Saturday, December 1, 2007

Concept 28.8

Question:
I. Identify 2 ways in which red algae are different from brown algae.

Answer:
a) Brown Algae: color results from the carotenoid FUCOXANTHIN; carbohydrate storage product: LAMINARIN

Red Algae: color results from PHYCOERYTHRIN; carbohydrate storage product: FLORIDEAN STARCH

b) many red algae contain an accessory pigment called phycoerythrin, which gives them a reddish color and allows them to carry out photosynthesis in relatively deep coastal water. Also unlike brown algae, red algae have no flagellated stages in their life cycle and must depend on water currents to bring gametes together for fertilization.

Question:
II. Why is it accurate to say that Ulva has true multicellularity but Caulerpa does not?

Answer:
a) Ulva's thallus contains many cells and is differentiated into leaflike blades and a rootlike holdfast. Caulerpa's thallus is composed of multinucleate filaments without cross-walls, so it is essentially one large cell.

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