Structure and Function in Living Things

2. Structure and Function in Living Things

3. Chapter Sixteen: Plants • 16.1 What are Plants? • 16.2 Roots, Stems, and Leaves • 16.3 Reproduction in Flowering Plants

4. Investigation 16A Leaf Structure and Function • What are the structures that make up a leaf and how do they function?

5. 16.2 Roots, Stems, and Leaves • Death Valley in California, is one of the hottest and driest places on Earth. • Over 1,000 species of plants flourish there, such as the Joshua tree. • Twenty-three of those species are found nowhere else in the world.

6. 16.2 Roots, Stems, and Leaves • The body of a plant is made up of three distinct regions known as roots, stems, and leaves.

7. 16.2 Roots, Stems, and Leaves • Seed plants contain vascular tissues that carry water and nutrients from one end of the plant to the other. • There are two types of vascular tissues: • Xylemis a vascular tissue that carries water. • Phloemis a vascular tissue that carries sugars and other foods throughout the plant.

9. 16.2 Roots systems • The main functions of the root system are to collect minerals and water from the soil and to anchor the plant. • The root system consists of a larger primary rootand thinner secondary roots.

10. 16.2 Roots systems • The layer of cells that covers the surface of roots is called the epidermis. • Some epidermal cells grow outward into root hairs. • Root hairs increase the surface area and maximize the amount of substances a plant can absorb.

11. 16.2 Stems • Stems connect the roots that gather water and nutrients to the leaves that carry out photosynthesis.

12. 16.2 Stems • Like roots, stems are covered in a layer of epidermal cells. • They also contain vascular tissues. • But those tissues are arranged differently in stems than they are in roots.

13. 16.2 Stems • Some plants have thin and flexible stems called herbaceous stems. • Trees and shrubs have woody stemsand produce a tough material called wood.

14. 16.2 Stems • The main function of leaves is to use sunlight to make food during the process of photosynthesis.

16. 16.2 Stems • Stomataallow carbon dioxide to enter the leaf and oxygen and water vapor to exit. • Each stoma is opened and closed by guard cells.

17. 16.2 Movement of fluid in plants • The vascular system of a plant is a bit like your circulatory system which carries fluids throughout your body. • Water moves through the xylem by two forces— capillary action and transpiration.

18. 16.2 Transpiration • Transpirationis the loss of water through the stomata. • As water exits the stomata, it draws more water along the xylem. • When the stomata are closed, transpiration stops.

19. 16.2 Plant responses • Plants respond to a stimulus by growing either away or toward the stimulus. • Growth in response to a stimulus is called a tropism. A change in the growth of a plant due to light is called phototropism.

20. 16.2 Plant responses • Plants also grow in response to gravity (gravitropism). • If a plant is turned upside down, it will grow away from the pull of gravity and turn upward.