Class 9 SST Chapter 1 Oceans and Life Question Answers (NCERT Solutions)

Class 9 SST Chapter 1 Oceans and Life Question Answers (NCERT Solutions)

Class 9 Social Science Chapter 1: Oceans and Life — Question & Answers

Part 1: The Big Questions

Q1. What is the importance of ocean relief?

Answer: Ocean relief (or submarine relief) refers to the physical landforms found on the ocean floor, including underwater mountains, valleys, plains, and deep trenches. The key reasons ocean relief is important include:

Resource-Rich Shelves: The shallow Continental Shelf (depths of 0–200 metres) receives ample sunlight, making it rich in marine life, fish, and economic resources like crude oil and natural gas.
Underwater Topography: Features like the Mid-Ocean Ridge form the world’s longest underwater mountain range, while deep trenches like the Mariana Trench represent the deepest places on Earth.
Marine Ecosystems: Seamounts, guyots, abyssal plains, and underwater slopes create unique habitats that support diverse sea plants and animal life.

Q2. How does ocean water movement impact life and the environment?

Answer: Ocean water is constantly moving through waves, tides, and ocean currents:

Waves: Driven primarily by winds, waves act as “coastal architects” that erode coastal rocks into sea caves, arches, stacks, and stumps, while depositing sand to build beaches.
Tides: Caused twice daily by the gravitational pull of the Sun and Moon, high tides raise coastal water levels to help large ships dock in ports, bring fish closer to shore for fishermen, and provide renewable tidal energy in areas like the Gulf of Khambhat, Gulf of Kutch, and Sundarbans.
Ocean Currents: Continuous streams of warm and cold water flow across oceans, regulating global coastal temperatures and climates.
Fishing Grounds: Regions where warm currents (like the Gulf Stream) and cold currents (like the Labrador Current) meet create nutrient-rich waters that form world-famous fishing grounds.

Q3. Why are maritime zones important for a country?

Answer: Maritime zones are legally established under international agreements like the United Nations Convention on the Law of the Sea (UNCLOS):

Territorial Waters: Extend up to 12 nautical miles from the coast, giving the nation full sovereign rights over security, customs, fiscal laws, and immigration control.
Exclusive Economic Zone (EEZ): Extends up to 200 nautical miles, granting coastal countries exclusive rights to explore and manage all living (fish) and non-living resources (oil, natural gas, minerals, wave/tidal energy).
Trade and Safety: They establish clear rules of navigation to protect international trade routes while safeguarding coastal ecosystems from illegal activities and pollution.

Q4. How can we use ocean resources in a sustainable way?

Answer: Ocean resources can be managed sustainably through the Blue Economy framework, defined by the World Bank as using ocean resources for economic growth and jobs while preserving marine ecosystem health:

Prevent Overfishing: Enforce fishing regulations and eliminate harmful subsidies so fish populations can naturally regenerate.
Reduce Pollution: Stop plastic waste, industrial sewage, and chemical dumping into ocean waters.
Protect Ecosystems: Preserve coral reefs, mangroves, and marine protected areas in line with UN Sustainable Development Goal 14 (Life Below Water).

Q5. How do early warning systems help protect people from tsunamis and cyclones?

Answer: Early Warning Systems act as real-time monitoring networks using seismic sensors, ocean bottom pressure recorders, satellites, radar, and tide gauges to detect undersea earthquakes and atmospheric disturbances:

Early Detection: Systems like India’s Storm Surge Early Warning System (SSEWS) and the Indian Tsunami Early Warning Centre (ITEWC) detect storm surges and tsunami wave movements.
Immediate Alerts: Devices like the GEMINI handheld receiver broadcast satellite warnings directly to fishermen’s mobile phones in regional languages.
Timely Evacuation: Early warnings allow disaster authorities to evacuate coastal residents to cyclone shelters built under projects like the National Cyclone Risk Mitigation Project (NCRMP), saving lives.

Part 2: End-of-Chapter Questions and Activities

Q1. How do different features of the ocean floor affect human activities such as fishing, transport, and underwater exploration?

Answer:

Fishing: The shallow Continental Shelf (0–200 metres) allows sunlight penetration, promoting rich plant life (plankton) and making it the primary zone for commercial fishing.
Transport: Ships navigating near shallow coastal channels or ports must monitor bathymetry and wait for high tides to pass safely without running aground.
Underwater Exploration: Bathymetric mapping of abyssal plains, Mid-Ocean Ridges, and ocean trenches helps scientists locate offshore oil/gas reserves, discover deep-sea minerals, and route undersea communication cables.

Q2. How do waves, tides, and ocean currents influence climate, marine life, and human activities around the world?

Answer:

Waves: Shape coastlines by forming beaches and rocky sea arches. However, storm waves and earthquake-triggered tsunamis cause severe coastal destruction.
Tides: Rhythmic sea-level changes raise coastal water levels during high tide, enabling large ships to enter harbours, aiding fishermen, and generating renewable tidal power.
Ocean Currents: Warm currents like the Gulf Stream keep high-latitude regions (such as Norway) ice-free, whereas cold currents like the Labrador Current carry freezing waters and icebergs. Where warm and cold currents mix, nutrient-rich waters create abundant fishing grounds.

Q3. Describe the importance of marine resources.

Answer: Marine resources are essential for human survival and global economies:

Food & Livelihoods: Marine living resources like coastal and oceanic fish provide essential protein and support millions of fishing and aquaculture jobs.
Energy & Minerals: Oceans supply conventional energy (offshore oil and natural gas), deep-sea minerals, sand, gravel, and renewable “blue energy” from tides and waves.
Trade & Tourism: Ships carry about 90% of global trade by volume, while coastal landscapes drive multi-billion-dollar tourist economies.
Cultural Values: In India, items like the sacred conch shell (śhaṅkha) and cowries (kapardikā) hold historical and spiritual significance tied to the mythological Samudra Manthana.

Q4. Draw a poster that encourages people to protect marine resources. Include a slogan (like Save Our Seas or Fish for the Future) and explain your message in 2–3 sentences.

Answer:

Suggested Slogan: “Save Our Seas: Clean Oceans, Sustainable Future!”
Poster Visual Description: Illustrate a clean blue ocean filled with vibrant coral reefs and marine life on one side, and a crossed-out symbol over plastic trash and oil spills on the other side.
Message: Oceans produce oxygen, regulate climate, and provide food for billions of people worldwide. We must eliminate plastic dumping and stop overfishing to preserve marine life. Protecting our oceans today ensures a healthy planet for future generations.

Q5. Using a map of India, mark at least five coastal states that might need tsunami warnings.

Answer: Five coastal states and Union Territories in India that critically require tsunami warning systems are:

Tamil Nadu
Andhra Pradesh
Keralam (Kerala)
Odisha
Puducherry (or the Andaman & Nicobar Islands)

Q6. Work in a group and act out what would happen when a cyclone warning is issued. Highlight what role different people, like scientists, officials, and coastal villagers, would play.

Answer:

Scientists (IMD & INCOIS): Use satellites and the Storm Surge Early Warning System (SSEWS) to track storm trajectories, calculate landfall times, and send urgent alerts to disaster management centers.
Government Officials: Use the Decision Support System under the National Cyclone Risk Mitigation Project (NCRMP) to send SMS warnings, halt fishing operations, and move communities into cyclone shelters.
Coastal Villagers & Fishermen: Check GEMINI handheld devices for real-time alerts, secure livestock and boats, stop going out to sea, and evacuate immediately to safe shelters.

Q7. Suppose a foreign ship is sailing through India’s territorial sea. What principle allows the ship to pass through these waters, subject to certain conditions?

Answer:

Principle: The Right of Innocent Passage.
Conditions: Foreign ships can pass through a country’s territorial sea as long as their passage is continuous, expeditious, and non-threatening to the peace, security, and good order of the coastal state.
Ships are strictly forbidden from stopping (except during emergencies), fishing, conducting military drills, or dumping pollutants.

Q8. A country has an Exclusive Economic Zone (EEZ) extending up to 200 nautical miles from its baseline. What rights does the country have over the natural resources in this zone?

Answer: Under UNCLOS regulations, a coastal country in its EEZ (up to 200 nautical miles) has:

Sovereign rights to explore, exploit, conserve, and manage all living resources (such as fish species) and non-living resources (offshore oil, natural gas, deep-sea minerals, and tidal/wave energy).
The country does not own the water column itself, so foreign vessels retain freedom of peaceful navigation and the right to lay undersea cables.

Q9. Create a model of an ocean with ship routes, protected zones, and safety measures. Based on the model, explain how it follows maritime laws and protects the ocean.

Answer:

Ship Routes & COLREGs: Ships follow designated shipping lanes and international collision prevention rules (COLREGs) by traveling at safe speeds, using proper navigation lights, and maintaining lookouts.
Marine Protected Zones: Designated ocean areas enforce conservation guidelines aligned with UN Sustainable Development Goal 14 (Life Below Water) and EEZ laws to prevent habitat destruction and overfishing.
Safety & Pollution Prevention: Vessels adhere to MARPOL anti-pollution standards preventing oil and chemical waste discharge, while tracking devices and tsunami detection buoys ensure maritime safety.