1. Which of the following phyla is characterized by the absence of true tissues?
a) Cnidaria
b) Porifera
c) Platyhelminthes
d) Annelida
Answer: Porifera
Explanation: Porifera (sponges) have cellular level of organization, lack true tissues. Cnidaria and Platyhelminthes have true tissues.
2. Coelom is absent in:
a) Annelida
b) Nematoda
c) Arthropoda
d) Mollusca
Answer: Nematoda
Explanation: Nematodes are pseudocoelomates (body cavity not completely lined by mesoderm). Others are true coelomates.
3. Which of the following exhibits radial symmetry?
a) Earthworm
b) Starfish
c) Hydra
d) Leech
Answer: Hydra
Explanation: Hydra (Cnidaria) exhibits radial symmetry. Starfish is pentaradial as adult; earthworm/ leech are bilateral.
4. The skeleton of echinoderms is made of:
a) Chitin
b) Calcium carbonate
c) Silica
d) Keratin
Answer: Calcium carbonate
Explanation: Echinoderms (starfish, sea urchins) have an endoskeleton of calcium carbonate. Chitin is in arthropods.
5. Which class of chordates is warm-blooded and has feathers?
a) Amphibia
b) Reptilia
c) Aves
d) Mammalia
Answer: Aves
Explanation: Birds (Aves) are warm-blooded and covered with feathers; mammals have hair.
6. Flame cells are found in:
a) Annelida
b) Platyhelminthes
c) Nematoda
d) Arthropoda
Answer: Platyhelminthes
Explanation: Flame cells are excretory structures in flatworms for osmoregulation
7. Which of the following is a deuterostome?
a) Ascaris
b) Amphioxus
c) Earthworm
d) Planaria
Answer: Amphioxus
Explanation: Deuterostomes develop anus first in embryogenesis. Chordates (Amphioxus) are deuterostomes.
8. Spicules are found in:
a) Cnidaria
b) Porifera
c) Ctenophora
d) Mollusca
Answer: Porifera
Explanation: Spicules provide support to sponge body; made of silica or calcium carbonate.
9. Which of the following is an acoelomate?
a) Annelida
b) Platyhelminthes
c) Mollusca
d) Arthropoda
Answer: Platyhelminthes
Explanation: Platyhelminthes lack coelom; Annelida, Mollusca, Arthropoda are coelomates.
10. Exoskeleton of arthropods is made of:
a) Cellulose
b) Chitin
c) Calcium carbonate
d) Silica
Answer: Chitin
Explanation: Arthropods have chitinous exoskeleton. Cellulose is plant cell wall; calcium carbonate in mollusks; silica in some sponges.
11. Which phylum shows segmentation (metamerism) most clearly?
a) Annelida
b) Mollusca
c) Arthropoda
d) Nematoda
Answer: Annelida
Explanation: True segmentation is well-developed in annelids; arthropods have tagmata, not true segmentation.
12. Which of the following is not a chordate?
a) Amphioxus
b) Frog
c) Starfish
d) Lizard
Answer: Starfish
Explanation: Starfish lacks notochord, dorsal hollow nerve cord, post-anal tail—chordate features.
13. Which phylum has a complete digestive system?
a) Platyhelminthes
b) Nematoda
c) Porifera
d) Cnidaria
Answer: Nematoda
Explanation: Nematodes have mouth and anus. Platyhelminthes have incomplete gut; Porifera/Cnidaria have gastrovascular cavity or intracellular digestion.
14. Cnidocytes are characteristic of:
a) Porifera
b) Cnidaria
c) Annelida
d) Mollusca
Answer: Cnidaria
Explanation: Specialized stinging cells used for prey capture. Unique to cni
15. Which animal is ovoviviparous?
a) Shark
b) Frog
c) Crocodile
d) Snake
Answer: Shark
Explanation: Eggs develop inside female and hatch internally; young are born live. Frogs and crocodiles are oviparous.
16. Adult tunicates lack:
a) Notochord
b) Pharyngeal slits
c) Dorsal hollow nerve cord
d) Endostyle
Answer: Notochord
Explanation: Adult ascidians (tunicates) lose notochord; larval stage shows chordate features.
17. Which organism reproduces mainly by gemmules?
a) Hydra
b) Porifera
c) Earthworm
d) Nematoda
Answer: Porifera
Explanation: Gemmules are resistant structures for asexual reproduction in sponges.
18. Which phylum is exclusively marine and diploblastic?
a) Ctenophora
b) Annelida
c) Mollusca
d) Arthropoda
Answer: Ctenophora
Explanation: Comb jellies (Ctenophora) are marine and diploblastic (ectoderm + endoderm).
19. Heart of an earthworm is:
a) Single-chambered
b) Three pairs of aortic arches
c) Four-chambered
d) Absent
Answer: Three pairs of aortic arches
Explanation: Earthworm has multiple aortic arches (functioning as hearts) that pump blood.
20. Which class of chordates lays eggs in water and is cold-blooded?
a) Reptilia
b) Amphibia
c) Mammalia
d) Aves
Answer: Amphibia
Explanation: Amphibians are ectothermic and oviparous; lay eggs in water; reptiles mostly lay eggs on land.
