Unit 3 answer and question

✅ Unit 3 — Pisces (Fishes) Q&A

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🔹 2 Marks Questions

Q1. Write two general characters of Pisces.

✔ Aquatic vertebrates with streamlined body.
✔ Respiration through gills.

Q2. Give two examples of cartilaginous fishes.

✔ Shark (Scoliodon), Dogfish.

Q3. Give two examples of bony fishes.

✔ Rohu, Tuna.

Q4. What is a homocercal tail? Give an example.

✔ Symmetrical lobes of caudal fin.
✔ Example: Rohu.

Q5. What is heterocercal tail? Give an example.

✔ Unequal lobes (upper > lower).
✔ Example: Shark.

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🔹 5 Marks Questions

Q1. General characters of Class Pisces.

• Aquatic habitat (freshwater/marine)
• Streamlined body with scales
• Respiration by gills
• Two-chambered heart
• Fins for locomotion
• Mostly oviparous
• Cold-blooded (poikilothermous)

Q2. Difference between Chondrichthyes and Osteichthyes.

Feature	Chondrichthyes (Cartilaginous)	Osteichthyes (Bony)
Skeleton	Cartilage	Bone
Mouth	Ventral	Terminal
Operculum	Absent	Present
Tail	Heterocercal	Homocercal
Swim bladder	Absent	Present
Examples	Shark, Dogfish	Rohu, Tuna

Q3. Accessory respiratory organs (any 2).

• Lungs → Lepidosiren (lungfish)
• Labyrinth organ → Anabas
• Suprabranchial chamber → Clarias

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🔹 12 Marks Questions

Q1. Structure & economic importance of Rohu.

✔ Streamlined body, homocercal tail, gills, swim bladder.
✔ Reproduction: Oviparous, external fertilization.
✔ Economic value: food, aquaculture, employment, export.

✅ Summary: Covers all 2M, 5M, and 12M exam questions.