Class 9 SST Part 2 Ch 1 NCERT Solution - Oceans and Life

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Chapter 01: Oceans and Life

Question 1. Explain the major features of ocean relief.

Answer: Ocean relief refers to the different physical features found on the ocean floor. The ocean floor is not flat; it has mountains, plains, slopes and deep depressions.

The major features are:

• Continental Shelf: The shallow, submerged part of a continent extending into the sea. It is rich in fish, oil and natural gas.
• Continental Slope: The steep slope connecting the continental shelf to the deep ocean floor.
• Abyssal Plain: A large, flat area of the deep ocean floor.
• Mid-Ocean Ridge: A long underwater mountain range.
• Ocean Trench: A long, narrow and very deep depression on the ocean floor.
• Seamount: An underwater mountain that does not reach the sea surface.
• Guyot: An underwater mountain with a flat top.

These features influence marine life, ocean resources and human activities.

Question 2. Explain the three major movements of ocean water.

Answer: The three major movements of ocean water are waves, tides and ocean currents.

Waves: Waves are the rise and fall of ocean water, mainly caused by winds blowing over the water surface. They shape coastlines through erosion and deposition.

Tides: Tides are the regular rise and fall of ocean water, mainly due to the gravitational pull of the Moon and the Sun.

Ocean Currents: These are continuous movements of ocean water in a particular direction. They are influenced by winds, Earth's rotation, temperature and salinity.

All three movements affect coastal areas, marine life, navigation and human activities.

Question 3. Differentiate between spring tides and neap tides.

Answer:

Spring Tides	Neap Tides
They occur during the new moon and full moon.	They occur during the first and third quarters of the Moon.
The Sun, Earth and Moon are aligned approximately in a straight line.	The Sun and Moon appear at approximately right angles as viewed from Earth.
The tidal range is greater.	The tidal range is smaller.
High tides are higher and low tides are lower than usual.	The difference between high and low tides is smaller.

Question 4. Explain the importance of tides.

Answer: Tides are important for several reasons:

Navigation: High tides can help ships enter shallow harbours.

Fishing: Tidal movements influence the movement of fish and can help fishing communities.

Energy: Tidal movements can be used to generate electricity.

Coastal environments: Tides affect coastal habitats and the movement of sediments.

Daily activities: Coastal communities consider tidal timings while planning fishing and other sea-related activities.

Question 5. What is a tsunami? How can early warning systems reduce its impact?

Answer: A tsunami is a series of large sea waves generally caused by powerful disturbances under the ocean, such as underwater earthquakes.

When a tsunami reaches shallow coastal water, the waves can rise and cause severe flooding and destruction.

Early warning systems reduce its impact by:

• Detecting underwater earthquakes and possible tsunami activity.
• Monitoring changes in ocean water levels.
• Sending warnings to authorities and coastal communities.
• Giving people time to evacuate to safer places.
• Helping disaster-management teams prepare emergency measures.

Question 6. Explain the importance of marine resources.

Answer: Marine resources are useful living and non-living resources found in oceans.

Their importance includes:

• Food: Fish and other marine organisms provide food and protein.
• Employment: Fishing, shipping and tourism provide livelihoods.
• Energy: Oceans contain oil and natural gas and offer potential for tidal and wave energy.
• Minerals: Oceans contain various mineral resources.
• Trade: Seas provide important routes for international transportation.
• Biodiversity: Oceans support a wide variety of living organisms.
• Tourism: Beaches, coral reefs and coastal areas attract visitors.

Question 7. What is the Blue Economy? Why is it important?

Answer: The Blue Economy means using ocean resources for economic development while protecting marine ecosystems.

Its main objectives are:

• Creating jobs and livelihoods;
• Supporting fishing, tourism and maritime trade;
• Developing ocean-based energy resources;
• Reducing marine pollution;
• Conserving marine biodiversity;
• Ensuring sustainable use of ocean resources.

The Blue Economy aims to balance economic growth with the protection of oceans for future generations.

Question 8. What is an Exclusive Economic Zone (EEZ)?

Answer: The Exclusive Economic Zone (EEZ) is a sea area extending up to 200 nautical miles from a country's baseline.

Within this zone, the coastal country has special rights to explore, use and manage natural resources, such as:

• Fish and other marine resources;
• Oil and natural gas;
• Other resources of the seabed and ocean floor;
• Energy generated from water, currents and winds.

However, the EEZ is not the same as territorial waters. Other countries retain certain freedoms, including navigation and overflight, under international law.

Question 9. What is innocent passage?

Answer: Innocent passage is the right of foreign ships to pass through another country's territorial sea, provided their passage does not threaten the peace, good order or security of that country.

Question 10. Explain the importance of UNCLOS, COLREGs and MARPOL.

Answer: These are important international maritime agreements and regulations.

UNCLOS (United Nations Convention on the Law of the Sea): It establishes the legal framework for maritime zones, ocean resources and the rights and responsibilities of countries.

COLREGs (Convention on the International Regulations for Preventing Collisions at Sea): These rules help ships avoid collisions by regulating navigation, lights, signals and safe movement.

MARPOL (International Convention for the Prevention of Pollution from Ships): It aims to prevent and reduce pollution of the marine environment caused by ships.

Together, these rules promote safer navigation, environmental protection and cooperation between countries.

Question 11. Describe India's tsunami early warning system.

Answer: India operates the Indian Tsunami Early Warning Centre (ITEWC) to detect and monitor possible tsunami threats.

The system uses several instruments:

Seismic stations: Detect earthquakes and help identify possible tsunami-generating events.

Ocean Bottom Pressure Recorders: Measure pressure changes under the ocean.

Tsunami detection buoys: Help monitor tsunami waves in the ocean.

Tide gauges: Measure changes in sea level along coastlines.

Communication networks: Transmit warnings to government authorities and coastal communities.

The information helps authorities issue timely warnings and organise evacuation when necessary. The system is important for protecting lives and reducing disaster-related damage.

Question 12. What happened during the Indian Ocean tsunami of 2004?

Answer: On 26 December 2004, a powerful undersea earthquake near Sumatra triggered a devastating tsunami in the Indian Ocean.

The disaster:

• Severely affected coastal regions of India, including Tamil Nadu and the Andaman and Nicobar Islands.
• Caused enormous loss of life;
• Destroyed homes and infrastructure;
• Damaged coastal environments;
• Affected several countries around the Indian Ocean;

Question 13. Why is the sustainable use of ocean resources necessary?

Answer: Sustainable use means using resources carefully so that they remain available for future generations.

It is necessary because:

• Oceans provide food and livelihoods to millions of people.
• Overfishing can reduce fish populations.
• Marine pollution harms aquatic organisms and ecosystems.
• Damage to coral reefs and coastal habitats reduces biodiversity.
• Irresponsible resource extraction can damage the ocean environment.
• Healthy oceans help regulate climate and support life on Earth.

Therefore, countries and communities should prevent pollution, practise responsible fishing, conserve marine habitats and cooperate internationally to protect oceans.

Question 14. How can ocean currents influence the climate of coastal regions?

Answer: Ocean currents transfer heat from one region to another and influence the climate of coastal areas.

Warm currents carry warm water and can make nearby coastal regions warmer.

Cold currents carry cold water and can make nearby coastal regions cooler.

Currents influence the temperature of the air above the ocean.

They also affect rainfall, fog and marine ecosystems in some regions.

Therefore, ocean currents are important in controlling regional climate and influencing human activities.

Question 15. Why are continental shelves important for the economy of a country?

Answer: Continental shelves are economically important because they contain valuable marine resources.

• They support rich fishing grounds.
• They may contain oil and natural gas deposits.
• They support marine biodiversity.
• They provide opportunities for offshore economic activities.

Therefore, continental shelves contribute to food security, energy supplies and economic development.

Question 16. Why can no single country manage all ocean resources independently?

Answer: Oceans are connected across national boundaries, and many ocean-related problems affect several countries.

• Ocean currents move water across different regions.
• Marine animals may travel through the waters of several countries.
• Pollution can spread from one area to another.
• Ships travel through international waters.
• Cyclones and tsunamis can affect several coastal countries.

International cooperation and agreements such as UNCLOS help countries manage shared challenges and use ocean resources responsibly.

Question 17. What could happen if ships did not follow international maritime rules?

Answer: If ships did not follow international maritime rules, several problems could arise.

• Collisions between ships could become more frequent.
• Oil spills and other forms of marine pollution could increase.
• Disputes between countries could become more difficult to resolve.
• Navigation and international trade could become less safe.
• Marine life and coastal communities could suffer greater harm.

Therefore, rules such as COLREGs and MARPOL are important for safe navigation and environmental protection.

Question 18. Why are maritime zones important for preventing disputes between countries?

Answer: Maritime zones define the rights and responsibilities of countries in different parts of the sea.

• The territorial sea defines the area where a coastal country exercises sovereignty. It extends up to 12 nautical miles from the baseline.
• The contiguous zone allows certain limited enforcement powers. It extends up to 24 nautical miles from the baseline.
• The Exclusive Economic Zone (EEZ) provides special rights over natural resources. It extends up to 200 nautical miles from the baseline.
• The high seas are governed by international law and are not under the sovereignty of any single country.

Clear legal boundaries help countries understand their rights, manage resources and resolve disputes peacefully.

Question 19. “Oceans are essential for life, but human activities can threaten their health.” Explain.

Answer: Oceans are essential because they support biodiversity, provide food, influence climate and facilitate international trade. They also provide jobs, energy and other valuable resources.

However, human activities such as overfishing, plastic pollution, oil spills and the destruction of marine habitats can damage ocean ecosystems.

To protect oceans, people and governments must reduce pollution, conserve marine biodiversity, use resources sustainably and follow international rules.

Thus, human well-being depends on maintaining healthy oceans.

Question 20. How can marine resources be used without damaging the ocean environment?

Answer: Marine resources can be used sustainably through careful planning and conservation.

• Prevent overfishing and follow fishing regulations.
• Reduce plastic waste and the discharge of harmful substances into the sea.
• Protect coral reefs and other marine habitats.
• Monitor offshore oil and gas activities.
• Promote responsible coastal tourism.
• Develop suitable renewable ocean energy projects.
• Enforce maritime environmental laws and encourage international cooperation.

These measures help balance economic development with the conservation of marine ecosystems.