PLANT FORM AND FUNCTION

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

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

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

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

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.

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

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

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

CONCEPT 35.2 MERISTEMS GENERATE CELLS FOR NEW ORGANS

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

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)

CONCEPT 35.3 PRIMARY GROWTH LENGTHENS ROOTS AND SHOOTS

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

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

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

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

CONCEPT 35.5 GROWTH, MORPHOGENESIS, AND DIFFERENTIATION PRODUCE THE PLANT BODY

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

PLANT HORMONES ABSCISIC ACID – MAKES SURE SEENDS 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

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