PG TRB ZOOLOGY ONLINE TEST / QUIZ AS PER LATEST SYLLABUS | Unit I - ANIMAL DIVERSITY AND PHYLOGENY | Retrogressive metamorphosis.

PG TRB ZOOLOGY ONLINE TEST / QUIZ AS PER LATEST SYLLABUS | Unit I - ANIMAL DIVERSITY AND PHYLOGENY | Retrogressive metamorphosis.

1. Which of the following is the most characteristic feature of retrogressive metamorphosis?

a) The larva is simpler than the adult. b) The larva is more advanced than the adult. c) The larva and adult are equally advanced. d) The adult is a simple, sessile form.

2. Retrogressive metamorphosis is a unique feature of which subphylum?

a) Cephalochordata b) Urochordata c) Vertebrata d) Hemichordata

3. The larva of an Ascidian is known as:

a) Bipinnaria larva b) Tornaria larva c) Tadpole larva d) Nauplius larva

4. During retrogressive metamorphosis in Ascidians, the notochord is:

a) Maintained throughout life b) Reduced to a vestigial structure c) Completely degenerated d) Transformed into a vertebral column

5. The most active and free-swimming stage in the life cycle of Herdmania is the:

a) Adult stage b) Tadpole larva stage c) Doliolaria larva stage d) Both a and b

6. The presence of a dorsal hollow nerve cord in the larval stage and its degeneration in the adult is a classic example of:

a) Direct development b) Progressive metamorphosis c) Retrogressive metamorphosis d) Neoteny

7. The structure responsible for the attachment of the Ascidian larva to a substratum is:

a) Oral tentacles b) Adhesive papillae c) Siphons d) Peduncle

8. What happens to the nervous system of the Ascidian larva during metamorphosis?

a) It becomes more complex. b) It transforms into a brain. c) It degenerates into a simple ganglion. d) It remains unchanged.

9. The tail of the Ascidian larva is absorbed primarily by which process?

a) Cellular division b) Excretion c) Apoptosis or autolysis d) Ecdysis

10. The adult Ascidian is a sessile filter feeder, which is considered a less advanced form of life than its free-swimming larva. This phenomenon is termed:

a) Progenesis b) Neoteny c) Retrogressive metamorphosis d) Paedogenesis

11. Which of the following is *retained* in the adult Ascidian after metamorphosis?

a) Notochord b) Tail c) Pharyngeal gill slits d) Dorsal hollow nerve cord

12. The disappearance of the notochord and the dorsal nerve cord in the adult stage of Urochordates is a crucial step in:

a) Progressive evolution b) Retrogressive metamorphosis c) Organogenesis d) Embryonic development

13. The larva of Herdmania, despite being small, exhibits all the hallmark features of a chordate, while the adult does not. This is a clear case of:

a) Larval adaptation b) De-differentiation c) Retrogressive metamorphosis d) Progenitorship

14. Which part of the Ascidian larva contains the notochord and nerve cord?

a) Trunk region b) Head region c) Tail region d) All of the above

15. During the attachment of the Ascidian larva, the adhesive papillae are located at the:

a) Anterior end of the tail b) Posterior end of the tail c) Anterior end of the trunk d) Posterior end of the trunk

16. The final adult form of an Ascidian is characterized by its:

a) High mobility and complex nervous system b) Free-swimming nature and sensory organs c) Sessile existence and simplified structure d) Internal skeleton and streamlined body

17. Which of the following is *not* a degenerative change during retrogressive metamorphosis?

a) Loss of the tail b) Loss of the nervous system c) Loss of the notochord d) Development of the branchial basket

18. The larval stage of Ascidians is considered a key factor in proving their affinity with:

a) Mollusca b) Arthropoda c) Chordata d) Annelida

19. Which of the following is an example of an Ascidian that undergoes retrogressive metamorphosis?

a) Amphioxus b) Balanoglossus c) Herdmania d) Branchiostoma

20. The sensory vesicles present in the Ascidian larva are lost in the adult stage. This loss is a result of:

a) Environmental factors b) Retrogressive metamorphosis c) Progressive evolution d) Asexual reproduction

21. The term "retrogressive metamorphosis" means that:

a) The adult is a higher form than the larva. b) The larva has regressed into a simpler form. c) The larval features are more advanced than adult features. d) The organism undergoes a second, backward metamorphosis.

22. The nervous system in the Ascidian larva is found in the form of:

a) A simple nerve ganglion b) A dorsal hollow nerve cord c) A ventral nerve cord d) Multiple nerve nets

23. The function of the adhesive papillae in the Ascidian larva is to:

a) Secrete digestive enzymes b) Aid in filter feeding c) Facilitate locomotion d) Help in permanent attachment

24. What is the fate of the larval tail during metamorphosis in Ascidians?

a) It is retained to aid in locomotion. b) It is cast off as a whole. c) It degenerates and its material is resorbed by the body. d) It transforms into the adult's excurrent siphon.

25. The adult Ascidian's nervous system is a simple ganglion, which is a reduction from the larva's:

a) Ventral nerve cord b) Paired nerve ganglia c) Dorsal hollow nerve cord d) Nerve net

26. Retrogressive metamorphosis is an adaptation for a:

a) Free-swimming adult life b) Sessile adult life c) Parasitic adult life d) Burrowing adult life

27. Which of the following is true about the Ascidian larva's notochord?

a) It extends throughout the body. b) It is present only in the trunk region. c) It is present only in the tail region. d) It is a permanent structure.

28. The adult Ascidian's branchial basket with numerous gill slits is a feature primarily adapted for:

a) Respiration c) Filter feeding c) Reproduction d) Locomotion

29. The loss of the tail and its contents is a process initiated by enzymes released from:

a) The adult test b) The cerebral ganglion c) The larval muscles and cells d) The pharynx

30. What is the primary purpose of the free-swimming larval stage in Ascidians?

a) To grow larger b) To feed and store energy d) To aid in dispersal and finding a suitable substratum d) To escape predators

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