Animal Kingdom — Class 11 Biology NCERT Solutions (Free)

Free step-by-step NCERT solutions for Class 11 Biology chapter "Animal Kingdom" — 8 important questions with detailed answers for CBSE board exam preparation.

✓ 100% Free ✓ No Login Needed ✓ NCERT / CBSE Aligned ✓ Download as PDF

TL;DR: Free step-by-step NCERT solutions for Class 11 Biology chapter "Animal Kingdom" — 8 important questions with detailed answers for CBSE board exam prep…

Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated Jul 23, 2026

🤖 Stuck on any question? Ask Syllab's free AI Tutor for a step-by-step explanation — instant, unlimited, no login.

Key Questions Covered:

Define phylum Porifera and name two characteristics.
What is a cnidocyte? Where is it found?
Distinguish between radial and bilateral symmetry with examples.
What are the main features of phylum Platyhelminthes?
Describe the structure and function of nephridia in earthworms.
What is a notochord? Why is it significant in classification?
+ 2 more questions in the full chapter

Solutions Summary:

Question	Status
Define phylum Porifera and name two characteristics.	✓ Solved
What is a cnidocyte? Where is it found?	✓ Solved
Distinguish between radial and bilateral symmetry with ex…	✓ Solved
What are the main features of phylum Platyhelminthes?	✓ Solved
Describe the structure and function of nephridia in earth…	✓ Solved
What is a notochord? Why is it significant in classificat…	✓ Solved

Showing 6 of 8 questions

Q1: Define phylum Porifera and name two characteristics.

Porifera are the simplest multicellular animals, commonly called sponges. Two key characteristics are: 1. Presence of pores or ostia on the body surface through which water enters. 2. Absence of true tissues and organs; body composed of loosely organized cells.

Q2: What is a cnidocyte? Where is it found?

A cnidocyte is a specialized stinging cell found in organisms of phylum Cnidaria (e.g., jellyfish, sea anemones, corals). It contains a nematocyst, an organelle with a coiled thread-like structure that ejects a toxin when triggered, used for capturing prey and defense.

Q3: Distinguish between radial and bilateral symmetry with examples.

Radial symmetry: Body parts arranged around a central axis; organism can be divided into equal halves by any plane passing through the center. Example: Sea anemone, jellyfish. Bilateral symmetry: Body has a distinct anterior (head) and posterior (tail) end; can be divided into identical left and right halves by only one plane. Example: Fish, earthworm, human.

Q4: What are the main features of phylum Platyhelminthes?

Main features of Platyhelminthes (flatworms): 1. Bilateral symmetry and presence of three germ layers (triploblastic). 2. Absence of body cavity (acoelomate). 3. Simple nervous system with a brain-like structure. 4. Many are parasitic; some are free-living. 5. Gas exchange occurs by diffusion across body wall. Examples: Planaria (free-living), Taenia, Fasciola (parasitic).

Q5: Describe the structure and function of nephridia in earthworms.

Nephridia are excretory organs in earthworms (segmented worms). Structure: Each segment typically contains a pair of nephridia, consisting of a funnel-like nephrostome opening into the coelom, a coiled tubule, and a nephridiopore opening to the exterior. Function: Nephridia collect metabolic wastes from the coelom and blood, and discharge them as urine through the nephridiopore, maintaining osmoregulation.

Q6: What is a notochord? Why is it significant in classification?

A notochord is a flexible rod of cartilaginous tissue running along the dorsal side of the body during embryonic development in chordates. It provides structural support. Significance: It is a key characteristic that defines the phylum Chordata. In most vertebrates, the notochord is replaced by the vertebral column during development, but its presence in embryos confirms chordate ancestry and is used to classify organisms as chordates.

Showing 6 of 8 questions. Visit the full page for complete solutions.