Question

1. What are the defining features of phylum Mollusca?
   
   
2. Determine which class is represented by:
   1. Snails and slugs (1 mark) =
   2. Chiton (1 mark) =
   3. Clams, oysters, scallops, mussels (1 mark) =
   4. Tusk shell (1 mark) =
   5. Squids, nautilus, octopus, and cuttlefish (1 mark) =

3. Which class is the only one with a closed circulatory system? (1 mark)

4. Which class has a modified foot (in which the foot has been modified into a muscular excurrent siphon and part of the tentacles)? (1 mark)

5. What is a radula? What is its function?

6. Which class is the only one that does not have a radula? (1 mark)

7. Which class is the only one that has torsion (this causes the anuSs and mantle to end up above the head)?     

(1 mark)

8. Which class is the only one that has organisms with a shell made of six to eight dorsal plates? (1 mark)

Answer 1

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Mollusca is characterized by the presence of a muscular foot that allows them locomotion, a nervus system comprised of two nerve cords, the feeding organ radula and a mantle from were the shell if present comes from.

They are coelom, tribalistic, protostomes and of bilateral symmetry

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a = gastropods

b = Polyplacophora

c = Bivalba

d = Schaphopoda

e = Cephalopoda

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Cephalopoda

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Cephalopoda

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The radula is a feeding organ made of hard chitin whit many teeth like a chain saw that serves to scrape surfaces of food to cut and process before entering the esophagus

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Bivalves

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Gasteropoda

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Polyplacophora