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25 terms

Chapter 35 Plant Structure, Growth, and Development

Mr. Jordan GHHS AP Bio
1. Explain how the basic plant organs are interdependent.
Roots support stem and leaves, send water and minerals;
Leaves make food, stem supports and exchanges the two
2. Relate the functions of roots to their tissue composition.
Epidermis protects and absorbs
Collenchyma and sclerenchyma support
Parenchyma stores
Xylem and phloem conduct
Meristems allow for growth Root hairs increase surface area
3. Describe the basic structure of plant roots.
Epidermis outside
Under that is ground tissue
In the center is vascular tissue
4. Describe and compare the structures and functions of fibrous roots, taproots, root hairs, and adventitious roots.
Shallow mat of thread-like roots
Large surface area for absorption and anchoring
One large vertical root with branches
Firm anchor, gets to deep resources, thick for storage
Root hairs:
Extensions of epidermal cells
Increase surface area
Roots originating aboveground
In corn they help support
5. Relate the functions of stems to their tissue composition.
Epidermis protects
Collenchyma and sclerenchyma support
Parenchyma stores
Xylem and phloem conduct
Meristems allow for growth
6. Describe the basic structure of plant stems.
Leaves are attached at nodes alternating with internodes
Apical buds emerge just above the leaves
At the tip, the terminal bud contains the apical meristem
7. Explain the phenomenon of apical dominance.
Terminal bud inhibits the growth of lateral buds; decreases with distance
Removal stops inhibition; growth of lateral buds = bushy
8. Describe the structures and functions of four types of modified shoots.
Stolons grown across the ground and may root
Rhizomes are enlarged underground stems for storage/dormancy
Tubers are the swollen ends of rhizomes for storage/dormancy
Bulbs have a short underground stem with leaves for storage/dormancy
9. Relate the functions of stems to their tissue composition.
Spongy parenchyma performs photosynthesis
Epidermis protects
Collenchyma and sclerenchyma support
Xylem and phloem conduct
10. Describe the unique adaptations of leaves.
Stomata control gas exchange
Leaf = blade + petiole
1 blade = simple; > ≥2 = compound
11. Describe and distinguish between the leaves of monocots and eudicots.
Monocots: many similar leaf veins run parallel
Dicots: branching, tapering veins
12. Describe and distinguish between the cells composing the three tissue systems of
plant organs.
Protects surfaces; extensions important in absorption
Epidermis thickened by cuticle; bark including cork
Transports water, minerals, metabolic products; supports
Xylem and phloem
Photosynthesis, storage, support
Parenchyma, collenchyma, sclerenchyma
Bulk of the young plant
13. Differentiate parenchyma, collenchyma, sclerenchyma, and the cell types composing
xylem and phloem.
Parenchyma Cells:
Thin walls with no secondary; large central vacuole
Carry on most of the metabolic functions
Ex.: leaf mesophylls, starch-storing cells in roots
Collenchyma Cells:
Thicker primary cell walls; no secondaries
Support without restraining growth
Ex. strings in celery, turgid cortex cells
Sclerenchyma Cells:
Thick secondary cell walls with lignin
Stiff, cannot expand; terminally differentiated
~Two forms:
-Long fibers as in flax
-Short, irregular sclereids in nut shells
Water-Conducting cells of the Xylem:
Water-conducting; secondary walls reinforced by spirals/rings
-Tracheids: overlapping, joined at thin-walled pits
-Vessel elements: end-to-end, joined by perforations
-Both dead and empty at maturity
Sugar-Conducting Cells of the Phloem:
End-to-end sieve tube members joined by sieve plates
No nuclei, ribosomes, vacuole
Tended by companion cells
14. Explain how plants are capable of indeterminate growth.
Stem cell tissues at the tips and in a layers under the bark
15. Define and distinguish between primary and secondary growth.
Primary growth:
Apical meristems lengthen the roots and shoots
Herbaceous plants, first year for woody plants
Secondary growth:
Growth in girth by lateral meristems
Woody plants
16. Distinguish between annual, biennial, and perennial plants.
Annuals must grow from seed each year: grains and legumes
Biennials grow the first year, flower the second: carrots and beets
Perennials live many years: grasses, trees
17. Distinguish dicot and monocot root structure.
Dicot xylem in center with spokes; phloem between spokes
Monocot xylem and phloem surround pith
18. Describe the primary growth of the tissues of roots.
From the tip: root cap and zones of cell division, elongation, maturationEpidermis outside; mixed parenchyma, collenchyma, sclerenchyma; endodermis; vascular stele
19. Describe the primary growth of the tissues of shoots.
Similar arrangement from the tip
Grasses have intercalary meristems allowing growth at each node
Epidermis outside
-Dicot: cortex, ring of vascular bundles, pith in center
-Monocot: scattered vascular bundles in ground tissue
20. Describe the specific tissue organization of leaves.
Epidermis outside with guard cells surrounding stomata
Two layers of photosynthetic parenchyma
-Tightly packed palisade mesophyll on top
-Loose spongy mesophyll below inside the stomata
Veins have xylem above phloem
21. Describe in detail the secondary growth of the tissues of shoots and roots.
Two lateral meristems
~Vascular cambium
-Between the xylem and phloem
-Cells divide to form xylem inside, phloem outside
~Cork cambium produces bark including corks cells with suberin
As the apical meristems lengthen the stem, lateral meristems make it thicker
Secondary xylem (wood) collects inside the vascular cambium
Cells are wider in the wetter spring = springwood
Cells are narrower in the drier summer = summerwood
Roots have similar growth patterns
Vascular cambium in the stele adds xylem inside, phloem outside
Secondary xylem shows annual growth rings
Cork cambium produces tough bark
22. Explain why Arabidopsis is an excellent model for the study of plant development. Describe the results of recent research on this plant's development.
Fits in test tubes
Six week generations
Small genome, sequence in hand
in situ hybridization shows where specific RNAs appear
Mutations affecting flower development have been isolated
23. Contrast the contributions of the plane of cell division and the symmetry of cell division to plant organ shape and cell fate.
Plane not important in maize tangled-1 mutants
Leaf shape is normal even though division planes aren't
Asymmetrical division signals key events
Also establishes polarity from the first division of the zygote
24. How is the orientation of cell expansion controlled in plant cells?
Cellulose fibrils resist stretching
Fibrils are synthesized around the cell to restrict expansion in particular directions
25. Compare the two types of hypotheses explaining the fates of plant and animal cells.
More important in animals
Involves transcription factors like Hox genes
More important in animals
Depends on cell to-cell commmunication