Transcript Plants - robertschem

Plants
Kingdom Plantae
• Plants evolved about 500 million years ago
from simple green algae that lived in the
ocean.
• All plants are autotrophic and some, like
the famous Venus fly-trap, can also be
heterotrophic.
Plant Cells
Like animal cells, plant
cells contain a nucleus
and organelles, but
they have two
distinguishing features:
– Cell wall (made of
cellulose - provides
rigid structural
support)
– Chloroplast
(conducts
photosynthesis)
Biodiversity & Plant Diversity
• Biodiversity refers to the # of different species and
the # of individuals within each species
• Currently over 350,000 species of plants, including:
–
–
–
–
Mosses
Ferns
Conifers (gymnosperms)
Flowering plants (angiosperms)
• Most plants live on land and can withstand a wide
variety of climates. Cacti live in arid, dry areas
whereas mosses need to be in moist environments to
survive.
• High biodiversity in rainforests (warm & wet) and low
biodiversity in extreme environments such as arctic
and deserts (extreme temp, windy, dry).
• Loss of a plant species can reduce biodiversity
(perhaps it is the only source of food for certain
animal species or insects, etc).
World Plant Biodiversity
Classifying
Plants
• Plants are classified based
on:
– the presence or absence of
vascular tissue
– Production of seeds (seed or
non-seed)
• Vascular tissue can be
compared to arteries and
veins:
– a network of specialized cells
that allows plants to transport
water, minerals and sugar
throughout the plant
• What would you expect a
non-vascular plant, without
vessels to transport nutrients
and water, to look like?
VASCULAR
PLANTS
DEFINITIO
N
Network of specialized cells to
provide transport of water and
nutrients throughout plant
EXAMPLES
Flowering plants
(angiosperms), conifers
(gymnosperms), ferns
STEMS,
ROOTS,
AND
LEAVES?
UPTAKE
OF WATER
AND
NUTRIENT
S
OTHER
Yes to all
Through stems, leaves and
roots, and their cells
Can grow tall, can live in
variety of environments
NON-VASCULAR
PLANTS (Bryophytes)
No network of specialized cells
for transport of water and
nutrients throughout plant
Mosses &
liverworts/hornworts
Lack true leaves and roots
Osmosis, diffusion and
active transport
Grow low and close to the ground;
must live in moist environments or
near presence of water
Classifying Plants: Seed or NonSeed
• Plants may or may not have the ability to
produce seeds as part of their reproductive
life cycle
– All plants, however, can reproduce sexually and
asexually = alternation of generations
• Seeds are specialized reproductive
structures that contain a plant embryo
• Non-Seed Plants: Mosses & Ferns
• Seed Plants: Flowering Plants
(Angiosperms) & Conifers (Gymnosperms)
Seed Plants
• Important to humans because they provide us
with food
• Why it is advantageous to be a seed plant:
– Can sexually reproduce without free water
– Can sexually reproduce with another individual far
away
– Plant embryo surrounded by a protective coat
– Seeds can be dormant till environmental
conditions are “just right”
– Seeds can be carried by wind, water or by
animals to other parts of the ecosystem (or even a
new ecosystem)
Seed Plants
• Can be grouped into:
– Angiosperms (flowering plants). They are
grouped further into:
• Monocots
• Dicots
More later on!
– Gymnosperms (conifers, etc)
ANGIOSPERMS
GYMNOSPERMS
TYPE OF
PLANTS
Herbaceous plants – lack woody
tissues; flowering plants (some
trees can be in this group)
Woody plants – wood-producing
trees & shrubs, conifers including
evergreens (pines, firs, cedars, etc)
LEAVES &
ROOTS
Leaves are usually flat to maximize
photosynthesis. Leaves have pores.
True roots to hold down plant & take
in nutrients.
Conifers have needles for leaves
(small surface area, thick waxy coat =
prevents water loss. Roots are
shallow & spread out = anchors the
tree in areas where soil is sparse.
SEEDS
Seed has coat. Male stamen and
female pistil (or carpel) on same
flower. Pollen from male moves down
flower to female part to fertilize the
egg. Embryo forms within seed.
ECOSYSTE
MS &
PRACTICAL
USES
Diverse ecosystems
Food crops and products,
perfumes, medicine
“Naked seed” = no coat
Conifers have male and female cones.
Pollen grains inside male cone are
carried by wind to female cone, where
egg is fertilized
Boreal Forest and Temperate Rain
Forests (hardier than angiosperms)
Wood, paper/pulp, varnishes, fuel
come from gymnosperms
1. Male anther produces
pollen grains (sperm)
2. Pollen grains from one
flower is carried by wind
or organisms (eg. Bird,
insect) to another flower.
Pollen grains travel
down pollen tube to the
ovary (female egg)
3. Sperm fertilizes the egg
to form a zygote
(embryo) within a seed
4. Seed can develop
further within a fruit
(ovary wall)
Angiosperms
5. Seed can be released
with or without the fruit
and will develop into a
new sporophyte plant
Male (bottom) and Female (top) Pine Cones
Gymnosperms
1. Male pollen cones
produce microspores,
which develop into
pollen grains (sperm)
2. Pollen grains from a
male cone is carried to
the female seed cone
by wind or an organism.
3. Sperm fertilizes the egg
to form a zygote
(embryo) within a seed
4. Zygote forms into a
seed cone (female)
5. Seed (with wing) can be
released and forms into
a new sporophyte
plant that will grow
more.