1. Roots, Stems, and Leaves Ms. Moore 9/6/2012

2. Small stem surrounded by leaves
Floral bud surrounded by leaves
Small stem surrounded by leaves
What part of the plant do we eat?
Label the stems, roots, and leaves of each vegetable.
Stem with eyes that grow into branches

3. Principal Organs of Seed Plants
Roots
Absorb water
Anchor plants into ground
Hold plants upright through weather
Stems
Support system
Transport system
Defense against predators and disease
Leaves
Photosynthesis
Protect against water loss

4. Tissue Systems Dermal Vascular Ground Meristematic
Epidermal cells: surround outer covering of a plant
Waxy layer protects against water loss and injury (cuticle)
Vascular
Xylem
Phloem
Ground
Between dermal and vascular tissues
Meristematic
Produces new cells by mitosis

6. Dermal Tissue Single layer of closely packed cells
Covers and protects the plant; acts as “skin”
Thick waxy layer, known as cuticle

7. Vascular Tissue Xylem Phloem Tracheid Vessel element
Sieve tube elements
Companion cells

8. Ground Tissue Parenchyma Collenchyma Sclerenchyma
Packed with chloroplasts; site of photosynthesis
Collenchyma
Celery “strings”; flexible walls for support
Sclerenchyma
Rigid; strength and support

9. Meristematic Tissue
Meristems: clusters of tissue responsible for continuing growth
Meristematic tissue: undifferentialted cells produced by mitosis
Apical meristem: group of cells near the end or top of plant that divide to produce increased length of stems and roots

11. Mastery What are the three main organs of seed plants?
List the three tissue systems of plants.
What two cell types make up xylem? Phloem?
What is the function of meristematic tissue in a plant?

12. Types of Roots Taproots Fibrous roots
Primary root grows long and thick
Mainly in dicots
Fibrous roots
No single root grows
larger than the rest
Mainly in monocots

13. Structure and Growth Root hair: water enters plant at tiny projections
Cortex: spongy layer of ground tissue
Endodermis: encloses vascular subsystem
Vascular cylinder: contains xylem and phloem
Root cap: protects root as it grows through soil
Casparian strip: waterproofs endodermis

14. Essential Plant Nutrients
Uptake of Nutrients
Essential Plant Nutrients
Nutrient
Role in Plant
Result of Deficiency
Nitrogen
Proper leaf growth and color; synthesis of amino acids, proteins, nucleic acids, and chlorophyll
Stunted plant growth; pale yellow leaves
Phosphorus
Synthesis of DNA; development of roots, stems, flowers, and seeds
Poor flowering; stunted growth
Potassium
Synthesis of proteins and carbohydrates; development of roots, stems, and flowers; resistance to cold and disease
Weak stems and stunted roots; edges of leaves turn brown
Magnesium
Synthesis of chlorophyll
Thin stems; mottled, pale leaves
Calcium
Cell growth and division; cell wall structure; cellular transport; enzyme action
Stunted growth; curled leaves

15. Mastery Compare a taproot and a fibrous root.
How are tissues distributed in a plant root?
What are the two main functions of roots?

16. Stem Structure and Function
Produce leaves, branches, and flowers
Hold leaves up to sunlight
Transport substances between roots and leaves
Primary Growth: cell divisions in apical meristem
Secondary Growth: growth in lateral meristems in conifers and dicots

18. Stem Structure Nodes: where leaves are attached
Internodes: region between two nodes
Buds: contain undeveloped tissue that can produce new stems, leaves, flowers
Pith: parenchyma cells inside ring of vascular tissue (outside cells = cortex) in stem

19. Monocot vs. Dicot

20. Growth Primary: apical meristem; all seed plants
Secondary: lateral meristem; dicots
Vascular cambium: increases the thickness of stems over time
Cork cambium: produces outer covering of stems

21. Formation of Wood
Heartwood: older xylem near center no longer conducts water; darker in color
Sapwood: active in fluid transport; surrounds heartwood; lighter in color
Bark: tissues outside the vascular cambium

22. Mastery
How do the functions of a stem relate to the roots and leaves of a plant?
Describe how the arrangement of vascular bundles differs between monocot and dicot stems.
What is primary and secondary growth?
How do heartwood and sapwood differ?

23. Leaf Structure
Structure is optimized for absorbing light and carrying out photosynthesis and gas exchange.
Blades: collect sunlight
Petiole: attachment
Vascular tissues are connected directly to stem’s vascular tissues.
Xylem and phloem tissues are gathered together into bundles that run from the stem into the petiole to the leaf blade.
In the leaf blade, vascular bundles are surrounded by parenchyma and sclerenchyma cells.

25. Leaf Function: Photosynthesis
Photosynthesis: 6CO2 + 6H2O  C6H12O6 + 6O2
Mesophyll: specialized ground tissue where most photosynthesis occurs
Palisade mesophyll: closely packed cells that absorb light; located under the epidermis
Spongy mesophyll: loose tissue with many air spaces (gas exchange)
Stomata: porelike openings in the underside of the leaf that allow CO2 and O2 to diffuse in and out of leaf
Guard cells: specialized cells in the epidermis that control the opening and closing of stomata (due to changes in water pressure)

26. Why is photosynthesis important to all life?

27. Leaf Function: Transpiration
The surfaces of spongy mesophyll are kept moist so that gases can enter and leave the cells easily.
Transpiration: the loss of water through the leaves

28. Leaf Functions: Gas Exchange
Leaves take in CO2 and give off O2 during photosynthesis.
Do leaves ever take in O2?
Gas exchange takes place in the stomata.
Plants keep stomata open just long enough to allow photosynthesis to occur.
Why don’t they keep stomata open at all times?
What cells regulate the opening and closing of stomata?

30. Mastery How is the structure of a leaf optimized for light absorption?
What factors regulate the opening and closing of guard cells?
Are stomata more likely to be open or closed on a hot day?
Describe transport of water and nutrients in a leaf.

31. Transport in Plants
Combination of root pressure, capillary action, and transpiration (loss of water through leaves) provides enough force to move water through the xylem tissue.
Up next…Transpiration Lab!

32. Water Transport How is water transported throughout the plant?
Water molecules are attracted to one another by a force called cohesion; they are attracted to other molecules by adhesion.
The tendency of water to rise in a thin tube (xylem) is called capillary action.
Water is attracted to the walls of the tube and they are also attracted to one another.

33. Nutrient Transport
Phloem carries out the seasonal movement of sugars within a plant.
Pressure-flow hypothesis: When nutrients are pumped into or removed from the phloem system, the change in concentration causes a movement of fluid in that same direction.
Source: an area rich in nutrients
Sink: an area that needs nutrients

34. Review
Vocabulary
Study Guide
Any Questions?