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Tropism 2013 - 7th grade
The document discusses different types of plant movements or tropisms in response to environmental stimuli. It describes positive and negative tropisms where a plant grows toward or away from a stimulus. Specific tropisms discussed include phototropism where a plant grows toward light, geotropism where a stalk grows away from gravity and roots grow toward it, and hydrotropism where roots grow toward water. It also describes thigmotropism where a plant grows around surfaces it touches and nastic responses as fast, reversible movements. Videos are provided exemplifying these different tropisms.
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Tropism 2013 - 7th grade
- 1. Plant Tropisms The movementor growth of a plant in response to a stimulus…
- 2. ENVIRONMENT The environment ofan organism is made up of all of the factors that affect it. A habitat is a zone with a certain range of factors, such as a savannah. An organism has adaptations that help it survive in its habitat. The better adapted it is, the more chance it has of successful reproduction – survival of the fittest.
- 3. Plant Responses (Tropisms) Tropism is growth in response to an external stimulus (Stimulus is a factor that elicits a response). Positive tropism: Plant growth toward a stimulus (Ex. water, sunlight) Negative tropism: Plant growth away from a stimulus (Ex. spilled gas, toxins, too much sun or not enough)
- 4. So, plants canmove to respond to the environment. The stimuli for growth may be: Light Temperature Water Chemicals Gravity Touch
- 5. Some of theseways are: Phototropism Geotropism Hydrotropism Thigmotropism
- 6. Phototropism Phototropism isa change in the growth of a plant in response to light. The stalk displays positive phototropism growing towards the light.
- 7. Why? Maximize amount ofsun for photosynthesis to make their food.
- 8. Positive Phototropism Plant Illustrate phototropism onyour paper. Label your illustration as you would any scientific drawing. (See rules on your paper!) This stalk displays positive phototropism growing towards the light.
- 9. Time Lapse ofPlants Following Light https://www.youtube.com/watch?v=wjZ1UYwrO8A
- 10. Corn Dance After 3 daysof growth in darkness, the pot of corn seedlings in this movie were exposed to light from a single light bulb placed in the center of the pot just above the seedling. The plants were then imaged at 10 min intervals for about 18 hours. For the first 14 hours the seedlings appear to be dancing to the light as they maintain phototropic curvature. After 14 hours, the point light source was turned off and diffuse room lighting was turned on, at which point geotropism becomes the dominant stimulus and the seedlings quickly return to a vertical orientation. Frame playback is at 12 frames per sec. https://www.youtube.com/watch?v=RZDwoteRuqA
- 11. Geotropism (Gravitropism) Geotropism isa change in the growth of a plant in response to gravity. The stalk displays a negative geotropism growing away from gravity. The roots display a positive geotropism growing towards gravity. Negative Positive Write the definitions and illustrate them. Label your illustration as you would any scientific drawing.
- 12. Negative Geotropism Illustrate geototropism onyour paper. Label your illustration as you would any scientific drawing. (See rules on your paper!) This stalk displays NEGATIVE geotropism growing away from the gravity.
- 13. Positive Geotropism Illustrate geototropism onyour paper. Label your illustration as you would any scientific drawing. (See rules on your paper!) The roots display POSITIVE geotropism growing towards gravity.
- 14. Why? Allows plants togrow properly and get nutrients and sunlight http://www.youtube.com/watch?v=8SkKuwbmR5Y&feature=related&safety_mode=true&persist_safety_mode=1 Gravitropism
- 15.
- 16. Phototropism and Geotropism TimeLapse Montage https://www.youtube.com/watch?v=F3Oj2er-91s
- 17. Hydrotropism Hydrotropism isa change in the growth of a plant in response to water. The roots display a positive hydrotropism growing towards water. Positive Water illustrate Hydrotropism. Label your illustration as you would any scientific drawing.
- 18. Hydrotropism Why? Rootssearch for and grow toward water, because it is needed for photosynthesis and to support cell structure. Positive Water Illustrate hydrotropism. Label your illustration as you would any scientific drawing.
- 19. Thigmotropism Thigmotropism isa movement in which an organism moves or grows in response to touch or contact stimuli. Thigmotropism usually occurs when plants grow around a surface, such as a wall, pot, or trellis. Illustrate thigmotropism. Label your illustration as you would any scientific drawing. https://www.youtube.com/watch?v=m2xKjA69jNM
- 20. Thigmotropism Why? tosupport leaves as they grow higher to reach the sun to make more food (photosynthesis). Label your illustration as you would any scientific drawing.
- 21. NASTIC RESPONSES arefast, reversible movements and are non-directional. The movement can be caused by changes in turgor pressure or changes in growth. http://www.youtube.com/watch?v=O7eQKSf0LmY Hungry Venus flytraps snap shut on a host of unfortunate flies. But, despite its name, flies aren’t the flytrap's only meal. As long as its prey is roughly the right size and touches two of its hairs within twenty seconds, the plant will dine on any insect or spider that comes its way. Glands in the lobes then secrete enzymes that break the dinner down into a digestible soup. Ten days later, the trap pops open to reveal nothing but a dried out husk. Venus Flytraps: Jaws of Death - BBC One
- 22. Mimosa Pudica – TheSensitive plant https://www.youtube.com/watch?v=BLTcVNyOhUc
- 23. Plants in Action Wetend to think of plants as being essentially stationary incapable of movement other than that generated by the wind. But all plants do move as they grow and respond to aspects of their environment. https://www.youtube.com/watch?v=zmxY6aD7ltM