Saturday, December 1, 2007

Concept 28.5

Question:
I. What unique cellular feature is common to all stramenopiles?

Answer:
a) Stramenopiles have "hairy" and smooth flagella. In some stramenopile groups, the only flagellated cells are motile reproductive cells.

b) A pair of flagella, one hairy and one smooth.

Question:
II. Compare the nutrition of oomycetes with that of golden algae.

Answer:
a) Golden Algae: all are photosynthetic, some are mixotrophic, & can also absorb dissolved organic compounds or ingest food particles and prokaryotes by phagocytosis. While, Oomycetes: do not carry out photosynthesis, instead they acuire nutrients as decomposers or parasites.

b) Oomycetes acquire nutrition mainly as decomposers or parasites; golden algae are photosynthetic, but some also absob dissolved organic compounds or ingest food particles and prokaryotes by phagocytosis.


Question:
III. How is the structure of a borwn alga such as Laminaria well suited to its intertidal zone habitat?

Answer:
a) They have unique adaptations that enable them to withstand the waves & the intense heat of the sun. For example, their cell walls are composed of cellulose and gel-forming polysaccharides that help cushion the thalli from waves and reduce drying when the algae are exposed.

b) The holdfast anchors tha alga to the rocks, while the wide, flat blades provide photosynthesis surfaces. The cellulose and algin in the alga's cell walls cushion the thallus from waves and protect it from drying out.

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