NCERT Class 11 Biology Chapter 7: Structural Organisation in Animals PDF Download and Chapter Summary

Chapter 7 of Class 11 Biology, Structural Organisation in Animals, explains how animals are built—from their body tissues to organs and complete organ systems. It focuses on the levels of structural organisation, such as cells, tissues, and organs, in different animals. Important topics include animal tissues, morphology and anatomy of earthworm, cockroach, and frog.

I decided to write about this topic because students often find it confusing due to the large number of scientific terms and animal examples. But once you break it down into simpler sections, it becomes easier to understand. This chapter is very useful, especially for NEET aspirants and board students. It not only builds your knowledge of animal biology but also helps you understand how body systems work in different organisms. Practical questions are often based on diagrams and comparison tables from this chapter. That’s why I think it’s important to review this topic properly and have a downloadable NCERT PDF for regular revision.

What is Structural Organisation in Animals?

This chapter deals with how animals are structured at different levels and how cells come together to form tissues, organs, and finally, functional systems.

1. Animal Tissues

There are four basic types of tissues in animals:

Epithelial Tissue – Covers body surface and organs (e.g., skin, lining of lungs)
Connective Tissue – Supports and binds other tissues (e.g., blood, bone, cartilage)
Muscular Tissue – Responsible for movement (e.g., skeletal, cardiac, smooth muscles)
Nervous Tissue – Transmits signals and controls body functions (e.g., neurons)

2. Morphology of Earthworm

Scientific Name: Pheretima posthuma
Body is segmented
No skeleton
Has a closed circulatory system
Both male and female reproductive organs (hermaphrodite)

3. Anatomy of Cockroach

Scientific Name: Periplaneta americana
Body divided into head, thorax, and abdomen
Open circulatory system
Separate sexes
Tracheal system for respiration

4. Anatomy of Frog

Scientific Name: Rana tigrina
Moist skin, no scales
Three-chambered heart
Well-developed digestive, nervous, and reproductive systems
Can live both on land and in water (amphibian)

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NCERT Class 11 History Chapter 3 PDF (Hindi): यायावर साम्राज्य

Chapter 3 of Class 11 History (Hindi Medium), यायावर साम्राज्य, introduces us to the powerful nomadic groups who lived on grasslands and shaped world politics through their mobility and warfare skills. Unlike settled civilizations, these groups did not build fixed cities. Instead, they lived in tents, moved across open steppe lands, and controlled vast territories using trained cavalry, swift horses, and disciplined armies. This chapter mainly focuses on the Mongols and the rise of the great leader Genghis Khan, who built one of the largest empires in world history.

The Mongols break this idea completely; they ruled not through stone buildings but with strategy, speed, and unity. They controlled long trade routes like the Silk Road, protected traveling merchants, and brought different cultures in contact with each other. Even though they were feared for their battles, they also encouraged trade, promoted communication, and created connections between Europe and Asia. This chapter helps us realise that history is not only written in monuments, but also in movement, leadership, and cultural exchange. Understanding the nomadic empire changes our view of how societies grow without cities and how mobility can be a source of power.

About Chapter 3: यायावर साम्राज्य

This chapter explains who nomads were, how they lived, how they organized themselves, and how they built one of the most influential empires.

Who Were the Nomads?

Nomads were communities that moved from one place to another instead of settling permanently. They traveled with:

Herds of sheep, horses, goats, camels
Portable tents (known as yurts)
Weapons designed for horseback combat

Rise of Genghis Khan

Genghis Khan, originally named Temujin, united different Mongol tribes and became a legendary leader.

Leader	Contribution
Genghis Khan	United tribes, created military discipline, expanded the empire through conquests
Ögedei Khan	Strengthened administration, continued expansion
Mongke and Kublai Khan	Controlled trade, governed China, expanded diplomacy