Chapter 4 Environmental Issues FREE PDF Download

CBSE 2024-25 Competency Based Questions with Answers: Well, assessment is an integral part of learning that helps build the knowledge that students acquire during the course. The assessment can be of different types and they are all designed to assess the students’ understanding of a particular topic or theme.

The Central Council for Secondary Education has made available the competency-based questions for the school year 2024-25. In this article, we will provide the students with competency-based questions for CBSE Class 12 Biology Chapter 4 Environmental Issues for the 2025 exam.

In addition, a free PDF with competency-based questions on environmental issues from chapter 4 of class 12 is also available to students via the provided link.

CBSE Class 12 Biology Chapter 4 Environmental Issues Competency Based Questions

Free Answer Question / Subjective Question

1. In a research paper titled “Ecological Risk of DDT – A Case Study of Biomagnification Driving Extinction Risk of Herring Gulls on Long Island” (Nakamaru and al, 2001), it was cited that the use of DDT poses immense risks of extinction of a bird called the Herring Gull. This has serious consequences.

(a) The herring gull is a top predator in the food chain of the area. What impact will its extinction have on the food chain?

Name ONE reason why biomagnification could cause the extinction of birds like the herring gull.

2. (a) E-waste recycling is one of the most popular methods of e-waste management in developing countries. It benefits a significant portion of the population by operating in such countries. What can be one of the major drawbacks of these recycling efforts?

Incineration, as a process of e-waste management, can destroy organic components in e-waste. What is the main advantage of incineration in a landfill?

3. Impurities in domestic sewage constitute 0.1% of the total wastewater. Such impurities include:

A: Suspended solids such as sand, silt and clay

B: colloidal material such as fecal matter, bacteria

C: dissolved substances such as nutrients (nitrates, ammonia, phosphate, sodium, calcium, etc.).

As a project manager for domestic wastewater treatment in a city, Shivam came up with the idea of ​​reusing the sewage for other processes in the area.

(a) How can Shivam remove the suspended solids from the sewage water?

(b) How can the colloidal impurities be used in other processes in the city?

(c) If domestic wastewater enters a pond or lake untreated, what ONE effect could it have on the water quality in the water body?

Answers

Answer 1

(a) 0.5 points for each correct answer:

• increase of other predators, carnivores and herbivores in the area
• imbalance in food availability

(b) 1 point for mentioning any of the following:

• decrease in fertility
• premature rupture of the eggshells
• thinning of eggshells

Answer 2

(a) exposes workers to hazardous and toxic substances during manual participation

(b) reduces the volume of waste

Answer 3

(a) 1 point for each correct answer, such as:

(b) in agricultural areas as organic fertilizer

(c) 1 point for mentioning any of the following: