14.2 pant growth factors Flashcards
(20 cards)
what is it called when something grows towards light?
positively phototropic
what is it called when something grows away from light?
negatively phototropic
what is it called when something grows away from gravity?
negatively gravitropic
what is it called when something grows towards gravity?
positively gravitropic
what is it called when something grows towards water?
positively hydrotropic
what is it called when something grows away from water?
negatively hydrotropic
give an example of a plant growth factor
indoleacetic acid (IAA)
are plant roots positively or negatively phototropic?
negatively phototropic
are plant roots positively or negatively gravitropic?
positively gravitropic
are plant roots positively or negatively hydrotropic?
positively hydrotropic
are plant shoots positively or negatively phototropic?
positively phototropic
are plant shoots positively or negatively gravitropic?
negatively gravitropic
are plant shoots positively or negatively hydrotropic?
negatively hydrotropic
what group of substances does IAA belong to?
auxins
role of IAA in elongation growth
- active transport of H^+ from the cytoplasm in the cell wall
- increase plasticity allowing the cell to elongate by expansion
what is the acid growth hypothesis?
proposed explanation of how IAA increases the plasticity of young cells
what does IAA do to shoots?
IAA stimulates growth in shoots
what does IAA do to roots?
IAA inhibits growth in roots
explain how the movement of IAA in shoots helps a plant to survive
- IAA moves towards the shaded side
- cells on the shaded side elongate faster than those on the light side
- shoot bends towards the light
- ensures that the shoot and leaves are in the sunlight
- needed for photosynthesis
suggest 2 advantages to a plant of having roots that respond to gravity by growing in the direction of its force
response ensures that roots grow down into the soil, anchoring the plant firmly and bringing them closer to water which is needed for photosynthesis
