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Plant Responses to the environment. “Tropisms”. Why is a sunflower called a sunflower?. What is a Tropism?. Tropism comes from the Greek word for “ Turning”
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Plant Responses to the environment “Tropisms”
What is a Tropism? • Tropism comes from the Greek word for “Turning” • So when an organism exhibits a tropism it either has a positive turning (toward the source) or a negative turning (away from the source) • Many organisms have tropisms
What kinds of tropisms do plants have? • Plants have 4 kinds of tropisms that we will learn about • Phototropism • Gravitropism • Hydrotropism • Thigmotropism
Phototropism • Photo means light • So a phototropism is a turning toward or away from light. • Plants stems and leaves exhibit positivephototropism, which means they turn toward light • Watch more phototropism videos here
Gravitropism • Gravi means gravity • So a gravitropism is a turning toward or away from gravity. • Plant roots exhibit positivegravitropism, which means they turn toward gravity. • Plant leaves and stems exhibit negative gravitropism, which means they turn away from gravity • Check out gravitropism videos
Hydrotropism • Hydro means water • So a hydrotropism is a turning toward or away from water. • Plant roots exhibit positivehydrotropism, which means they turn toward water
Thigmotropism • Thigmo means touch • So a thigmotropism is a turning toward or away from touch. • Some plant leaves and stems exhibit positivethigmotropism, which means they turn toward touch • Check out more thigmotropisms here
Plant AdaptationsWhen tropisms help survival • Sometimes plants can’t get all the resources they need. • Over long periods of times tropisms evolve into adaptations for survival
Plant AdaptationsWhen tropisms help survival • Cacti have taken hydrotropism to an extreme! • Cacti live in VERY dry, Very hot conditions so they have modifications to help them cope with the weather
Plant AdaptationsWhen tropisms help survival • Their roots are LONG and shallow to seek out water • They have also modified their leaves down into to tiny thorns to keep the water from evaporating • And their stems are filled with vascular tissue to store water
Plant AdaptationsWhen tropisms help survival • Venus Fly Traps and other carnivorous plants have taken thigmotropism to an extreme! • They live in nitrogen poor soil and can’t get enough nutrients from the soil
Plant AdaptationsWhen tropisms help survival • They use their touch sensitive fibers to know when an insect lands on their traps and then they close, digest the insect and suck up all the delicious nitrogen from the insect • Check it out here
Question 1 • Which of the following is false about tropisms? • A. they can be positive or negative • B. they only occur in plants • C. they happen when organisms move toward or away from something • D. they are natural occurrences
Question 2 • What does positive phototropism mean? • A. the organism moves toward light • B. The organism moves away from light • C. the organism moves toward the picture • D. the organism moves away from the picture
Question 3 • What part of the plant has a positive gravitropism? • A. the roots • B. the stem • C. The leaves • D. the flowers
Question 4 • Which tropism would help a cactus survive best? • A. phototropism • B. geotropism • C. hydrotropism • D. thigmotropism
Question 5 • Which tropism is being displayed most here? • A. phototropism • B. geotropism • C. hydrotropism • D. thigmotropism
Question 6 • Which tropism is being displayed most here? • A. phototropism • B. geotropism • C. hydrotropism • D. thigmotropism
Question 7 • Which tropism is being displayed most here? • A. phototropism • B. geotropism • C. hydrotropism • D. thigmotropism
Question 8 • What adaptations does this plant have? • A. thick stem to store water • B. tiny leaves to conserve water • C. long root system to search out water • D. all of the above
Question 9 • Where would you most likely find carnivorous plants? • A. nitrogen poor swamps • B. nutrient rich rain forests • C. temperate forest • D. all of the above