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Kingdom Plantae
Chapters 30 - 33
How have modern plants evolved?
• Had to develop adaptations for life on
land
• Evolved from plantlike protists – green
algae
• First plants were similar to today’s
mosses – dependent on water
Plant Adaptations to Land
•
•
•
•
•
Problems:
Need minerals
Gravity
Increase in
Height for Light
Adaptations for
Drier
environment
Reproduction
Solutions:
• Roots absorb H2O &
minerals
• Lignin & cellulose in cell
walls
• Vascular Transport
System
• Waxy cuticle &
stomata with guard
cells
• Pollen containing sperm
3
What are characteristics of plants?
Multicellular
Eukaryotic
cellulose cell walls
autotrophic (photosynthetic)
Chlorophylls a and b in thylakoid
membranes
• Store reserve food as amylose
(starch)
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•
What is the plant life cycle?
• Alternation of generations:
– Sporophyte – 2n – Diploid – produce haploid
spores by meiosis
– Gametophyte - (1n) – haploid undergoes
mitosis to produce eggs and sperm – the eggs
and sperm (gametes)
– Zygote - merge to grow into a 2n sporophyte
(cycle continues)
Alternation of Generations
Gametophyte
2n Sporophyte
2n gametophyte
1n pollen
2n seed with
plant embryo
Ovary with
1n ovules
(eggs)
Sporophyte
6
What do plants need to survive?
• Sunlight - energy of sun captured by
chlorophyll and used to join CO2 and H2O
to form glucose (C6H12O6); plants need
broad leaves to maximize light absorption
• Water and minerals - roots to absorb
these
• Gas Exchange – stomata in leaves
• Movement of water and nutrients
– Most plants have tubes – phloem (nutrients
down) and xylem (water up)
– Some small plants use diffusion
Nonvascular Plants
• Do not have
vascular tissue
for support or
conduction of
materials
• Called
Bryophytes
• Require a
constantly moist
environment
Sporophyte stage
Gametophyte
Stage
Moss Gametophytes &
Sporophytes
8
Nonvascular Plants
• Plants can’t grow as tall
• Cells must be in direct contact
with moisture
• Materials move by diffusion
cell-to-cell
• Sperm must swim to egg
through water droplets
9
Vascular System
• Xylem tissue carries water and
minerals upward from the roots
• Phloem tissue carries sugars made
by photosynthesis from the leaves
to where they will be stored or
used
• Sap is the fluid carried inside the
xylem or phloem
10
What are the four main groups of plants?
• Mosses – Bryophytes (15,600 species)
• Ferns – Pterophytes (11,000 species)
• Gymnosperms - Cone-bearing Plants (760
species)
• Angiosperms - Flowering Plants (245,000
species)
What are the characteristics of the
mosses? BRYOPHYTA
• Low-growing, live in moist areas, depend
on water for reproduction
• No true stems, leaves, or roots (rhizoids,
instead), no seeds, non-vascular
LIVERWORT
• http://bryophytes.science.oregonstate.edu/conoceph.JPG
HORNWORT
•
http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/AnthoGametoSporoOver500.jpg
CLUB MOSS
•
http://farm1.static.flickr.com/23/25669152_3a451c3b04.jpg
HORSETAILS
•
http://www.english-country-garden.com/a/i/flowers/horsetail-1.jpg
What is the life cycle of the mosses?
What is sphagnum moss?
What is peat moss?
• Dried sphagnum moss (from bogs) can
absorb a lot of water
• Dead sphagnum moss form peat moss –
used in gardening - absorbs water &
lowers acidity
What are club mosses?
Horsetails?
• Lycophyta – miniature pine trees –
holiday greens
• Vascular – but no seeds
• Equisetum - vascular, seedless,
What are the characteristics of
ferns? PTEROPHYTA
• Vascular
– true roots
– Stems
– leaves
• seedless
What is the life cycle of ferns?
What are the characteristics of seed plants?
• Vascular, seeds – divided into two groups
• Adaptations to reproduce without water
– Cones and flowers
– Pollen
– Protective seeds
What are the CONIFEROPHYTA?
•
•
•
•
•
Cone bearing
needles with thick waxy covering
Stomata in cavities below surface
Seeds are carried on the surfaces of cones
Evergreen
Male (left) and female (right) pine cones
What are the ANTHOPHYTA?
• Flowering
• Seeds are within a layer of protective tissue
• Flowers, ovaries, pollinators (insects, etc.)
What are monocots?
• Single cotyledon – number of seed leaves
• parallel veins (venation), floral parts in
multiples of 3, fibrous roots, scattered
vascular bundles
What are dicots?
• Two cotyledons, branched veins (net
venation), floral parts in multiples of 4-5,
taproot, ring of vascular bundles.
What are the structures of a plant?
• Dermal Tissue – thick waxy layer, sometimes
fuzzy, roots have hairs (water absorption),
stomata for gas exchange
• Stems – vascular tissue – phloem and xylem
– Monocot and dicot differences:
• In dicots – cambium forms xylem to the inside and
phloem to the outside (pith in the middle)
– Wood is layers of xylem
Parts cont’ - leaves
Parts cont’
• Meristem – plant tissue that produces
new cells by mitosis
• Roots – tap roots and fibrous roots
– E.g. (onion root tips)
http://library.thinkquest.org/28751/media/review/figure/flower.jpg
What is alternation of generations in gymnosperms?
What is alternation of generations in angiosperms?
Plant life cycle
Sporophyte (2n)
fertilization
meiosis
Gametes (1n)
Spores
mitosis
mitosis
Gametophyte (1n)
How does water transport work in plants?
• Root pressure – active transport and
movement of water into roots
• Capillary action – water molecules
attracted to one another by cohesion and
to walls of xylem by adhesion
• Transpiration – evaporation from surface
of leaves
How do hormones affect plant growth?
• Chemical
messengers that
respond to the
environment
• Growth regulators
b/c they stimulate or
inhibit growth
What are tropisms?
• Plant movement based on environmental
stimulus (page 654)
– Gravitropism – response to gravity
– Phototropism – response to light direction
– Chemotropism – response to chemicals
– Thigmotropism – response to touch
What is photoperiodism?
• plant response to length of day and night
• Can affect flowering times, etc.
How do we get maple syrup?
(fyi only)
In 1663, English chemist Robert Boyle told
associates in Europe, “There is in some parts of New
England a kind of tree whose juice that weeps out its
incision, if it is permitted slowly to exhale away the
superfluous moisture, doth congeal into a sweet and
saccharin substance and the like was confirmed to
me by the agent of the great and populace colony of
Massachusetts.
Tapping is done in late winter (cold nights and warmer days).
Enzymes begin to break the starch into sugar. It will flow
during the day. Tapping is done into the phloem.