Lecture Twenty - Plant diversity II Flashcards
How have algae evolved?
Red and green algae have their characteristics depending on whether they have evolved to have chlorophyl a (red algae) or chlorophyl a and b (chlorophytes, charophytes and embryophytes).
What characteristics do Charophytes and Embryophytes share?
Charophytes and embryophytes are share a common ancestor.
Cellulose synthesis by protein rosettes.
Phragmoplasts - serves as a scaffold for cell plate assembly and subsequent formation of a new cell wall separating the two daughter cells.
Sperm ultrastructure.
Peroxisome enzymes.
Sporopollenin - major component of the tough outer (exine) walls of plant spores and pollen grains.
Describe a unique characteristic of embryophytes (a type of green algae).
Embryos and alternation of sporophyte and gametophyte generations - key to survival on land.
Alternation of generations involves the haploid gametes to undergo syngomy, forming a diploid zygote.
The zygote forms multicellular gametophyte (2n).
Undergoes meiosis, producing many haploid offspring.
These offspring then form a sporophyte (n).
Describe the pros and cons of living on the land.
Abundant sunlight on land.
Abundant CO2.
Restricted water availability.
Which plants evolved from the embryophytes (original land plants)
The bryophytes grade includes the liverworts, mosses and horn warts.
These are the dominant, photosynthetic gametophytes (gamete-producing and usually haploid phase of the alternating generations).
Nutritionally dependant sporophytes.
Water required for fertilisation.
The tracheophytes include the lycophytes, pleidophytes, gymnosperms and angiosperms.
These are dominant, photosynthesis sporophytes.
Vascular tissues for support (large size) and transport.
What has the colonisation of plants on land enhanced or produced?
Leads to the creation of soil. Increases the rate of geochemical recycling. Increases the rate of erosion. Decreases the levels of CO2 in the atmosphere.
What adaptations have allowed for survival of plants on land despite reduced water avaliability.
Spores with sporopollenin.
Water conducting tissues.
Multicellular gametanglia.
Cuticle.
