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AP Biology 2006-2007
Plant Anatomy
AP Biology
Basic plant anatomy 1 root
root tip root hairs
AP Biology
Plant Body Hierarchy Tissue
Cells with a common function Organ
3 basic organs Roots Stems Leaves
AP Biology
Roots Roots anchor plant in soil, absorb
minerals & water, & store food fibrous roots (1)
mat of thin roots that spread out monocots
tap roots (2) 1 large vertical root also produces many small lateral,
or branch roots dicots
root hairs (3) increase absorptive
surface area
2
1
3
AP Biology
Basic plant anatomy 2 root
root tip root hairs
shoot (stem) nodes
internodes buds
terminal or apical buds axillary buds flower buds & flowers
AP Biology
Modified shootsstolons (strawberries) rhizome (ginger)
tuber (potato) bulb (onion)
AP Biology
Basic plant anatomy 3 root
root tip root hairs
shoot (stem) nodes
internodes buds
terminal or apical buds axillary buds flower buds & flowers
leaves mesophyll tissue veins (vascular bundles)
AP Biology
Leaves Function of leaves
photosynthesis energy production CHO production
gas exchange transpiration simple vs. compound
AP Biologysucculent leaves
Modified leavestendrils (peas) spines (cacti)
colored leaves (poinsetta)
AP Biology
AP Biology
Both systems depend on the other roots depend on
sugars produced by photosynthetic leaves
shoots depend on water & minerals absorbed from the soil by roots
Interdependent systems
water &minerals
sugars
AP Biology
Plant TISSUES Dermal
epidermis (“skin” of plant) single layer of tightly
packed cells that covers & protects plant
Ground bulk of plant tissue photosynthetic mesophyll,
storage Vascular
transport system in shoots & roots
xylem & phloem
AP Biology
Plant CELL types in plant tissues Parenchyma
“typical” plant cells = least specialized photosynthetic cells, storage cells tissue of leaves, stem, fruit, storage roots
Collenchyma unevenly thickened primary walls support
Sclerenchyma very thick, “woody” secondary walls support rigid cells that can’t elongate dead at functional maturity
If I’d onlyhad triplets!
AP Biology
Parenchyma Parenchyma cells are unspecialized, thin, flexible &
carry out many metabolic functions all other cell types in plants develop from parenchyma
AP Biology
Collenchyma Collenchyma cells have thicker primary walls &
provide support help support without restraining growth remain alive in maturity
the strings in celery stalksare collenchyma
AP Biology
Sclerenchyma Thick, rigid cell wall
lignin (wood) cannot elongate mostly dead at maturity
Cells for support xylem vessels xylem tracheids fibers
rope fibers sclereids
nutshells seed coats grittiness in pears
AP Biologytracheids
vessel elements Vascular tissue
Aaaah…Structure–Function
again!
vessel element
dead cells
Xylem move water & minerals up from roots dead cells at functional maturity
only cell walls remain need empty pipes to efficiently move H2O transpirational pull
AP Biology
Phloem: food-conducting cells carry sugars & nutrients throughout plant
sieve tube
companion cell
living cells
plasmodesmata sieve plate
AP Biology
Phloem: food-conducting cells sieve tube elements & companion cells
AP Biology
Phloem Living cells at functional maturity
cell membrane, cytoplasm control of diffusion
lose their nucleus, ribosomes & vacuole more room for specialized transport of
liquid food (sucrose)
Cells sieve tubes
sieve plates — end walls — have pores to facilitate flow of fluid between cells
companion cells nucleated cells connected to the sieve-tube help sieve tubes
Aaaah…Structure–Function
again!
AP Biology
Vascular tissue in stems
dicottrees & shrubs
monocotgrasses & lilies
collect annual rings
AP Biology
Vascular tissue in roots: dicot
xylemphloem
AP Biology
xylem
phloem
Vascular tissue in roots: monocot
AP Biology
Putting it all together Obtaining raw materials
sunlight leaves = solar collectors
CO2
stomates = gas exchange H2O
uptake from roots nutrients
uptake from roots
AP Biology
Plant Growth Apical meristem
Growth in length Primary
Lateral meristem Growth in diameter Secondary
AP Biology
AP Biology
Woody plants grow in height from tip primary growth apical meristem
Woody plants grow in diameter from sides secondary growth lateral meristems
vascular cambium makes 2° phloem & 2° xylem
cork cambium makes bark
Growth in woody plants
Primaryphloem Primary
xylemSecondaryphloem
Secondaryxylem
Annualgrowthlayers
Lateralmeristems
Primaryxylem
Primaryphloem
Bark
Epidermis
AP Biology
Primary growth of roots Root cap
Protects root as it grows Cell division (mitosis)
Cells small Cell elongation Cell differentiation
Cells mature into
final cell types
AP Biology
Primary growth of stems Shoot apical
meristem Dividing cells at
shoot tip
Develop from axillary bud on stem’s surface
AP Biology
Secondary plant growth: vascular cambium Adds secondary
xylem & phloem Thickens roots &
stems Heartwood
Close to center Does not transport
water Sapwood
Transport xylem sap
Outer layers
AP Biology
Secondary plant growth: cork cambium Periderm
Cork cambium & tissues
Produces thick covering Protects from water
loss Phelloderm
Thin layer of parenchyma
Secondary tissue Exterior of cork
cambium Suberin - waxy
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