BIS 2C L14(II) LG
4. Describe and differentiate the diversity in liverworts, moss, and hornworts.
-Liverworts: have no true stomata (really, guard cells) , sporophyte does not function in dispersal but rather hangs underneath(gemmi cups; No, gemmae cups function in asexual reproduction)) and functions in sexual reproduction, flat 2-d growth called (thallose & leafy). -Moss: has taller 3-d growth, with sporophyte on elongated structure that culminates in a cap sporangium, sporophyte nutritionally dependant on gametophyte. -Hornworts: have persistently green sporophyte and their gametophyte does photosynthesis, sporophyte dependent on gametophyte for nutrition, meristem cells at base.
5. Understand the morphological changes associated with the evolution of vascular plants.
-No vascular tissue -lignified tracheids -No true roots-branched roots -Bad gas exchange-controlled stomata -Swimming sperm-loss of swimming sperm
1. Define the features of bryophytes, including their anatomy, phylogeny, and life cycles.
Bryophytes are a paraphyletic group that consists of liverworts, mosses, and hornworts. They are non-vascular meaning they lack vasculature, and they live in cool, moist habitats. They tend to be relatively small in size. Features: Homosporous alternation of generation life cycle No vascular system; uses turgor pressure for support No lignin (therefore limited in terms of growth) Swimming sperm Sporophyte is nutritionally dependent on gametophyte Rhizoids
3. Explain the limitations of the non-vascular lifestyle in bryophytes, especially in terms of their reproduction and growth.
Bryophytes are restricted in size because they lack lignin and an efficient vascular system, lack the vascular tissues (xylem and phloem) found in vascular plants, No vascular system - No true roots , Inefficient gas exchange , Swimming sperm. All true, but they are very good at what they do. They occupy a unique niche in plants so don't think of them as 'primitive'.
2. Contrast the role of spores in the land plant life cycle with the role of gametes; identify the structures associated with the dispersal of spores in bryophytes.
Spores grow into gametophytes through mitosis Gametes fertilize and become a zygote Sporophytes in liverworts: spore-containing capsule underneath the umbrella-like structures Sporophyte in moss: the stalk-like structure with bulb at the end Sporophyte in hornwort: tapering/horn-like spikes; the sporophyte is persistently green and photosynthetic. But, it is still attached to the gametophyte. Recall the clicker question focused on this gray area.
