Transcript seed

What is a Plant?
1. Multicellular
2. Eukaryotic
3. Cell walls of cellulose
4. Carry out photosynthesis
5. Store energy as starch
6. Autotrophic
ADAPTATIONS TO SURVIVE ON LAND
1. To prevent water loss, many plants have–
A. Waxy cuticle – thick layer for protection
B. Stomata – Open during day; close at night;
regulated by guard cells
2. Leaves are specialized for photosynthesis
*Shape to trap light energy
*Gas exchange occurs here
Organ of
photosynthesis
is the leaf!
What is the
organelle?
3. Specialized roots for absorption of water
and minerals
4. Specialized stem for transporting
materials
5. Reproduction on lands needs to occur
with little or no water
****MANY PLANTS PRODUCE
SPORES
****AND SOME
PRODUCE SEEDS
Evolution of Plants
• Using the following words, put them in
order of how you think they evolved….
EVOLUTIONARY PERSPECTIVE OF
DEVELOPMENT
OF PLANT TYPES:
ALGAE  MOSSES 
FERNS 
CONE-BEARING 
FLOWERING
TWO MAIN CATEGORIES OF
PLANTS :
1. NONVASCULAR
2. VASCULAR
Examples of Nonvascular Plants -
LIVERWORTS
MOSSES
No vascular tissue!
Water moves by osmosis
Low-growing
Include 3 Main Groups:
A. Ferns
(Seedless)
B. Gymnosperms
(Seeds in cones)
C.Angiosperms
(Seeds in flowers)
A. XYLEM Cells in tubes that transport water and
minerals
B. PHLOEM Tubes that transport food
Sugars
Actively
transported;
water also moves
(By osmosis)
through the phloem
from the SOURCE
to the (Place that
stores or uses
sugars) SINK
**PRESSURE FLOW
HYPOTHESIS
Phloem Transport
Phloem Xylem
Sugar
molecules
Source cell
Movement
of water
Movement
of sugar
Sink cell
Vascular Plants Include 3 Main Groups:
A. Ferns
(Seedless)
B. Gymnosperms
(Seeds in cones)
C.Angiosperms
(Seeds in fruits,
Produce flowers)
A.Ferns –
Seedless
Vascular plants
Require water
for sperm to swim
to egg
Leaves called
fronds
B. Gymnosperms
Vascular plants
Produce seeds on scales called cones
“Naked seeds”
***Water not needed
for reproduction
Pollen grain contains
gametophyte and sperm!
Carried to female cone by wind, water,
insects, ... (Pollination)
****Pollen grows
tube to join egg
(fertilization)
forming seed
Life cycle of
gymnosperm
Most produce
seeds in woody
cones
Female (seed)
and
Male (pollen)
cones
The Structure of a Seed
Seed coat
Seed
Embryo
Wing
B
Stored
food supply
A
AFTER FERTILIZATION
Zygote becomes an EMBRYO
(Diploid sporophyte)
COTYLEDONS –
Seed leaf of embryo
SEED COAT –
Protects embryo
Advantages of Seeds
*Food supply for growing plant
*Protection by seed coat
*Provides less competition with “parents”
*Water not needed for fertilization
Largest Group of Gymnosperms are the
Conifers
Needle – Like leaves help
retain water
Flexible branches and
needles so they don’t
break with the weight of
snow!
Most are EVERGREEN
so can carry on
photosynthesis as soon
as spring arrives
A few are DECIDUOUS
(Lose their leaves at
same time) so are
dormant in winter
Grow tall because
of wood tubes
(tracheids) that
support water and
dissolved minerals
Are these xylem or
phloem???
**Bark reduces water loss
WHAT ARE ANGIOSPERMS?
VASCULAR PLANTS
PRODUCE FLOWERS
DEVELOP SEEDS IN FRUITS
WHICH HELPS PROTECT EMBRYO
TWO CLASSES OF ANGIOSPERMS:
1. Monocots
• One seed leaf in embryo
• Includes grasses, orchids,
lilies, palms
•Parallel veins in leaves
• Flower parts in multiples of
three
2. Dicots
• Two seed leaves in embryo
• Most flowering plants
• Leaves with netted veins
• Flower parts in multiples of four
or five
Monocot vs. Dicot
Monocot
Dicot
Cotyledons
(seed leaves)
Leaf Veins
Mono=1
Di=2
Parallel
Branched
Flower Parts
(#petals,
stamen,
carpels, etc)
Roots
Always in
multiples of 3
(ex. 3, 6, 9)
In multiples of
4s and 5s
fibrous
Tap root
Monocot or Dicot????
Monocot or Dicot?
Monocots vs. Dicots
Absorption
Support; transport
Photosynthesis
Contain xylem and phloem
1. Roots
Two types of root systems:
A. TAPROOT SYSTEM –
Large central roots, Ex: Carrot!
(most dicots)
B. FIBROUS ROOT SYSTEM –
Highly branched
(Most monocots)
ROOT HAIRS increase surface area for absorption
ROOT CAP - Covers tip of the root and protects it
MERISTEM – Growth area just behind the root tip
~Was this primary or secondary growth?
Structure of a Root
Epidermis
Endodermis
Root hairs
Ground tissue
(cortex)
Phloem
Xylem
Vascular
Cylinder
Ground tissue (cortex)
Epidermis
Endodermis
Vascular cylinder
Zone of
maturation
Zone of
elongation
Apical meristem
Root cap
Cross Section of Plant Root
(magnification: 40x)
2. STEMS
Two kinds –
A. HERBACEOUS –
Flexible vascular
bundles scattered
B. WOODY –
Rigid
Have
growth
rings of
vascular
tissue that
determine
age
Layers of a Tree Trunk
Wood
Bark
Cork
Contains old,
nonfunctioning
phloem that
protects the tree
Xylem:
Heartwood
Contains old,
nonfunctioning
xylem that helps
support the tree
Cork Cambium
Produces
protective layer
of cork
Phloem
Transports sugars
produced by
photosynthesis
Xylem: Sapwood
Contains active xylem
that transports water
and minerals
Vascular Cambium
Produces new xylem
and phloem, which
increase the width of
the stem
3. LEAVES
A. SIMPLE –
One leaf blade
attached to stem
B. COMPOUND –
Divided leaf blade
attached to stem
PETIOLE – stalk that
attaches leaf to stem
Cross Section of a Typical Leaf
MESOPHYLL –
Ground tissue full
of chloroplasts
XYLEM
PHLOEM
STOMA
GUARD CELL
Epidermis
Cuticle
Guard cell
Stomata
Structure of a leaf: STOMATA
Structure of a Flower
1. SEPALS –
Leaflike; green; arranged in circle beneath
the petals
*Protects
the ovary!
*Protects the
Flower while
Developing!
2. PETALS –
Leaf-like and colorful to attract insects!
3. STAMEN –
MALE!
Male part made of
ANTHER and
FILAMENT
Anther: produces
pollen (sperm!)
Filament: stalk that
supports the anther
4. PISTIL/CARPEL –
FEMALE!
Female part made
of sticky STIGMA
(where pollen
grains land), STYLE
(transports sperm
to egg), and OVARY
which contains
OVULES with eggs
inside
COMPLETE
FLOWER –
Has all four
organs
INCOMPLETE
FLOWER –
Lacks one or
more organs
What is this picture missing?
The Structure of a Flower
Stamen
Anther
Filament
Ovule
Stigma
Style
Carpel
Ovary
Petal
Sepal
POLLINATION –
Transfer of pollen from the
stamen to the pistil
Adaptations for Pollination that Attract
Particular Animals:
1. Nectar
2. Petal Color
3. Scent
Types of Pollination
1. SELFPOLLINATION –
Stigma receives
pollen from the
same plant
2. CROSS-POLLINATION –
• POLLEN FROM ONE PLANT
IS CARRIED TO STIGMA OF
ANOTHER OF SAME TYPE OF
PLANT
• ALLOWS FOR EXCHANGE OF
GENETIC MATERIAL
After the pollen grain lands on the stigma,
the pollen tube cell grows a tube to the ovary.
The two sperm
cells move
through the
tube into
the ovule
-One sperm joins
with the egg in the
Ovule.
-The other sperm
joins with the
central cell (2N) to
form the endosperm
(3N).
This process is called
double fertilization!!!
Seed Formation
After fertilization occurs, the flower dies and the seed
develops.
Ovule becomes the seed coat which protects the embryo.
The zygote divides becoming the embryo.
The 3N central cell develops into the endosperm which is
food-storage tissue.
Fruits
The ovary
develops into
the fruit!
Parts of a Seed
Fruits can be dry (Nuts and grains)
or
Fleshy (Oranges, Peaches Tomatoes, Squash,…)
***Fruits protect the seeds and
aid in dispersal***
Seed Germination
Seeds remain dormant until conditions are right for
development and growth!
****GERMINATION – Development of the seed into a
new plant!
Water, oxygen,
and warm
temperatures are
Needed!
Root appears first,
then the stem,
and finally the leaves
Growth and Development
Plants respond to stimuli from the environment
This process is called TROPISM
POSITIVE TROPISM – growth towards the stimulus
NEGATIVE TROPISM – growth away from the stimulus
PHOTOTROPISM –
Response to light
GRAVITROPISM –
Response to gravity
THIGMOTROPISM –
Response to touch
PLANT HORMONES
HORMONES – Chemicals made in one part of an organism
that cause a change somewhere else
*Produced in ROOTS!
AUXINS – Growth hormones;
cause cells to elongate,
inhibit growth of side
branches
Auxins and Phototropism
High
concentration
of auxin
Low
concentration
of auxin
Control
Tip
removed
Opaque
cap
Clear
cap
Opaque shied
over base
Apical Dominance
Apical meristem
Lateral buds
Auxins produced in the apical meristem
inhibit the growth of lateral buds.
Apical meristem removed
Without the inhibiting effect of auxins
from the apicial meristem, lateral buds
produce many branches.
TAKS Review
1. How are chloroplasts and mitochondria
alike?
a.
b.
c.
d.
Get energy directly from the sun
Found in humans
Found in plants
Responsible for energy conversions
2. Plants give off oxygen in what process?
a.
b.
c.
d.
Photosynthesis
Aerobic respiration
Chemosynthesis
Anaerobic respiration
TAKS Review Cont….
1.
2.
3.
4.
5.
6.
Production of Carbon Dioxide and sugar
Production of Oxygen and sugar
Exposure to light
Breakdown of protein
Intake of carbon dioxide
Intake of oxygen
Three of the statements above are stages in
photosynthesis. Select and arrange in order 3
stages of photosynthesis.
a. 3-4-1
b. 4-3-2
c. 3-5-2
d. 3-6-1
TAKS Review Cont….
4. What are the function of stomata?
a. sugar production
b. protection
c. gas exchange
d. water storage
5. What is the function of xylem? Phloem?
a. transport water; transport food
b. transport food; transport water