Chapter 2: Oceans and Continents

Answer: A continent is a large, continuous expanse of land on Earth's surface. There are commonly $\textbf{7}$ continents: Africa, Antarctica, Asia, Australia, Europe, North America, and South America.

Explanation

Reference: Chapter 2 – Oceans and Continents, $\text{Pages 28 \& 34–35}$

Key Points:

$\text{Continent} = \text{Large continuous landmass on Earth's surface}$

• A continent is also called a $\textbf{landmass}$
• Most widely adopted count: $n = 7$ continents
• Europe $+$ Asia $=$ single landmass $\Rightarrow$ called $\textbf{Eurasia}$ by geologists

Answer: An ocean is a vast body of saltwater. Oceans cover nearly $\dfrac{3}{4}$ of the Earth's surface. There are $\textbf{5 oceans}$, all interconnected.

Explanation

Reference: Chapter 2 – Oceans and Continents, $\text{Pages 28 \& 31–32}$

$\text{Earth's Surface} = \underbrace{\frac{3}{4}}_{\text{Water (Oceans)}} + \underbrace{\frac{1}{4}}_{\text{Land (Continents)}}$

Order by size (largest to smallest):

$\text{Pacific} > \text{Atlantic} > \text{Indian} > \text{Southern} > \text{Arctic}$

Answer: An island is a piece of land surrounded by water on all sides but smaller than a continent. India has $> 1300$ islands.

Explanation

Reference: Chapter 2 – Oceans and Continents, $\text{Page 37}$

$\text{Island} \subset \text{Landmass},\quad \text{Island} \not\subset \text{Continent}$

Island Group	Location
Andaman & Nicobar	Bay of Bengal
Lakshadweep	Arabian Sea

• Largest island in the world $= \textbf{Greenland}$
• $\text{Area of Greenland} \approx \text{Area of top 10 largest Indian states}$

Answer: This is a map-drawing activity. Draw all $7$ continents from memory and compare with $\textbf{Fig. 2.3}$.

Explanation

Reference: Chapter 2, $\text{Page 39}$

Relative sizes (approximate $\%$ of total land area):

$\text{Asia} \approx 30\% > \text{Africa} \approx 20\% > \text{N. America} \approx 16\% > \text{S. America} \approx 12\% > \text{Antarctica} \approx 9\% > \text{Europe} \approx 7\% > \text{Australia} \approx 6\%$

• Step 1: Sketch the world outline on a blank sheet
• Step 2: Place and colour each continent in correct position
• Step 3: Compare your drawing with Fig. 2.3 on Page 32

Answer: Label $7$ continents and $5$ oceans in their correct positions.

Explanation

Reference: Chapter 2, $\text{Pages 32 \& 39}$

Continents $(n = 7)$:

$\{\ \text{Africa},\ \text{Antarctica},\ \text{Asia},\ \text{Australia},\ \text{Europe},\ \text{N. America},\ \text{S. America}\ \}$

Oceans $(n = 5)$:

$\{\ \text{Pacific},\ \text{Atlantic},\ \text{Indian},\ \text{Southern},\ \text{Arctic}\ \}$

Hemisphere distribution:

$\text{Northern Hemisphere} \Rightarrow \text{more land}$ $\text{Southern Hemisphere} \Rightarrow \text{more water}$

Answer: $\textbf{OXYGEN}$

Explanation

Reference: Chapter 2, $\text{Page 38}$

$\text{Oceans produce} > 50\%\ \text{of Earth's total oxygen}$

• Produced by marine flora: algae and seaweeds
• This is why oceans are called $\textbf{"the planet's lungs"}$
• World Oceans Day $= \text{June 8}$ (designated by the United Nations)

Answer: $\textbf{CONTINENT}$

Explanation

Reference: Chapter 2, $\text{Page 28}$

$\text{Land covers} \approx \frac{1}{4}\ \text{of Earth's surface}$

$\text{Number of continents} = \begin{cases} 4 & \text{(Africa-Eurasia, America, Antarctica, Australia)} \\ 5 & \text{(Africa, America, Antarctica, Australia, Eurasia)} \\ 6 & \text{(Africa, Antarctica, Australia, Eurasia, N. America, S. America)} \\ 7 & \text{(most widely used)} \end{cases}$

Answer: $\textbf{ASIA}$

Explanation

Reference: Chapter 2, $\text{Pages 35–36}$

$\text{Asia} = \text{Largest continent} \approx 30\%\ \text{of total land area}$

$\text{Indian Ocean boundaries:} \begin{cases} \text{North} & \Rightarrow \text{Asia} \\ \text{West} & \Rightarrow \text{Africa} \\ \text{East} & \Rightarrow \text{Australia} \end{cases}$

Answer: $\textbf{PLASTIC}$

Explanation

Reference: Chapter 2, $\text{Page 38}$

$\text{Plastic waste dumped into oceans} = \text{several million tonnes per year}$

Two major threats to marine life:

$\text{Threats} = \underbrace{\text{Plastic Pollution}}_{\text{choking marine life}} + \underbrace{\text{Overfishing}}_{\text{decline of fish species}}$

Answer: $\textbf{ANTARCTICA}$

Explanation

Reference: Chapter 2, $\text{Pages 35 \& 37}$

$\text{Antarctica} \Rightarrow \text{coldest, windiest, and driest continent on Earth}$

India's Antarctic Research Timeline:

$1981 \xrightarrow{\text{Programme begins}} 1983 \xrightarrow{\text{Dakshin Gangotri}} \text{2 more bases established later}$

• $\approx 40$ teams of Indian scientists have conducted research there
• Research focus: evolution of climate and environment

Answer: $\textbf{GREENLAND}$

Explanation

Reference: Chapter 2, $\text{Page 37}$

$\text{Area of Greenland} \approx \sum_{i=1}^{10} \text{Area of India's}\ i\text{-th largest state}$

• Located in the North Atlantic Ocean
• Despite its size, it is classified as an island, not a continent

Answer: $\textbf{TSUNAMI}$

Explanation

Reference: Chapter 2, $\text{Pages 33–34}$

$\text{Tsunami} \Rightarrow \text{caused by} \begin{cases} \text{Submarine earthquake} \\ \text{Volcanic eruption (ocean floor)} \end{cases}$

2004 Indian Ocean Tsunami:

$\text{Date} = 26\ \text{December}\ 2004$ $\text{Cause} = \text{Earthquake in Indonesia}$ $\text{Countries affected} = 14\ \text{(including India)}$ $\text{Lives lost} > 2{,}00{,}000\ \text{people}$

Real-world link: Protected by the $\textbf{Indian Ocean Tsunami Warning System}$ — a multi-country collaboration involving India and many other nations.

Answer: $\textbf{AUSTRALIA}$

Explanation

Reference: Chapter 2, $\text{Pages 35–36}$

Size order (smallest to largest):

$\text{Australia} < \text{Europe} < \text{Antarctica} < \text{S. America} < \text{N. America} < \text{Africa} < \text{Asia}$

$\text{Australia} \approx 6\%\ \text{of total land area} \Rightarrow \textbf{smallest continent}$

Answer: $\textbf{PACIFIC}$ Ocean

Explanation

Reference: Chapter 2, $\text{Page 32}$

Size order of oceans (largest to smallest):

$\text{Pacific} > \text{Atlantic} > \text{Indian} > \text{Southern} > \text{Arctic}$

Real fact: The Pacific Ocean alone is larger than all the continents combined, spanning both the Northern and Southern Hemispheres.

Answer: $\textbf{ISLAND}$

Explanation

Reference: Chapter 2, $\text{Page 37}$

$\text{Island} = \text{Landmass surrounded by water on all sides},\ \text{Area} \ll \text{Continent}$

$\text{India's islands} > 1300$

$\text{Major groups} = \begin{cases} \text{Andaman \& Nicobar} & \Rightarrow \text{Bay of Bengal} \\ \text{Lakshadweep} & \Rightarrow \text{Arabian Sea} \end{cases}$

Real fact: Greenland is the largest island on Earth, yet it is still classified as an island and not a continent due to its size relative to recognized continents.