PLANT TROPISM Objectives n n n Identify tropisms

PLANT TROPISM

Objectives n n n Identify tropisms in plants. Examine effects of tropisms in plants. Recall differences in tropisms and effects of tropisms in plants.

What is Tropism? A growth movement whose direction is determined by the direction of the stimulus. n Tropisms cause a change in growth pattern. n

Two Types of Tropisms 1. Positive Tropism 2. Negative Tropism

Positive Tropism n Grows in the direction from which the stimulus originates. Growth toward the sun is a Positive Phototropism

Negative Tropisms n Growth away from the stimulus. Growth away from gravity is a Negative Geotropism

http: //www. cccmkc. edu. hk/~sbjbiology/AL%20 BIO/Continuity%20 of%20 life%20 growth%20 and%20 development/Growth%20 and%20 development_image/Tropism_image/Phototropism%20 in%20 mung%20 bean%20 seedling. jpg

4 TYPES OF TROPISMS Phototropism n Geotropism (Gravitropism) n Hydrotropism n Thigmotropism n

PHOTOTROPISM n Response to light

GEOTROPISM or GRAVITROPISM n Response to gravity

HYDROTROPISM n Response to water

THIGMOTROPISM n Response to touch

Summary What is a tropism? n A growth movement towards a stimulus. 4 Types of Tropisms n Phototropism-growth toward light. n. Geotropism-growth due to gravity. n. Hydrotropism-growth toward water. n. Thigmotropism -growth due to touch. n