- Haploid (n)
- One copy of genome
- Gametophytes
- Transpiration
- Evaporation pulls up water through the stems.
- Symplast
- Moves within cells
- Apoplast
- Moves between cells
Plant Evolution
- Aquatic Plants
- Non-vascular
- Avascular
- Land Plants
- Mainly vascular
- Some avascular plants in moist conditions.
- Began in oceans (aquatic plants).
- Adaption to survive in dry environments (land plants).
- Developed vascular tissues (diversification).
- Pollination/seeds/woody structures (success/animal involvement).
- Flowers and fruits (diversification, co-evolve with animals).
Adaptions for Plants to Colonize Land
- Adapt to Air
- Structural support
- Cell wall for growth
- Cuticle, waxy coating
- Stomata, guard cells, for gas exchange
- Vasculature for water and nutrient transport.
- Reproduction
- Gametangia prevents gametes from drying
- Embryos for young plants
- New dispersal
- Alternation of generations.
- Survival
- Pigments
- Spores
- Associations w/ fungi?
Aquatic Plants
All nonvascular.
- Outgroup
- Unicellular
- Has peptidoglycan
- Red Algae
- Lacks chlorophyll B
- Lacks starch storage
- Has phycoerythrin pigments (red color).
- Green Algae
- Contains chlorophyll B
- Has starch storage
Starch storage is unique to green algae/plants
Starch storage in stroma in chloroplasts.
- Algae
- Refers to all aquatic photosynthetic eukaryotes.
- Colonial Multicellularity
- Such as volvox.
- SIngle cells to multicellular colonies w/ cell complexity = evolution.
- Differentiated Cell/Tissue Multicellularity
- Such as stoneworts
-
- Stoneworts
- Freshwater aquatic green algae
- Not related with land plants (mosses).
Land Plants
- Land Plants
- Embryophytes (has protected embryos).
- Mostly vascular, though some nonvascular.
-
- Nonvascular kinds (mosses, liverworts, hornworts) live in wet places, but not immersed in water.
- Has alternation of generations (haploid <-> diploid).
Nonvascular Land Plants
- Circulation of water and minerals by diffusion.
- Gametophyte (n) (haploid) dominates.
- Sporophytes (2n) (diploid) dependent.
- Have rhizoids (no true roots)
Vascular Land Plants
- Has true roots
- Lignin provide rigid structure to grow tall
- In cell walls
- Height is good to intercept sunlight and disperse spores more efficiently.
- Have rhizomes.
- An underground system of roots.
- Mycorrhizomes are the root system of fungal plants.
- The diploid sporophyte stage dominates
- Does not depend on water to reproduce.
- Has true vasculature.
- Tracheids (xylem) are dead cells that transport water/?
- Phloem are living cells that transport sugars/?
- Vasculature
- Has complex fluid system.
-
- Xylem vessel
- Vessel cells?
- "Roots to shoots"
- Dead
- One-way flow.
- Phloem vessel?
- Companion cells?
- Sieve, tube-like cells
- Live cells
- Two-way flow.
Leaves
- 1st primitive leaf-like structures called 'microphylls'.
- w/ branching structures 'megaphylls'.
- overtopping growth form (net venation?)?
- Vascular Leaves
- Leafy greens = sporophytes
- Smaller, dependent gametophytes inside flowers.
- Nonvascular
- Leafy green = gametophytes
- Smaller, dependent sporophytes.
Seeds Plants
- Gymnosperms
- "Naked seed"
- Reproduction via strobili (cones)
- Cones are unisex
-
- Conifers
- Female cones & male cones (pollen) = sexual reproduction.
- Female cones are higher to reduce chance of self-pollination
-
- To increase genetic diversity.
- Angioperms
- "Enclosed seed"
- Flowering plants
- Flowers are sexual organs
- Fruits are seed protection and dispersal.
- Ovule and seeds protected in a modified leaf called a carpel.
- Ferns
- Earliest land plants
- Ferns are exceptions, they need water! Have flagellated sperm.
- Ferns have spores, not seeds, clusters called sporangia.
- Spore dispersal needs air like vascular plants.
- Fertilization needs water like non-vascular plants.
- Similar to both aquatic plants and land plants.
-
- More similar to land plants because they have true vasculature.
Plant Vasculature
Table 1: Phloem vs. Xylem
| Xylem | Phloem | |
|---|---|---|
| driving force | transpiration from leaves | active transport of sucrose |
| cell type (type) | tracheids | sieve tube elements |
| living cells or nonliving cells | nonliving | living |
| pressure (+ or -) | negative | positive |
| direction of transport | root to shoot | source to sink |
- Transpiration-Cohesion-Tension Mechanism
- For water control in plants, getting it to the leaves.
- Transpiration and evaporation pulls water up through the stems.
- Water evaporation + tension pulls up the water column against gravity.
- Positive water pressure at ground level, negative water pressure higher up.
- Pressure Flow Model for Phloem Sap Transport
- Energy stored in 'sink' cells such as fruit, tubers, seeds.
- Active transport of the sugar sucrose into concentrated areas require ATP energy.
-
- This creates the fruits, tubers, or seeds.
- Source Cells
- Phloem transports against the concentration gradient into the 'sink' cells.
Structure
- All vascular plants have stomata.
- All land plants have cuticles.
- Cell Wall
- Made of cellulose, lignin.
- Cellulose is make of glucose
- Lignin is a protein for the structure.
- All land plants have a cell wall.
- Stomata
- Pores in cuticle help conserve H20.
- Guard cells open and close these.
- Waxy Cuticle
- Conserves water
Water Conduction in Vascular Plants
- Cohesion Surface tension
- Interacts with other water molecules (attraction)
- Adhesion
- Water is attracted to other things that have dipoles (are polar molecules).
Energy Storage
- Starch
- Also made of glucose for energy in plants.
- Long thin structure is hard to make available quickly.
- Glycogen
- Made of glucose for energy in animals.
- Easier to snip off the ends since it's a branching pattern for quick energy release.
Roots
- Root Hairs
- Increase the surface area for uptake of water/minerals.
How water moves into plants?
- Symplast
- Movement through cell to cell regulated by plasmodesmata (proteins that create channels between cells).
- Easier to regulate.
- Apoplast
- Movement of water between cells.
- Less regulated.