PG TRB ZOOLOGY ONLINE TEST / QUIZ AS PER LATEST SYLLABUS | Unit I - ANIMAL DIVERSITY AND PHYLOGENY | Origin, Evolution and general characters of Agnatha (Ostracoderms and Cyclostomes). Early Gnathostomes (Placoderms).

PG TRB ZOOLOGY ONLINE TEST / QUIZ AS PER LATEST SYLLABUS | Unit I - ANIMAL DIVERSITY AND PHYLOGENY | Origin, Evolution and general characters of Agnatha (Ostracoderms and Cyclostomes). Early Gnathostomes (Placoderms).

1. Which of the following is an extinct group of jawless vertebrates belonging to Agnatha?

• A) Cyclostomes
• B) Ostracoderms
• C) Chondrichthyes
• D) Osteichthyes

2. The term "Agnatha" refers to a group of vertebrates that lack:

• A) Notochord
• B) Vertebral column
• C) Jaws
• D) Paired fins

3. Which of the following is a key characteristic of Cyclostomes?

• A) Presence of scales
• B) Presence of paired fins
• C) Cartilaginous skeleton
• D) Presence of jaws

4. The dermal armor of Ostracoderms was primarily composed of:

• A) Chitin
• B) Bone
• C) Keratin
• D) Cellulose

5. What is the feeding habit of Lampreys during their adult stage?

• A) Herbivorous
• B) Filter feeders
• C) Parasitic
• D) Scavengers

6. The larval stage of a Lamprey is known as:

• A) Tadpole
• B) Ammocoete
• C) Axolotl
• D) Planula

7. Placoderms were a group of primitive fishes that possessed:

• A) Cartilaginous skeleton
• B) Scales but no jaws
• C) Jaws and a bony armor
• D) No paired fins

8. The class Myxini includes:

• A) Lampreys
• B) Hagfishes
• C) Sharks
• D) Bony fishes

9. What is a notable characteristic of Hagfishes?

• A) Presence of vertebrae
• B) Production of slime for defense
• C) Parasitic lifestyle
• D) Presence of a suction disc

10. The first group of vertebrates to have true jaws are:

• A) Ostracoderms
• B) Cyclostomes
• C) Placoderms
• D) Amphibians

11. A feature that distinguishes Lampreys from Hagfishes is the presence of:

• A) A notochord
• B) A complete vertebral column
• C) Rudimentary vertebrae
• D) Paired fins

12. The earliest known jawed vertebrates are:

• A) Ostracoderms
• B) Placoderms
• C) Acanthodians
• D) Chondrichthyes

13. The fossil record of Ostracoderms dates back to the:

• A) Jurassic period
• B) Cambrian period
• C) Ordovician period
• D) Permian period

14. What is the primary characteristic that separates Cyclostomes from Ostracoderms?

• A) Ostracoderms are jawed; Cyclostomes are jawless.
• B) Cyclostomes have bony armor; Ostracoderms do not.
• C) Ostracoderms are extinct; Cyclostomes are extant.
• D) Cyclostomes have paired fins; Ostracoderms do not.

15. The term "Gnathostomata" refers to vertebrates that possess:

• A) A notochord
• B) A vertebral column
• C) Jaws
• D) Paired appendages

16. Which of the following is an example of an extant Cyclostome?

• A) Dunkleosteus
• B) Pteraspis
• C) Myxine
• D) Cephalaspis

17. Placoderms are considered a paraphyletic group because:

• A) They gave rise to both Chondrichthyes and Osteichthyes.
• B) They are the direct ancestors of all jawless fishes.
• C) They possess jaws and a bony skeleton.
• D) They have a protective dermal armor.

18. The evolution of jaws in early Gnathostomes is believed to have originated from the modification of:

• A) Gill arches
• B) Vertebrae
• C) Scales
• D) Cranial bones

19. Ostracoderms are generally characterized by a terminal mouth and:

• A) A complex brain
• B) A lateral line system
• C) A suction-cup like mouth
• D) A heavily armored head region

20. Which of the following is a key feature of Placoderms' body plan?

• A) Homocercal tail
• B) Heterocercal tail
• C) A distinct head shield and trunk shield
• D) Naked body without scales

21. The term "Cyclostomata" translates to:

• A) Jawed mouth
• B) Circular mouth
• C) Scaleless body
• D) Dermal plates

22. Which group of Ostracoderms had a flattened body and a horseshoe-shaped mouth?

• A) Pteraspidomorphi
• B) Cephalaspidomorphi
• C) Anaspidida
• D) Thelodonti

23. The absence of a stomach and the presence of a single, continuous intestine are characteristic of:

• A) Placoderms
• B) Chondrichthyes
• C) Cyclostomes
• D) Osteichthyes

24. What geological era did Placoderms dominate?

• A) Cretaceous
• B) Jurassic
• C) Devonian
• D) Triassic

25. The skeleton of Placoderms was primarily:

• A) Fully cartilaginous
• B) Fully bony
• C) A mix of cartilage and bone
• D) Made of chitin

26. The larval stage of Hagfish is:

• A) Ammocoete
• B) Free-swimming larva
• C) Direct development, no larval stage
• D) Zoaea

27. Which of the following is a filter-feeding Agnathan?

• A) Adult Lamprey
• B) Adult Hagfish
• C) Ammocoete larva
• D) Placoderm

28. The earliest and most primitive group of jawed fishes were the:

• A) Chondrichthyes
• B) Osteichthyes
• C) Placoderms
• D) Ostracoderms

29. The mouth of a typical adult Lamprey is characterized by:

• A) A pair of powerful jaws
• B) A suctorial funnel with horny teeth
• C) An un-armored, simple opening
• D) A beak-like structure

30. Which of the following is a reason for the extinction of Ostracoderms?

• A) Competition from jawed fishes
• B) Climate change
• C) Over-specialization
• D) All of the above

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