5th std EVS chapter 18 the environment and us l question and answer l easy explanation in marathi

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Environmental Studies -  5th Standard

18. The Environment and Us

Question And Answer

Q1. What’s the solution ?

Rivers and lakes are filled with water hyacinth.

Ans: Water hyacinth is one of the fastest growing plants. Its primary means of reproduction is by way of runers. The following solutions can be used:

1) We can take out the hyacinth from the water manually when the water level is low.

2) Machineries like JCB can be used to pull out them from the water.

Q2. Use your brain power !

What would happen if no kites (birds) are left in a particular region ? Which living things would increase in number ? Which would decrease ?

Ans: If no kites are left in particular region then the smaller animals like rodent will increase. Kite is a top predator hence it is not the food for others. And there will be little difference in any other animal’s population.

Q3. Answer the following questions.

(a) What is meant by migration ?

Ans: Migration is the movement of animals in large numbers from one place to other. In search of food or to avoid unfavourable condition.

(b) Describe the lifecycle of birds.

Ans: Birds are born inside hard-shelled eggs. For many days they are protected and kept warm by their parents. After hatching they come out and fed by their parents. When the young ones develop wings and are able to fly. They leave the nest and go away from the parents.

(c) Give two causes of air pollution.

Ans: 1) Industries and factories burn fuel and causes smoke and pollutant gases.

2) Vehicles during transport emit poisonous gases and particles. The slow burning of fuels produce lots of carbon dioxide.

(d) For what purpose do we use land obtained by clearing forests ?

Ans: 1) After clearing the forest, the land which is obtained is used for either building roads, bridges, housing etc. 

2) The world human population is rising day by day therefore more and more land is required for all such activities.

Q4. Give reasons.

(a) It is important to conserve the living components of the environment.

Ans: 1) If the living components of the environment do not exist, then the food chain will not function.

2) Some species will get extinct and it is not possible to get them back.

3) If the balance in nature is disturbed it will affect human beings too. Therefore it is important to conserve the living components of the environment.

(b) The numbers of wild animals are falling day by day.

Ans: 1) Due to human interventions many food chains are disturbed.

2) Forests are cleared for making land available hence wild animals are displaced.

3) Hunting and poaching of wild animals have also reduced their numbers.

4) Due to climate change natural cycle also disturbed causing survival of wild animals difficult. All these factors are responsible for falling number of wild animals day by day.

Q5. True or false ?

(a) Dead plants and animals are abiotic components.

Ans: True

(b) It is necessary to conserve biodiversity.

Ans: True

Q6. Classify the following as natural or man-made. Soil, horse, stone, water hyacinth, book, sunlight, dolphin, pen, chair, water, cottonwool, table, trees, brick.

Ans:

1) Natural : Soil, horse, stone, water hyacinth, sunlight, dolphin, water, cottonwool, trees.

2) Man-made : book, pen, chair, table, brick.

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