Transcript Kingdom Plantae Introduction PreAP web

Kingdom Plantae
Key Questions
1.What do plants need to survive?
2. How did plants adapt to land?
3. What feature defines most plant life?
Characteristics of Plants.
Traditionally plants have been characterized as members of
the kingdom plantae.
Characteristics of Plants.
You already know that trees, shrubs and grass are plants.
Characteristics of Plants.
Mosses, ferns and green algae are also plants.
Characteristics of Plants.
Green algae use to be classified as protists, but in recent
years biologists have reclassified them as plants.
Characteristics of Plants.
Plants are eukaryotes that have cell walls made of cellulose
and carry out photosynthesis using chlorophyl a and b.
Characteristics of Plants.
Comparison of chlorophyl a and b.
Chlorophyll a molecule
Chlorophyll b molecule
Characteristics of Plants.
Chlorophyll a absorbs light within the violet, blue and red
wavelengths while mainly reflecting green.
This reflectance gives chlorophyll its green appearance.
Characteristics of Plants.
Within the reaction centers of both photosystems I and II,
are a pair of chlorophyll a molecules that pass electrons on
to the ETC (electron transport chain).
Characteristics of Plants.
In land plants, the light harvesting antennae around
photosystem II contain the majority of chlorophyll b
Characteristics of Plants.
Most plants are autotrophs, but a few are parasites or
saprobes.
Plants have developed a variety of adaptions to enable
them to succeed as a stationary land organisms.
The basic needs of plants are:
1)
2)
3)
4)
sunlight
gas exchange
water
minerals
1. Sunlight
Plants use energy from sunlight to carry out photosynthesis.
Every plant displays adaptations based on that need for sunlight.
Photosynthetic plant organs such as leaves are typically
broad and flat to maximize exposure to sunlight.
2. Gas Exchange
Plants require oxygen gas to support cellular respiration.
They also require carbon dioxide gas to carry out photosynthesis.
During photosynthesis, plants produce more oxygen than they
need, so they release the excess oxygen gas into the air.
3. Water
On hot sunny days, plants can lose a lot of water to
the air, just as when we sweat.
3. Water
Water is also a reactant that is required for
photosynthesis to occur, so it is consumed when the
sun is shining.
3. Water
Land plants have evolved structures that limit water loss.
Other structures speed up intake of water from the ground.
Stomata
Root hairs
4. Minerals
Plants also absorb minerals through their root system.
Minerals are nutrients in the soil needed by plants
Evolution of Plants
For most of Earth’s history, land plants DID NOT exist.
Life was concentrated in the oceans, lakes and streams.
Evolution of Plants
Photosynthetic prokaryotes like the cyanobacteria added
oxygen to the planet’s atmosphere.
Evolution of Plants
Fossil records indicate plants and animals originated in the water.
For many years now biologist have placed green algae in the
kingdom protista, however it has become clear that they are
actually true plants.
Evidence that green algae should be classified as plants includes:
1. They have cell walls identical to plants
2. They have photosynthetic pigments identical to plants
3. They have reproductive cycles very similar to plants.
4. Comparison of genomes shows they are related.
Evolution of Plants
The first land plants.
Fossil spores of land plants have been found in rocks 475
million years old.
Evolution of Plants
The first land plants.
The oldest fossils of plants themselves are only 50 million
years old.
Evolution of Plants
The first land plants.
The greatest challenge for these new land plants was
obtaining water, which they achieved by growing close to
the ground.
Evolution of Plants
The first land plants.
Over time, the demands of life on land favored the evolution
of plants:
1. more resistant to the drying rays of the sun
2. more capable of conserving water
3. more capable of reproducing without water
Evolution of Plants
The first land plants.
The appearance of land plants changed the rest of life on earth.
Land plants change the environment in ways that allowed new
species to evolve, new ecosystems to develope, and organic
soil to build up.
Evolution of Plants
The first land plants.
Several groups of plants evolved from the first pioneering
land species:
1. Mosses
2. Ferns
3. Cone-bearing plants
4. Flowering plants
Evolution of Plants
The first land plants.
Botanist today divide the plant kingdom into 5 major groups.
The Plant’s Life Cycle
Land plants have a distinctive sexual life cycle that
sets them apart from most other living organisms.
The life cycle of land plants has two alternating
phases, a diploid (2N) phase and a haploid (N) phase.
Conclusion