Question

5. Which of the following statements does not describes the filter feeding, gas exchange and digestion of the Gastropods? a. The mantle cavity ventral to the gills is in the exhalant region, and the cavity dorsal to the gills is the inhalant region b. Cilia move water into the mantle cavity through an incurrent opening of the mantle. c. Water exits the bivalve through a pat of the mantle cavity at the dorsal aspect of the gills, called the suprabranchial chamber. d. Water rushing out when the valves are forcefully closed washes pseudofeces from the mantle cavity

6. Which of the following best describes the locomotion of the class Cephalopoda? a. Cephalopods depend on their ability to move quickly using a jet propulsion system. b. Normally they crawl over the substrate using their tentacles. c. In most cephalopods, the use of the mantle in locomotion coincides with the loss of an external shell. d. All of these are correct

7. Class Gastropoda a. Body enclosed in a shell consisting of two valves, hinged dorsally, no head or radula. b. Shell when present, usually coiled, body symmetry distorted by torsion. c. Foot modified into a circle of tentacles and a siphon, shell reduced or absent, d. None of these are correct.

8. Class Cephalolopoda a. Body enclosed in a shell consisting of two valves, hinged dorsally, no head or radula. b. Shell when present, usually coiled, body symmetry distorted by torsion. c. Foot modified into a circle of tentacles and a siphon, shell reduced or absent, d. None of these are correct.

9. Class Bivalvia a. Body enclosed in a shell consisting of two valves, hinged dorsally, no head or radula. b. Shell when present, usually coiled, body symmetry distorted by torsion. c. Foot modified into a circle of tentacles and a siphon, shell reduced or absent, d. None of these are correct.

10. Some gastropods have a rolled extension of the mantle called ___________________. a. siphon b. radula c. odontophore cartilage d. radula sac

11. Which of the following characteristics describes phylum Annelida? a. Body metameric, bilaterally symmetrical, and wormlike. b. Open circulatory system c. Metanephridia (usually) or protonephridia d. Both A and B

12. Which of the following statements is not an advantage of metamerism? a. Each segment can be controlled independently on distant segments, and muscles can act as antagonistic pairs with segment. b. It lessens the impact of injury. c. It permits the region of modification of certain regions of the body for specialized functions such as feeding, locomotion and reproduction. d. None of these

Answer 1

6. a .Cephalopods depend on their ability to move quickly using a jet propulsion system.This is achieved when they need to gain speed.Water flows through the mantle cavity and over the gills and comes out through an opening in the head.Pressure is created in the mantle and water is propolled out through a tube called funnel in form of a jet.

7. b. Shell when present, usually coiled, body symmetry distorted by torsion.A coiled shell is present which is either right handed or left handed.In young or larval stage, gastropods undergo torsion in which entire body undergoes 180 degree turn such that head reaches the foot.

8.c.Foot modified into a circle of tentacles and a siphon, shell reduced or absent. Tentacles are a striking character of cephalopods.and shell is reduced as in cuttlefish and squid and absent in octopus.

9.a. Body enclosed in a shell consisting of two valves, hinged dorsally, no head or radula.The bodies of bivalves are laterally compressed in a shell.So they have no head and lack radula.

10.a.siphon. Marine gastropods and burrowers have siphon extending from the ridge of mantle.Siphon helps to draw water into the mantle cavity is used to taste water and detect prey in it.

11.a. Body metameric, bilaterally symmetrical, and wormlike as seen in earthworms. they have closed circulatory system and excreation is through metanephridia and not protonephridia.

12. d.None of these as all the other options define metamerism and are advantageous.Each segmant is capable of functioning independently lesses injury due to presence of septa which maintains normal function.permits modification of certain regions for specialized functions a feeding, locomotion known as tagmatization.