Download Unit 6 Review The major evolutionary trend among plants is a

Unit 6 Review
The major evolutionary trend among plants is a reduction in the size of the gametes and an increase in the
size of the sporophyte.
Sequence for the Alternation of Generations:
Gametophyte
gametes
zygote
sporophyte
spores
Plankton – Produce most of the oxygen in the atmosphere
Euglenoid – both plant-like – can photosynthesize and animal-like motility
Algae – carry on most of the world’s photosynthesis
- They are not considered true plants because they lack vascular tissue
- They are separated into various phyla based on color
- Green algae share most of the characteristics of plants. They can be unicellular, filamentous or
colonial.
Phylum Bryophyta – simplest plants
- Gametophyte is dominant and larger than the sporophyte
- Mosses and Liverworts both belong to this phylum
Mosses:
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Is the most complex plant form without water conducting tissue (non-vascular plant)
No true roots, stems, and leaves
Because mosses are non-vascular they cannot grow taller than 20cm
A root-like structure called the rhizoid absorbs minerals and water in mosses and helps to
anchor them to the soil
A structure called the antheridia produce a flagellated swimming sperm in the gametophyte
stage. For this reason moss needs moisture (water) to allow for fertilization. During this stage
the egg is also produced.
In mosses the haploid gametophyte generation is dominant
Mosses do not produce windblown spores
The sporophyte (sporangium) is the diploid phase in the life cycle and begins with fertilization
Meiosis occurs during the formation of the spores
Ferns:
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Are seedless vascular plants with true leaves, roots and stems which require moisture for
reproduction (primitive characteristic)
The heart-shaped gametophytes (which are actually non-vascular) are called the prothallus and
the sex organs are found on the lower surfaces of them
The sporophyte is the dominant stage in the fern and the spores are produced in this stage in a
structure called the sorus (sori)
Ferns are better adapted to life on land than mosses because they have vascular tissue whereas
mosses do not
The leaves of ferns are called fronds and the spoophye leaves first appear in a curled-up form
termed a fiddlehead