PLANT FORM AND FUNCTION

1. PLANT FORM AND FUNCTION

2. YOU MUST KNOW… • THE FUNCTION OF XYLEM AND PHLOEM TISSUE • THE SPECIFIC FUNCTIONS OF TRACHEIDS, VESSELS, SIEVE-TUBE ELEMENTS, AND COMPANION CELLS • THE CORRELATION BETWEEN PRIMARY GROWTH AND APICAL MERISTEMS VERSUS SECONDARY GROWTH AND LATERAL MERISTEMS

3. CONCEPT 35.1 • THE PLANT BODY HAS A HIERARCHY OF ORGANS, TISSUES, AND CELLS

4. ROOT SYSTEM – ANCHORS THE PLANT, ABSORBS WATER AND MINERALS, AND OFTEN STORES SUGARS AND STARCHES • FIBROUS ROOTS – THIN ROOTS THAT ARE SPREAD JUST BELOW THE SOIL’S SURFACE (MONOCOTS) • TAPROOTS – ONE THICK, VERTICAL ROOT WITH MANY LATERAL ROOTS COMING OUT FROM IT (DICOTS) • ROOT HAIRS – INCREASE THE SURFACE AREA MAKING EFFICIENT ABSORPTION OF WATER AND MINERALS POSSIBLE • MYCORRHIZAE – SYMBIOTIC RELATIONSHIP WITH FUNGI AT THE TIPS OF THE ROOTS, ASSIST IN THE ABSORPTION PROCESS

6. SHOOT SYSTEM CONSISTS OF • STEM – FUNCTION TO DISPLAY LEAVES • TERMINAL BUD – LOCATED AT THE TOP END OF THE STEM WHERE GROWTH USUALLY OCCURS • APICAL DOMINANCE - THE TERMINAL BUD PROHIBITS THE GROWTH OF THE AXILLARY BUDS. IT CONCENTRATES THE GROWTH OF THE PLANT UPWARD TOWARD LIGHT • AXILLARY BUDS – LOCATED IN THE V FORMED BETWEEN THE LEAF AND THE STEM, FORM LATERAL SHOOTS • LEAVES – MAIN PHOTOSYNTHETIC ORGAN

8. 3 PLANT ORGAN TISSUES • DERMAL TISSUE – CLOSELY PACKED CELLS THAT PROTECTS PLANT AGAINST WATER LOSS AND INVASION OF PATHOGENS • VASCULAR TISSUE – TRANSPORTS MATERIALS BETWEEN ROOTS AND SHOOTS XYLEM – TRANSPORTS WATER AND MINERAL UP FROM THE ROOTS PHLOEM – TRANSPORTS FOOD FROM THE LEAVES TO OTHER PARTS OF PLANT • GROUND TISSUE – BETWEEN THE DERMAL AND VASCULAR TISSUE. MAKES UP MOST OF THE BODY OF THE PLANT.

9. DIFFERENTIATED CELLS XYLEM – MOST ARE DEAD CELLS 2 TYPES OF CELLS 1. TRACHEIDS – LONG THIN WALLS STRENGTHENED WITH LIGNIN, WATER MOVES FROM CELL TO CELL THROUGH THE PITS IN IT 2. VESSELS – FOUND MAINLY IN ANGIOSPERMS, HAVE PITS AND PERFORATED END WALLS FOR MOST EFFICIENT WATER MOVEMENT

10. DIFFERENTIATED CELLS PHLOEM – LIVE CELLS – CONDUCT SUGAR AND OTHER ORGANIC COMPOUNDS - 2 TYPES • SIEVE TUBES – CHAINS OF CELLS THAT ARE HIGHLY MODIFIED FOR TRANSPORT, LACKING A NUCLEUS, RIBOSOMES, AND A CENTRAL VACUOLE • COMPANION CELLS – PROVIDE MOLECULAR NEEDS OF SIEVE, ARE CONNECTED TO THE SIEVE BY PLASMODESMATA

12. GROUND TISSUE – SUBDIVIDED INTO 3 TYPES • PARENCHYMA – MOST ABUNDANT, THROUGHT PLANT, PERFORM MOST OF THE METABOLISM (INCLUDING PHOTOSYNTHESIS) • COLLENCHYMA – GROUPED IN CYLINDERS THAT PROVIDE FLEXIBILITY AND HELP SUPPORT GROWING PARTS OF THE PLANT (MAINLY IN STEM AND LEAVES) • SCHLERENCHYMA – IN PARTS THAT ARE NO LONGER GROWING, IT PROTECTS SEEDS AND SUPPORTS PLANT

13. CONCEPT 35.2 • MERISTEMS GENERATE CELLS FOR NEW ORGANS

14. LIFE CYCLE • ANNUALS – LIFE CYCLE COMPLETED IN ONE YEAR • BIENNIALS – LIFE CYCLE COMPLETED IN TWO YEARS • PERENNIALS – LIFE CYCLE CONTINUES FOR MANY YEARS

15. MERISTEMS • EMBRYONIC TISSUES RESPONSIBLE FOR INDETERMINATE GROWTH • APICAL MERISTEM – LOCATED AT THE TIPS OF ROOTS AND IN BUDS OF SHOOTS AND RESULTS IN GROWTH IN IS IN LENGTH (HEIGHT) (PRIMARY GROWTH) • LATERAL MERISTEM – RESULTS IN GROWTH THAT THICKENS THE SHOOTS AND ROOTS (WIDTH) (SECONDARY GROWTH)

17. CONCEPT 35.3 • PRIMARY GROWTH LENGTHENS ROOTS AND SHOOTS

18. ROOT CAP – PROTECTS THE MERISTEM OF THE ROOT TIP AS IT PUSHES THROUGH SOIL • ROOT TIP – 3 ZONES OF CELLS • ZONE OF CELL DIVISION – INCLUDES ROOT APICAL MERISTEM, CELLS ARE ACTIVELY DIVIDING TO MAKE NEW CELLS • ZONE OF ELONGATION – CELLS ABSORB H2O AND ELONGATE SIGNIFICANTLY • ZONE OF MATURATION – COMPLETE DIFFERENTIATION AND BECOME FUNCTIONALLY MATURE

20. STOMATA – SMALL PORES ON THE UNDERSIDE OF LEAVES FLANKED BY GUARD CELLS (OPEN/CLOSE STOMATA) • IN LEAVES, GROUND TISSUE IS SANDWICHED BETWEEN THE UPPER AND LOWER EPIDERMIS IN THE MESOPHYLL – MADE OF PARENCHYMA CELLS WHERE PHOTOSYNTHESIS OCCURS

22. CONCEPT 35.4 • SECONDARY GROWTH ADDS GIRTH TO STEMS AND ROOTS IN WOODY PLANTS

23. 2 LATERAL MERISTEMS • VASCULAR CAMBIUM – PRODUCES SECONDARY XYLEM (WOOD) • CORK CAMBIUM – PRODUCES A TOUGH COVERING THAT REPLACE EPIDERMIS EARLY IN SECONDARY GROWTH • BARK – OUTSIDE THE VASCULAR CAMBIUM, INCLUDES THE PHLOEM, VASCULAR AND CORK CAMBIUM

25. CONCEPT 35.5 • GROWTH, MORPHOGENESIS, AND DIFFERENTIATION PRODUCE THE PLANT BODY

26. IT IS THE CELL EXPANSION THAT ACCOUNTS FOR THE ACTUAL INCREASE IN PLANT MASS • MORPHOGENESIS – DEVELOPMENT OF BODY FORM AND ORGANIZATION • PATTERN FORMATION – THE DEVELOPMENT OF SPECIFIC STRUCTURES IN SPECIFIC LOCATION

27. PLANT HORMONES • ABSCISIC ACID – MAKES SURE SEEDS DON’T GERMINATE TOO EARLY, INHIBITS CELL GROWTH, AND STIMULATES THE CLOSING OF THE STOMATA • AUXIN – LEADS TO ELONGATION OF STEMS AND PLAYS A ROLE IN PHOTOTROPISM AND GRAVITROPISM

28. CYTOKININS – PROMOTE CELL DIVISION AND LEAF ENLARGEMENT, SLOWS DOWN AGING OF LEAVES • ETHYLENE – INITIATES FRUIT RIPENING AND CAUSES FLOWERS AND LEAVES TO DROP (ASSOCIATED WITH AGE) • GIBBERELLINS – ASSISTS IN STEM ELONGATION, INDUCES THE GROWTH OF DORMANT SEEDS, BUDS, AND FLOWERS