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
TRACHEIDS
. For plant support and to transport water ( perform both functions well)
A more primitive cell type
Common in pine and other gymnosperms
. They lack PERFORATION PLATES but have PITS
. They are longer than vessel members, but less tapered end walls and more pits than FIBERS.
4 types of adaptations of plants living on land
Vascular tissue Root Leaf Leaf design Desert plants Carnivorous plants
Eg of intertidal habitat adaptations
Brown algae ( division PHAEOPHYTA)
The xylem cells in hardwoods
Usually have
Fibers
Tracheids
Vessel members
Xylem cells of gymnosperms ( conifers)
Lack vessel members
Have tracheids
Fewer fibers
Xylem cells in BROPHYTES
Lack xylem ( they are none vascular)
Xylem cells InFerns and lower vascular plants
Only tracheids as water carrying cells
Xylem cells in pine
Consist entirely if tracheids
The growth rings in pine is made up
Each year a new layer of xylem is laid down as annual growth ring
Purpose of roots
Anchor plants to soil
Absorb water from the ground
TAPROOT SYSTEM
Eg carrots
Characterized by a single main root axis with smaller branch roots
. Taproots penetrate deeply into the soil
FIBROUS ROOT SYSTEM
Eg. Grass
Comprise of smaller roots that radiate from the base of the plant
. They spread out in a dense mat closer to the soil surface
PROP ROOTS
Eg. Mangrove, corn
Provide additional support to the plant
AERIAL ROOTS
Eg. Epiphytic orchids, cypress
Provide support and function in photosynthesis
CONTRACTILE ROOTS
Found in plants that have bulbs. They pull bulbs deeper into the ground
PNEUMATOPHORES
Roots ( knees) that grow out of the soil and assist in getting oxygen. When the soil is saturated with water
Butter cups ( runnuculus are what type of anigiosperms
Dicots
The outermost layer of the buttercup root is
The epidermis from which hairs emerge
Cortex
lies inside the epidermis. A multilayered tissue used for storage - STARCH GRANULES
ENDODERMIS
The innermost layer of the cortex. Separates the cortex from the from the CENTRAL CYLINDER OR STELE
CENTRAL CYLINDER OR STELE
Contains a cross shaped central area with large cells ( xylem cells,) along with the phloem
The rate of water absorption and movement is controlled by the rate of
TRANSPIRATION ( evaporation) from a plant’ s leaves
STOMA
(stoō’-muh) (plural, stomata) A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant.
How do the STOMA play a role in controlling transpiration
each STOMA is surrounded by GUARD CELLS. When guard cells absorb water they swell and open the STOMA. When they lose water to neighboring cells they collapse and close the STOMA.
How are the leaves of hydrophytes adapted to living in water
The UPPER PALISADE MESOPHYLL is well adapted for photosynthesis ( contains the guard cells and the stomata)
. The LOWER MESOPHYLL is loosely arranged and surrounds large air cavities that help the leaf float.
. STOMATA are located on the upper surface
MESOPHYTE LEAVES
.Belong to terrestrial plants with adequate amounts of water
.Eg. The PRIVET
. UPPER PALISADE MESOPHYLL well developed for photosynthesis
. The LOWER SPONGY MESOPHYLL allows for gasses to diffuse throughout the leaves
XEROPHYTE LEAVES
Eg. Rubber tree
. Adapted to living in dry arid conditions.
. Thick cuticle
. Extra layer …. HYPODERMIS with water filled cells
. Stomata are on the lower surface of The leaf. They Are sunken to help reduce water loss
Adaptations in dessert plants
. Few or no leaves which reduces transpiration
. Extremely long and deep roots ( mesquite trees)
.shedding leaves and going dormant in harsh conditions
.germinate only after heavy seasonal rain then complete their reproductive cycle quickly
. Cacti have shallow root systems, allow them to quickly take up soil moisture following light rain.
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.
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Adaptation in the leaves and stems of dessert plants
Spines… Modified leaves that are photosynthetic but does. to loose water
. Low surface area
.translucent tips
CONVERGENT EVOLUTION
The process where distantly related species evolve similar traits , in response to living in similar environments, not from a common ancestor.
Adaptations in rainforest species
. BARKS:
..thick barks in drier deciduous forests reduce moisture loss
..thin smooth barks in rain forests
.DRIP TIPS
..common in rainforest trees( tapered ends that allow draining after a rain… This preven mosses from growing on the leaves and reducing photosynthesis
.BUTTRESSED BASES
…PROVIDE GREATER STABILITY N WET SOILS WHERE ROOTS DO NOT PENETRATE deeply
. EPIPHYTES
..air plants that live on the surface of other plants to take advantage of the sunlight in canopy
..eg. Ferns, bromeliads, orchids
CARNIVOROUS PLANTS
. Live in acidic soil where nutrients are unavailable
.they instead get nutrients especially nitrogen from captured insects
. Snap traps with sensitive triggers
. Pitfall traps with waxy surface
. Sticky surfaces
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