1 / 118

Specialized Tissues in Plants

Specialized Tissues in Plants. Seed Plant Structure. The three principal organs of seed plants are roots, stems, and leaves. These organs perform functions such as the transport of nutrients, protection, and coordination of plant activities. Seed Plant Structure. Roots:

carterr
Download Presentation

Specialized Tissues in Plants

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Specialized Tissues in Plants

  2. Seed Plant Structure • The three principal organs of seed plants are roots, stems, and leaves. • These organs perform functions such as the transport of nutrients, protection, and coordination of plant activities.

  3. Seed Plant Structure • Roots: • absorb water and dissolved nutrients. • anchor plants in the ground. • protect the plant from harmful soil bacteria and fungi.

  4. 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.

  5. 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.

  6. Plant Tissue Systems • Plants consist of three main tissue systems: • dermal tissue • vascular tissue • ground tissue

  7. Seed Plant Structure Leaf Stem Root

  8. Dermal Tissue • Dermal tissue is the outer covering of a plant and consists of epidermal cells. • Epidermal cells make up dermal tissue. • Epidermal cells are covered with a thick waxy layer, called the cuticle, which protects the plant against water loss and injury.

  9. Dermal Tissue • Some epidermal cells have projections called trichomes, that help protect the leaf and also give it a fuzzy appearance. • In roots, dermal tissue includes root hair cells that provide a large amount of surface area and aid in water absorption. • On the underside of leaves, dermal tissue contains guard cells, which regulate water loss and gas exchange.

  10. Vascular Tissue • Vascular tissue forms a transport system that moves water and nutrients throughout the plant. • Vascular tissue is made up of xylem, a water-conducting tissue, and phloem, a food-conducting tissue.

  11. Vascular Tissue • Vascular tissue contains several types of specialized cells. • Xylem consists of tracheids and vessel elements. • Phloem consists of sieve tube elements and companion cells.

  12. Vascular Tissue Cross Section of a Stem Tracheid Companion cell Sieve tube element Vessel element Phloem Xylem

  13. Vascular Tissue • Xylem • All seed plants have tracheids. • Tracheids are long, narrow cells that are impermeable to water, but they have holes that connect cells. Tracheid Vessel element

  14. Vascular Tissue • Angiosperms also have vessel elements. • Vessel elements form a continuous tube through which water can move. Tracheid Vessel element

  15. Vascular Tissue • Phloem • Phloem contains sieve tube elements and companion cells. • Sieve tube elements are phloem cells joined end-to-end to form sieve tubes. Companion cell Sieve tube element

  16. Vascular Tissue • The end walls of sieve tube elements have many small holes that sugars and other foods can move through. Companion cell Sieve tube element

  17. Vascular Tissue • Companion cells are phloem cells that surround sieve tube elements. • Companion cells support sieve tubes and aid in the movement of substances in and out of the phloem. Companion cell Sieve tube element

  18. Between dermal and vascular tissues are ground tissues. • Three kinds of ground tissue: • Parenchyma- thin walls and large central vacuoles • Collenchyma- strong, flexible cell walls that help support larger plants • Sclerenchyma- extremely thick, rigid cell walls = tough and strong

  19. Plant Growth and Meristematic Tissue • In most plants, new cells are produced at the tips of the roots and stems. • These cells are produced in meristems. • A meristem is a cluster of tissue that is responsible for continuing growth throughout a plant's lifetime.

  20. Plant Growth and Meristematic Tissue • The new cells produced in meristematic tissue are undifferentiated. • As the cells develop into mature cells, they differentiate to produce dermal, ground, and vascular tissue.

  21. Plant Growth and Meristematic Tissue • Near the tip of each growing stem and root is an apical meristem. • An apical meristem is at the tip of a growing stem or root.

  22. Plant Growth and Meristematic Tissue • Meristematic tissue is the only plant tissue that produces new cells by mitosis.

  23. Roots

  24. Types of Roots • In some plants, the primary root grows long and thick and is called a taproot. • Fibrous roots branch to such an extent that no single root grows larger than the rest.

  25. Types of Roots • A carrot is an example of a taproot. Fibrous Roots Taproot

  26. Types of Roots • Fibrous roots are found in grasses. Fibrous Roots

  27. Root Structure and Growth • Roots contain cells from dermal, vascular, and ground tissue.

  28. Root Structure and Growth • A mature root has an outside layer, the epidermis, and a central cylinder of vascular tissue. • Between these two tissues lies a large area of ground tissue. • The root system plays a key role in water and mineral transport.

  29. 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

  30. Root Structure and Growth Epidermis • The epidermis (including root hairs) protects the root and absorbs water.

  31. Root Structure and Growth • Inside the epidermis is a layer of ground tissue called the cortex. Ground tissue (cortex)

  32. Root Structure and Growth • The cortex extends to another layer of cells, the endodermis. • The endodermis completely encloses the vascular cylinder. Endodermis

  33. Root Structure and Growth • The vascular cylinder is the central region of a root that includes the xylem and phloem. Phloem Vascular cylinder Xylem

  34. Root Structure and Growth • Roots grow in length as their apical meristem produces new cells near the root tip. Apical meristem

  35. Root Structure and Growth • These new cells are covered by the root cap that protects the root as it forces its way through the soil. Apical meristem Root cap

  36. Root Functions • Roots anchor a plant in the ground and absorb water and dissolved nutrients from the soil.

  37. Root Functions • Uptake of Plant Nutrients • To grow, flower, and produce seeds, plants need a variety of inorganic nutrients in addition to carbon dioxide and water.

  38. Root Functions • The most important nutrients plants need include: • nitrogen • phosphorus • potassium • magnesium • calcium

  39. Root Functions • Active Transport of Minerals • The cell membranes of root epidermal cells contain active transport proteins.

  40. Root Functions • Transport proteins use ATP to pump mineral ions from the soil into the plant. Root hairs

  41. Root Functions • The high concentration of mineral ions in the plant cells causes water molecules to move into the plant by osmosis.

  42. Root Functions • Movement Into the Vascular Cylinder • Osmosis and active transport move water and minerals from the root epidermis into the cortex. • The water and dissolved minerals pass the inner boundary of the cortex and enter the endodermis.

  43. Root Functions • The endodermis is composed of many individual cells. Endodermis

  44. Root Functions • Each cell is surrounded on four sides by a waterproof strip called a Casparian strip. Casparian strip Casparian strip

  45. Root Functions • The Casparian strip prevents the backflow of water out of the vascular cylinder into the root cortex.

  46. Root Functions • Water moves into the vascular cylinder by osmosis. • Because water and minerals cannot pass through the Casparian strip, once they pass through the endodermis, they are trapped in the vascular cylinder. • As a result, there is a one-way passage of materials into the vascular cylinder in plant roots.

  47. Root Functions • Root Pressure • As minerals are pumped into the vascular cylinder, more and more water follows by osmosis, producing a strong pressure. • This root pressure forces water through the vascular cylinder and into the xylem.

  48. Root Functions • As more water moves from the cortex into the vascular cylinder, more water in the xylem is forced upward through the root into the stem. • Root pressure pushes water through the vascular system of the entire plant.

  49. Stems

  50. Stem Structure and Function • Stem functions: • they produce leaves, branches and flowers • they hold leaves up to the sunlight • they transport substances between roots and leaves • Can do photosynthesis

More Related