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Science - 4th Grade
Standard 5 Objective 2
Students will understand the plants and animals found in Utah deserts and how these organisms have adapted to their environment.
Plants and animals will use many methods to survive in the environment available to them. Desert plants must adapt to their dry environment in a variety of creative and useful ways that allow them to survive.
One way is through changes in stomata. Stomata are the holes in plants leaves where water transpires. Many desert plants have very small stomata or fewer than normal. Cacti have stomata that are deep in the plants tissues, which reduces water loss.
The leaves and stems of many desert plants have a thick, waxy covering. This waxy substance also helps reduce moisture loss. Small leaves mean less evaporative surface per leaf. It also means that it won't get as hot as a large leaf would in the sun.
Some plants, such as Mormon tea and cacti, carry out most of their photosynthesis in their green stems. Some grow leaves during the rainy season and then shed them when it becomes dry again. Blackbrush only has photosynthesis during these rainy periods, and other plants can totally shut down photosynthesis to reduce water loss. Junipers have the ability to cut off water to a major branch during a drought, resulting in a dead branch but a live tree.
Other desert adaptation can be shallow widespread roots that will absorb a maximum of rainfall, or spines and hairs that shade the plants and break up drying winds across the leaf surface. Desert annuals avoid drought and heat by surviving as seeds stored in the soil, sometimes for many years.
Some desert plants take advantage of cooler temperatures at night to become "active." Plants like evening primrose bloom at night. The paintbrush plants use another adaptation. They are partial parasites. Their roots tap into nearby plant roots, usually sagebrush or grasses, and suck food and moisture from their host.
This investigation actually contains many different activities that you can choose to do. Some of the activities can take a few days to see the results. Plan ahead for the desired results.
1. Use a Science Process and Thinking Skills
Pre-Assessment/Invitation to Learn
Brainstorm ways that desert plants are different from or similar to wetland plants. Use a copy of the Venn diagram to summarize the student responses.
Homework and Family Connections
Go on a scavenger hunt in the familys backyard or an area nearby. Observe different kinds of plants and make observations about adaptations and physical characteristics they possess.
Desert origami books are a good product to assess student understanding of this concept. Share student products with a buddy class.