Chapter: 04. Major Water Bodies
A. Choose the correct option.
The Mariana Trench lies in which of these oceans? Which of these is the busiest ocean? Which of these is named after a country? Which of these statements is not true? (ii) Lake Onega is the largest lake in Europe. Which of these oceans lies within the Arctic Circle and, therefore, remains frozen for most part of the year? B. Match the following.
C. Fill in the blanks.
A sea is a part of an ocean that is smaller and more shallow. Gulfs are more indented than bays and also more enclosed. A strait is a narrow stretch of water that joins two large water bodies. The Aral Sea, the Black Sea and the Caspian Sea are also known as inland seas. The five Great Lakes of the USA include Lake Superior, Huron, Michigan, Ontario and Erie. D. State whether the following are true or false. Rewrite the false statements correctly.
Lake Baikal is located in south-east Siberia, and is the deepest lake in the world. Lake Victoria is the largest lake in Africa and is the main reservoir of the Nile River. The Amazon River is the world's longest river. False. The Nile River is the world's longest river. The Rhine is one of the longest and most important rivers of Australia. False. The Rhine is one of the longest and most important rivers of Europe. The Indus Valley Civilization flourished on the banks of the river Ganga. False. The Indus Valley Civilization flourished on the banks of the river Indus. E. Explain the differences between each of the following pairs.
Pacific and Atlantic oceans Pacific Ocean: It is the largest ocean, covering over one-third of the globe and is almost circular in shape. It is bordered by new fold mountains with active volcanoes (the 'Ring of Fire') and contains the deepest part of the Earth's crust, the Mariana Trench. Atlantic Ocean: It is shaped like the letter 'S' and is about half the size of the Pacific Ocean, but has a longer total coastline. It is the busiest ocean for trade and transportation routes and contains the Mid-Atlantic Ridge. Arctic and Antarctic oceans Arctic Ocean: This is the northernmost ocean, located mostly within the Arctic Circle, and therefore remains frozen for most of the year. It is the smallest and shallowest ocean, surrounding the North Pole. Antarctic Ocean (Southern Ocean): This ocean surrounds the continent of Antarctica. It is formed by the merging of the Pacific, the Atlantic, and the Indian oceans, and is the fourth largest ocean in the world. Gulf: A gulf is a deep inlet of the sea almost surrounded by land, with a narrow mouth. Gulfs are generally more indented and more enclosed than bays. Bay: A bay is an open, curving indentation made by the sea or a lake into a coastline. Bays are typically broader and less enclosed compared to gulfs. F. Answer the following questions in brief.
How is a lake different from an island? A lake is a body of water that is completely surrounded by land, whereas an island is a piece of land that is completely surrounded by water. The Aral Sea, the Black Sea and the Caspian Sea are also called inland sea. Why? These are called inland seas because they are very large, saline water bodies that are cut off from the open ocean and are entirely enclosed by land, functioning much like enormous lakes. Where does a river normally originate? A river normally originates from its source, which typically lies in a high ground area such as a hill or a mountain. Where does a river normally ends? A river normally ends its journey at its mouth, which is the place where it enters a larger body of water like a sea or a lake. Surface run-off is the water from sources such as rain or melting snow that flows over the land surface, contributing to the water cycle and often carrying substances into other water bodies. G. Answer the following questions.
Give any three importance of oceans. Oceans are vast storehouses of essential oil and mineral resources. They provide habitats and support a wide variety of aquatic life forms. Oceans facilitate global commerce and trade by serving as important routes for transportation. What is the course of a river? What are its different parts? The course of a river refers to the entire route or path it takes from its point of origin (source) to its end point (mouth). Upper Course: This stage is typically found in mountainous or hilly regions where the land is steep, causing the river to flow very swiftly. Middle Course: After descending from the mountains, the river enters the plains. Its speed decreases significantly as it flows through areas with a gentler slope, often developing meanders. Lower Course: Near its mouth, the river is in its lower course where the land's slope is almost flat. As a result, the river's flow is very slow, leading to deposition of sediments. Mention any three facts about the river Ganga. The Ganga River is considered the most important river of India. It originates from the Himalayas. It flows through both India and Bangladesh. Write three major causes of water pollution. Untreated liquid waste: Discharging raw liquid waste from households (kitchens and toilets) directly into rivers contaminates water and spreads diseases. Industrial discharge: Liquid waste from thermal power plants and other industries, when released into water bodies, can alter water chemistry and harm aquatic life. Surface run-off from farms: Water flowing off agricultural lands carries fertilizers and pesticides into water bodies, causing algal blooms and reducing oxygen levels. What is an oil spill? Why is it harmful for the environment? An oil spill occurs when crude oil or refined petroleum products are accidentally released into the environment, typically into the sea, often during transportation or due to accidents involving tankers or offshore drilling rigs. Oil spills are extremely harmful for the environment because they coat and suffocate marine animals, contaminate marine food sources, destroy habitats like coral reefs and coastal wetlands, and can poison marine life and birds through ingestion or contact, leading to widespread long-term ecological damage. H. Map work
With the help of your atlas, identify and mark the following water bodies on an outline map of the world. Gulf of Alaska: Located off the southern coast of Alaska, North America. Palk Strait: Located between the Indian subcontinent and Sri Lanka. Bay of Bengal: Located to the east of the Indian subcontinent and west of Myanmar and Thailand. Persian Gulf: Located between the Arabian Peninsula and Iran. Caribbean Sea: Located southeast of the Gulf of Mexico, bordered by Central and South America and the Caribbean islands. Bering Sea: Located in the northern Pacific Ocean, between Alaska (USA) and Siberia (Russia). Bass Strait: Located between mainland Australia and the island of Tasmania. Aral Sea: Located in Central Asia, between Kazakhstan and Uzbekistan. With the help of an atlas, identify the following features on the physical map of the world and then mark and label them on a blank outline map of the world. (i) A gulf between North America and South America in the Atlantic Ocean. (ii) A gulf north of Australia. (iii) A strait at the southern tip of South America. (iv) A strait between India and Sri Lanka. (v) A bay just north of North America. I. Source-based questions
Identify the geographical feature. (Hint: This feature is formed at the mouth of a river.) Explain this feature in two sentences and give an example of this feature from India. A delta is a triangular or fan-shaped landform created at the mouth of a river where its flow slows down and deposits sediment as it enters a larger body of water like a sea or ocean. This accumulation of sediment builds up new land over time, often forming a network of distributaries. An example of a delta from India is the Ganga-Brahmaputra Delta (also known as the Sunderbans Delta). 
Answers to textbook exercises