1. Inquiry into Life Twelfth Edition
Lecture PowerPoint to accompany
Inquiry into Life Twelfth Edition
Sylvia S. Mader
Chapter 9
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 9.1 Plant Organs

3. 9.1 Plant Organs Vegetative Organs Reproductive Structures Roots Stems
Leaves
Reproductive Structures
Flowers
Seeds
Fruits

4. Organization of a Plant Body

5. Organization of a Plant Body

6. 9.1 Plant Organs
Roots
Generally, the root system is at least equivalent in size and extent to the shoot system
Anchors plant in soil
Absorbs water and minerals
Produces hormones
Root hairs:
Projections from epidermal root hair cells
Greatly increase absorptive capacity of root

7. 9.1 Plant Organs
Stems
The main axis of a plant that elongates and produces leaves
Nodes occur where leaves are attached to the stem
Internode is region between nodes
Stems have vascular tissue that transports water and minerals
In some plants, stems carry on photosynthesis, or store water and nutrients.

8. 9.1 Plant Organs
Leaves
Major part of the plant that carries on photosynthesis
Deciduous plants are those that lose their leaves every year.
Evergreens retain their leaves for two to seven years.
Foliage leaves are usually broad and thin
Blade - Wide portion of foliage leaf
Petiole - Stalk attaches blade to stem
Leaf Axil - Axillary bud originates

9. 9.1 Plant Organs Some Specialized Types of Leaves
Tendrils - Leaves that attach to objects
Bulbs - Leaves that store food
Some leaves are designed to protect buds, and in some cases leaves capture insects.

10. 9.2 Monocot Versus Eudicot Plants

11. 9.2 Monocot Versus Eudicot Plants
Cotyledons = seed leaves.
Flowering plants are divided into two groups dependent upon the number of cotyledons are present in the embryonic plant.
Monocots (one cotyledon)
Eudicots (two cotyledons)

12. Structural Differences in Monocots and Dicots

13. 9.3 Plant Tissue
Meristematic tissue allows plants to grow their entire lives.
Apical meristems are located at or near the tip of stem and roots, increasing the length of these structures.

14. 9.3 Plant Tissue Meristematic tissue gives rise to: Epidermal tissue
Ground tissue
Vascular tissue

15. 9.3 Plant Tissue Epidermal Tissue Specialized Epidermal Cells
Contains closely packed epidermal cells
Specialized Epidermal Cells
Epidermal cells exposed to air have a waxy cuticle
Minimizes water loss
Protection from disease
Root epidermis has root hairs
Absorb water
Anchor the plant

16. 9.3 Plant Tissue Specialized Epidermal Cells Trichomes Stomata
Protect the plant from too much sun
Produce toxic substances
Stomata
Gas exchange
Periderm contains cork cells
Protect the plant

17. Modification of Epidermal Tissue

18. 9.3 Plant Tissue Ground Tissue Ground tissue forms the bulk of a plant
Parenchyma cells
Collenchyma cells
Sclerenchyma

19. 9.3 Plant Tissue Parenchyma cells: Collenchyma cells:
Least specialized and are found in all organs of plant
Can divide and give rise to more specialized cells
Collenchyma cells:
Have thicker primary walls
Form bundles underneath epidermis
Flexible support to immature regions of the plant

20. 9.3 Plant Tissue Sclerenchyma cells:
Have thick secondary walls impregnated with lignin
Most are nonliving
Primary function is to support mature regions of the plant
Two types of sclerenchyma cells
Fibers
Sclereids

21. Ground Tissue Cells

22. 9.3 Plant Tissue Vascular Tissue Vascular tissue is for transport
Xylem transports water and minerals form the roots to the leaves
Phloem transports sucrose and other organic compounds (including hormones) from the leaves to the roots).
Xylem and phloem are complex tissues because they are composed of two or more types of cells.

23. 9.3 Plant Tissue Xylem has two types of conducting cells
Vessel Elements
Larger, with perforated plates in their end walls
Tracheids
Long, with tapered ends
Pits in end walls
Vascular rays
Fibers

24. Xylem Structure

25. 9.3 Plant Tissue Phloem Sieve-Tube Members Are the conducting cells,
Arranged to form a continuous sieve tube
Contain cytoplasm but no nuclei
Have a nucleated companion cell
Plasmodesmata extend from one cell to another through sieve plates

26. Phloem Structure

27. 9.4 Organization of Leaves

28. 9.4 Organization of Leaves

29. 9.4 Organization of Leaves
Leaf Diversity

30. Classification of Leaves

31. Leaf Diversity

32. 9.5 Organization of Stems

33. 9.5 Organization of Stems
Woody twigs provide a good example for studying stem organization.
Terminal Buds
Leaf Scars and Bundle Scars
Axillary Buds

34. Stem of a Woody Twig

35. 9.5 Organization of Stems Shoot Apical Meristem
Produces new cells for growth
Protected by leaf primordia
Primary Meristems
Protoderm
Ground Meristem
Parenchyma tissue

36. Shoot Tip and Primary Meristems

37. 9.5 Organization of Stems Herbaceous Stems
Mature nonwoody stems exhibit only primary growth
Outermost tissue covered with waxy cuticle
Stems have distinctive vascular bundles
Herbaceous eudicots - Vascular bundles arranged in distinct ring
Monocots - Vascular bundles scattered throughout stem

38. Herbaceous Stems

39. 9.5 Organization of Stems Woody Stems
Woody plants have both primary and secondary tissues
Primary tissues formed each year from primary meristems
Secondary tissues develop during first and subsequent years from lateral meristems

40. 9.5 Organization of Stems Woody Stems
Woody stems have no vascular tissue, and instead have three distinct regions
Bark
Wood
Pith

41. Secondary Growth of Stems

42. 9.5 Organization of Stems Bark
Bark of a tree contains cork, cork cambium, and phloem
Cork cambium produces tissue that disrupts the epidermis and replaces it with cork cells.
Cork cells provide waterproofing
Lenticels are pockets of loosely arranged cork cells that allow gas exchange
Phloem transports organic nutrients

43. 9.5 Organization of Stems Wood
Wood is secondary xylem that builds up year after year
Vascular cambium dormant during winter
Annual ring is made up of spring wood and summer wood
In older trees, inner annual rings no longer function in water transport
Annual rings can provide a growth record.

44. Three-Year-Old Woody Twig

45. Tree Trunk

46. 9.5 Organization of Stems Stem Diversity Stolons: Rhizomes:
Above-ground horizontal stems
Produce new plants when nodes touch the ground
Rhizomes:
Underground horizontal stems
Contribute to asexual reproduction
Variations:
Tubers - Enlarged portions functioning in food storage
Corms - Underground stems that produce new plants during the next season

47. Stem Diversity

48. 9.6 Organization of Roots Root Apical Meristem
Protected by the root cap
Three Regions
Zone of Cell Division
Zone of Elongation
Zone of Maturation

49. Eudicot Root Tip

50. 9.6 Organization of Roots Tissue of a Eudicot Root Epidermis Cortex
Endodermis
Casparian Strip
Vascular Tissue
Pericycle

51. Branching of A Eudicot Root

52. 9.6 Organization of Roots Monocot Roots
Ground tissue of root’s pith is surrounded by vascular ring
Have the same growth zones as eudicot roots, but do not undergo secondary growth

53. Monocot Root

54. Root Diversity
Primary root (taproot) - Fleshy, long single root, that grows straight down
Stores food
Fibrous root system - Slender roots and lateral branches
Anchors plant to the soil

55. Root Diversity Root Specializations
Adventitious roots - Roots develop from organs of the shoot system
Prop roots
Haustoria:
Rootlike projections that grow into host plant
Make contact with vascular tissue and extract water and nutrients
Mycorrhizas:
Associations between roots and fungi
Assist in water and mineral extraction
Root Nodules - Contain nitrogen-fixing bacteria

56. Root Diversity

57. 9.7 Uptake and Transport of Nutrients

58. 9.7 Uptake and Transport of Nutrients
Water Uptake and Transport
Water moves into root cells by osmosis; minerals by diffusion and active transport
Root pressure is generated by water moving into the roots pushes xylem sap
Root pressure can push xylem sap up to a height of about 10.4 meters
Many trees are taller, so other forces are necessary

59. 9.7 Uptake and Transport of Nutrients
Cohesion-Tension Model of Xylem Transport
Relies on the properties of water
Transpiration-evaporation from the leaves creates a “sucking” force that pulls water upward through the xylem
Adhesion-water molecules interact with the walls of the xylem vessels to reinforce strength of column
Cohesion-water molecules are attracted to each other and form a continuous column within xylem from leaves to roots
Tension-created by transpiration; reaches from the leaves to the roots as long as column is continuous

60. Cohesion-Tension Model of Xylem Transport

61. Conducting Cells of Xylem

62. 9.7 Uptake and Transport of Nutrients
Opening and Closing of Stomata
Each stoma in leaf epidermis is bordered by guard cells
Increased turgor pressure in guard cells opens stoma
Caused by active transport of K+ into guard cells

63. Opening and Closing of Stomata

64. 9.7 Uptake and Transport of Nutrients
Mineral Uptake and Transport
Epiphytes- “air plants” that grow on larger plants; absorb moisture from the air
Parasitic plants have haustoria that tap into the xylem and phloem of hosts
Carnivorous plants have various adaptations for catching insects
Root nodules- in leguminous plants, house nitrogen-fixing bacteria
Mycorrhizae - symbiotic relationship between roots and fungi that increases surface area for absorption and the fungi break down organic matter for the plant to absorb

65. Root Nodules

66. Mycorrhizae

67. 9.7 Uptake and Transport of Nutrients
Organic Nutrient Transport
Role of Phloem
Transports products of photosynthesis from the leaves to the site of storage
Pressure-flow Model of Phloem Transport
Sugars produced in the leaves are actively transported into sieve tubes; water follows by osmosis
The buildup of water in the sieve tubes creates pressure that starts the phloem sap flowing
Other plant organs serve as the “sink”- sugars are actively transported out for use or storage and water follows by osmosis
Phloem sap always flows from source to sink

68. Pressure-flow Model of Phloem Transport