P-1 Carbon Compounds — Science STD 10 — Question

How do guard cells regulate opening and closing of stomatal pores?

Give one function of each of the following atellites:
i. Communication satellite
ii. Earth observation satellite

State two effects of humidity present in atmosphere.

What is “baking powder”? How does it make the cake soft and spongy?

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?

what is the difference between the molecules of elements and compounds?

The focal length of a convex lens is 20 cm. What is the power?

State the characteristics of an image formed by a concave lens.

How would you convert:

1. Ethanol into ethene?
2. Propanol into propanoic acid?

Name the process in each case and write the equations of the reactions involved.

What shape are your eye-lenses:

1. When you look at your hand?
2. When you look at a distant tree?