Class 6 Science Chapter 11: Nature's Treasures Notes

Nature’s treasures

Bhoomi and Surya spend their school holidays with their Ajji (grandmother) in a village at the edge of a forest in the Western Ghats. The air is fresh, the soil is fertile, the sun shines brightly, and there are hills, streams, plants, animals and birds all around. Ajji calls these the treasures of nature. We need them to survive and to make our lives comfortable; without them, no life on Earth is possible. We, too, are part of nature.

Air

Try holding your breath: soon you must breathe again, because the body needs the oxygen in air to work. We can live for a few days without food or water, but not for even a few minutes without oxygen.

Air is a mixture of gases: about 78% nitrogen, 21% oxygen and 1% argon, carbon dioxide and other gases. Moving air is called wind. It turns a paper firki, and it turns the wings of windmills, which run flour mills, pull up water from wells or generate electricity. India has many windmill farms, such as Muppandal in Tamil Nadu, the Jaisalmer Wind Park in Rajasthan and Brahmanvel in Maharashtra.

Water

We need water for drinking, cooking, bathing, washing, cleaning, farming and industry. Water covers about two-thirds of the Earth’s surface, but most of it is in the oceans and seas and is salty. Freshwater is found as ice and snow, in rivers and lakes, and underground, and only a small part of it, in ponds, rivers, lakes and wells, is easy to reach. Many places in India face water shortages. So we must stop wasting water, keep it clean and conserve it, for example by rainwater harvesting. Stepwells such as the bawadi of Rajasthan and the vav of Gujarat have harvested water for centuries. World Water Day is observed on 22 March.

Energy from the Sun

The Sun is the main source of energy on Earth. Plants use sunlight to make food, animals eat plants, and we get food from both, so all our food energy first came from the Sun. We also use its heat and light to dry clothes, chillies and grains, and its energy directly in solar panels (electricity), solar cookers and solar water heaters.

Forests

Forests are large areas with a dense growth of plants. They give food and shelter to wild animals, birds and insects, and give us wood, fruits, medicinal plants and more. Forest cover has been shrinking because of large-scale tree cutting, and a forest takes many years to regrow. India has a long tradition of protecting forests: sacred groves, the forest festival Van Mahotsav in July, and the Chipko movement, which began in the early 1970s in present-day Uttarakhand, when local women hugged trees to save them.

Soil, rocks and minerals

Roots hold the soil and stop it from being washed away, and fallen leaves decay and enrich it: recycling in nature. Soil forms when rocks break apart under the action of the Sun, water and living things over thousands of years. Rocks such as granite, sandstone, marble, slate and laterite are used for buildings, roads and tools. Rocks are made of minerals, from which metals like aluminium, gold, copper and iron are extracted; a basic mobile phone has about a dozen minerals in it.

Fossil fuels

Petrol, diesel and kerosene come from petroleum. Petroleum, natural gas and coal are fossil fuels, formed over millions of years from the buried remains of microorganisms and plants. Natural gas is used for cooking, for electricity and, as CNG, as a cleaner fuel for vehicles; coal is mainly used to produce electricity. Fossil fuels are limited, and burning them produces smoke and carbon dioxide that pollute the air. Walking, cycling and public transport help save them.

Renewable and non-renewable resources

Resources from nature are natural resources; things people make from them, like bulbs, furniture, solar panels and bicycles, are human-made resources. Renewable resources, such as air, water and forests, are renewed by nature within a reasonable time. Non-renewable resources, such as minerals, soil, rocks, coal, petroleum and natural gas, are limited and get used up. Read more in what are natural resources, renewable and non-renewable resources and how to conserve natural resources. Answers to the whole chapter are in the NCERT solutions for Chapter 11.