Topic: Plants Aim: Describe the role of tropisms in plants.

1. Identify some external stimuli that plants respond to. Tough, light gravity

Movement caused by a change in growth 2. Describe tropisms. Movement caused by a change in growth

Negative: plant grows away from stimulus 3. Describe the difference between a negative and positive tropism. Negative: plant grows away from stimulus Positive: plant grows towards the stimulus

4. Describe how plants respond to the following stimuli:

What is the external stimulus for this plant response?

What is the external stimulus for this plant response?

a. Touch Plant bends and twists around any object it touches Thigmotropism Positive tropism http://www.youtube.com/watch?v=_SIJ4ov_FxA

What is the external stimulus for this plant response?

b. Light Plant bends toward light Phototropism Positive tropism

What is the external stimulus for this plant response?

c. Gravity Roots grow downwards Stems grow upwards Gravitropism or Geotropism

Roots - Positive tropism

Stems - Negative tropism http://bcs.whfreeman.com/thelifewire/content/chp38/3802001.html

http://www.youtube.com/watch?v=F3Oj2er-91s&feature=related

What is the external stimulus for this plant response?

Plant grows towards water Positive d. Water Hydrotropism Plant grows towards water Positive

5. Describe auxins. Plant hormones that causes plants to respond to stimuli. Tips covered Tips were removed Observe the diagram above. In which part of the plant are auxins produced?

Let’s summarize…. Describe tropisms. What are some examples of external stimuli that cause tropisms? Explain phototropism. Explain geotropism. Explain thigmotropism. Explain hydrotropism

Plant substances that affect plant growth are called tropisms glucose germination hormones

Plant response to a stimulus is called photosynthesis transpiration tropism locomotion

An example of a negative tropism is stems growing up and away from gravity plants bending towards light roots growing down towards gravity Plants growing towards a water source

Which has the favorable adaptation? Support your answer. What part of Darwin’s Theory of Natural Selection is this diagram representing? Variation Which has the favorable adaptation? Support your answer. Medium mice. They have the greatest population.

Identify The parts to Darwin’s Theory of Natural Selection. Differences among the organisms within a species exists. A species produces more offspring than can actually survive. Organisms will struggle with each other for limited resources. Overtime, a species can evolve into different species. Organisms that are most fit will survive, reproduce and pass on the trait to offspring. Variation Overproduction Competition Speciation Survival of the fittest

(2.) show no similarity as adults   According to one theory, similarities in these embryos suggest common ancestry. As these embryos mature, they will most likely  (1.) develop new organs according to the nutritional requirements of each organism  (2.) show no similarity as adults  (3.) continue to closely resemble each other as adults  (4.) develop the distinctive characteristics of their species

(1.) variation due to genetic mutations (2.) rapid fossil formation According to Charles Darwin, one factor that affects the evolution of a species is  (1.) variation due to genetic mutations  (2.) rapid fossil formation  (3.) survival of the fittest  (4.) exposure to environmental pollutants                                                      

Which of the following is most likely to cause an organism to become extinct? A mutation develops. The major change in the environment occurs and organisms cannot adapt. DNA is not readily passed on to offspring . Malnutrition occurs over an organism’s lifetime.