P-2 Environmental management — Science STD 10 — Question

State two hazards associated with the use of electricity.

Some insects are very useful for us. We get many products from them. e.g. Honey bee, Lac insect, Silk worm, are the insects that provide us with honey and wax, lac and silk respectively. The culture experiments are done on these insects for large scale production of these substances. Butterflies help in the pollination of crops and are thus helpful for the farmers and gardeners. Lady bug beetle is an insect which acts as a natural pest control as it attacks the other harmful insect pests.

In biological pest control methods it is widely used. Some insects, on the contrary are very harmful. Mosquito, bed bugs, lice are blood sucking parasites which can spread the diseases. Mosquito is a vector for dengue, filariasis and malaria. Some are biting insects that can cause wounds, some cause allergies of various kinds. The grains and crops are destroyed to great extent by the insects. In this way the insects belonging to the phylum Arthropods are harmful to health, wealth and peace of mind too.

(ii) Which are the animals from phylum Arthropoda those have shortest and longest life span?

DEFINE : Asexual reproduction

How many chambers are there in the heart of:

1. An amphibian.
2. A mammal.
3. A fish?

1. Copper.
2. Zinc.
3. Nickel.
4. Gold.
5. Silver.

A person can read a book clearly only if he holds it at an arm's length from him. Name the defect of vision:

1. If the person is an old man.
2. If the person is a young man.

Explain the meaning of following symbols