BISC 110 Chapter Notes -Mycelium, Gymnosperm, Meiosis

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Published on 26 Feb 2014
1. Only forty years ago, plants and fungi were placed in the same kingdom. Even
today, mycology (the study of fungi) is often included in botany courses. Explain,
with reference to the characteristics of these two groups, why plants and fungi are
now placed in separate kingdoms.
Plants and fungi are very different structurally and functionally and have entirely
separate origins from distinct protist ancestors. Plants are multicellular
photosynthetic eukaryotes, with cellulose cell walls, in which the sporophyte
embryo is protected within specialized structures within the female gametophyte.
Fungi are (primarily) multicellular absorptive heterotrophic eukaryotes, with
chitinous cell walls.
2. A number of adaptations have allowed plants to move from aquatic to terrestrial
a. Give examples of specific structural and reproductive characters of plant
groups that limit them to moist or periodically moist environments.
All plants require water, however the life cycles of bryophytes and seedless
vascular plants (such as ferns) further restrict them to periodically moist
environments. The gametophytes of these groups produce flagellated sperm
that require a film of water in order for the sperm to swim to the egg.
b. Give examples of specific structural and reproductive characters of plant
groups that allow them to survive and reproduce in dry environments.
All plants, as compared with their algal ancestors and relatives, have a cuticle to
help prevent water loss. Some bryophytes have membranes and organelles
that are able to withstand temporary desiccation during periods of drought.
Additionally, bryophytes and ferns are able to survive periods of drought as
drought resistant spores, and then germinate when conditions are suitable.
Gymnosperm and angiosperm are the best suited to dry environments as the
sperm travel as pollen and do not require a film of moisture. The seeds of
gymnosperms and angiosperms are also able to withstand periods of drought.
3. Fungal hyphae fuse to form a diploid nucleus, only to restore the haploid state by
meiosis before the growth of new mycelia. What is the significance of the
formation of a transient diploid stage in fungi?
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