Transcript Pre AP Plant notes 2

Plant Anatomy
Basic plant anatomy 1
A. root
– root tip-roots grow
at the tip
– root hairsincrease
absorptive surface
area
Roots
1
• 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 secondary roots
• dicots
– root hairs (3)
• increase absorptive
surface area
2
3
Basic plant anatomy 2
B. shoot (stem)
– Nodes-where leaves
attach
• Internodes-space
between nodes
– Buds
• Meristems are where
plant shoots grow
• terminal or apical buds
at top of stem
• axillary buds- at base of
leaf on stem
• flower buds-produce
flowers
Basic plant anatomy 3
C. leaves
– Cuticle- waterproof layer
– Epidermis- covers top &
bottom surface
– mesophyll tissue
• Palisade- columnar cells, with
choloroplasts just below upper
epidermis
• Spongy- irregularly shaped cells
with air spaces between them
below palisade
– veins (vascular bundles)
Leaves
• Function of leaves
– photosynthesis
• Traps solar energy
• Produces sugars (food)
– gas exchange- occurs
through pores called
stomates
• Guard cells open or close
stomates-depends on water
– Transpiration- water loss
through the stomates
Plant adaptations
1. Roots– Tap root-used for food storage (carrot)
2. Stems
-rhizomes (iris) & stolons (strawberry)- used to
make new plants
- tubers- (potato) used for storage
- Bulbs- (onion) buds used for storage & new
plants
Modified shoots
stolons (strawberries)
tuber (potato)
rhizome (ginger)
bulb (onion)
Plant adaptations
3. Leaves
• CAM & C4-photosynthesis- chemical
adaptation for plants in hot climates
• Enlarged darker leaf-jungle plants-low light
• Spines & poisons- defense against
herbivores
• Thickened leaf- water storage
• Tendrils- climbing plants- attach & support
• Bright colors- leaves doing job of petals
Modified leaves
tendrils (peas)
succulent leaves
spines (cacti)
colored leaves (poinsetta)
Interdependent systems
• 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
sugars
water &
minerals
Vascular tissues
• 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
vessel elements
vessel
element
dead cells
tracheids
sieve tube
companion cell
sieve plate
plasmodesmata
living cells
Phloem: food-conducting cells
• carry sugars & nutrients throughout plant
• sieve tube elements – Living cells at
functional maturity
– cell membrane, cytoplasm
• control of diffusion
– lose their nucleus, ribosomes & vacuole
– sieve plates — end walls — have pores to
facilitate flow of fluid between cells
• companion cells- are attached to the sieve
tubes
– run the cell- have nucleus & cell structures
Vascular tissue in stems
dicot
monocot
trees & shrubs
grasses & lilies
collect annual rings
Putting it all together
• Obtaining raw materials
– sunlight
• leaves = solar collectors
– CO2
• stomates = gas exchange
– H2O
• uptake from roots
– nutrients
• uptake from roots
Growing Cycles
• Perennials - live several years, and
reproduce many times, woody plants are
perennials
• Annuals - a plant that completes its life
cycle in one growing season (grows,
flowers, reproduces and then dies)
• Biennials - takes two growing seasons to
complete, it reproduces in the second
growing season
Growing Cycles
• Plants grow only at their tips in regions
called MERISTEMS
• PRIMARY GROWTH makes a plant taller
at roots and stems
• SECONDARY GROWTH makes a plant
wider, or adds woody tissue
How Old Is That Tree?
• Tree Rings tell age of a tree,
each ring represents one
growing season. This tree
has been through four
growing seasons. The lighter
thinner rings are winter
periods.
• VASCULAR CAMBIUM:
area of the tree that makes
more xylem and phloem and
forms the annual rings