stomatal pits on the underside
What do we see in higher plants?
Leaf layer specialization. Upper surface, = light harvesting impermeable to water. Lower surface = gas exchange.
What are guard cells?
- Pair guards stomata
- Symplastically isolated
- Have chloroplasts
What are the stages of stomata opening?
- Response to light
- H+ ions out, K+ ions out
- Starch is metabolized
- Results in a fall of water potential
- Water moves in
- Guard cells swell and stomata open
What is Phytohormone and what does it do?
- It’s an Abscisic Acid
- Plant signalling molecule
- Control of guard cell turgor by light can be overridden when water is scarce
- ABA binds to receptor on plasma membrane
- Triggers signalling cascade
What do stomata have to balance?
Rate of CO2 entering and water vapor exiting
What is water potential?
Measure of pressure - water declines = more negative
What happens when roots wilt?
ABA is triggered.
What does stomatal density depend on?
Concentration of CO2 eg low CO2 = more stomata
How can plants survive with less water?
- Deep roots
- Store water eg succulents
- Lose less water eg spikes
- Cope with very little amounts of water
- Have dormant seeds
What do cells in the epidermis do?
Have no photosynthetic capacity - help refract light into the cells which do
What is meant by autotroph?
Synthesis everything they need
Where does the Calvin Cycle occur?
Chloroplast
What is RuBisCO?
Enzyme for carbohydrate synthesis
What happens when light hits PSII?
- Energy from photons excite electrons
- Move along the photosystem
- Electrons are replaced by splitting water
How is ATP generated?
Protons released by splitting water accumulate in the lumen. Protons are moved through ATP synthase to make ATP.
How is NADPH produced?
Through the PSI complex