P-2 Environmental management — Science STD 10 — Question

Explain concept with example/explain with the help of a balanced equation.
Minerals

An object is placed at 10 cm from a convex lens of focal length 12 m. Find the position and nature of the image.

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 position of image when an object is placed at a distance of 10cm from a convex lens of focal length 10cm?

Give explanations for the statements: Genetic recombination occurs in pachytene phase of prophase of meiosis-I.

Indicate the following terms related to spherical mirrors in figure 7.1: pole, centre of curvature, radius of curvature, principal focus.

Describe a test for carboxylic acids.

Many times, we experience dryness in mouth.