Lab 7 plant adaptations Flashcards
Selection pressures are
Environmental characteristics that favor specific adaptations to local and regional environments
Because plants are predominately non motile they must
They must directly adapt to local environment conditions
Example of selection pressures
Rainfall
Soil characteristics
Natural fires
Biological agents
XYLEM
Vascular tissue in plants that transport water from the soil to the tissues
. Since they are necessary for life on land it has been retained evolutionarily in plants regardless of the habitats they occupy
Where did plants first evolve
In the oceans
The first plants can be described as
A group of photosynthetic cells clinging to one another in colonies.
These cells ultimately specialized assuming different functions.
This specialization continued until colonial organisms evolved into true multicellular organisms.
Multicellular aquatic plants have no need for specialized cells t o carry water why?
Since they are surrounded by water and each cell can get all that it needs by osmosis
Large algae inhabit Intertidal zones ( similar conditions to what the first species to make the transition from water to land)
An experience of periods of submergence and emergence
Adaptations of large algae for living in intertidal habitats are
Intertidal zones that are exposed during periods of low tide run the risk of being dehydrated.some means of attachment to ensure that are not washed away when the water retreats.
Holdfast - roots for attachment
Stipe- stems for support
Blade- leaves for photosynthesis
What are the 3 basic parts of the brown algae
- Holdfast ( root) attachment
- Stipe( stem ) support
- Blade ( leaves) photosynthesis
Also had cells walls modified to conserve water and specialized cells for transporting material within the plants
Cuticle
(kyū’-tuh-kul) (1) A waxy covering on the surface of stems and leaves that prevents desiccation in terrestrial plants.
Prevents uncontrolled evaporation from a plant’s leaves
Evolution of brown algae to plants
Holdfasts evolved into true roots to absorb water and nutrients from the soil
. Blades- leaves for photosynthesis and transporting sugars and other compounds
. Stipe - stems for support
. Surface cells on blades- evolved into systems that produce waxes that coat the aerial portion of terrestrial plants with a waterproof cuticle
Brown algae belong to what division
PHAEOPHYTA
XYLEM
The plant tissue that transport water and dissolve minerals
PHLOEM
Specialized tissue that carries sugars from leaves.
It transports products of photsynthesis to parts of the plant that are not photosynthesic
Plants that have xylem and phloem are called
Vascular plants
Eggs of vascular plants
Ferns
Conifers
Angiosperms
3 types of xylem cells in angiosperms
Tracheids
Vessel members
Fibers
They are dead at maturity and had thick cell walls
FIBRES
Specialized for support and often found in clusters
- Thin cells with tapered ends that interlock to give additional strength to tissues
VESSEL MEMBERS
Modified for transporting water
. Secondarily provide support for plants
. Shorter and broader, with less tapered ends
.sidewalls of vessel members are interrupted by opening called PITS that allow water to pass out of the xylem to neighboring cells.
. The ends of vessel members have one or more large holes - the PERFORATION PLATE that allow free and easy passage of water between cells.
They stack up like pieces of pipe to form long xylem vessels that carry water