Curiosity Class 8 Science Chapter 12 How Nature Works in Harmony Case Study Questions

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Last Updated on January 20, 2026 by XAM CONTENT

Hello students, we are providing case study questions for Class 8 Science. Case study questions are the new question format that is introduced in CBSE board. The resources for case study questions are very less. So, to help students we have created chapterwise case study questions for Class 8 Science. In this article, you will find case study questions for CBSE Class 8 Science chapter 12 How Nature Works in Harmony.

Chapter	How Nature Works in Harmony
Type of Questions	Case Study Questions
Nature of Questions	Competency Based Questions
Board	CBSE
Class	Class 8
Subject	Maths
Useful for	Class 12 Studying Students
Answers provided	Yes
Difficulty level	Mentioned
Important Link	Class 8 Science Chapterwise Case Study

Table of Contents

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Case Study Questions on How Nature Works in Harmony

We hope the given case study questions for How Nature Works in Harmony Class 8 helps you in your learning.

Case Study 1:

Researchers conducted a study (Refer NCERT Activity 12.3) to understand how aquatic life influences terrestrial vegetation. They observed two distinct ponds: Pond A, which contained fish, and Pond B, which had no fish. The researchers noted that the number of dragonflies was significantly lower around Pond A compared to Pond B. Conversely, the population of pollinators like bees and butterflies was higher near Pond A. Surprisingly, the study concluded that the flowering plants near Pond A produced significantly more seeds than those near Pond B. This experiment highlights how biotic components interact in complex ways, creating indirect effects within an ecosystem.

Questions

(i) Based on the feeding relationships observed in this activity, which of the following correctly represents the food chain operating in this ecosystem?
A. Plants → Fish → Dragonflies
B. Plants → Pollinators → Dragonflies → Fish
C. Plants → Fish → Pollinators
D. Dragonflies → Fish → Plants

Question Type: MCQ
Difficulty Level: Medium

Ans. B. Plants → Pollinators → Dragonflies → Fish
Explanation: Fish eat dragonfly larvae. Dragonflies eat flies, bees, and butterflies (pollinators). These pollinators feed on nectar from plants. Therefore, the flow of energy is Plants → Pollinators → Dragonflies → Fish.

(ii) Explain the biological mechanism behind the observation that plants near Pond A (with fish) produced more seeds than plants near Pond B (without fish).

Question Type: Conceptual
Difficulty Level: Medium

Ans. The presence of fish in Pond A leads to a decrease in the dragonfly population because fish prey on dragonfly larvae. Since dragonflies are predators of pollinators (bees and butterflies), a reduction in dragonflies allows the pollinator population to thrive. An increased number of pollinators visiting the nearby flowers leads to higher rates of pollination, which directly results in increased seed production for the plants.

(iii) What immediate change would occur in the dragonfly population if fish in Pond A were removed?

Ans. The dragonfly population would increase.
Explanation: The absence of the predator (fish) removes the check on the prey (dragonfly larvae), leading to a higher number of dragonflies in Pond A.

(iv) Figure 12.4 (Refer NCERT) describes the effect of fish on plants as “indirect.” Define this indirect effect in the context of this experiment and contrast it with a direct interaction.

Question Type: Conceptual
Difficulty Level: Medium

Ans. Indirect Effect: An indirect effect occurs when one organism affects another through a third intermediary species, rather than interacting with it face-to-face. In this study, fish benefit the plants not by touching or eating them, but by eating the dragonflies that hunt the plant’s pollinators.

Direct Interaction: This involves physical contact or immediate action, such as the fish eating the dragonfly larvae or the bees collecting nectar from the flowers.