Nutrient uptake and the Nernst equation Flashcards
Whats the difference between accumulator and excluder ions ?
Accumulator ion concentrations are larger inside the plant cells than in the soil. Excluder ion concentrations are higher outside the cells than in.
Why do grasses uptake silicon when most exclude it ?
Grasses use the silicon to create sticky “glass teeth” seeds for dispersion.
What size are the gaps in the cell walls of plant cells ?
5nm
How do plants alter roots to accumulate nutrient ions ?
The root structure will extend to mine for the nutrients. The mass of the roots however does not change.
What is the symplast ?
The thin layer found just inside the plasma membrane of plant cells.
What is the endodermis of roots ?
The endodermis separates the transport vessels from the cortex of the roots. Inside is an impermeable waxy casparian strip which plugs the gaps allowing selective nutrient uptake.
How many different channel proteins can be found in the plasma membranes of plants ?
17
How are toxic ions excluded ?
Due to the lack of transport channels.
Theoretically why do plants hyperaccumulate toxic metals ?
To deter herbivores and pathogens
Where are hyperacumulated metals stored ?
In the vacuoles.
What is the Km constant in the nernst equation ?
The concentration of nutrient ions at 0.5 Vmax
What is the Vmax ?
The maximum uptake rate of external nutrient ions.
How do plants create a potential difference and what value is it ?
They pump Hydrogen ions out o the cell using H+ ATPase. Creaes -150mV potential difference
WHat is the Nernst potential ?
The difference in the electrical potentials that would hold an ion at equilibrium in a plant cell.
