Transcript UNIT V - Father Michael McGivney Catholic Academy

UNIT V
PLANTS: Anatomy,
Growth and Function
Kingdom Plantae
• Multicellular, non-motile, cell wall
with cellulose, mostly autotrophic
• Plant life cycles
• Plant Structures relate to plant needs
– Sunlight, water and minerals, gas exchange,
– Reproduce without water to transmit male
gamete (in Angiosperms)
– Vascular tissue, roots,
stems, leaves, seeds,
flowers
Vascular and Non-vascular plants (13.1)
• Plants consist of 3 main parts:
– Roots: anchor plant to soil, helps
obtain water
– Leaves: surface area for
photosynthesis
– Stems: rigidity and support for leaves
• In order to supply each of these parts
with water, energy and nutrients, plants
contain vascular tissue  made up of
cells that conduct solutions throughout
the plant, linking the tips of the roots to
the highest leaves
– Transports water, dissolved minerals
and sugars to all parts of the plant
• Non-vascular plants: mosses, liverworts,
and hornworts  no or poorly
developed roots, leaves and stems
Reproductive Strategies
• Algae: release
unprotected gametes
into water
• Pollen (male gametes)
carried to female plants
by wind, insects or other
animals
• Zygote develops inside
a seed
• Seed = embryo, stored
food and a tough
waterproof coat
Major Groups of Plants
• Three traditional groupings:
– Bryophytes—nonvascular plants
– Pteridophytes — vascular, seedless plants
– Seed plants
• Gymnosperms
• Angiosperms
Ginkgo biloba
Ginkgos are often
very long-lived.
Some specimens are
thought to be more
than 3,500 years old.
Classification of Plants (13.2)
Evolutionary tree for major
plant groups
Non-vascular Plants
• Do not posses vascular system
• Require moist environment for reproduction
and the transfer of water and food by
osmosis and diffusion
• They have no roots or poorly developed
roots (rhizoids), stems and leaves
• 3 divisions: mosses (bryophytes, hornworts
(Anthocerophytes), and Liverworts
(Hepatophytes)
• Grow in mats of low tangled vegetation that
can hold water
• Life cycle is dominated by gametophyte
phase
• Gametophytes are the green plants
commonly found in moist shady areas
• Moisture is required for the sperm to swim
to the egg during fertilization
• After fertilization the zygote remains on the
female plant to develop into a sporophyte
Life Cycle of a Moss
Sexual Reproduction in Plants
• Seeds are the product of sexual reproduction in most
plants.
• SEED = EMBRYO + FOOD + PROTECTIVE COATING
• A seed can remain dormant and therefore will live
through rough times while adult plants may die off.
This ensures the survival of the species.
• Flowering Plants are more successful than conifers
because they produce a protective coating around their
seeds which increases the chance of the embryo
surviving in rough times.
• Seed-bearing plants can be classified into two groups:
– angiosperms and
– gymnosperms.
Gymnosperms (14.1)
• Have seeds without a seed coat
• They are attached to the scales
of cones
• They thrive in environments with
long cold winters and low
amount of nutrients in the soil
• They provide fibres for making
paper and wood for building
materials
• Pollination in gymnosperms:
the pollen from the male cones
are carried by the wind to the
female cones to make seeds in
a process similar to
angiosperms
• The seeds are protected by a
structure like a maple key and
fall to the ground to germinate
and grow into new trees.
Tutorial 30.1 Life
Cycle of a Conifer
Angiosperms – flowering plants
• Their number is far greater than gymnosperm species
• They are also more diverse
• They are important as a source of food for many
organisms, including humans
• Flowers are the angiosperm’s reproductive organs which
mature into seed containing fruit
• E.g.: trees, grasses, vegetables, wildflowers and herbs
• They two angiosperm classes are monocots (have one
cotyledon) and dicots (two cotyledons)
•
•
•
•
•
Pollination in angiosperms: pollen is spread from the anther to the
stigma of another plant (cross-pollination) or the same plant (selfpollination) by bees, insects, wind, etc.
a pollen tube grows down the style into the ovary
a sperm travels down the tube to fertilize one egg resulting in the
development of a seed Pollination in angiosperms: pollen is spread
from the anther to the stigma of another plant (cross-pollination) or
the same plant (self-pollination) by bees, insects, wind, etc.
a pollen tube grows down the style into the ovary
a sperm travels down the tube to fertilize one egg resulting in the
development of a seed
Life Cycle of
an
Angiosperm
Monocots
• About 10% of all
monocots are woody
(tough and rigid) stems
• E.g. palm and bamboos,
other are dates,
coconuts, bananas, palm
oil and sugar (found in
warm climates)
• Most monocots are nonwoody or herbaceous
(soft/fleshy stems) 
orchids, lilies, tulips,
onions and grasses
(wheat, corn and rice)
• Most Canada’s native
tree species are dicots
• Most native wildflowers
are also dicots
• E.g.: lettuce, tomatoes,
radishes and sunflower
sprouts
• The staples foods of
many cultures are dicots
e.g.: yam, potatoes,
cabbage (rich in starch),
bean (rich in protein)
Dicots
The Differences Between Monocot
and Dicot Plants
MONOCOTS
•One cotyledon (1 Seed
Leaf)
•Leaves of 3 petals
•Parallel Veins
•Scattered Vascular Bundles
• DICOTS
•One cotyledon (2 Seed Leaves)
•Leaves of 4 or 5 petals
•Network Veins
•Vascular Bundles in RINGS
True dicots vs
monocots
Structure of a Seed
• Epicotyl: cells at the tip of the
embryo that form the leaves
and upper stem of the plant
• Hypocotyl: middle part of the
embryo that becomes the
lower part of the stem
• Radicle: cells on the other
end of the embryo that
develop into the roots system
of the young plant
• Cotyledon: a source of
energy and nutrients for the
embryo
• Seed coat: protects the seed
and also controls germination
by restricting water and
oxygen to the embryo
Life cycle
of a lily
Tutorial 39.1 Double Fertilization
Plant Tissue
There are Four Main types of plant Tissue:
1. Protective: epidermis and cuticle
• prevents disease and foreign invaders
2. Fundamental: cortex and parenchyma
• provides support
Morphology of a
tomato plant
Body plan for a
tomato plant
3. Meristemic: the area of the plant where growth occurs (due to
hormones)
a. Apical
– found in tips of roots and leaves
makes roots, leaves and flowers
b. Lateral
– found in the sides of stems
– makes xylem and phloem (vascular cambium)
– makes bark (cork cambium)
4. Conductive: xylem and phloem
• carries water, nutrients and minerals
• arranged in bundles
•
The tissues of a plant are organized into three tissue systems: the dermal
tissue system, the ground tissue system, and the vascular tissue system.
Tissue System
and Its Functions
Component Tissues
Dermal Tissue System Epidermis
• protection
Periderm (in older
• prevention of water
stems and roots)
loss
Ground Tissue
System
• photosynthesis
• food storage
• regeneration
• support
• protection
Parenchyma tissue
Collenchyma tissue
Sclerenchyma tissue
Vascular Tissue
System
• transport of water and
minerals
• transport of food
Xylem tissue
Phloem tissue
Location of Tissue
Systems
14.2 Vascular Systems
• Plants with Vascular Tissue are
so successful because...
– vascular Tissue is well
adapted to carry water
– vascular Tissue is very
strong and provides support
• The vascular bundles in a stem arc
continuous, tube-like strands
connecting the vascular tissue of the
root to the vascular tissue in the
leaves.
• The transportation of water and
dissolved minerals is carried out by
specialized tissue called xylem in the
vascular bundles.
• The transportation of dissolved food
is carried out by specialized tissue
called phloem in the vascular
monocot
bundles.
dicot
Xylem
• Xylem is the principal water conducting
tissue of vascular plants.
• It consists of tracheids and vessel
elements/members
Vessel Elements
– Larger in diameter than tracheids
– They are dead at maturity and
contain no cytoplasm
– They are arranged end to end just like
barrels piled on top of each other
Tracheids
– Long thick wall cells with tapering
ends
– They are dead at maturity and are
hollow
– They ends of the tracheids overlap,
allowing water to pass from one cell
to the next
Transpiration Cohesion Theory
1.
2.
3.
4.
Water enters the roots by
osmosis. This causes root
pressure which pushes the
water into the xylem.
Water molecules climb the
sides of the xylem vessels by
clinging to the narrow vessel
walls (molecular adhesion)
Each water molecule clings to
the next one forming a
continuous column from the
roots to the leaves (molecular
cohesion)
Transpiration causes water to
move through the leaf by
osmosis, pulling water out of
the xylem cells.
The
Cohesion
Tension
Theory
http://academic.kellogg.cc.mi.us/herbrands
onc/bio111/animations/0031.swf
Phloem
The phloem is made up of a companion
cell, sieve-tube elements and sieve
plates.
• These cells remain alive, unlike the
xylem cells.
• Although sieve-tube elements lack a
nucleus at maturity, because they have
a cytoplasm and all of the other
organelles it is still able to function.
• The cytoplasm of the sieve-tube cell is
connected by pores to a nucleated
companion cell next to it. It appears that
the companion cell directs the activity of
the sieve-tube cell.
• The sieve-tube elements are arranged
end-to-end with sieve
plates separating them. Because of the
large pores in the sieve plates, the
cytoplasm of extends from one sievetube cell to the next
Animation - Phloem
Loading
The Bulk Flow Theory
Sources and Sinks
Source: the places where
sugars are made. Since
photosynthesis occurs in
the leaves, this will be the
place where sugars are
loaded into the phloem
Sink: The plant parts that
require carbohydrates.
These are the places
where the sugars are
unloaded from the
phloem
The conducting tissue of the phloem
connects the sources with the
sinks.
1.
Active transport moves solute
into phloem
2.
Sieve tube solution is now
concentrated, therefore water
moves in from neighbouring
cells
3.
Hydrostatic pressure is created
and the solution inside the sieve
tube cells moves from source to
sink by bulk flow
4.
Active transport moves solute
out into sink cells
5.
Solution in sieve cells is now
less concentrated and water
moves out
Tutorial 36.1 The Pressure
Flow Model
Sugar
Transport in
Plants
Substance It
Carries
Xylem
Phloem
Water & Minerals
Glucose
Direction It
Carries It
Upwards
(from soil to leaves)
Method Of
Carrying It
1. Root Pressure:
no where for the water to
go but up
Capillary Action:
 water is polar and "sticks"
to the sides of the xylem tube,
climbing up
Cohesion-Tension :
 water evaporates off the
leaves so more water moves
there to replace it
Structure
- hollow, dead cells
Downwards
(from leaves to stem)
1. Mass-Flow Theory
high concentration of
glucose in leaves and low
water, therefore water moves
in by osmosis and "washes"
the glucose down the stem
-living cells
Vascular tissues
14.3: Structure and Function
Leaf Cross Section
The Leaf
• Epidermis: protects the inside tissue of a leaf from injury
and from drying out
• Cuticle: waxy substance secreted by the epidermal cells
• Palisade layer: long narrow parenchyma cells where
photosynthesis takes place
• Spongy layer: smaller more loosely packed
parenchyma cells where photosynthesis takes place
• Stomata: allow movement of gases and water vapour
into and out of the leaf
• Guard cell: these cells change shape and by doing so,
open and close the stomata. These cells also contain
chloroplasts unlike other epidermal cells
• Vascular bundle (xylem and phloem): transport water
and food
Leaf structure
Gas Exchange in Leaves
The guard cells are the only cell in the epidermis that
contain chloroplasts. They must therefore perform
photosynthesis. It is the occurrence of photosynthesis
that causes a stoma to open in the morning and close at
night.
An Open Stoma
• In daylight, the guard cells produce glucose via
photosynthesis
• The presence of sugar inside the guard cells causes
water to enter by osmosis from neighbouring epidermal
cells
• The increase in turgor pressure causes the guard cells to
swell opening the stoma between them
• The open stoma allow O2 and CO2 to leave and enter
the leaf
Gas Exchange in Leaves
A Closed Stoma
• When the sun sets,
photosynthesis stops and
the guard cells stop
producing glucose.
• Water no longer enters
the cells by osmosis and
the turgor pressure
decreases
• The stoma then close
http://trc.ucdavis.edu/biosci10
v/bis10v/week8/stomata.mov
The Root
• All roots are responsible for:
– anchoring the plant to the ground
– extracting water and minerals from the soil
– Some plant roots also store food energy (as starch).
• There are three main types
of roots:
– tap root
– fibrous root
– adventitious
Root Structures
15.2: Importance of Plants to Humans
• Food source – Wheat, grains, fruits,
vegetables
• Medicine – Aspirin, cancer treatments,
stimulants
• Industry – Agriculture, wood products,
cotton
Sugercane
How Plants Help the Atmosphere
Removal of Carbon
• Carbon can be stored in
organic tissue  carbon
storage
• Trees and vegetation can
store excess carbon in their
tissues for as long as they
are alive.
• Carbon sink: an area
where there is a lot of
carbon stored in organic
tissue
Production of Oxygen
• Give up oxygen during the
process of photosynthesis
16.2: The Process of Succession
Primary Succession: sequence of change in a
community that starts with bare rock and ends
with a stable ecosystem
Secondary succession: sequence of
change in a community that begins with a
previously existing but disturbed
Tutorial 55.1 Primary Succession on a
community
Glacial Moraine
Primary Succession
Secondary Succession
Climax Community
• Final stage of succession rocks broken
down and converted to fresh soil
• Canada’s Biomes: temperate forest,
boreal, tundra…