1. Slide 1 of 34 Copyright Pearson Prentice Hall Biology

2. Slide 2 of 34 Copyright Pearson Prentice Hall Chapter 23: Plants

3. 23–1 Specialized Tissues in Plants Slide 3 of 34 Copyright Pearson Prentice Hall Seed Plant Structure Plant Structure What are the three principal organs of plants? roots, stems, and leaves. These organs perform functions such as the transport of nutrients, protection, and coordination of plant activities.

4. 23–1 Specialized Tissues in Plants Slide 4 of 34 Copyright Pearson Prentice Hall Seed Plant Structure Roots: absorb water and dissolved nutrients. anchor plants in the ground. protect the plant from harmful soil bacteria and fungi.

5. 23–1 Specialized Tissues in Plants Slide 5 of 34 Copyright Pearson Prentice Hall Seed Plant Structure Stems provide: a support system for the plant body. a transport system that carries nutrients. a defense system that protects the plant against predators and disease.

6. 23–1 Specialized Tissues in Plants Slide 6 of 34 Copyright Pearson Prentice Hall Seed Plant Structure Leaves: are a plant’s main photosynthetic systems. increase the amount of sunlight plants absorb. Adjustable pores conserve water and let oxygen and carbon dioxide enter and exit the leaf.

7. 23–1 Specialized Tissues in Plants Slide 7 of 34 Copyright Pearson Prentice Hall What specialized cells make up vascular tissue? Vascular Tissue

8. 23–1 Specialized Tissues in Plants Slide 8 of 34 Copyright Pearson Prentice Hall Vascular Tissue Vascular tissue forms a transport system that moves water and nutrients throughout the plant.

9. 23–1 Specialized Tissues in Plants Slide 9 of 34 Vascular tissue is made up of xylem, a water- conducting tissue, and phloem, a food-conducting tissue. Copyright Pearson Prentice Hall

10. 23–1 Specialized Tissues in Plants Slide 10 of 34 Copyright Pearson Prentice Hall Types of Roots What are the two main types of roots? The two main types of roots are: taproots, which are found mainly in dicots, and fibrous roots, which are found mainly in monocots. Types of Roots

11. 23–1 Specialized Tissues in Plants Slide 11 of 34 Copyright Pearson Prentice Hall In some plants, the primary root grows long and thick. This primary root is called a taproot. A carrot is an example of a taproot. Taproot Fibrous Roots Types of Roots

12. 23–1 Specialized Tissues in Plants Slide 12 of 34 Copyright Pearson Prentice Hall Fibrous roots branch to such an extent that no single root grows larger than the rest. Fibrous roots are found in grasses. Types of Roots Fibrous Roots

13. 23–1 Specialized Tissues in Plants Slide 13 of 34 Copyright Pearson Prentice Hall Root Structure and Growth The root’s surface is covered with cellular projections called root hairs. Root hairs provide a large surface area through which water can enter the plant. Root hairs

14. 23–1 Specialized Tissues in Plants Slide 14 of 34 Copyright Pearson Prentice Hall Root Functions What are the different functions of roots? Roots anchor a plant in the ground and absorb water and dissolved nutrients from the soil.

15. 23–1 Specialized Tissues in Plants Slide 15 of 34 Copyright Pearson Prentice Hall Stem Structure and Function What are the three main functions of stems? Stems have three important functions: they produce leaves, branches and flowers they hold leaves up to the sunlight they transport substances between roots and leaves

16. 23–1 Specialized Tissues in Plants Slide 16 of 34 Copyright Pearson Prentice Hall Stem Structure and Function Stems make up an essential part of the water and mineral transport systems of the plant. Xylem and phloem form continuous tubes from the roots through the stems to the leaves. This allows water and nutrients to be carried throughout the plant.

17. 23–1 Specialized Tissues in Plants Slide 17 of 34 Copyright Pearson Prentice Hall Monocot and Dicot Stems The arrangemnet of tissues in a stem differs among seed plants. How do monocot and dicot stems differ?

18. 23–1 Specialized Tissues in Plants Slide 18 of 34 Copyright Pearson Prentice Hall Monocot and Dicot Stems Monocot Stems vascular bundles are scattered throughout the stem

19. 23–1 Specialized Tissues in Plants Slide 19 of 34 Copyright Pearson Prentice Hall Monocot and Dicot Stems Dicot Stems vascular bundles are arranged in a ringlike pattern Dicot Cortex Pith Vascular bundles Epidermis

20. 23–1 Specialized Tissues in Plants Slide 20 of 34 Copyright Pearson Prentice Hall Leaf Structure How does the structure of a leaf enable it to carry out photosynthesis? The structure of a leaf is optimized for absorbing light and carrying out photosynthesis.

21. 23–1 Specialized Tissues in Plants Slide 21 of 34 Copyright Pearson Prentice Hall Leaf Structure To collect sunlight, most leaves have thin, flattened sections called blades. Blade Stem Bud Petiole Simple leaf Compound leaf Leaflet

22. 23–1 Specialized Tissues in Plants Slide 22 of 34 Copyright Pearson Prentice Hall Leaf Structure Leaves are covered on the top and bottom by epidermis. Epidermis

23. 23–1 Specialized Tissues in Plants Slide 23 of 34 Copyright Pearson Prentice Hall Leaf Structure The epidermis of many leaves is covered by the cuticle. Epidermis Cuticle

24. 23–1 Specialized Tissues in Plants Slide 24 of 34 Copyright Pearson Prentice Hall Leaf Structure The cuticle and epidermal cells form a waterproof barrier that protects tissues inside the leaf and limits the loss of water through evaporation. The vascular tissues of leaves are connected directly to the vascular tissues of stems. In leaves, xylem and phloem tissues are gathered together into bundles that run from the stem into the petiole.

25. 23–1 Specialized Tissues in Plants Slide 25 of 34 Copyright Pearson Prentice Hall Leaf Structure All these tissues form the veins of a leaf. Xylem Phloem Vein

26. 23–1 Specialized Tissues in Plants Slide 26 of 34 Copyright Pearson Prentice Hall Leaf Functions Most leaves consist of a specialized ground tissue known as mesophyll. Palisade mesophyll Spongy mesophyll

27. 23–1 Specialized Tissues in Plants Slide 27 of 34 Copyright Pearson Prentice Hall Leaf Functions The layer of mesophyll cells found directly under the epidermis is called the palisade mesophyll. These closely-packed cells absorb light that enters the leaf. Palisade mesophyll

28. 23–1 Specialized Tissues in Plants Slide 28 of 34 Copyright Pearson Prentice Hall Leaf Functions Beneath the palisade mesophyll is the spongy mesophyll, a loose tissue with many air spaces between its cells. Spongy mesophyll

29. 23–1 Specialized Tissues in Plants Slide 29 of 34 Copyright Pearson Prentice Hall Leaf Functions The air spaces connect with the exterior through stomata. Stomata are porelike openings in the underside of the leaf that allow carbon dioxide and oxygen to diffuse into and out of the leaf. Stoma

30. 23–1 Specialized Tissues in Plants Slide 30 of 34 Copyright Pearson Prentice Hall Leaf Functions Each stoma consists of two guard cells. Guard cells are specialized cells that control the opening and closing of stomata by responding to changes in water pressure. Guard cells

31. 23–1 Specialized Tissues in Plants Slide 31 of 34 Copyright Pearson Prentice Hall Leaf Functions Transpiration The surfaces of spongy mesophyll cells are kept moist so gases can enter and leave the cells easily. Water evaporates from these surfaces and is lost to the atmosphere.

32. 23–1 Specialized Tissues in Plants Slide 32 of 34 Copyright Pearson Prentice Hall Leaf Functions Transpiration is the loss of water through its leaves. This lost water is replaced by water drawn into the leaf through xylem vessels in the vascular tissue.

33. 23–1 Specialized Tissues in Plants Slide 33 of 34 Copyright Pearson Prentice Hall Leaf Functions Gas Exchange How does gas exchange take place in a leaf? Plant leaves allow gas exchange between air spaces in the spongy mesophyll and the exterior by opening their stomata. Plants keep their stomata open just enough to allow photosynthesis to take place but not so much that they lose an excessive amount of water.

34. 23–1 Specialized Tissues in Plants Slide 34 of 34 Copyright Pearson Prentice Hall Leaf Functions Guard cells are specialized cells that control the stomata. Stomata open and close in response to changes in water pressure within guard cells.

35. 23–1 Specialized Tissues in Plants Slide 35 of 34 Copyright Pearson Prentice Hall Leaf Functions When water pressure within guard cells is high, the stoma open.

36. 23–1 Specialized Tissues in Plants Slide 36 of 34 Copyright Pearson Prentice Hall Leaf Functions When water pressure within guard cells decreases, the stoma closes.

37. 23–1 Specialized Tissues in Plants Slide 37 of 34 Copyright Pearson Prentice Hall Leaf Functions Plants regulate the opening and closing of their stomata to balance water loss with rates of photosynthesis. Stomata are open in daytime, when photosynthesis is active, and closed at night, to prevent water loss. In hot, dry conditions stomata may close even in bright sunlight, to conserve water.