ShmoopTube

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Here’s your shmoop du jour, brought to you by light…

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… the natural phenomenon that ruins your plans to catch some Zs until noon on Saturdays… [Boy in bed as the sun beams on his face]

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A plant’s response to light is known as…what?

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And here are the potential answers: Okay..Chemotaxis is the ability

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of a cell to detect certain chemicals in the environment, like amino acids and sugars. [amino acids and sugars travelling through tissue]

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Bacteria cells, including E-coli, swim toward plant roots like they’re being called home [E-coli cell moving towards a plants roots]

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for lunch.

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These bacteria are taken up into the roots where they’re used as nutrients.

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Sounds yummy.

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Sounds like… the wrong answer, too.

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Now onto circadian rhythms. [A jamaican band singing on stage]

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No, that’s not the newest reggae band to break into the Top 40.

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The term actually describes the biological clock of plant life.

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i.e. the flower petals closing at nightfall… [A flower petal closing at night time]

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…the leaves changing their position after dark…

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…and then the neighborhood rabbit eating most of your berries around midnight. [A rabbit eating a blackberry]

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OK, that’s not a true example of circadian rhythms, but Answer D isn’t true, either.

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So cross out D!

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Then there is answer B. Photoperiodism.

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Various plants respond differently to seasonal changes in the length of daylight. [Two different plants and a light bulb appears]

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Poinsettias and chrysanthemums have a certain… snob appeal toward shorter days.

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While lettuce and petunias are examples of plants that “party hearty” when days are [lettuce and petunias at the beach partying]

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longer.

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That is what photoperiodism is about…proving it is not the correct answer.

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Looks like the only one left is C.

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Phototropism is a response by plants to light from a particular direction. [A sunflower on the window sill responding to the sunlight]

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Ever notice how the leaves on that potted plant your mom has on the windowsill appear

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to be get real cozy with the glass?

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If you go ahead and turn that plant around 180 degrees… without dropping it… [Man turning a plant pot around]

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…come back in a few hours and its leaves will be pointed toward the window again.

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Welcome to the world of “tropisms”, and in particular phototropism, the correct answer

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to our exercise. [Phototropism circled as the correct answer]

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If you got this one right, you may spend some time near your favorite window.

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Don’t have too much fun… [Man stood waving by the window]

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