CBSE Class 7 An Alien Hand Chapter 3: The Desert - NCERT Solutions

(i) Two phrases that depict the common belief about deserts are: "a flat, unchanging wasteland of dry sand" and "waterless and without shelter". These phrases highlight the popular image of deserts as desolate and inhospitable places.

(ii) Two phrases that reflect the specialist's view of the desert are: "a beautiful place" and "home of a variety of people, animals and plants".

The description provided by specialists is arguably more apt. This is because their perspective is grounded in scientific observation and study, acknowledging the desert's unique beauty and the diverse life it supports, rather than relying on superficial assumptions or limited beliefs.

Here are the correct matches between the phrases:

1. an endless stretch of sand matches with nothing but sand as far as one can see. This phrase emphasizes the vast, uniform sandy landscape characteristic of many deserts.
2. waterless and without shelter matches with no water and no shade. This highlights the scarcity of essential resources like water and protection from the elements in a desert.
3. an oasis matches with fertile place with water and plants in a desert. An oasis is a stark contrast to the surrounding arid land, providing life-sustaining resources.
4. hidden by a cover of grass matches with not visible because the grass is thick. This phrase describes a situation where something is concealed due to dense vegetation, which is less common in typical desert imagery but can occur in specific desert environments or transitional zones.

The text explains that camels can endure long periods without drinking water primarily because they sweat very little. This minimal sweating helps them conserve body water. Additionally, they can tolerate a high body temperature, which further reduces their need to sweat and lose water. Consequently, they are able to retain the water they consume for a significant duration.

Smaller desert animals have developed specific strategies to meet their water needs. Many of them do not drink water directly. Instead, they often burrow underground during the intense heat of the day to stay cool and emerge only during the cooler nights. Their water intake comes from their diet: some consume other animals and obtain moisture from the flesh, while others eat plants and seeds, deriving the necessary water from the juices present in these plant materials.

The text explains that in humid climates, the moisture present in the air acts like a protective blanket. This atmospheric moisture helps to regulate the temperature by shielding the Earth's surface from the sun's intense heat during the day and retaining some warmth at night. In contrast, desert lands typically lack this moisture blanket. As a result, the ground heats up very quickly under the sun's rays during the day, leading to high temperatures. Conversely, without the insulating effect of moisture, the heat dissipates rapidly once the sun sets, causing the temperature to drop sharply at night.

A desert is a vast, arid region characterized by extremely low rainfall, making it difficult for most plants and animals to survive. Contrary to the common image of endless sand dunes, deserts can also feature rocky plains, gravelly surfaces, and even mountains. Despite the harsh conditions, deserts are not lifeless; they host a variety of specially adapted plants, like cacti that store water, and animals, such as camels, reptiles, and insects, that have unique ways to cope with the heat and scarcity of water. Temperatures can fluctuate dramatically, being very hot during the day and surprisingly cold at night. Oases, small fertile areas with water, are vital spots where life can flourish amidst the dryness.

To answer this question effectively, you would need to visit a library and research the lives of people in desert regions like the Sahara, the Gobi, or the Arabian Desert. Key areas to investigate include:

• Food: What staple foods do they consume? How do they obtain or grow food in an arid environment? (e.g., dates, drought-resistant grains, hunted animals).
• Clothes: What type of clothing do they wear? Consider the climate and how their attire protects them from sun, heat, and sand (e.g., loose-fitting, light-colored robes, head coverings).
• Work/Occupations: What are the common ways people earn a living in deserts? (e.g., nomadic herding, oasis farming, trade, resource extraction).
• Social Customs: Are there unique traditions, community structures, or ways of life shaped by the desert environment? (e.g., hospitality, nomadic traditions, water management practices).

After gathering this information, organize it clearly and present it to your classmates, highlighting the resilience and unique adaptations of desert communities.