AP Biology, Chapter 35
Plant Structure and Function

SUMMARY
INTRODUCTION

INTRODUCTION TO MODERN PLANT BIOLOGY
	Molecular biology is revolutionizing the study of plants
		1. Explain why Arabidopsis is an excellent model for the study of plant development. 			Describe the results of recent research on this plant's development.
			a. Traits
				i. Fits in test tubes
				ii. Six week generations
				iii. Small genome, sequence in hand
			b. Results
				i. in situ hybridization shows where specific RNAs appear
				ii. Mutations affecting flower development have been isolated
	Plant Biology reflects the major themes in the study of life

THE ANGIOSPERM BODY
	A plant's root and shoot systems are evolutionary adaptations to living on land
		2. Provide a more complete structural differentiation of eudicots and monocots than that 
		provided in Chapter 30.
			a. Monocots: one seed leaf, parallel venation, scattered vascular bundles, fibrous 
			root systems, flower parts in 3s
			b. Eudicots: two seed leaves, branched venation, vascular bundles in a ring, 				taproot, flower parts in 4s and 5s
		3. Describe and compare the three basic organs of plants. Explain how these basic 
		organs are interdependent.
			a. Three organs
				i. Roots
					.Functions: anchor, support, store, absorb
					.Common tissues: epidermis, collenchyma, xylem, phloem, 
					meristems, sclerenchyma
					.Unique feature: root hairs
				ii. Stems
					.Functions: support, transport
					.Same common tissues
				iii. Leaves
					.Functions: major photosynthetic organs, some modified for 
					defense
					.Same common tissues
					.Unique features: stomata, photosynthetic parenchyma
					.Structure: blade + petiole; simple or compound
			b. Interdependence: roots support stem and leaves, send water and minerals; 
			leaves make food, stem supports and exchanges the two
		4. Describe the basic structure of plant roots.
			a. Epidermis outside
			b. Under that is ground tissue
			c. In the center is vascular tissue
			d. Dicot vs. monocot
				i. Dicot xylem in center with spokes; phloem between spokes
				ii. Monocot xylem and phloem surround pith
		5. Describe and compare the structures and functions of fibrous roots, taproots, root 
		hairs, and adventitious roots.
			a. Fibrous
				i. Shallow mat of thread-like roots
				ii. Large surface area for absorption and anchoring
			b. Taproot
				i. One large vertical root with branches
				ii. Firm anchor, gets to deep resources, thick for storage
			c. Root hairs
				i. Extensions of epidermal cells
				ii. Increase surface area
			d. Adventitious
				i. Roots originating aboveground
				ii. In corn they help support
		5. Describe the basic structure of plant stems.				
			a. Leaves are attached at nodes alternating with internodes
			b. Apical buds emerge just above the leaves
			c. At the tip, the terminal bud contains the apical meristem
		6. Explain the phenomenon of apical dominance.
			a. Terminal bud inhibits the growth of lateral buds; decreases with distance
			b. Removal stops inhibition; growth of lateral buds  bushy
		7. Describe the structures and functions of four types of modified shoots.
			a. Stolons grown across the ground and may root
			b. Rhizomes are enlarged underground stems for storage/dormancy
			c. Tubers are the swollen ends of rhizomes for storage/dormancy
			d. Bulbs have a short underground stem with leaves for storage/dormancy
		8. Describe and distinguish between the leaves of monocots and eudicots.
			a. a Monocots: many similar leaf veins run parallel
			b. Dicots: branching, tapering veins
	Structural adaptations of protoplasts and walls equip plant cells for their specialized 
	functions
		9. Differentiate parenchyma, collenchyma, sclerenchyma, and the cell types composing 
		xylem and phloem.
			a. Parenchyma
				i. Thin walls with no secondary; large central vacuole
				ii. Carry on most of the metabolic functions
				iii. Ex.: leaf mesophylls, starch-storing cells in roots
			b. Collenchyma
				i. Thicker primary cell walls; no secondaries
				ii. Support without restraining growth
				iii. Ex. strings in celery, turgid cortex cells
			c. Sclerenchyma
				i. Thick secondary cell walls with lignin
				ii. Stiff, cannot expand; terminally differentiated
				iii. Two forms
					.Long fibers as in flax
					.Short, irregular sclereids in nut shells
			d. Xylem
				i. Water-conducting; secondary walls reinforced by spirals/rings
				ii. Types
					.Tracheids: overlapping, joined at thin-walled pits
					.Vessel elements: end-to-end, joined by perforations
					.Both dead and empty at maturity
			e. Phloem 
				i. End-to-end sieve tube members joined by sieve plates
				ii. No nuclei, ribosomes, vacuole
				iii. Tended by companion cells
	The cells of a plant are organized into dermal, vascular, and ground tissue systems
		10. Describe and distinguish between the cells composing the three tissue systems of 
		plant organs.
			a. Dermal
				i. Protects surfaces; extensions important in absorption
				ii. Epidermis thickened by cuticle; bark including cork
			b. Vascular
				i. Transports water, minerals, metabolic products; supports
				ii. Xylem and phloem
			c. Ground
				i. Photosynthesis, storage, support
				ii. Parenchyma, collenchyma, sclerenchyma
				iii. Bulk of the young plant

PLANT GROWTH
	Meristems generate cells for new organs throughout the lifetime of a plant: an 
	overview of plant growth
		9. Explain how plants are capable of indeterminate growth.
			a. Meristems
			b. Stem cell tissues at the tips and in a layers under the bark
		10. Distinguish between annual, biennial, and perennial plants.
			a. Annuals must grow from seed each year: grains and legumes
			b. Biennials grow the first year, flower the second: carrots and beets
			c. Perennials live many years: grasses, trees
		11. Define and distinguish between primary and secondary growth.
			a. Primary growth
				i. Apical meristems lengthen the roots and shoots
				ii. Herbaceous plants, first year for woody plants
			b. Secondary growth
				i. Growth in girth by lateral meristems
				ii. Woody plants
	Primary growth: Apical meristems extend roots and shoots by giving rise to the 
	primary plant body
		12. Describe in detail the primary growth of the tissues of roots and shoots. 
			a. Roots
				i. From the tip: root cap, meristems, zone of elongation, zone of 
				maturation
				ii. Epidermis outside; mixed parenchyma, collenchyma, sclerenchyma; 
				endodermis; vascular stele
				iii. Dicot/monocot
					.Dicot: stele with xylem in the center with spokes
					.Monocot: pith in the center, alternating xylem/phloem
			b. Shoots
				i. Similar arrangement from the tip
				ii. Grasses have intercalary meristems allowing growth at each node
				iii. Epidermis outside
					.Dicot: cortex, ring of vascular bundles, pith in center
					.Monocot: scattered vascular bundles in ground tissue
		13. Describe the specific tissue organization of leaves.
			a. Epidermis outside with guard cells surrounding stomata
			b. Two layers of photosynthetic parenchyma
				i. Tightly packed palisade mesophyll on top
				ii. Loose spongy mesophyll below inside the stomata
			c. Veins have xylem above phloem
	Secondary growth: Lateral meristems add girth by producing secondary vascular 
	tissue and periderm
		14. Describe in detail the secondary growth of the tissues of shoots and roots.
			a. Two lateral meristems
				i. Vascular cambium
					.Between the xylem and phloem
					.Cells divide to form xylem inside, phloem outside
				ii. Cork cambium produces bark including corks cells with suberin
			b. As the apical meristems lengthen the stem, lateral meristems make it thicker
				i. Secondary xylem (wood) collects inside the vascular cambium
				ii. Cells are wider in the wetter spring = springwood
				iii. Cells are narrower in the drier summer = summerwood
			c. Roots have similar growth patterns
				i. Vascular cambium in the stele adds xylem inside, phloem outside
				ii. Secondary xylem shows annual growth rings
				iii. Cork cambium produces tough bark