5th std EVS 2 Chapter 4 Evolution l Question and Answer l Explanation in Marathi

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Environmental Studies-2 -  5th Standard

4. Evolution

Question And Answer

1. Fill in the blanks.

(a) The first systematic explanation of the concept of evolution was given by Charles Darwin.

(Charles Darwin, Willard Libby, Louis Leakey) 

(b) Mammals are the most evolved animals among vertebrates.

(Aquatic animals, Amphibians, Mammals)

2. Answer each question in one sentence.

(a) What do we call animals which live in water and also on land?

Ans: The animals which live in water and also on the land are called amphibians.

(b) Where did the first humans appear?

Ans: The first humans appeared on the African continent.

3. Give reasons for the following :

(a) The species of dinosaurs, which were enormous in size, suddenly became extinct.

Ans: Species which are capable of adapting to environmental changes are able to survive. Some natural calamities or environmental changes led to extinction of enormous dinosaurs. 

(b) In the course of time, a new species with characteristics different from the original species is created

Ans: Characteristics of species change according to theory of evolution. Some of the characteristics of the species change

while adjusting the surrounding which is called adaption. These characteristics are then transferred to the next generation. 

4. Fill in the blanks in the concept chart given below.

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5th Std EVS 2 Chapter 3 Life on Earth l Question and Answer l Explanation in Marathi

YADNYA e-Learning

Environmental Studies-2 -  5th Standard

3. Life on Earth

Question And Answer

Q1. Answer each question in one sentence.

(a) What instrument do we need to see a unicellular organism?

Ans: We need microscope to see a unicellular organism.

(b) Where did the protozoa appear first?

Ans: The protozoa had appeared first in water.

Q2. Answer the following in brief.

(a) How were the sun and the planets in our solar system created?

Ans: 1) On the basis of scientific research it is believed that around 4.5 billion year ago an enormous cloud of very hot gases and dust spinning at the great speed was formed in space.

2) Its circular motion and great speed caused it to divide into several portions thus creating the sun and the planets which

revolve around the sun.

(b) Write any two characteristics of animals.

Ans: Characteristics of animals are as follows:

1) Animals breathe

2) Animals move in order to get food or for other purposes.

Q3. Find the names of the planets in the box below.

Ans:

Q4. Arrange the events given below in chronological order.

(a) Water bodies appeared on the earth’s surface.

(b) The sun and the planets revolving around it were created.

(c) Protozoa appeared in water.

(d) An enormous cloud of hot gases and dust was formed in space.

Ans:

a) An enormous cloud of hot gases and dust was formed in space.

b) The sun and the planets revolving around it were created.

c) Water bodies appeared on the earth’s surface.

d) Protozoa appeared in water.

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6th Std Science 13 Sound l Question and Answer l

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Science Studies -  6th Standard

13. Sound 

Question And Answer

1. Fill in the blanks with the proper words.

(a) The propagation of sound does not occur through a air

(b) Noise pollution is a social issue.

(c) The sound which is disagreeable to the ears is called Noise.

(d) Noise has adverse effects on our health. 

2. What should we do ?

(a) The silencer of a motorcycle is broken.

Ans: In absence of well-maintained silencer motorcycles will create noise and air pollution thus we should repair or replace silencer of motorcycle as soon as possible.

b) A factory in the surroundings is producing continuous loud noise.

Ans: 1) We should as the head of factory to control the noise in factory.

2) If proper action is not taken by factory authority then we should consult the noise in the factory.

3. Write the answers in your own words.

(a) What is meant by vibration ?

Ans: Vibration is periodic back and forth motion of the particles of an elastic body or medium occurs when any physical system is displaced from its equilibrium condition and allowed to respond to the forces that tend to restore equilibrium.

(b) Explain with the help of practical examples how sound is propagated through solids.

Ans: Sound is said to be propagate when sound waves spread in all directions from a source of sound. Ex. Stand at the end of big table and make a friend to stand on the other end. Ask the friend to knock lightly on the table you will hear a joint sound. Now you press your ear to the table and ask the friend to repeat the knock. You will hear a clear sound.

(c) What is meant by noise pollution?

Ans: The noise pollution is defined as the unwanted sound which is released into the environment. It’s disturb the human being and cause an adverse effect on the mental and psychological well-being.

(d) What measures will you take to control noise pollution ?

Ans: 1) We should avoid blowing the horn.

2) The volume of the TV or radio in the house should be restricted to those watching the programs.

3) Vehicle should be maintained properly to reduce the unnecessary sounds they produce.

4) Factories airports, railway stations and bus stands should be located at the proper distance away from residential areas.

4. Complete the table.

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6th Std Science 12 Simple Machines l Question and Answer l

YADNYA e-Learning

Science Studies -  6th Standard

12. Simple Machines

Question And Answer

1. Classify the following as a lever, a pulley and an inclined plane :

A wedge, a needle, a staircase, a slide, the wheel of a flagpole, nutcrackers, scissors, an opener, an axe, a crane, a knife.

2. Fill in the blanks using the proper word and complete the statements.

(a) The fulcrum in the centre, the load on one side and the effort on the other side make a lever of the first order. 

(b) The load in the centre, the fulcrum on one side and the effort on the other side make a lever of the second order. 

(c) The effort in the centre, the fulcrum on one side and the load on the other side make a lever of the third order.

3. Which machines will you use to do the following work ?

Write their types.

(a) To remove the lid of a tin.

Ans: Machine: Can opener

Type: Inclined plane

(b) To lift bricks to the top of a tall building.

Ans: Machine: Wheel and the rope

Type: Pulley

(c) To cut vegetables.

Ans: Machine: Knife

Type: Wedge

(d) To draw water from a well.

Ans: Machine: wheel and rope

Type: Pulley

(e) To hold a papad for roasting it.

Ans: Machine: Pair of tongs

Type: Lever

4. Write the answers to the following questions in your own words.

(a) What is meant by simple machines ?

Ans: The machines which have only one or two parts and a simple and easy structure such machines are called simple machines.

Ex. The nail cutter, the bottle opener 

(b) Mention the advantages of using a machine.

Ans: Advantages of using machine are as fallows:1) Machines are used for reducing efforts.

2) They save our time and do more work in less time. 

(c) What is meant by complex Machines ?

Ans: The machines which have many parts and carry out many processes for completing a task and their parts are joined to one another. Therefore, these machines are called complex machines. E.g sewing machine, mixer

(d) What is a lever ? How are the orders of the lever

determined ?

Ans: A lever is simple machine. It has three components i.e fulcrum, load and effort order of lever is determinant on the

basis of the efforts, the fulcrum and the load.

1) Lever of the first order: The fulcrum is in the centre, load at one end and effort at other end.

2) Lever of second order: The load is in the centre, the fulcrum on one side and effort on other side.

3) Lever of the third order: The effort is in the centre, the fulcrum on one side and the load on other side.

5. Why is this so ?

(a) Traveller’s bags have wheels.

Ans: Traveller’s bags have wheels just because of easy movement of bags from one place to another. It convenient and easy to lift bag from one end to other in upward direction. 

(b) Machines have to be maintained.

Ans: Parts of machine rub against one another when they are used. Soiled, dusty part create more friction some parts, affected by the weather, rust and erode. Machines get damage or become useless due to such wear and tear. To avoid this, it is necessary to maintain and take care of machines.

(c) A bicyle is said to be a complex machine.

Ans: A bicycle is a complex machine because its parts are joined to one another. The structure is complicate. Hence a bicycle is said to be a complex machine. 

6. Name the levers mentioned in the following passage. Identify the fulcrum, load and effort of each and say which type of lever it is.

Ravi and Savita sit on a sea-saw in a garden. In the mean time, a gardener is trimming trees in the garden. He puts the leaves and other garbage in the wheelbarrow. Later, Ravi gets thirsty and he buys lemon sherbet. The sherbet seller cuts the lemon and squeezes it using a lemon squeezer. He puts small pieces of ice in the glass with the help of the tongs. 

Ans:

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6th Std Science 11 Work and Energy l Question and Answer l

YADNYA e-Learning

Science Studies -  6th Standard

11. Work and Energy

Question And Answer

1. Fill in each blank with the appropriate term from the brackets.

(a) A bucketful of water is to be drawn from a well. Work will be done when a force is applied to do this, because there will be a displacement of water.

(displacement, work, force)

(b) If a ball is dropped on the sloping roof of a house, it acquires motion and falls on the ground. That is, transformation of potential energy into kinetic energy takes place.

(kinetic, potential, motion)

(c) You might have seen some beautiful fireworks during Diwali. It is an example of transformation of chemical energy into light energy.

(light, atom, chemical, solar) 

(d) The solar cooker is an application of the heat energy of the sun, while solar cells, solar lamps are applications of the light energy of the sun.

(light, chemical, heat)

(e) One labourer carried four pans of road metal through a distance of 100 metres. If he carries two pans of road metal through a 200 metre distance. equal work will be done.

(equal,more, less) 

(f) The capacity that an object has for doing work is called energy.

(energy, displacement, force)

2. Match the pairs.

3. Can you tell ?

(a) When can we say that displacement has taken place ?

Ans: We can say that displacement has done when the position of the object change.

(b) What should be taken into account for measuring work ?

Ans: Force and displacement

(c) What are the various forms of energy ?

Ans: 1) Mechanical energy 2) Heat energy 3) Light energy 4) Sound energy 5) Chemical energy 6) Electrical energy

(d) Describe one natural chain of transformation of energy.

Ans: 1) Water cycle evaporate due to heat of the sun. This water vapour forms clouds that gives rain.

2) Rainwater flows into rivers and a store in reservoirs on dams.

3) This hour at a height and therefore their water has potential energy which transfer made into kinetic energy as the water falling downward.

4) When the water falls on the turbine, its kinetic energy is transferred to the turbine.

5) The turbine producing electrical energy. Electrical energy is used in our house for various purpose. 

(e) Why should we save energy ?

Ans: 1) Saving energy is as good as generating energy.

2) Due to the increasing population and increasing use of energy resources, there is a danger that the limited resources of coal, petrol, diesel, crude oil and natural gas will be exhausted.

3) Also due to overuse of energy, lots of polluting gases are released in the atmosphere this leads to pollution and global warming. Thus in order to preserve natural resources and conserve environment, we must save energy. 

(f) What is ‘green energy’ ?

Ans: The energy resources which do not produce smoke and carbon gases such as carbon dioxide or carbon monoxide is

called green energy.

(g) What are the non-conventional energy resources ?

Ans: Non-conventional energy resources are inexhaustible and continuous and can be used in various forms again and again. Ex. 1) solar energy 2) wind energy 3) tidal energy 4) hydroelectric or hydro power 5) atomic energy 

(h) Which forms of energy from the sun are used in solar energy devices ?

Ans: Heat energy, Light energy, Chemical energy

(i) Why should we maximise the use of non-conventional

energy resources ?

Ans: Due to increasing population and increasing use of energy resources were there is a danger that the limited resources of coal, petrol, diesel, crude oil and natural gas will get exhausted. Therefore we should maximize the use of non-conventional energy resources.

4. Who is the odd-one-out ?

(1) Diesel, crude oil, natural gas, wind

Ans: Wind

(2) A running car, hauling a log, a book kept on a table, picking up the school bag.

Ans: A book kept on a table

(3) Sunlight, wind, waves, petrol

Ans: Petrol

(4) Leaving the fan on in a vacant room, leaving the TV on while working, using AC during winter, putting off the light when

going out.

Ans: Putting off the light when going out 

5. Find out the types of energy from the following puzzle.

Ans:

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