Class 9 Social Science – Geography Chapter 1: Oceans and Life

 

Section A: 2-mark questions

Q1. Why is the continental shelf important for fishing and economic activities? (2 marks)

Answer:

1. The continental shelf is rich in marine life and supports fishing activities.
2. It contains valuable resources such as oil and natural gas.

Q2. A coastal village experiences erosion, and a beach gradually develops elsewhere along the coast. Which ocean process is responsible? Explain briefly. (2 marks)

Answer:
Waves are responsible. They erode coastal rocks and transport sediments. When these sediments are deposited along the coast, depositional landforms such as beaches develop.

Q3. Why do spring tides occur during the full moon and new moon? (2 marks)

Answer:
During the full moon and new moon, the Sun, Earth and Moon are aligned approximately in a straight line. The combined gravitational effects of the Sun and Moon produce unusually high tides and unusually low tides.

Q4. A warm ocean current flows towards a cold coastal region. How may it affect the region's climate? (2 marks)

Answer:
A warm current transfers heat to the surrounding atmosphere and coastal waters. It can make the nearby coastal region relatively warmer, as illustrated by the influence of the Gulf Stream on waters near Norway.

Q5. Differentiate between a seamount and a guyot. (2 marks)

Answer:

• Seamount: An underwater mountain, usually of volcanic origin, that does not reach the ocean surface.
• Guyot: A flat-topped underwater mountain, usually formed when an earlier seamount is eroded and later submerged.

Q6. What is the Blue Economy? Mention one objective. (2 marks)

Answer:
The Blue Economy means using ocean resources sustainably to promote economic growth, livelihoods and employment while preserving marine ecosystems. One objective is to protect marine biodiversity while supporting economic development.

Q7. Why are early warning systems important for coastal communities? (2 marks)

Answer:

1. They help detect and predict hazards such as cyclones and tsunamis.
2. They provide timely alerts, enabling people and authorities to evacuate and take protective measures.

Q8. What is meant by innocent passage in a country's territorial sea? (2 marks)

Answer:
Innocent passage allows foreign ships to pass through a country's territorial sea, subject to the applicable conditions. The passage must respect the coastal country's laws and must not threaten its peace, security or order.

Section B: 3-mark questions

Q9. Explain three ways in which ocean relief influences human activities. (3 marks)

Answer:

1. The continental shelf supports fishing and provides resources such as oil and natural gas.
2. Ocean-floor features influence marine habitats and the distribution of marine organisms.
3. Knowledge of underwater topography helps in navigation, undersea exploration and planning activities on the ocean floor.

Q10. Explain three differences between waves, tides and ocean currents. (3 marks)

Answer:

• Waves: The surface of the ocean rises and falls alternately, primarily due to winds blowing across the water.
• Tides: These are the rhythmic rise and fall of ocean water caused mainly by the gravitational effects of the Moon and Sun.
• Ocean currents: These are continuous streams of water flowing in definite directions, influenced by winds, Earth's rotation, temperature, salinity and the shape of ocean basins.

Q11. Why do regions where warm and cold ocean currents meet often become important fishing grounds? (3 marks)

Answer:

1. These regions are associated with nutrient-rich waters that support marine productivity.
2. The availability of nutrients supports a wide variety of fish.
3. The abundance of fish makes these regions important for commercial fishing and the livelihoods of fishing communities.

Q12. A fisherman receives a cyclone warning on his mobile phone while at sea. Explain three ways in which warning technology can help him. (3 marks)

Answer:

1. Satellite-based information and marine weather services can provide alerts about cyclones, high waves and strong winds.
2. The GEMINI device can receive information from the GAGAN satellite and transfer it to a mobile phone through Bluetooth.
3. The fisherman can use the warning to avoid dangerous sea conditions and follow appropriate safety instructions.

Q13. How do waves create erosional coastal landforms? (3 marks)

Answer:

1. Hydraulic action and abrasion enlarge cracks in coastal rocks.
2. Continued erosion can turn cracks into sea caves and enlarge caves until sea arches form.
3. The collapse of an arch may leave a sea stack, which can later be eroded into a stump.

Section C: 4-mark questions

Q14. A shipping company plans to take a large oil tanker through a shallow sea channel. Explain why tidal information is important for safe navigation. (4 marks)

Answer:

1. Tides cause the regular rise and fall of sea level.
2. During high tide, greater water depth may allow large ships to pass through shallow channels more safely.
3. During low tide, insufficient water depth may cause a ship to run aground.
4. Therefore, ships must check water depth and tidal conditions before entering ports or crossing shallow channels. Large vessels may need to wait for high tide.

Q15. Compare spring tides and neap tides. (4 marks)

Answer:

Basis	Spring tides	Neap tides
Position of celestial bodies	Sun, Earth and Moon are approximately aligned	Sun and Moon act in different directions relative to Earth
Lunar phase	Full moon and new moon	First-quarter and third-quarter moon
Tidal range	Greater difference between high and low tides	Smaller difference between high and low tides
Water levels	Unusually higher high tides and lower low tides	Less extreme high and low tides

Q16. A coastal district has experienced repeated cyclone damage. Suggest four measures to reduce the loss of life and property. (4 marks)

Answer:

1. Strengthen cyclone monitoring and forecasting through satellite observations and meteorological services.
2. Send timely warnings through mobile alerts, SMS, public announcements and other communication channels.
3. Construct and maintain cyclone shelters and arrange safe evacuation routes.
4. Train local communities in disaster preparedness, evacuation procedures and emergency response.

These measures are consistent with the chapter's discussion of cyclone warning services and the National Cyclone Risk Mitigation Project.

Q17. Explain four ways in which marine resources contribute to human welfare and the economy. (4 marks)

Answer:

1. Food security: Fish and seafood provide food and protein.
2. Employment: Fishing and aquaculture support livelihoods and related industries.
3. Energy: Oceans provide oil, natural gas and renewable energy potential from tides and waves.
4. Trade and tourism: Sea routes support international trade, while coastal areas attract tourists and generate income.

Marine resources must be used responsibly to avoid damaging marine ecosystems.

Q18. Distinguish between the territorial sea, contiguous zone and Exclusive Economic Zone (EEZ). (4 marks)

Answer:

Maritime zone	Extent and rights
Territorial sea	Extends up to 12 nautical miles from the baseline; the coastal state exercises sovereignty, subject to the right of innocent passage for foreign ships.
Contiguous zone	Extends up to 24 nautical miles from the baseline; the state has limited powers relating to customs, fiscal matters, immigration and related controls.
Exclusive Economic Zone (EEZ)	Extends up to 200 nautical miles from the baseline; the coastal state has sovereign rights over natural resources and specified economic activities.

These zones are defined within the framework of international law, including the United Nations Convention on the Law of the Sea (UNCLOS).

Section D: 5-mark questions

Q19. “Ocean water movement is important for both the natural environment and human activities.” Justify the statement. (5 marks)

Answer:

1. Coastal landforms: Waves erode coastlines and transport sediments, creating features such as caves, arches, stacks and beaches.
2. Marine life: Waves, tides and currents influence marine habitats and the movement of nutrients and organisms.
3. Climate: Ocean currents redistribute heat. Warm and cold currents influence the temperatures of nearby coastal regions.
4. Fishing: Tidal movements can bring fish closer to shore, while regions where warm and cold currents meet often support productive fishing grounds.
5. Navigation and energy: High tides help ships enter certain ports, tidal currents affect coastal navigation, and tidal and wave movements provide potential sources of renewable energy.

Q20. Describe how a tsunami early warning system operates and explain how it helps save lives. (5 marks)

Answer:

1. Detection: Seismic stations detect undersea earthquakes in real time.
2. Confirmation: Ocean Bottom Pressure Recorders (OBPRs) on the seafloor detect tsunami waves and help confirm the threat.
3. Tracking: Coastal tide gauges and other monitoring systems track changes in sea level and the movement of tsunami waves.
4. Warning dissemination: The Indian Tsunami Early Warning Centre (ITEWC) communicates alerts through government agencies and communication channels such as satellites, SMS and emails.
5. Public response: Authorities and coastal communities use the warning to initiate evacuation, move people to safer locations and follow disaster-management procedures.

An effective system requires continuous monitoring, reliable communication, public awareness and preparedness.

Q21. What is the Blue Economy? Explain how ocean resources can be used sustainably. (5 marks)

Answer:

The Blue Economy promotes economic growth, employment and improved livelihoods through the sustainable use of ocean resources while preserving the health of marine ecosystems.

Its sustainable use can be promoted through the following measures:

1. Responsible fishing: Regulate fishing to prevent overfishing and protect marine biodiversity.
2. Pollution control: Reduce plastic waste, oil spills and other sources of marine pollution.
3. Renewable ocean energy: Develop tidal, wave and other suitable ocean-based energy sources responsibly.
4. Marine conservation: Protect coral reefs, coastal habitats and other sensitive marine ecosystems.
5. International cooperation: Follow maritime laws and conservation measures to resolve disputes and ensure the responsible use of ocean resources.

The objective is to balance economic development with the long-term health of the oceans.

Q22. Explain the importance of maritime laws and regulations for countries and the international community. (5 marks)

Answer:

1. Defining maritime zones: International law helps establish the rights and responsibilities of countries in territorial seas, contiguous zones and EEZs.
2. Preventing disputes: Common rules help resolve disagreements over marine boundaries and resources.
3. Safe navigation: COLREGs establish rules that help ships avoid collisions and navigate safely.
4. Marine environmental protection: Agreements such as MARPOL aim to reduce pollution from ships.
5. Supporting trade and cooperation: Maritime regulations promote safer sea routes, protect sailors and coastal communities, and support international trade and peaceful cooperation.

Section E: Case-based competency questions

Q23. Case study: Tides and coastal transport (4 marks)

Read the passage and answer the questions that follow.

A port handles large cargo ships that must cross a shallow channel before reaching the harbour. The port authority observes that ships can enter more safely at certain times of the day. It also notices that tidal conditions influence fishing activities along the nearby coast.

(a) Why can ships enter shallow channels more safely during high tide? (1 mark)

Answer: High tide raises the water level and increases the depth available for ships.

(b) What may happen if a large ship crosses the channel during low tide? (1 mark)

Answer: The ship may run aground because the water depth may be insufficient.

(c) Explain two ways in which tides support human activities. (2 marks)

Answer:

1. High tides can facilitate navigation and the entry of ships into ports.
2. Tidal movements support fishing activities and can be used to generate electricity.

Q24. Case study: Ocean currents and climate (4 marks)

Read the passage and answer the questions that follow.

A student compares two coastal regions. Region A is influenced by a warm ocean current, while Region B is influenced by a cold ocean current. The student finds that the nearby marine environments and coastal conditions differ.

(a) What is an ocean current? (1 mark)

Answer: An ocean current is a continuous stream of ocean water flowing in a definite direction.

(b) Name one factor, other than temperature, that influences ocean currents. (1 mark)

Answer: Winds. Other acceptable answers include Earth's rotation, salinity differences or the shape of ocean basins.

(c) Explain how warm and cold currents can influence coastal regions. (2 marks)

Answer:

1. Warm currents transfer heat to surrounding waters and the atmosphere, making nearby coastal waters relatively warmer.
2. Cold currents bring colder water and can influence coastal temperatures and the formation of sea ice in suitable conditions.

Q25. Case study: Protecting fishermen from ocean hazards (5 marks)

Read the passage and answer the questions that follow.

A fishing community receives warnings about a developing cyclone. Some fishermen are still at sea, while others are preparing to leave for fishing. The local administration begins issuing alerts and arranging emergency support.

(a) What causes cyclones according to the chapter? (1 mark)

Answer: Cyclones are caused by atmospheric disturbances over warm ocean waters.

(b) Name the Indian organisation responsible for providing cyclone forecasts. (1 mark)

Answer: The India Meteorological Department (IMD).

(c) Explain three measures that can reduce risks to fishermen and coastal residents. (3 marks)

Answer:

1. Send timely warnings about cyclones, strong winds and high waves.
2. Advise fishermen to avoid dangerous sea conditions and follow official safety instructions.
3. Arrange evacuation, cyclone shelters and emergency assistance for vulnerable coastal residents.

Q26. Case study: Sustainable use of ocean resources (5 marks)

Read the passage and answer the questions that follow.

A coastal state earns income from fishing, tourism and offshore energy projects. However, increasing marine pollution and excessive fishing are damaging the coastal environment. The government wants to develop the local economy without destroying marine resources.

(a) What is the Blue Economy? (1 mark)

Answer: It is the sustainable use of ocean resources to promote economic growth, livelihoods and jobs while preserving marine ecosystems.

(b) State one environmental problem mentioned in the passage. (1 mark)

Answer: Marine pollution or excessive fishing.

(c) Suggest three measures for sustainable ocean development. (3 marks)

Answer:

1. Regulate fishing to prevent overexploitation of marine resources.
2. Reduce marine pollution through effective waste management and pollution-control measures.
3. Protect marine ecosystems and develop suitable renewable ocean-energy projects responsibly.

Section F: Higher-order thinking questions (HOTS)

Q27. A country has a long coastline but suffers from marine pollution and declining fish stocks. Explain why a long coastline alone cannot ensure sustainable economic development. (3 marks)

Answer:

1. Marine resources can be depleted by excessive fishing and unsustainable exploitation.
2. Pollution damages marine habitats and threatens biodiversity and fisheries.
3. Long-term development requires conservation, pollution control, responsible fishing and effective maritime regulation.

Q28. A foreign ship passes through India's territorial sea without threatening security or violating applicable conditions. Should every such passage be prohibited? Give a reasoned answer. (2 marks)

Answer:

No. Under the principle of innocent passage, foreign ships may pass through a country's territorial sea subject to the applicable conditions. This balances the coastal state's sovereignty with lawful international navigation.

Q29. Why is international cooperation necessary for the sustainable use of the high seas? (3 marks)

Answer:

1. The high seas are not under the sovereignty of a single country.
2. Problems such as overfishing, illegal fishing and disputes over resources can affect several countries.
3. International cooperation and maritime rules help protect marine resources, support safe navigation and reduce conflicts.