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18 years ago
Did you know ?
How many kind insects are there ?
What do most people think of when you mention 'insects'? Well, they may think of pets, such as flies, mosquitoes, moths, and beetles. Or they may think of ants and bees and wasps; and attractive insects like butterflies. And then if you ask if they can think of any other insects, they might be able to think of a few more.
But do you know how many different kinds of inscets there actually are? There are somewhere between two and four million different kinds of insects!
Scientists have actually described in scientific language as many as 625 000 different kinds. They practically have no hope of ever being able to classify every single kind of insect that exist.
When it comes to trying to estimate how many insects are living in the world today, the number is so vast that the human mind cannot imagine it! The only way scientists can even begin to count the insect population in any one area is to count insects that can be found in and on a square metre of rich, moist soil.
Remember that if you, who are untrained in observing insects, were to go over this hectare and count insects, you would see only an occasionally butterfly, bumblebee, or beetle.
But the majority of insects are so small that the human eye does not readily notice them. Many are microscopic. And there are only a few thousand insects of all those that exist that become annoying enough to man for him to control them.sourse (my science book)
Did you know ?
How did swim start?
Man does not swim naturally, as certain animals do. He has had to learn how to swim.
Originally, man must have learned to swim by watching animals that swim by instinct. Early man probably had to learn how to swim in order to survive under certain conditions.
The first effort man made to swim imitated a dog. Such a stroke has always been known as the ‘dog paddle’. But then man wanted to find a way of swimming that gave him more buoyancy and an opportunity to coordinate the motions of the arms and legs.
So more than two thousand years ago he developed the method of swimming known as the breast stroke. This stroke is still used by many people for restful distance swimming in rough open water.
Swimming was rated highly in the days of ancient Greece and Rome and was used as part of the training of warriors.
Did you know ?
How the new flowers grow?
Every living thing has some means of reproducing itself. In flowers, the process takes place as follows:
A typical flower has four main parts. There is usually a green outer cup made up of leaflike sepals. Within the sepals are the petals. Within the petals are the reproductive organs necessary for producing seeds.
In the very centre of the flower are one or more pistils. Around the pistils ia a ring of stamens. The pistil is the female part of the flower. The bottom of it is enlarged and is called the ovary.
Inside the ovary are little round ovules, which later become seeds. But they become seeds only if they are fertilized by the contents of a pollen grain.
Pollen grains are produced by the stamens, the male organs of the flower. If seeds are to form, the pollen grains must go through the top of the pistil and reach the ovules at the bottom. The top of the pistil is called the stigma.
Pollen grains first fall on the stigma. They absorb moisture there from the sugary liquid on the surface. Then they swell and grow. The grain pushes down and becomes a tube.
The tube keeps growing down through the stalk of the pistil, then through the wall of the ovary, and then into an ovule.
The contents of the tube then empty into the ovule and fertilize it. Many pollen tubes may grow down to an ovary at the same time. Each tube will enter and fertilize a single ovule.
Only pollen from the same kind of plant will grow tubes and reach the ovules. The part of the stamen that produces pollen is called the anther.
The transfer of pollen from another to stigma is called pollination. If it takes place in the same flower, it is called self-pollination. If the pollen goes to a flower on a different plant of the same kind, it is called cross-pollination.
Cross-pollination of flowers is done by the wind, by insects, by birds, and by certain animals. Later on, the seeds that develop also have to be carried to a place where they can take root and grow into flowers.Sourse(my science book)
Did you know ?
petani di india duduk di bendang padi menantikan turunnya hujan dalam masa dunia sedang menghadapi krisis bekalan makanan .(sourse dewan kosmik)
Did you know ?
more than 40 of the compound in the tar of tabacco smoke have shown to cause cancer(source biology six edition)
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