Transcript Plants

Plants
Chapters 22, 23, & 25
Are eukaryotic, are
multicellular, and have cell
walls.
Adaptations of plants
Meristem– where new cells are found;
tip of stem.
• Plants grow in response to
environmental factors:
– Light
– Moisture
– Gravity
– Temperature
Adaptations of plants
Some plants respond to chemicals or
hormones.
Auxin – is a hormone that makes
stems grow toward light ad away
from the pull of gravity. They make
roots grow away from sunlight and
toward the pull of gravity.
Cytokinins – hormones that stimulate
cell division and make dormant seed
sprouts. Opposite of auxins.
Adaptations of plants
Tropisms – response to gravity, light,
and touch.
• Gravitropism – response of a plant
to gravity. Ex. Roots grow into soil.
• Phototropism – response of a plant
to light. Ex. Change in color; leaves
fall off; grow in direction of light.
• Thigmotropism – plant’s response to
touch. Ex. Venus flytrap.
Adaptations of plants
Adaptations
• Aquatic plants – live in mud with little oxygen so
have air-filled sacs that oxygen diffuses out of.
• Salt water plants – cells pump slat out of leaves.
• Desert plants – (xerophytes) tolerate heat, sand,
winds and little rain. Seeds are often dormant.
• Carnivorous & Parasitic plants – soil has
little nutrients so must trap & digest insects
or live on a host plant to get nutrients.
• Epiphytes – not rooted in soil so grow directly on
other plants. (not parasites)
• Many plants produce chemicals that are
poisonous if eaten. Tobacco – Nicotine.
Classification of Plants
Plant Kingdom
Non-flowering
Plants
Flowering
Plants
Plant Life Cycle
• 2 phases
– Sporophyte – diploid (2N)
– Gametophyte – haploid (N)
Alternating from diploid to haploid is
called alternation of generations.
• Use energy from sunlight to carry
out Photosynthesis.
A plant can be divided into 3 parts
. 3 groups
Non - flowering Plants
Mosses
Ferns
Gymnosperms
Do NOT produce flowers
Examples of Mosses
Spore-producing capsule
spores
Characteristics of Mosses
(Bryophytes)
.Simplest plants
.No true roots, No vascular tissues (no transport)
.Simple stems & leaves
.Have rhizoids for anchorage; no roots
.Spores from capsules (wind-dispersal)
.Damp terrestrial land
A leaf (finely
divided into
small parts)
underground
stem
root
Characteristics of Ferns
.True roots, feathery leaves & underground stems
.have vascular tissues (transport & support)
.Spore-producing organ on the underside
of leaves called a sporangia (reproduction)
.Damp & shady places
needle-shaped leaves
Male cones
(in clusters)
Female cones
(scattered)
Characteristics of Gymnosperms
.tall evergreen trees
.roots, woody stems
.needle-shaped leaves
.vascular tissues (transport)
.cones with reproductive
structures
.naked seeds in female cones
.dry places
Angiosperms – Flowering Plants
• Have reproductive organs called
flowers.
• Flowers attract animals which carry
pollen (pollination).
• Seeds are protected and develops into
a fruit.
• 2 groups – monocot (1 seed leaf)&
dicot (2 seed leaves).
• Annuals (1 season), Biennials (2
seasons), Perennials (many years)
. 2 groups
Flowering
Plants
Monocotyledons
Dicotyledons
.
roots, stems, leaves
.
vascular tissues (transport)
.
flowers, fruits (contain seeds)
Monocotyledons
Parallel veins
Characteristics of Monocotyledons
. one seed-leaf
. leaves have parallel veins
. herbaceous plants
. e.g. grass, maize
Dicotyledons
Veins in network
Characteristics of Dicotyledons
.
two seed-leaves
.
leaves have veins in network
.
e.g. trees, sunflower, rose
Roots, Stems, & Leaves
• Made up of:
– Dermal tissue -“skin”; prevents water
loss.
– Vascular tissue -moves water &
nutrients.
– Ground Tissue – cells that lie b/w
dermal & vascular.
– Meristematic – responsible for new
plant cells and growth.
Roots, Stems, & Leaves
Roots:
• Seedlings grow into primary roots,
then to secondary roots.
• Has a vascular cylinder (xylem &
phloem).
• Function is to anchor plant to ground
& absorb water and dissolved nutrients
from the soil.
• Root pressure forces water upward.
Roots, Stems, & Leaves
Stems:
• Function is to produce leaves, branches &
flowers; hold leaves upright to sun;
transport water & nutrients b/w roots
and leaves.
• Monocot stems-vascular bundles are
scattered throughout stem.
• Dicot stems-vascular bundles are in a ring
& contain xylem and phloem tissue.
Roots, Stems, & Leaves
Leaves:
• Plants main organs.
• Make food (photosynthesis).
• Have chloroplasts.
• Xylem and Phloem tissue are in
bundles called veins which connect to
the stem.
• Stomata allow air/gases in & out.
Transport in Plants
•
•
•
•
Xylem – moves water.
Phloem – moves sugars.
Root pressure forces water up.
Water is pulled up by a force called
cohesion (molecules pulled together).
• Water molecules are also attracted
to other molecules by adhesion.
• Capillary action is cohesion and
adhesion together causing water to
move upward. Water will move
higher in a narrow tube than in a
wider tube.
Plant Classification
Plants
Non-flowering
Sporebearing
No
roots
Mosses
with
roots
Ferns
Naked
seeds
Gymnosperms
Flowering
1 seedleaf
Monocots
2 seedleaves
Dicots