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

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

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

4. 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

5. 4. Describe how plants respond to the following stimuli:

6. What is the external stimulus for this plant response?

7. What is the external stimulus for this plant response?

8. a. Touch Plant bends and twists around any object it touches
Thigmotropism
Positive tropism

10. What is the external stimulus for this plant response?

11. b. Light
Plant bends toward light
Phototropism
Positive tropism

13. What is the external stimulus for this plant response?

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

15. Roots - Positive tropism

17. Stems - Negative tropism

20. What is the external stimulus for this plant response?

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

22. 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?

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

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

25. Plant response to a stimulus is called
photosynthesis
transpiration
tropism
locomotion

26. 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

27. 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.

28. 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

29. (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

30. (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
                                                     

31. 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.