Phototropism is the growth of a plant towards or away from the sunlight. Photropism can be considered negative or positive. Postive photropism is when the shoot of a plant grows towards the light. Negative photropism is when the shoot of a plant grows away from the light. For example if the shoot of a grass was iluminated by one side, it would bend to the side that the light is coming from because the coleoptile, where the seedling is kept, was being lit up. However, if it was dark, it would keep growing up straight because there is no light for it to bend to.
In the picture below, phototropism is shown because the plant is bending towards the windowsill where sunlight is coming from. The plant receives the light, therefore naturally causing it to bend. It curves toward the light because of a higher concentration of the growth-promoting chemical on the darker side of the coleoptile.
Works Cited:
Campbell, Neil, Jane Reece, and Lawrence Mitchell. “Control Systems In Plants.” Biology. Fifth ed. Menlo Park: Jim Green Publishing, 1999. 752. Print.
No comments:
Post a Comment