Coordination and Response

what is the response to the stimulus light called?

phototropism

how do shoots respond to the stimulus off light and what do we call it?

they grow towards light we can say they are positively phototropic

how does plants growing towards the light increase their chance of survival?

when shoots grow towards the light it means plants can photosynthesis more as they can absorb more light by chlorophyll

what is the response to the stimulus gravity called?

geotropism

how do shoots respond to the stimulus off gravity?

they grow away from gravity, we say they are negatively geotropic

how do roots respond to the stimulus of gravity?

they grow towards the force of gravity, they are positively phototropic

how does roots growing towards gravity increase their chance chances of survival?

this ensures roots grow downwards into soil so they can take in water and mineral ions and anchors them

what do auxins do?

they control the growth at the tip of shoots and roots

what do auxins do in stems?

when the tip of the stem detects a stimulus is releases auxins. The auxins then move down the stem by diffusion where they cause the cells to elongate

what do auxins do in the roots?

when the tip of the root detects the stimulus it releases auxins which diffuse down the root. Auxins inhibit cell elongation slowing down the growth of cells

describe the differences in an animals response to light compared to the a plants response to light?

• in animals the eyes response involves electrical impulses and muscles and uses nerves

• plants use auxin

how do auxins causes positive phototropism in shoots?

• if light hits a shoot unevenly when the auxins diffuse from the tip they diffuse away from light so more of them are on the side that is in the shade

• this means that side grows faster than where there is less auxin

• causing the shoot to bend towards the light