Plant coordination Flashcards
Give some examples of how plants respond to stimuli to increase their chances of survival
- Plant sense the direction of light and grow towards it to maximise the light for photosynthesis
- plants sense gravity so their roots and shoots grow in the right direction
- Climbing plants have a sense of touch so they can find things to climb in order to reach sunlight
What do some plants produce to avoid being eaten by predators (animals)?
Toxins
If plants respond to abiotic stress (and anything harmful that’s natural but nonliving like a drought) they are more likely to _______
Survive
What are auxins?
Plant growth hormones
What do auxins control?
Growth at the tips of shoots and roots. They moved through the plant in solution.
Where is auxin produced and where does it travel?
Auxin is produced in the tips and diffuses backwards to stimulate the cell elongation process which occurs in the cells just behind the tips
Auxin promotes growth in the shoots but _________ growth in the root
Inhibits
What does geotropic mean?
Grows away or towards gravity
What does positively phototropic mean?
Grows towards light
Shoots are positively phototropic. When a shoot tip is exposed to light, does it accumulate more auxin on the side that’s in the shade or in the light? What effect does this have on the shoot tip?
In the shade. This makes the cells grow faster on the shaded side so the shoot bends towards the light.
Shoots are negatively geotropic. When a shoot is growing sideways gravity produces an unequal distribution of oxygen on the tip with more oxygen on the low side what is the result of this?
The lowest side will grow faster bending the shoot upwards.
Roots are positively geotropic. A growing sideways will have more auxin on its lower side. What effect will this have?
The extra auxin inhibits growth which means the cells on top elongate faster so the root bends downwards
Roots are negatively phototropic. If a route is exposed to light more auxin accumulates on the shaded side. What effect will this have?
The auxin inhibits growth on the shaded side so the root ends downwards back into the ground. Roots under the ground grow downwards due to positive gravitropism.
