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NCERT Solutions Curiosity Chapter 12 .5 Who Eats Whom? — Activity 12.7: Let us draw

Book page 19912 Updated on2026-09-05

Q1.
Count the number of each type of organism in Fig. 12.10a. Make a table and set a number in the table against each of the organisms.
Answer

Counting plot by plot across the nine squares of the crop field in Fig. 12.10(a):

OrganismRole in the food chainNumber counted in Fig. 12.10(a)
Millet plantsProducerabout 50
MouseHerbivore (consumer)15
EagleCarnivore (consumer)1

The mice are easy to count exactly — 15, spread across the plots. The millet plants are drawn as clumps and a few are hidden behind the tree, so different students will get slightly different totals, somewhere near 50. Count your own picture carefully and use your own figure; what matters is not the exact number but the order: millets ≫ mice ≫ eagle.

Check it yourself: if your count gives more mice than millet plants, count again. A field cannot feed more herbivores than it has plants.
Q2.
Arrange the numbers in the ascending order, consider the highest number at the base and the lowest at the top. Place the mouse, millet, and eagle appropriately in Fig. 12.10b.
Answer

Ascending order of the counts: 1 (eagle) < 15 (mice) < about 50 (millets). Put the largest number at the base and the smallest at the top:

Eagle — 1 Mouse — 15 Millet plants — about 50 3rd level 2nd level 1st level Producers at the base, the top carnivore at the tip
Fig. 12.10(b) completed: the millet–mouse–eagle food chain drawn to scale.
Millet (producer, 1st trophic level) → Mouse (2nd) → Eagle (3rd)
Q3.
What figure do you get?
Answer

A pyramid — broad at the base and narrow at the top.

It comes out that way because of how energy moves along the chain. A mouse does not turn all the millet it eats into mouse. Most of that food is used up in moving, breathing, keeping warm and growing, and is finally lost as heat. Only a small part is left stored in the mouse's body for the eagle to get.

Energy stored in about 50 millet plants → supports 15 mice
Energy stored in 15 mice → supports 1 eagle
Why it happens: at every step from one trophic level to the next, most of the energy is spent and lost. So each level can support far fewer individuals than the one below it, and the chain narrows as you go up. This is also why food chains are short — after four or five steps there is simply not enough energy left to support another level. Energy flows through an ecosystem one way and leaves as heat; only matter is recycled.
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