movement in plants continued. phloem phloem transport sugars, hormones and other organic molecules...
TRANSCRIPT
![Page 1: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/1.jpg)
Movement in Plants
continued
![Page 2: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/2.jpg)
Phloem• Phloem transport sugars, hormones and other
organic molecules throughout the plant. This process is called translocation.
• While xylem transport is generally one direction, the transport of materials within the phloem can go in any direction.
• In addition, phloem is composed of living cells. • How materials move within the phloem is yet to be
determined. • One of the most supported theories is the Pressure
Flow Hypothesis, also called the Mass Flow Hypothesis.
![Page 3: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/3.jpg)
• In the leaf, glucose is produced by photosynthesis and is converted into sucrose for transportation.
• The sucrose is actively transported into the cells of the phloem.
• This lowers the concentration of water in the phloem.
• Water from the xylem moves into the phloem by osmosis and increases the pressure in the phloem area.
• As the pressure increases, the sucrose will move to areas of lower pressure.
![Page 4: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/4.jpg)
• Once the sucrose arrives at the lower pressure areas it is actively removed from the phloem and into the surrounding cells.
• The cells will convert the sucrose back to glucose or another organic compound.
• When the sucrose is removed, the pressure drops as water also moves out of the phloem by osmosis.
![Page 5: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/5.jpg)
Tropisms• A Venus fly trap plant is one of
the few carnivorous plants that exist.
• Through highly sensitive hairs, the lobes of the Venus fly trap can rapidly close upon stimulation trapping the unsuspecting insect or spider.
• Once trapped inside, any movement by the insect triggers the lobes to close tighter and digestive enzymes are secreted by glands inside the lobes.
• This type of rapid movement is seen in very few plants.
![Page 6: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/6.jpg)
• http://www.arkive.org/venus-flytrap/dionaea-muscipula/video-00.html
• However, all plants show movement in response to an external stimulus like the sun, gravity or touch.
• This type of motion is called tropism. • If a plant moves towards the stimulus, then it
is a positive tropism. If the plant moves away from the stimulus, then it is negative tropism.
• Some parts of a plant may show positive tropism and other parts of the same plant may show negative tropism.
![Page 7: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/7.jpg)
Phototropism• This tropism is a response to
light. • The tips and stems of plants
demonstrate positive tropism as they grow towards the light.
• The roots of plants grow away from the light and are negatively phototropic.
• You will recall that the hormone auxin is released to stimulate growth in stem cells that are not exposed to sunlight.
![Page 8: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/8.jpg)
Geotropism or Gravitropism• This type of tropism is affected by gravity. • Roots will display positive tropism and stems
and shoots will demonstrate negative tropism. • Charles Darwin was one of the first scientists
to identify the growth responses in both roots and stems in relation to gravity.
![Page 9: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/9.jpg)
Thigmotropism• This growth movement is in
response to physical contact with another object.
• Ivy clinging to the surface of walls is an example of positive tropism.
• An example of negative tropism includes roots growing away from objects in the soil.
![Page 10: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/10.jpg)
Hydrotropism
• Growth of roots towards water is an example of a positive hydrotropism.
• Roots will gravitate towards a supply of water.
![Page 11: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/11.jpg)
Nastic Response• The movement shown by the Venus fly trap is
an excellent example of nastic movement. • The nastic movement of plants is not
dependent on the direction of the stimulus. • Rather the movements are random and are
not permanent.
![Page 12: Movement in Plants continued. Phloem Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation](https://reader036.vdocuments.us/reader036/viewer/2022082505/56649dd15503460f94ac764a/html5/thumbnails/12.jpg)
Homework
• Various tropism videos:• http://plantsinmotion.bio.indiana.edu/plantm
otion/movements/tropism/tropisms.html• http://www.nasa.gov/audience/foreducators/
topnav/materials/listbytype/Tropisms_of_Plants.html#.VWt2rtLBxjM