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16.4: Plant Adaptations and Responses

Difficulty Level: At Grade Created by: CK-12
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Key Concept

Plants live just about everywhere on Earth, so they have evolved adaptations that allow them to survive and reproduce under a diversity of conditions. Various plants have evolved adaptations to live in the water, in very dry environments, or in the air as epiphytes. Like all organisms, plants detect and respond to stimuli in their environment. Their main response is to change how they grow. This is controlled by hormones.


  • NSES.9–12.C.6.2
  • AAAS.9–12.5.F.6

Lesson Objectives

  • Explain how plants have adapted to a diversity of environments.
  • Identify types of plant responses to environmental stimuli.

Lesson Vocabulary

  • epiphyte: plant that is adapted to grow on other plants and obtain moisture from the air
  • tropism: turning by an organism or part of an organism toward or away from an environmental stimulus
  • xerophyte: plant that is adapted to a very dry environment

Teaching Strategies

Introducing the Lesson

Bring a cactus plant to class. Challenge students to identify ways the cactus might be adapted to an arid habitat. Tell students they will learn more about plant adaptations such as these in this lesson.


Have students go to the URL below to observe different types of plant motions through time-lapse photography. Discuss what triggers and controls each type of motion.

Differentiated Instruction

Pair less proficient readers and English language learners with students who are excelling in the class. Ask partners to work together to create a cluster diagram of plant adaptations, with separate circles for adaptations to water, extreme dryness, and air. LPR, ELL


Have interested students explore how plants use chemicals to defend themselves from insect pests. The video and article at the URLs below are possible sources. Ask the students create a poster or PowerPoint to share what they learn with the rest of the class. Discuss with the class how natural plant defenses might be used to protect crop plants and reduce the use of chemical herbicides.

Science Inquiry

Assign the online activity Plant Adaptations to the Desert. Students will investigate the relationship between leaf surface area and water intake, as well as the function of waxy cuticle in limiting water loss.

Real-World Connection

Discuss why plants have been the source of many medicinal drugs. Give examples, such as aspirin from willow trees. You can find many other examples at the URL below.

Reinforce and Review

Lesson Worksheets

Copy and distribute the lesson worksheets in the CK-12 Biology Workbook. Ask students to complete the worksheets alone or in pairs as a review of lesson content.

Review Questions

Have students answer the Review Questions listed at the end of the lesson in the FlexBook®.

Points to Consider

In this chapter you read about the cells, tissues, and organs that make up plants. You also read about plant life cycles. Like plants, animals are complex organisms with tissues and organs. Animals also have life cycles.

  • How do the cells of animals differ from those of plants? What tissues and organs might be found in animals?
  • What is the general animal life cycle? How does it differ from the general life cycle of plants?

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