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Wednesday, 27 June 2012

Which group of animal is called 'The first mammals'?

Protozoa are called 'the first mammals'.They are minute organisms made up of only one cell,and form the lowest major division or phylum of the animal kingdom.
Protozoa are very tiny and generally you cannot see them without a microscope. sometimes though,they appear in such huge numbers so that they are visible.The green scum you see on top of stagnant ponds are actually a type of protozoa.

Where did dinosaurs come from?

Dinosaurs evolved from a group called Archosauria(ruling reptiles), which appeared about 250 million years before the first dinosaurs.

Which was the biggest ever land mammal?

The biggest ever land mammal was INDRICOTHERIUM,an early kind of rhinoceros.It weighed as much as four elephants, and was one and a half times the height of modern giraffe

Tuesday, 26 June 2012

Why did early land animals stay near water?

Early land animals like lchthyostega and acanthostega,who were ancestors of modern amphibians, stayed close to water because they laid their jelly-like eggs in water.They also had to keep their skin damp always.

Why it is said that life began at sea?

Oceans and seas were formed long,long ago,before there were any plants,animals or people on earth.The earth was made up of red hot rocks then.when they cooled,they gave off steam.
This steam became rain,which fell and filled up the hollows and deep holes in the earth's surface to become oceans.The first plants appeared on this planets as microscopic,single-single celled organism floating in the worlds's oceans,billion of years ago. That is why we say that life began,not on land, but on water.....

Why, and how are plants and animals different?

plants and animals are as different from each other as a rose is different from a rabbit.!
most plants, with a few exceptions like the swimming algae,cannot move about from place to place, while animals can move freely.
most plants manufacture their on food withe help of their green coloring which is called chlorophyll.animals must rely on plants for their food,or hunt other animals.
Animals have a nervous system which makes them sensitive to touch,heat,cold,pain and other stimuli.Plants do not have a nervous were some plants do fold their leaves when touched.others sense that a support is near,and twine themselves around it.
The cell structure of plants and animals is different too.most plants have rigid cell walls, and contain cellulose.animals cells do not have cellulose.

Why is it said we have all evolved from a single cell?

when the earth was first formed, there was no life on it.its surface was boiling hot,and had giant volcanoes that threw fiery rocks,dust,and gases into the air.
The form of life was an organism consisting of only one single cell.these single celled organisms developed into multi cellular organisms that first plants, and then animals,evolved. so we can say that we have all evolved from a single cell!

Which came first,Plants or Animals?

Have you ever wondered what it must have been like millions and millions of years ago,When the earth came into existence?Were there plants and animals then?
It is estimated that the first life forms on earth were primitive,one-celled organism that appeared about 3 billion years ago in the ocean.these single celled organism gradually became multi-cellular time,the ocean began to fill up with more complex forms of life.
one of the first forms of life was very simple plant celled algae.Different types of plants came later on.Animal life appeared only after the appearance of plant life.............