Transcript A. Functions of Roots

Slide 1
Chapter 23
Structure
of
Plants
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Slide 2
1.
2.
3.
A. Functions of Roots
Anchor & support
plant in the ground
Absorb water &
minerals
Hold soil in place
Root Hairs
Fibrous Roots
Slide 3
B. Root Types
Tap Root
1. Fibrous Roots:
2. Tap Roots –larger central
branching roots hold soil in
place to prevent soil erosion
root reaches deep water sources
underground
Ex. Grasses
Ex. Trees, Carrots, & Dandelions
Slide 4
C. The Structure of a Root
Root
Hairs
Phloem
Xylem
Meristem
Root
Cap
1. Root Hairs:
increase surface
area for water &
mineral
absorption
2. Meristem:
region where
new cells are
produced
3. Root Cap:
protects tip of
growing root
Slide 5
A. Functions of Stems
1.Support system for plant body
2.Transport system carries
water & nutrients
3.Holds leaves & branches
upright
Looking at the
Each light and dark
picture
the left:
tree ringtoequals
one
year of annual growth.
What
years
had
Light rings for fast
the
most
rain?
spring
growth,
dark for
slow summer growth.
What
Smalleryears
rings tell of
experienced
the
past droughts that
have occurred.
worst
drought?
Slide # 6
A. Functions of Leaves
1. Main photosynthetic organ
2. Broad, flat surface increases
surface area for light
absorption
3. Have systems to prevent
water loss
• Stomata open in day but
close at night or when hot
to conserve water
• waxy cuticle on surface
4. System of gas exchange
• Allow CO2 in and O2 out of
leaf
Elephant Ear Plant
Slide # 7
B. Leaf Structures
Leaf Cross-Section
1.Cuticle: waxy layer;
covers upper surface
Cuticle
Mesophyll
• Protects leaf against
water loss
2.Veins: transports water,
nutrients and food
• Made of xylem and
phloem
3.Mesophyll: contains
cells that perform
photosynthesis
b/c they contain
Chloroplasts.
Veins
Stoma
(Opening)
2 Guard
Cells
Surround
each
Stoma
Stoma- singular
Stomata-plural
Slide # 8
More Plant Parts…
4. Guard cells:
• cells that open
and close the
stoma
5. Stomata: openings
in leaf’s surface;
when open:
•
•
GAS EXCHANGE:
Allows CO2 in & O2
out of leaf
TRANSPIRATION:
Allows excess H2O
out of leaf
Guard Cells
Stoma
Slide # 9
What
goes O2
out?
What
goes
in?
Stoma
Function of Stomata
•What process involves
Guard Cells
Guard Cells
using CO2 and H2O
H2O releasing O2 as a waste
product?
•Photosynthesis
CO2
Stoma Open
•What is the plant using this
processStoma
to make?
Closed
•Carbohydrates-glucose
•If the plant needs water for
photosynthesis, why is water
coming out of the stoma?
Slide # 10
Function of Guard Cells
•These stomata
(leaf
Guard Cells
openings) naturally allow
water to evaporate out.
Guard Cells
•Why would the plant close
stomata with guard cells?
•Prevent excess water loss
through transpiration.
(conserveStoma
water)Open
•So what is the point of
having stomata?
•Allow gas exchange for
photosynthesis
Stoma Closed
Slide # 11
C. Plants find a use for Transpiration
1. Transpiration: loss
of excess water from
plant leaves
2. Significance:
a. Transpiration causes enough
pressure to help pull water
(& required nutrients) up
stem from roots.
b. As part of the water cycle,
trees transpire water back into
the atmosphere.
c. Transpiration provides much
of the daily rain in rainforest.
A
B
A average size maple tree can
transpire 200 liters of water
per hour during the summer.
Transpiration is the #1 driving
force for pulling water up
stems from roots.
Slide # 12
Structure of a Flower
1.Pistil:female reproductive
structure
a.Stigma: sticky tip; traps
pollen
b.Style: slender tube;
transports pollen from
stigma to ovary
c.Ovary: contains ovules;
ovary develops into fruit
d.Ovule: contains egg
cell which develops into
a seed when fertilized
Stamen
Anther
Filament
Ovule
Stigma
Pistil
Style
Ovary
Petal
Sepal
Slide # 13
Structure of a Flower
2.Stamen: male
reproductive structure
a.Filament: thin stalk;
supports anther
b.Anther: knob-like
structure; produces
pollen
c.Pollen: contains
microscopic cells that
become sperm cells
Stamen
Anther
Filament
Ovule
Stigma
Pistil
Style
Ovary
Petal
Sepal
Slide # 14
Structure of a Flower
3.Sepals: encloses &
protects flower before it
blooms
Stamen
Anther
Filament
Stigma
Pistil
Style
Ovary
4.Petals: usually colorful
& scented; attracts
pollinators
Ovule
Petal
Sepal
Slide # 15
Cross Pollination
• How does pollination
happen?
• Pollen from an anther
is caught by the
stigma, travels
through style to the
ovules in the ovary.
• What is the result of
pollination?
• A Fruit: An ovary
containing seeds.
Slide # 16
Plant
Responses
and
Adaptations
Slide #17
Hormone Action on Plants
A. Plant cells can produce
hormones: which are
chemical messengers that
travel throughout the plant
causing other cells called
target cells to respond.
B. In plants, hormones
control:
Movement
of hormone
Hormoneproducing
cells
Target
cells
1. Plant growth &
development
2. Plant responses to
environment
Cells in one blooming
flower signals other blooms
using hormones to open.
Slide # 18
C. Plant cells will send signals
to one another to tell them:
1. When trees to drop their leaves.
2. When to start new growth.
3. When to cause fruit to ripen.
4. When to cause flowers to bloom.
5. When to cause seeds to sprout.
Tree
Budding
Fruit
Ripening
Cactus
Blooming
Leaf Drop
Sprouting
Corn Seeds
Slide # 19
D. Ethylene causes
Fruit to Ripen
1.Fruit tissues release a
small amount of ethlyene
2.Causes fruits to ripen.
3.As fruit become ripe, they
produce more and more
ethlyene, accelerating
the ripening process.
Ethylene released
by apples and
tomatoes causes
fruit to age quickly.
Slide # 20
Plant Tropisms
1. Tropism: the way a plant grows in response to
stimuli in the environment.
a.Phototropism: growth response to light
-Plants bend towards light
a.Geotrophism: growth response to gravity
-plant roots grow down with gravity, shoots (stems) grow
up against gravity and out of the soil.
a.Thigmotropism: growth response to touch
-vines grow up around trees, venus flytrap closes when
leaves are touched
Slide # 21
What type of tropism is shown in these pictures?