Plant Internal Systems
Organize these words into a flow chart:
Sunlight
Soil
Water
Nutrients
Carbon Dioxide
Sugars
Minerals
Fertilizers
Oxygen
1
Seed Germination
What do seed need to germinate?
Water
germination
Heat
Click here for Radish seed germination video
2
Plant Hormones
Plants need to maintain their internal balance as well (homeostasis). As in animals, hormones act as chemical messengers to assist in regulating growth and responding to the external environment (light, gravity, nutrients, competition). Hormones also help plants respond to internal needs such as repair and reproduction.
3
Auxins
­cause the stem of the plant to bend towards light and roots to grow away from light
­in the stem, auxins are sent to the side of the plant that is away from light, causing the cells to elongate and bend the stem towards the light
­in the roots, auxins cause the root to grow downward with the pull of gravity. If the root is exposed to light, the auxins move to the side where there is light, causing the root to bend away from the light.
4
Gibberellins
­are produced in both the meristem (are of active growth as in at shoot and root tips) and in leaf chloroplasts
­increase the uptake of starch and stimulate the development of vascular tissue
­cause plants to grow stronger and taller and promote the development of fruits
­can be sprayed artificially to increase fruit size or cluster size (as in grapes)
Roadside spectacle
(not a result of gibberellins!)
5
Cytokinins
­promote cell division and cell differentiation
­produced in the roots
­delays the aging process in plants (used to make commercially sold cut flowers last longer)
6
Tropisms
­the way a plant responds to external stimuli from its external environment
Positive tropism ­ plant grows towards stimulus
Negative tropism ­ plant grows away from stimulus
Phototropism
­response to stimulus of light.
Shoots ­ positive phototropism
Roots ­ negative phototropism
Click for vid
7
Gravitropism
­plant response to gravity
Shoots ­ negative gravitropism
Roots ­ positive gravitropism
Click for vid
Thigmotropism
­plant response to contact/touch
Vines ­ positive thigmotropism allow them to coil around other objects
Click for vid
8
Attachments
root gravitropism_﴾converted﴿.mpg