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ZingPath: Plant Structure and Function

Nastic Movement

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Plant Structure and Function

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Lesson Focus

Nastic Movement

Biology

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You will learn how to familiarize yourself with the significant parts of plants, and what they do. Experiment on coleoptiles to discover how plants grow toward light, and test your knowledge of plant physiology by designing an award-winning xeroscape garden.

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Now You Know

After completing this tutorial, you will be able to complete the following:

  • Define nastic movements.
  • Explain nastic movements in a plant.
  • Give examples of plants with nastic movements.

Everything You'll Have Covered

What makes the leaves of a mimosa plant fold inward after they have been touched?

~ When mimosa leaf is touched, ions in its inner cells are transported outside the cells. Because of this, the inner cells lose water through osmosis, which lowers their osmotic pressure and causes the cells to shrink. Osmotic pressure is a hydrostatic pressure caused by a difference in the amounts of solutes between solutions that are separated by a semi-permeable membrane. In the mimosa plant, the outer cells do not lose water; therefore, they have a higher osmotic pressure, which pushes the inner cells and causes the leaf to fold.

Explain the process that occurs when the Venus flytrap closes and traps its prey inside.

~ When a fly touches the sensitive hairs on a Venus flytrap leaf, a signal is transmitted from cell to cell. Because of the osmotic pressure change in the cells receiving this signal, the leaf rapidly snaps shut, trapping the prey inside. This snapping action occurs in as little as 100 milliseconds.

What is nastic movement? Is it reversible or irreversible? Explain your answer.

~ Nastic movement is movement that happens independent of the direction of a stimulus. Nastic movements take place because of osmotic pressure changes and are therefore reversible. After some time, both the mimosa and Venus flytrap leaves return to their original positions after osmotic pressure has returned to normal. If the movements were to take place because of cell growth, they would be permanent and irreversible.

Tutorial Details

Approximate Time 2 Minutes
Pre-requisite Concepts Students should have an intellectual grasp on the following terms: mimosa, nastic movement, and osmotic pressure.
Course Biology
Type of Tutorial Animation
Key Vocabulary mimosa, nastic movement, osmotic pressure