Plant Tropism PDF

PLANT TROPISM  Organisms, must adapt to their constantly- changing environments. Plants also respond to a stimulus, but they tend to respond more slowly than animals do. While animals are able to move from one place to another, plants, being sessile (unable to move), are unable...

PLANT TROPISM  Organisms, must adapt to their constantly- changing environments. Plants also respond to a stimulus, but they tend to respond more slowly than animals do. While animals are able to move from one place to another, plants, being sessile (unable to move), are unable to do the same and must find other ways of handling unfavorable environmental conditions.  Plant tropisms are mechanisms by which plants adapt to environmental changes. A tropism is a growth toward or away from a stimulus (causes a reaction or response). Common stimuli that influence plant growth include light, gravity, water, and touch. Plant tropisms are the result of differential growth. Positive tropism - growth towards the direction of a stimulus Negative tropism - growth away from a stimulus Phototropism From the prefix "photo" means "light," and the suffix "tropism" means "turning", phototropism is when plants turn or bend toward light. Positive Phototropism – growth towards the light source Negative Phototropism –  Plants need light to stimulate the production of energy; this process is called photosynthesis. Phototropism is likely a survival mechanism adopted by plants so that they can get as much light as possible. When plant leaves open toward light, more photosynthesis can take place, allowing for more energy to be generated. Thigmotropism The directional movement of plants in response to the stimulus of touch. Positive Thigmotropism - a plant, or a part of it, grows toward the touch stimulus Negative Thigmotropism - a plant, or a part of it, grows away from the touch stimulus Gravitropism Gravitropism or geotropism is growth in response to gravity Positive Gravitropism - occurs when roots grow into soil because they grow in the direction of gravity Negative Gravitropism - occurs when shoots grow up toward sunlight in the opposite direction of gravity. Hydrotropism Hydrotropism is directional growth in response to water concentrations. This tropism is important in plants for protection against drought conditions through positive hydrotropism and against water over-saturation through negative hydrotropism.  Positive Hydrotropism - is one in which the organism tends to grow towards moisture Negative Hydrotropism - is when the organism grows away from moisture Thermotropis m The movement of a plant or a part of plant in response to a change in temperatur e.  Positive Thermotropism - is when the growth or movement of an organism is towards the source of heat or cold Negative Thermotropism - is when the organism tends to grow or move away from the source of heat or cold Observable biological oscillations that occur with a 24-hour periodicity. Circadian Rhythm  Plant movements in response to a stimulus but are different from tropisms. Nastic movemen Tropisms is directional movements or growth response of a plant to the stimulus. t In nastic movements, the response of the plant is non-directional. THIGMONASTI C MOVEMENT QUESTION  ACTIVITY #1(SHORT BOND PAPER - PORTRAIT) Name: __________ Section: __________ Teacher: __________ Date: __________ Fill in the table below. Then draw an illustration to help you remember each word. PLANT TROPISM DEFINITION DRAW THE ILLUSTRATION 1. 2. 3. 4. 5.