Category Science

Which actions of human are responsible for disappearing homes of natural habitant?

As human numbers grow, more and more wild land is used to grow crops and raise animals.

Today many farmers also use chemicals to grow bumper crops. These harm wild creatures.

Fields that were once home to all kinds of wildlife now hold just one crop.

Chemicals that kill weeds and pests kill all kinds of wildlife.

Many farmers spray their crops with chemicals to get rid of weeds and insects. These poisons kill all kinds of wildlife. However, organic farmers grow crops without using chemicals. Many more species are found on their farms.

Prairie chickens almost died out due to habitat loss in the US.

Wild grasslands such as the American prairies once covered large areas on mangy continents.

Now much of this wild land has been ploughed up to grow crops. This has driven wild birds such as prairie chickens to the point of extinction.

Goats have eaten all the grass on this farm in Africa.

Farmers rear herds of cattle, sheep and goats on land that is too poor for crops. But sometimes domestic animals strip all the vegetation, so wild creatures have nothing to eat.

If all the grass is eaten, winds and storms can blow or wash away the soil. This problem is called erosion.

Barn owls can be poisoned by chemicals used in farming.

When farmers spray their fields to get rid of pests, wild animals are affected too. The poison can spread through the food chain.

Mice absorb the chemicals when they eat grain that has been sprayed. The poison is stored in their bodies. Barn owls that eat poisoned mice may die, too.

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Does craze of keeping pets at home and developing zoo, endangers wildlife?

Some animals and plants are rare because people take them from the wild and sell them.

People who steal rare animals and plants are called poachers. Most poached animals become pets. Others end up in zoos.

In the past, zoos treated animals badly. But many zoos today are helping to save rare species.

Some poachers steal young apes.

Poaching for the pet trade threatens apes such as orang-utans, as well as small creatures like reptiles, fish and even spiders.

The poachers usually kill the adult apes and steal their babies because they are small and easier to manage. Many baby apes also die because their new owners don’t look after them properly.

People capture parrots for sale as pets.

Most animals taken from the wild do not thrive away from home. Captured animals are frightened and confused. Many are sold abroad. On the journey they are often kept in cramped cages. Many die on the way.

Ninety types of parrot are endangered because so many birds have been captured as pets.

Many zoos today are trying to save rare species like condors.

In the past, animals in zoos were not always well treated. Some were kept in small cages. A few species almost died out because too many were captured for zoos.

Nowadays, zoos often help to save rare species, by breeding the animals in captivity. If breeding is successful, the young animals may be released into the wild.

Animals born in the wild do not usually make good pets.

If your family buys a pet, make sure that is has been bred from captive animals, not taken from the wild. The pet shop should tell you where the animal came from.

Parrots, reptiles, fish and other animals bred in captivity make better pets than wild ones, because they are more used to humans and easier to look after. Make sure you find out about the food and conditions your pet needs.

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Hunting endangers wildlife, how?

For thousands of years, people have hunted animals for meat and for their skins.

People once hunted with simple weapons. But modern weapons make killing easy. Hunters may soon wipe out some animals.

Some people hunt animals for sport. We also kill sharks and tigers because they frighten us.

People kill cheetahs for their beautiful fur.

            Around the world, many kinds of animals are still hunted for their skins and other body parts. Big cats such as cheetahs are killed for their fur, which is used to make expensive clothes.

            Elephants and rhinos are hunted for their tusks and horns, which are used to make ornaments. A lot of this killing is now against the law, but it still goes on.

Chimpanzees are now rare because of hunting.

Hundreds of years ago, people lived by hunting wild animals and gathering plant food. Now farms and ranches provide the food we need, but in some countries, hunting still goes on.

In Africa, rainforest animals are hunted and sold as “bush meat”. Threatened species include gorillas and leopards.

Farmers set traps for foxes that steal chickens and lambs.

Dangerous creatures such as tigers, sharks and poisonous snakes are hunted because people are frightened of them.

Farmers set traps for foxes and wolves because they sometimes kill farm livestock. All kinds of other animals die in the traps.

Passenger pigeons died out because of sport hunting.

Hunting also goes on in the name of sport. In the space of just a few centuries, European hunters wiped out a bird called the passenger pigeon in North America.

Passenger pigeons were once found in huge numbers, but their large flocks made easy targets for European hunters. The very last passenger pigeon died in a zoo in 1914.

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Why it is called that changing climate also puts wildlife in danger?

Factories, power stations and cars give off waste gases. These pollute the atmosphere.

This pollution is trapping the Sun’s heat near the Earth. This is helping to make the weather warmer.

This is called “global warming”. It is already causing problems for wildlife in many parts of the world.

Global warming threatens coral reefs rich in sea life.

Coral reefs are living communities of sea creatures called polyps. These reefs provide a home for fish and many other creatures. However, coral polyps can only thrive in clear, shallow water of a certain temperature.

Warmer water, rising sea levels and pollution are all harming the coral, causing a threat to other reef life.

Global warming is melting the polar ice. This threatens penguins.

As temperatures rise, the ice in the Polar Regions is beginning to melt. This threatens the survival of polar animals such as seals, penguins and polar bears.

The melting ice is making sea levels rise. Whole islands may one day disappear beneath the waves, wiping out local wildlife.

Climate change may have wiped out the Golden Toad.

Global warming is causing swamps and pools to dry out in many areas. This threatens amphibians such as the European natter jack toad.

In Central America, scientists report that the Golden Toad has already died out, probably due to warming in its forest habitat.

We can all help to reduce the damage caused by global warming.

We all add to the problem of global warming as we travel in cars and planes that give off waste gases, and use energy produced by power stations. So everyone can help to reduce the effects of global warming.

Switching off machines when you’re not using them helps to save energy. Walking, cycling or using public transport causes less pollution than going by car.

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WHAT IS REACTIVITY?

The ability of an element to take part in a chemical reaction is called reactivity. Metals vary in their reactivity. Some alkali metals, such as sodium and potassium, are so reactive that they have to be stored in oil. They would react strongly with the oxygen in air or water. The least reactive metal is gold.

The metal reactivity series is a commonly taught concept in chemistry, placing the metals, as its name suggests, in order of reactivity from most reactive to least reactive. It’s also a useful tool in predicting the products of simple displacement reactions involving two different metals, as well as providing an insight into why different metals are extracted from their ores in different manners. This graphic places a selection of common metals into order of reactivity, as well as showing their reactions with air, water and steam.

Metals have a range of relativities – to illustrate this, you have to look no further than the classic alkali metals in water demonstration commonly used in chemistry classes. In this demonstration, small pieces of three different metals from group 1 of the periodic table are dropped into a large bowl of water. Lithium fizzes gently, sodium fizzes vigorously, and potassium’s reaction is so energetic it bursts into a lilac flame as it zips across the water’s surface. Cesium, the most reactive metal in the periodic table, reacts extremely violently – hence why it can’t be demonstrated in a classroom! This can be compared to other common metals, such as iron and copper, which produce no reaction when dropped into water.

The reactivity series offers a ranking of the metals in order of their reactivity. Group 1 metals, the most reactive metals in the periodic table, head up the rankings. They’re closely followed by the marginally less reactive group two metals. The metals designated as the transition metals in the periodic table are much less reactive, and metals such as gold and platinum prop up the bottom of the series, exhibiting little in the way of chemical reaction with any everyday reagents.

Tin cans are made of steel, not tin, but they do have a coating of tin to stop food inside corroding the steel. Drinks cans are often made of aluminium.

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HOW DO METALS AND NON METALS DIFFER?

There are over 80 different metals. They tend to conduct heat and electricity well, and many of them can be shaped by pulling, beating, or melting and pouring into a mould. Metals with similar properties are often grouped together, although a metal may sometimes appear in more than one group, as these pages show. Unlike most non-metals, metals are shiny when cut. Metals have played an enormous part in the history of human activity, which is why some periods, such as the Iron Age and the Bronze Age, are known by the names of metals. Some people say that our present period should be called the Silicon Age. But silicon is what is known as a semi-metal, having some but not all of the properties of metals.

Hard, shiny, and tough—metals are the macho poster boys of the material world. Learning how to extract these substances from the Earth and turn them into all kinds of useful materials was one of the most important developments in human civilization, spawning tools, jewelry, engines, machines, and giant static constructions like briges and skyscrapers. Having said that, “metal” is an almost impossibly broad term that takes in everything from lead (a super-heavy metal) and aluminum (a super-light one) to mercury (a metal that’s normally a liquid) and sodium (a metal soft enough to cut like cheese that, fused with chlorine, you can sprinkle on your food—as salt!).

When we talk about nonmetals, it ought to mean everything else—although things are a bit more complex than that. Sometimes you’ll hear people refer to semi–metals or metalloids, which are elements whose physical properties (whether they’re hard and soft, how they carry electricity and heat) and chemical properties (how they behave when they meet other elements in chemical reactions) are somewhere in between those of metals and nonmetals. Semi-metals include such elements as silicon and germanium—semiconductors (materials that conduct electricity only under special conditions) used to make integrated circuits in computer chips and solar cells. Other semi-metals include arsenic, boron, and antimony (all of which have been used in the preparation—”doping”— of semiconductors).

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