NCERT Solutions Curiosity Chapter 10 .5.1 — Activity 10.5: Let us analyse

Book page 198 & 19910 Updated on2026-09-05

Q1.

How will you decide which stage (larva or pupa) comes immediately after the egg stage? Suppose you are given a container with water from a puddle containing larvae and pupae. Design an activity to find out the correct sequence of these stages.

Answer

Separate the two kinds of creature and watch which one turns into the other. Whatever changes into the other must come first.

Here is the plan, following Avadhi's design in the book:

Step	What I will do
Step 1	I have a water container with mosquito larvae and pupae.
Step 2	I will separate 4–5 larvae and 4–5 pupae into two separate containers with the same water. Label them L and P.
Step 3	I will observe them every day until I see them changing to the next stage.
Step 4	If the larvae change into pupae, it would mean that the larval stage comes before the pupal stage — or, if the opposite happens, the other way round.
Step 5	I will keep watching both containers to see in which one a mosquito appears first.

What you will actually find: container L shows larvae turning into pupae after a few days; container P shows adult mosquitoes emerging first. So the sequence is

Egg → Larva → Pupa → Adult mosquito

Why the “which appears first” test in Step 5 clinches it: the pupa is nearer the adult stage, so pupae become mosquitoes sooner. Two independent pieces of evidence — larvae turning into pupae, and adults appearing sooner from the pupae — point to the same order. Two agreeing tests are far stronger than one.

Safety: cover both containers with a fine cloth held by a rubber band. Air gets in, but any mosquito that emerges cannot fly out into the room. When the activity is over, pour the water on dry ground.

Q2.

Now, suppose you are given a container filled with water from a puddle which contains larvae and pupae. Without separating them from the container, how would you design an activity to decide which stage, out of the two, gives way to the next?

Answer

Now you must get the answer by counting instead of separating.

Count on Day 1. With a hand lens, count how many larvae and how many pupae are in the container. Write both numbers down.
Change nothing else. Keep the container covered with a fine cloth, in the same place, and do not add or remove any creature.
Count again every day for a week, at the same time each day, and record the two numbers plus the number of adult mosquitoes that have emerged.
Read the trend.

Day	Larvae	Pupae	Adults emerged
1	20	6	0
2	17	8	1
3	13	10	3
4	8	11	6
5	3	9	11

How to read this table: the number of larvae keeps falling while the number of pupae first rises and adults keep appearing. Larvae are clearly being converted into pupae, and pupae into adults.

Larvae ↓ Pupae ↑ then ↓ Adults ↑ → Larva comes before pupa

A second, simpler clue in the same container: if you can mark one individual — for example by keeping a single larva in a transparent glass tube open at the top and floating it in the same container — you can watch that one creature change. Watching one individual change is the strongest evidence of all, because nothing else can explain it.

Q3.

Significant changes occur in the appearance, body shape and structure during the various stages in the life cycle of a mosquito. Is it easy to imagine that a mosquito emerges from a pupa?

Answer

No — it is very hard to imagine, and that is exactly why the life cycle of a mosquito is worth studying.

Stage	What it looks like	Where it lives	How it feeds
Stage I — Egg	A tiny dark speck, floating alone or in a raft	On or near water	Does not feed
Stage II — Larva	A long, segmented, bristly wriggler with a distinct head	In water; comes to the surface for air	Feeds and grows
Stage III — Pupa	Short and comma-shaped, no bristles	In water; comes to the surface for air	Does not feed — a resting stage
Stage IV — Adult	A slender flying insect with wings, six legs and long feelers	In air and on land	The female sucks blood

The book puts it plainly: the shape of the egg is quite different from the larva; the larva appears very different from the pupa; and the pupa appears very distinct from the adult mosquito.

The adult that emerges from the pupa rests briefly on the surface of the water and then flies away. It may survive for 10 to 15 days. The adult female then lays eggs directly on or near water, and the cycle continues.

Why such a complete change is useful to the mosquito: the larva and the adult live in totally different places and eat totally different things, so they never compete with each other for food. The pupa is the quiet workshop in between, where the swimming body is rebuilt into a flying one.

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