Biology: 2J Coordination and Response: Plants

What are directional growth responses made by plants in response to light and gravity known as?

Tropisms

What are tropism known as if the growth is toward/away from the stimulus?

towards tropism is positive

away tropism is negative

What is Phototropism?

Growth towards or away from the direction of the light source

What is an example of negative and positive phototropism?

Positive phototropism is the growth of shoot upwards.

Negative phototropism is the growth of roots downwards.

What is geotropism?

Growth towards or away from the source of gravity

What is an example of negative and positive geotropism?

Positive geotropism is roots grow downwards into the soil towards gravity

Negative geotropism is shoots grow upwards, away from gravity

What are auxins?

plant growth regulators that coordinate and control directional growth responses

Where are auxins produced?

mostly in the tips of growing shoots and then diffuses down to the region where cell division occurs

What do auxins do?

stimulates the cells in this region to elongate (get larger); the more auxin there is, the faster they will elongate and grow

What will happen if light is shown on one side?

auxin produced in the tip concentrates on the shaded side, making the cells on that side elongate and grow faster than the cells on the sunny side

causes the shoot to bend and grow in the direction of the light