1. BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor From PowerPoint ® Lectures for Biology: Concepts & Connections CHAPTER 31 Plant Structure, Reproduction, and Development

2. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings This giant sequoia, the General Sherman, is the largest plant on Earth –It is 84 m (275 ft) tall –Its trunk is 10m in diameter A Gentle Giant

3. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The General Sherman has been growing for about 2,500 years

4. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Growth rings mark each year in a tree's life –Rings vary in thickness depending on weather conditions during the growing season

5. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Humans depend on plant products –Lumber –Fabric –Paper –Food –Industrial chemicals

6. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Plants are vital to Earth's well-being –They provide food for land animals –They offer shelter and breeding areas for animals, fungi, and microorganisms –Their roots prevent soil erosion –Photosynthesis in plant leaves helps reduce carbon dioxide and adds oxygen to the air

7. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Katherine Esau was one of the twentieth century's most prolific plant scientists Her early research on sugar beets led to important discoveries about –phloem –viral infections of plant tissue 31.1 Talking About Science: Plant scientist Katherine Esau was a preeminent student of plant structure and function Figure 31.1A

8. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Dr. Esau later used an electron microscope to continue studying the relationship between plant structure and function She discovered that plant viruses are transmitted through plant tissues via plasmodesmata Figure 31.1B

9. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Angiosperms, or flowering plants, are the most familiar and diverse plants There are two main types of angiosperms –Monocots include orchids, bamboos, palms, lilies, grains, and other grasses –Dicots include shrubs, ornamental plants, most trees, and many food crops 31.2 The two main groups of angiosperms are the monocots and the dicots PLANT STRUCTURE AND FUNCTION

10. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Monocots and dicots differ in seed leaf number and in the structure of roots, stems, leaves, and flowers Figure 31.2 SEED LEAVESLEAF VEINSSTEMSFLOWERSROOTS MONOCOTS One cotyledon Main veins usually parallel Vascular bundles in complex arrangement Floral parts usually in multiples of three Fibrous root system Two cotyledons Main veins usually branched Vascular bundles arranged in ring Floral parts usually in multiples of four or five Taproot usually present DICOTS

11. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Root system –Provides anchorage –Absorbs and transports minerals and water –Stores food Root hairs increase the surface area for absorption 31.3 The plant body consists of roots and shoots

12. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Shoot system –Consists of stems, leaves, and flowers in angiosperms –Stems are located above the ground and support the leaves and flowers –Leaves are the main sites of photosynthesis in most plants

13. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 31.3 Terminal bud Blade Petiole Axillary bud Leaf Stem Taproot SHOOT SYSTEM ROOT SYSTEM Root hairs Internode Node Flower

14. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The terminal bud is located at the tip of a stem –It is the growth point of the stem Axillary buds can give rise to branches In apical dominance, the terminal bud produces hormones that inhibit the growth of axillary buds –This results in a taller plant that has greater exposure to light

15. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Roots and stems are adapted for a variety of functions –Storing food –Asexual reproduction –Protection Plant breeders have improved the yields of root crops by selecting varieties, such as the sugar beet plant, with very large taproots 31.4 Many plants have modified roots and shoots Figure 31.4A

16. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Modified stems include –runners, for asexual reproduction –rhizomes, for plant growth and food storage –tubers, for food storage in the form of starch Figure 31.4B STRAWBERRY PLANT POTATO PLANT IRIS PLANT Runner Tuber Taproot Rhizome Root

17. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Modified leaves include tendrils and spines –Tendrils help plants to climb –Spines may protect the plant from plant-eating animals Figure 31.4C

18. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 31.5 Plant cells and tissues are diverse in structure and function Figure 31.5A

19. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings There are five major types of plant cells –Parenchyma –Collenchyma –Sclerenchyma –Water-conducting cells –Food-conducting cells

20. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Parenchyma cells function in food storage, photosynthesis, and aerobic respiration Figure 31.5B Primary wall (thin) Pit

21. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Collenchyma cells provide support in parts of the plant that are still growing Figure 31.5C Primary wall (thick)

22. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sclerenchyma cells provide a rigid scaffold that supports the plant –Fiber cells Figure 31.5D Pits Primary wall FIBER Secondary wall Fiber cells

23. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –Sclereids (stone cells) Figure 31.5D continued Secondary wall Sclereid cells Primary wall Pits SCLEREID

24. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Water-conducting cells convey water from the roots to the stems and leaves –Chains of tracheids or vessel elements form a system of tubes for water transport Figure 31.5E Pits Vessel element Tracheids Pits Openings in end wall

25. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Food-conducting cells function in the transport of sugars, other compounds, and some mineral ions –Sieve-tube members are arranged end-to-end, forming tubes –Their end walls are perforated with plasmodesmata, forming sieve plates –At least one companion cell flanks each sieve- tube member

26. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 31.5F Sieve plate Companion cell Cytoplasm Primary wall

27. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Complex tissues are composed of more than one type of plant cell Vascular tissues are complex tissues that conduct water and food –Xylem contains water-conducting cells that convey water and dissolved minerals –Phloem contains sieve-tube members that transport sugars

28. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Roots, stems, and leaves are made of three tissue systems –The epidermis –The vascular tissue system –The ground tissue system 31.6 Three tissue systems make up the plant body Figure 31.6A Leaf Stem Root Epidermis Ground tissue system Vascular tissue system

29. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The epidermis covers and protects the plant –The cuticle is a waxy coating secreted by epidermal cells that helps the plant retain water The vascular tissue contains xylem and phloem –It provides support and transports water and nutrients

30. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The ground tissue system functions mainly in storage and photosynthesis –It consists of parenchyma cells and supportive collenchyma and sclerenchyma cells

31. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The ground tissue system of the root forms the cortex –The cortex consists mostly of parenchyma tissue The selective barrier forming the innermost layer of the cortex is the endodermis

32. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 31.6B Xylem Phloem Epidermis VASCULAR TISSUE SYSTEM GROUND TISSUE SYSTEM Cortex Endodermis

33. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings These microscopic cross sections of a dicot and a monocot indicate several differences in their tissue systems Figure 31.6C

34. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The three tissue systems in dicot leaves –The epidermis consist of pores called stomata (singular, stoma) flanked by regulatory guard cells Figure 31.6D

35. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –The ground tissue system of a leaf is called mesophyll and is the site of photosynthesis Figure 31.6D

36. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –The vascular tissue consists of a network of veins composed of xylem and phloem Figure 31.6D

37. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Most plants exhibit indeterminate growth –They continue to grow as long as they live In contrast, animals are characterized by determinate growth –They cease growing after reaching a certain size 31.7 Primary growth lengthens roots and shoots PLANT GROWTH

38. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Annuals complete their life cycle in a single year or growing season –Examples: wheat, corn, rice, and most wildflowers Biennials complete their life cycle in two years, with flowering occurring in the second year –Examples: beets and carrots Perennials live and reproduce for many years –Examples: trees, shrubs, and some grasses

39. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Growth in all plants originates in tissues called meristems –Meristems are areas of unspecialized, dividing cells Apical meristems are located at the tips of roots and in the terminal buds and axillary buds of shoots –They initiate primary growth, lengthwise growth by the production of new cells –Roots and stems lengthen further as cells elongate and differentiate

40. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 31.7A Terminal bud Axillary buds Arrows = direction of growth Root tips

41. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 31.7B Vascular cylinder Cortex Epidermis Root hair Cellulose fibers Apical meristem region Root cap DIFFERENTIATION ELONGATION CELL DIVISION

42. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 31.7C Apical meristem Leaves Axillary bud meristems 12

43. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings An increase in a plant's girth results from secondary growth Secondary growth involves cell division in two cylindrical meristems –Vascular cambium –Cork cambium 31.8 Secondary growth increases the girth of woody plants

44. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Vascular cambium thickens a stem by adding layers of secondary xylem, or wood, next to its inner surface –It also produces the secondary phloem, which is a tissue of the bark Cork cambium produces protective cork cells located in the bark

45. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 31.8A

46. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Everything external to the vascular cambium is considered bark –Secondary phloem –Cork cambium –Protective cork cells Heartwood in the center of the trunk consists of older, clogged layers of secondary xylem Sapwood consists of younger, secondary xylem that still conducts water

47. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A woody log is the result of several years of secondary growth Figure 31.8B Sapwood Heartwood Rings Wood rays Heartwood Sapwood Vascular cambium Bark Secondary phloem Cork cambium Cork

48. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The angiosperm flower is a reproductive shoot consisting of –sepals –petals –stamen –carpels 31.9 Overview: The sexual life cycle of a flowering plant PLANT REPRODUCTION Figure 31.9A Stigma Ovary Carpel Anther Petal OvuleSepal Stamen

49. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sepals are usually green and resemble leaves in appearance –Sepals enclose and protect the flower bud before the flower opens Petals are often bright and colorful –They attract insects (pollinators)

50. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stamens are the male reproductive organs of plants –Pollen grains develop in anthers, at the tips of stamens Carpels are the female reproductive organs of plants –The ovary at the base of the carpel houses the ovule

51. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The life cycle of an angiosperm involves several stages Figure 31.9B Ovary, containing ovule Fruit, containing seed Seed Embryo Germinating seed Seedling Mature plant with flowers, where fertilization occurs

52. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The plant life cycle alternates between diploid (2n) and haploid (n) generations Double fertilization is unique to plants 31.10 The development of pollen and ovules culminates in fertilization

53. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 31.10

54. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings After fertilization, the ovule becomes a seed –The fertilized egg within the seed divides to become an embryo –The other fertilized cell develops into the endosperm, which stores food for the embryo A resistant seed coat protects the embryo and endosperm 31.11 The ovule develops into a seed

55. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 31.11A Triploid cell OVULE Zygote Two cells Embryo Root SEED Shoot Endosperm Cotyledons Seed coat

56. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Seed dormancy is an important evolutionary adaptation in which growth and development are suspended temporarily –It allows time for a plant to disperse its seeds –It increases the chance that a new generation of plants will begin growing only when environmental conditions favor survival

57. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Comparison between dicot and monocot seeds Figure 31.11B Seed coat Embryonic leaves Embryonic root Embryonic shoot Cotyledons Fruit tissue Seed coat Endosperm Embryonic shoot Embryonic root Cotyledon Embryonic leaf Sheath COMMON BEAN (DICOT) CORN (MONOCOT)

58. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The ovary develops into a fruit which helps protect and disperse the seeds 31.12 The ovary develops into a fruit Figure 31.12A

59. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings There is a correspondence between flower and fruit in a pea plant –The wall of the ovary becomes the pod –The ovules develop into the seeds Upper part of carpel Ovule Ovary wall Sepal Seed Pod (opened) Figure 31.12B

60. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –The small, threadlike structure at the end of the pod is what remains of the upper part of the flower's carpel –The sepals of the flower stay attached to the base of the green pod Upper part of carpel Ovule Ovary wall Sepal Seed Pod (opened) Figure 31.12B

61. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Simple fruits develop from a flower with a single carpel and ovary –Apples, pea pods, cherries Aggregate fruits develop from a flower with many carpels –Raspberries Multiple fruits develop from a group of flowers clustered tightly together –Pineapples Figure 31.12C

62. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A seed starts to germinate when it takes up water, expands, and bursts its seed coat Metabolic changes cause the embryo to resume growth and absorb nutrients from the endosperm An embryonic root emerges, and a shoot pushes upward and expands its leaves 31.13 Seed germination continues the life cycle

63. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Pea germination (a dicot) Corn germination (a monocot) Figure 31.13A, B Embryonic shoot Foliage leaves Cotyledons Embryonic root Protective sheath enclosing shoot Embryonic root Cotyledon Foliage leaves

64. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Many plants can reproduce asexually via bulbs, sprouts, or runners Asexual reproduction often involves fragmentation –Fragmentation is the separation of parts from the parent plant and regeneration of those parts into whole plants 31.14 Asexual reproduction produces plant clones Figure 31.14A

65. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sprouts from the roots of a coast redwood tree may eventually take the place of its parent in the forest Figure 31.14B

66. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings These creosote bushes came from generations of vegetative reproduction by roots Figure 31.14C

67. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Most grasses can propagate asexually by sprouting shoots and roots from runners Figure 31.14D

68. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Propagating plants from cuttings or bits of tissue can increase agricultural productivity –But it can also reduce genetic diversity 31.15 Connection: Vegetative reproduction is a mainstay of modern agriculture

69. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Test-tube cloning is the growth of a plantlet from a few meristem cells cultured on a chemical medium – A single plant can be cloned into thousands of copies that will continue to grow when planted in soil –Orchids and certain pine trees used in mass plantings are propagated this way Figure 31.15A

70. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Protoplast fusion is the fusion of plant cells that have had their cell walls removed by treatment with enzymes –Plant species unable to interbreed in nature can be fused in the laboratory –This produces a hybrid plant with a desirable combination of traits Figure 31.15B

71. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings "GM" (genetically modified) plants are created when foreign genes are incorporated into a single parenchyma cell –The cell is then cultured until it develops into a new plantlet The commercial adoption of GM crops has been rapid –However, many people are concerned about the potential environmental risks associated with their use

72. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Monocultures are large areas of land planted with a single crop Gene-cloning techniques and monocultures have led to crop plants with little genetic diversity –This increases the likelihood that a small number of diseases could devastate large crop areas