Lecture 17: Adaptations Flashcards
Bryophytes
Mosses
Ferns
Seedless Vascular plants
Gymnosperms
Cone trees
Flowers
Flowering plants
origin of land plants
450 million years ago
Plants Evolved from…
Green Algae
Primary Challenges to Life on Land (expanded version)
- Obtaining resources: algae absorbs CO2 and minerals from the water; whole alga performs photosynthesis
- Maintaining moisture: algae absorbs water from living in the aqueous environment
- Staying upright: algae is supported and stays buoyant by the surrounding water (or floats in it)
- Reproduction: algae uses water, which is required for male sperm to reach female egg (and water prevents offspring from drying out)
Primary Challenges to Life on Land (short version)
- Obtaining resources
- Maintaining moisture
- Staying upright
- Reproduction
Earliest land plants did NOT have true roots (only______ )
rhizoids
Adaptations of Land Plants
- Plant body: obtaining resources, maintaining moisture, and staying upright
- Symbiosis with fungi: mycorrhizae
- Large, compact, multicellular: specialize in a variety of
functions (e.g., leaf)
- Waterproofing: cuticle, 3D plant body, seeds/spores
- Stem support: Led to the evolution of wood
- Root systems: minerals from soil (earliest land plants had a rhizoid that only anchored plant) - Life cycles
- Embryo:young plants in a protective structure
- Gamete protection: multicellular structures for protection
- Coordination: gamete provided with moisture
Explain role of Mycorrhizae in plants
- Mutualistic (both benefit), symbiotic (two different species living together) association between fungi and plant
- Fungus provides water & nutrients (esp. phosphorus) via hyphae (similar to roots with high surface-to-volume ratio)
- Plant provides sugars from photosynthesis
Heterophylly
Occurs when there are different leaf shapes on the same plant.
Give an example of lignified xylem
wood
Major root functions
- Anchor the plant firmly to a substrate
- Absorb water and minerals
- Produce hormones
All Land Plants developed from an…
embryo that is protected by tissues of the parent plant.
All Land Plants have…
multicellular, gamete-producing structures.
Gametes
mature reproductive or sex cell that contains a haploid number of chromosomes.
All Land Plants have protected, multicellular, spore-producing structures (_______) that produce gametes.
sporangia
Major Types of Sexual Life Cycles (expanded version)
- Diploid-dominant:multicellular,diploid stage is the most obvious life stage
• Diploid means having both sets of chromosomes (from each parent)
• Only haploid cells, meaning only one set of chromosomes, are the gametes
• Gametes are the reproductive/sex cells (i.e., egg/sperm cells)
• Humans and most animals are “diploid dominant”
• Human chromosome number = 46 (23 46 (23 from each parent) - Haploid-dominant: multicellular, haploid stage is the most obvious life stage
• Fungi and some algae - “Alternation of generations”: haploid and diploid stages both multicellular and both dominate at some point
• Multicellular structures develop to protect the reproductive structures
• Aided the transition to life on land
• Plants and some algae have an “alternation of generations”
All Land Plants have __________ life cycle to protect of reproductive structures.
alternation of generation
________ and _______ are the processes that result in diploid or haploid forms, respectively.
- fertilization
- meiosis
Major Types of Sexual Life Cycles
- Diploid-dominant
- Haploid-dominant
- “Alternation of generations
