Answer key

Prepared by: learnloophq@gmail.com

Last edited 43 days ago by Learn LoopHQ.

Chapter: 04. Major Water Bodies

⁠

I. Multiple Choice Questions

c) Pacific Ocean

b) Atlantic Ocean

c) Mariana Trench

b) Migratory birds

d) 80 per cent

II. Fill in the Blanks

Indian

strait

Nile

typhoid (or cholera or amoebic dysentery)

III. True or False

True

False (Lake Victoria is the main reservoir of the Nile River)

True

False (Oil spills are very harmful for fish, birds, and other animals dependent on oceans and seas)

IV. Short Answer Questions

A sea is a part of an ocean that is smaller and shallower. It is usually located close to the edge of a land mass or continent.

Oceans are important as great storehouses of oil and mineral resources, they support a large variety of aquatic life, and they facilitate international trade by providing trade routes.

The three main causes of water pollution are liquid waste from thermal power plants, surface run-off from farms, and untreated liquid waste from households.

Surface run-off is water from rain, melting snow, or other sources that flows over land, often carrying pollutants like fertilizers from farms into water bodies.

Marie Tharp discovered the Mid-Atlantic Ridge, a vast underwater mountain range in the Atlantic Ocean.

Plastic pollution harms marine animals through suffocation, entanglement, laceration, infections, and internal injuries when they ingest plastic mistakenly for food.

V. Diagram-Based Questions

The stage of the river shown in Part 1 is the upper course. Here, the river flows very swiftly because the land is steep.

The landform typically created by the river at the end of Part 3 is a delta.

VI. Long Answer Questions

The course of a river is divided into three distinct stages. In the upper course, located in mountains, the land is steep and the river flows very swiftly, actively eroding the landscape. As it descends to the plains, it enters its middle course, where the slope is gentler, causing the flow speed to decrease considerably and often forming meanders. Finally, near its mouth, the river is in its lower course, where the slope is negligible, and its flow has nearly halted, leading to significant deposition of sediments and often the formation of a delta.

Plastic pollution poses severe challenges to oceans, as highlighted by SDG 14, with plastic waste making up 80% of all marine pollution. Millions of tons of plastic are discarded into oceans annually, leading to projections that plastic could outweigh all fish by 2050. This plastic takes thousands of years to degrade, breaking into harmful microplastics. The pollution catastrophically harms marine life by causing suffocation, entanglement, laceration, infections, and internal injuries when animals ingest plastic, necessitating urgent global action for sustainable marine resource use.

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