Step 3 · Choose a topic · Class 9

Biology

Look inside cells and discover how living systems work.

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Your suggested learning path

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Explore → practise → quiz → revise. Earlier topics are recommended preparation; every topic stays open.

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Category3 of 3 topics

01Cell transport

Watch osmosis

NCERT chapter connection

A selectively permeable membrane lets water through but keeps the model solute particles on their own sides. In this simplified equal-volume model, net water movement is towards the side with the greater solute concentration.

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02Ecology

Population growth

Suggested-level exploration

Explore a simplified population that grows by the same percentage each generation, starting with 100 individuals. Real populations face changing resources and other limits.

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03Cells

Cell size and exchange

NCERT chapter connection

Represent a cell as a cube. Its surface-area-to-volume ratio falls as it gets larger. The second control models a group of identical cells; the group has the same ratio.

Interactive explainer 3-round quiz

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