Saturday, December 1, 2007

Concept 28.4

Question:
I. What morphological feature supports molecular data that suggest dinoflagellates, apicomplexans, and ciliates are members of a single clade?

Answer:
a) Membrane-bounded sacs under the plasma membrane


Question:
II. Why is a 'red tide' a cause for concern to people who eat locally caught seafood?

Answer:
a) Red Tide
is a microorganism containing a concentrated toxin and occasionally washes onshore. Though not all people are susceptible to the effects of red tide, it can be absorbed by humans directly, as well as be absorbed in shellfish. Red tide can also affect humans if they consume contaminated molluscan shellfish. During a red tide, bivalve shellfish, including clams and oysters, concentrate the toxin. This concentrated toxin can cause neurotoxic shellfish poisoning (NSP) in humans who eat bivalve shellfish. Both mild gastrointestinal and neurological symptoms occur in NSP.
b) A red tide is a bloom of dinoflagellates, some of which produce deadly toxins that accumulate in molluscs and can affect people who eat molluscs.

Question:
III. Why is it incorrect to refer to conjugation in ciliates as a form of reproduction?

Answer:
a) During conjugation, two ciliates exchange micronuclei, but no new individuals are produced.

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