PLANT RESPONSES

Read the article and decide for yourself Do plants have minds? ??? Read the article and decide for yourself

Do plants have stress? Do they respond?

What are some abiotic stresses faced by plants? *Turn to a partner & list some abiotic stresses faced by plants*

Abiotic Environmental Stresses -temperature (too hot, too cold) -amount of sunlight (too much, too little) -water availability (too much, too little) -lack of nutrients in soil -others you came up with??

What are some biotic stresses faced by plants? *Turn to a partner & list some biotic stresses faced by plants*

Biotic Environmental Stresses predators (omnivores/herbivores) disease (caused by bacteria, fungi, viruses and/or animals) competition with other plants others you came up with??

How do plants deal with these stresses? ADAPTATIONS!

Tropisms

Tropisms A tropism is “the turning of all or part of an organism in a particular direction in response to an external stimulus.” It is derived from Greek tropos meaning “turning”

Tropisms Can be Positive or Negative If a plant turns towards the stimulus, then it is a positive tropism. If a plant turns away from a stimulus, then it is a negative tropism.

Phototropism Phototropism is “the orientation of a plant or other organism in response to light, either toward the source of light (positive phototropism) or away from it (negative phototropism).”

Positive Phototropisms Stems exhibit positive phototropism when leaning towards light

Negative Phototropisms Roots exhibit negative phototropism when growing away from the light http://leavingbio.net/Plant%20Responses.htm#tropisms

Gravitropism Gravitropism is “the growth of a plant or other organism in response to gravity, either being pulled down by gravity (positive gravitropism) or growing against it (negative gravitropism).”

Positive Gravitropism Roots exhibit positive gravitropism when growing down towards gravity

Negative Gravitropism Stems & leaves exhibit negative gravitropism when growing up against gravity

Thigmotropisms are growth responses to touch

Positive Thigmotropisms Plant stems (tendrils) exhibit positive thigmotropism when they coil around an object. Venus fly traps exhibit positive thigmotropism when they snap shut at the touch of an insect landing inside

Negative Thigmotropisms Roots exhibit negative thigmotropisms when they grow away from or around an object in the soil