BIOLOGY 207 Lecture Notes - Lecture 11: Sphagnum, Drought Tolerance, Embryophyte
Document Summary
Pretty much all life started out as aquatic and then had to become very specialized to adapt to terrestrial life: drought tolerance. Moss" baggage of their algal ancestors is the problem of moving the sperm to the egg in the water; need to stop relying on water being the medium to move the sperm and egg. Top 20 organism: sphagnum (peat moss: found in places where breakdown is very slow, creating an anoxic layer with its own environment. Combination of haploid/diploid (diplohaplontic; gametophyte is dominant) Differences between green algae and land plants: all land plants have alternation of generations; green algae had a mixture, green algae had asymmetric and symmetric flagella, land plants only have asymmetric. Green algae ca 600 million years ago: parenchymatous tissue: as cells divide, there might be 2 or three dimensions, asymmetric flagella, egg stays on the gameotophyte. Charophytes (102: gametangia (sex organs)= antheria & oogonia, zygote immediately undergoes meiosis, no alteration of generations.
