In Focus

Plants and the environment

1. What happens to all the leaves that fall?
2. How do forests help improve the air?
3. What is the nitrogen cycle?
4. How do plants colonize bare ground?
5. How are plants used to clean up sewage?

Rocks and minerals

1. What are the most valuable minerals?
2. What are the most common rocks?
3. Is coal a rock?
4. What is the hardest mineral?
5. What are elements and minerals?

Animal kingdom

1. Name the fish that can live out of water.
2. What does the word amphibian mean?
3. What distinguishes frogs from toads?
4. How long can frogs or toads live?
5. Which frog keeps its eggs in a sack under its throat?

[Answers]

Plants and the environment

1. A huge amount of leaves from plants and trees fall on the ground. However, they don’t collect on the forest floor from year to year. Instead, the dead leaves decay. Once they fall to the ground bacteria and fungi attack the leaves and break them down. Gradually the leaves become a part of the soil. Apart from this process, many animals including worms, insects, slugs, snails, millipedes and woodlice eat the leaves.

2. They do so by releasing huge quantities of water vapour and oxygen into the atmosphere. Plants also absorb carbon dioxide which can be harmful if this gas builds up in the atmosphere.

3. There is a certain amount of nitrogen in the air. Bacteria in the soil use the nitrogen in the air to turn the soil into a form that plants can use. Then the plants use the nitrogen that builds up in their cells, to make many complex compounds. When animals eat plants, the nitrogen returns to the soil in their droppings. It also gets back into the soil when animal bodies and plants decay and rot.

4. There are some plants that can quickly colonize bare soil by germinating rapidly from lightweight, wind-blown seeds. Some colonizing plants spread by putting out runners, which split off, becoming new plants.

5. Sewage works use tiny algae and other microscopic organisms in their filter beds. These algae and other organisms feed on the pollutants in the water and help to make it clean.

Rocks and minerals

1. Gemstones such as diamonds, rubies, sapphires and emeralds are valuable minerals. Gold and silver are also regarded as minerals although they occur as free elements.

2. Sedimentary rocks cover over 75 per cent of the Earth’s surface. But igneous rocks make up 95 per cent of the rocks in the top 16 km of the Earth’s crust.

3. It is sometimes called an organic rock but it is not a proper rock, as rocks are inorganic (lifeless). Coal, like oil and natural gas was formed millions of years ago from the remains of once living things. That is why coal, oil and gas are called fossil fuels.

4. A pure but rare form of carbon - diamonds are the hardest mineral. It is formed under great pressure, deep inside the Earth.

5. Earth’s crust contains 92 elements of which the two most common are oxygen and silicon. Aluminium, iron, calcium, sodium, potassium and magnesium are also common. These eight elements make up 98.59 per cent of the weight of the Earth’s crust. Some elements such as gold occur in a pure state. But most minerals are chemical combinations of elements.

For example, minerals made of oxygen and silicon often, with other small amounts of elements, are called silicates. They include feldspar, quartz and mica - all found in granite.

Animal Kingdom

1. There are some kinds of fish that can live out of water from time to time. The flying fish can glide over the surface of water through the air for over 400 metres and rise up to 6 m above sea water. African fish cat can breathe air through its lungs and live out of water for many days. Tree climbing fish can also live out of water.

2. Amphibian means ‘living a double life.’ Frogs, toads, newts and salamanders are amphibians that live on land and in water.

3. At a glance the similarities are many and it’s not easy to tell them apart. However, toads lay fewer eggs, spend most of their adult life on land, they don’t have webbed feet and move by walking or hopping. They are also fatter than frogs.

4. They can live up to 30 or 40 years.

5. An Australian male frog called the Darwinian frog gulps in the eggs and keeps them safely in a sack under its throat. When the eggs hatch, they come out of his mouth.

Win a valuable book from Books.lk

“Reading maketh a full man,” it is said and the importance of reading need not be reiterated. And, it is with the objective of promoting the habit of reading among children that the Junior Observer in collaboration with Bookazone (Pvt.) Ltd; the innovators of the country’s first web portal (www.books.lk), launched a competition in September.

We give a lucky reader an opportunity to win a valuable book priced at Rs 1000 from books.lk. All you have to do is answer a the question and mail it to the address given, on or before Friday of that week.

The name of each week’s winner will be published later.

Here is how Bookazone will help you enter the magical world of books, to not only entertain yourself but also enhance your knowledge.

It allows you to purchase any title of book regardless of the author, publisher, or the country of origin. Although Bookazone web portal was limited to English users since 2009, the latest additions of Sinhala and Tamil is also accessible on www.poth.lk and www.puththagam.lk listing a wide range of books written and published in local languages in addition to what is offered in English apart from magazines, CDs and DVDs.

Once you place an order at Bookazone and make your payment,the deliveries are made free of charge using the best secured mode to any part of the island.

So, keep improving your general knowledge to answer the question posed every week. And what better way to do so than by READING!

Winner of coupon No 9 is :

Sivarathan Lakshman,
1/3,2/1 Windsor Avenue,
Off Vanderwert Place,
Dehiwela.