Plant Responses Flashcards
Define the term phototropism?
The directional growth response of a plant in response to light.
What are auxins?
They are growth factors that control the growth of a plant trough cell elongation.
How does Indoleacetic acid control positive phototropism in the shoots?
The IAA produced on the tips of the shoots diffuses into the shoot and moves into the side of the shoot that is not facing the light. It then promotes growth which causes the shaded side to grow more quickly compared to the side facing the sun. This causes the shoot to bend towards the light.
How does Indoleacetic acid control negative phototropism in the roots?
The IAA produced on the tips of the roots diffuses into the root and moves to the bottom of the root. It then inhibits growth which causes the shaded side to grow slower compared to the side that is illuminated. This causes the shoot to bend away from the light.
What is gravitropism?
The directional growth response of a plant in response to gravity.
How does Indoleacetic acid control negative gravitropism in the shoots?
The IAA produced on the tips of the shoots diffuses into the rest of the shoot. It then builds up in the lower side of the shoot and promotes growth, which causes the bottom side to grow faster compared to the top side. This causes the shoot to bend upwards and against gravity.
How does Indoleacetic acid control positive gravitropism in the shoots?
The IAA produced on the tips of the shoots diffuses into the rest of the shoot. It then builds up in the lower side of the shoot and inhibits growth, which causes the bottom side to grow slower compared to the top side. This causes the shoot to bend downwards.
