1 / 11

Plant Tropisms

Plant Tropisms. What are we talking about?. Tropism - directional growth of a plant, or part of a plant, in response to an external stimulus. What are we talking about?. Stimulus – an action or condition that causes a response

ivo
Download Presentation

Plant Tropisms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Plant Tropisms

  2. What are we talking about? • Tropism - directional growth of a plant, or part of a plant, in response to an external stimulus

  3. What are we talking about? • Stimulus – an action or condition that causes a response • Response – an action or condition that is a reaction to a stimulus • Negative response – when the growth of a plant is away from the stimulus • Positive response – when the growth of the plant is towards the stimulus

  4. Types of Tropism • We are going to be studying 6 Tropisms: Thermotropism Hydrotropism Thigmotropism Gravitropism Heliotropism Phototropism

  5. Hydrotropism • Stimulus: Water • Response: A plant’s roots grow towards the source of water • Is this a positive or negative response?

  6. Thermotropism • Stimulus: Temperature • Response: a plant grows in the direction of/away from a source of heat or cold • Example: In the first picture, this tree has a positive response to the cold. • Example: A plant called a Rhododendron curls its leaves away when it experiences cold weather.

  7. Gravitropism • Stimulus: Gravity • Reaction: • Positive – the roots grow downward, with gravity • Negative – the stalk grows upward, against gravity

  8. Thigmotropism • Stimulus: Touch • Response – the leaves (or part of the plant that is touched) move or coil away from the touch, or trigger some other action • Example: The Venus Fly Trap is a plant that shows thigmotropism. It closes when a bug or some other object touches it.

  9. Photropism • Stimulus: Light • Response – the plant grows in the direction of a unidirectional light (it only comes from one direction) • What type of response is this?

  10. Heliotropism • Stimulus: Sunlight • Response – a plant grows or turns to face the direction of the sun • Example: Young Sunflowers face the sun all day long. As the sun goes across the sky, the sunflower turns so that it is always facing it. • Is a Sunflower growing towards the sun an example of Phototropism or Heliotropism?

  11. References • Pictures: • http://virtualastronaut.tietronix.com/textonly/act25/images/hydrotropism.gif • http://k53.pbase.com/u48/roving_rube/large/30489110.a.c.birch.jpg • http://www2.brevard.edu/jefrick/rhod.htm • http://www.xtec.cat/~mherna23/summer03/amspot/picture/gravitropism.gif • http://img1.photographersdirect.com/img/17231/wm/pd1198793.jpg • http://wpcontent.answers.com/wikipedia/commons/9/9d/Dionaea_muscipula_closing_trap_animation.gif • http://img1.photographersdirect.com/img/17231/wm/pd1198796.jpg • http://farm2.static.flickr.com/1423/1402179998_4e1712d584.jpg • Information: • http://www.hasc.qld.edu.au/csnotes06/biowedGG/Notes%20for%20Sandra/Plant%20Tropisms.doc • www.wikipedia.org

More Related