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NCERT Solutions for Class 8 Science Chapter 8 Cell Structure and Functions are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 8 Cell Structure and Functions.

NCERT Solutions for Class 8 Science Chapter 8 Cell Structure and Functions

NCERT TEXTBOOK EXERCISES

Question 1.
Indicate whether the following statements are True (T) or False (F):
(a) Unicellular organisms have a one-celled body. (T/F)
(b) Muscle cells are branched. (T/F)
(c) The basic living unit of an organism is an organ. (T/F)
(d) Amoeba has an irregular shape. (T/F)
Answer.
(a) True
(b) True
(c) False
(d) True.

Question 2.
Make a sketch of the human nerve cell. What function do nerve cells
perform?
Answer.

The nerve cell receives and transfers messages, thereby helping to control and coordinate the working of different parts of the body.

Question 3.
Write short notes on the following:

1. Cytoplasm
2. Nucleus of a cell.

Answer.

1. It is the jelly-like substance found between the nucleus and the cell membrane. It contains the nucleus and many small structures called organelles. Cytoplasm, along with nucleoplasm, forms the living substance of the cell, called the protoplasm.
2. It is an important component of the living cell. It is generally spherical and located in the center of the cell. The Nucleus is separated from the cytoplasm by a membrane called the nuclear membrane. The liquid substance of the nucleus is termed nucleoplasm. There is a smaller spherical body in the nucleus which is called the nucleolus. The Nucleus also contains thread-like structures called chromosomes. These carry genes and help in inheritance. The Nucleus acts as the control center of the activities of the cell.

With a microscope of higher magnification, we can see a smaller spherical, dense body in the nucleus. It is called the nucleolus. In addition, the nucleus contains thread-like structures called chromosomes. These carry genes and help in the inheritance or transfer of characters from the parents to the next generation. The chromosomes can be seen only when the cell divides. The nucleus, in addition to its role in inheritance, acts as the control centre of the activities of the cell.

Question 4.
Which part of the cell contains organelles?
Answer.
The Cytoplasm contains organelles of the cell.

Question 5.
Make sketches of animal and plant cells. State three differences between them.
Answer.

Question 6.
State the difference between eukaryotes and prokaryotes.
Answer.

Question 7.
Where are chromosomes found in a cell? State their functions.
Answer.
Chromosomes are found in the nucleus of the cell. They carry genes and help in inheritance i.e., transfer of characters from the parents to the offspring.

Question 8.
‘Cells are the basic structural units of living organisms. Explain.
Answer.
All organisms are made up of cells. They have different designs, shapes and sizes in the living organism. All the life processes take place inside a cell. Many similar cells aggregate together to make tissue. So many tissues are organised to form organs and finally, many organs are organised to form a system. So we can say that cells are the basic units of living organisms.

Question 9.
Explain why chloroplasts are found only in plant cells?
Answer.
Chloroplasts contain chlorophyll which synthesizes food in plants by the process of photosynthesis. As photosynthesis does not occur in animals, it does not contain chloroplasts.

Question 10.
Complete the crossword with the help of clues given below:
Across
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.
Down
1. Green plastids.
2. Formed by a collection of tissues.
4. It separates the contents of the cell from the surrounding medium.
5. Empty structure in the cytoplasm.
7. A group of cells.
Answer.

We hope the NCERT Solutions for Class 8 Science Chapter 8 Cell Structure and Functions help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 8 Cell Structure and Functions, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 8 Science Chapter 7 Conservation of Plants and Animals are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 7 Conservation of Plants and Animals.

NCERT Solutions for Class 8 Science Chapter 7 Conservation of Plants and Animals

NCERT TEXTBOOK EXERCISES

Question 1.
Fill in the blanks:

1. A place where animals are protected in their natural habitat is called………….
2. Species found only in a particular area is known as…………
3. Migratory birds fly to faraway places because of…………… changes.

Answer.

1. wildlife sanctuary
2. endemic species
3. climatic.

Question 2.
Differentiate between the following:

1. Wildlife sanctuary and biosphere reserve
2. Zoo and wildlife sanctuary
3. Endangered and extinct species
4. Flora and fauna

Answer.

1. Wildlife Sanctuary: The area that is reserved in a forest for the protection and preservation of wild animals. It also provides suitable living conditions.
   Biosphere Reserve: The area that is meant for the conservation of biodiversity. It also helps to maintain the culture of that area. One biosphere reserve may also contain other protected areas in it.
2. Zoo: A place where animals are protected in an artificial habitat.
   Wildlife Sanctuary: The area, that is reserved in a forest for the protection and preservation of wild animals.
3. Endangered Species: The animal species whose numbers are diminishing to a level that they might face extinction.
   Extinct Species: The animal species, whose numbers are nil (zero), because of changes in their habitat and other calamities.
4. Flora: The plants that are found in a particular area are called flora. For example, Sal, teak, jamun etc.
   Fauna: The animals that are found in a particular area are called fauna. For example, Chinkara, cheeta, leopard etc.

Question 3.
Discuss the effects of deforestation on the following:

1. Wild animals
2. Environment
3. Villages (Rural areas)
4. Cities (Urban areas)
5. Earth
6. The next generation

Answer.

1. They won’t get their natural habitat and surroundings, as well as food. So either they will extinct or reach the verge of extinction or they will migrate to another forest. In course of their migration, they might be killed by humans.
2. Climatic changes disturb the environment. Global warming is caused due to accumulation of carbon dioxide. Because of deforestation and an increase in the temperature on earth, the water cycle will get disturbed and the reduced rainfall will cause droughts.
3. Villagers cannot grow food (crops) because of no rain as drought situations will prevail. Many poor villagers may die for want of food. The villagers will move to towns and cities. On one hand, villages will be completely deserted and on the other hand, the towns and cities will be overcrowded.
4. Cities flooded with drought-affected villagers will disturb the environment. Food-grains will either not available or if available, they will be costlier. People will also not get wood for making furniture and buildings.
5. Deforestation is a major cause, which leads to change in soil properties. Gradually the land will get converted into a desert. On the other hand, the snow of the mountains will melt due to global warming, and many coastal cities will be flooded causing disaster.
6. The next generation will either be extinct or if at all it exists, it will suffer from diseases and face life scarcity of food in life. So, the next generation will be ill, weak, and, consequently, face extinction.

Question 4.
What will happen if:

1. we go on cutting trees.
2. the habitat of an animal is disturbed.
3. the top layer of soil is exposed.

Answer.

1. If we go on cutting trees, then:
   • The survival of mankind will become a threat, because of the low oxygen concentration in the atmosphere.
   • We have to face high temperatures and increased pollution levels.
   • Natural calamities will disrupt our life.
   • The water cycle will be disturbed.
2. If the habitat of an animal is disturbed, then:
   • The animals will lose their natural habitat and ultimately will be at the periphery to become endangered.
   • The survival of animal will be difficult, because of the drought and the rise in temperature.
3. If the top layer of soil is exposed, then:
   • The exposed top layer loses all its nutrients, especially the hummus.
   • It leads to a decrease in the water holding capacity of the soil.
   • The vegetation will go off from the field, and desertification will be the result.

Question 5.
Answer in brief.

1. Why should we conserve biodiversity?
2. Protected forests are also not completely safe for wild animals. Why?
3. Some tribals depend on the jungle. How?
4. What are the causes and consequences of deforestation?
5. What is Red Data Book?
6. What do you understand by the term migration?

Answer.

1. Biodiversity refers to the variety in life existing on Earth, their interrelationships, and their relationship with the environment, so we should conserve as the food chain should not get disturbed, otherwise the whole ecosystem will be affected.
2. Protected forests are also not completely safe for wild animals, because poaching or capturing of the animal takes place in these areas. Wild animals are killed by poachers.
3. Tribes, usually the residents of the jungle, are dependent on the jungle for the fulfillment of their daily needs of life.
4. The causes and consequences of deforestation are:
   • It increases the temperature and pollution level on earth.
   • It decreases the level of oxygen in the atmosphere and groundwater level is also lowered.
   • The rainfall and the fertility of the soil will decrease.
   • The chances of natural calamities are more because of deforestation.
   • It changes the soil properties.
   • It affects the top layer of the soil, which exposes the lower hard and rocky layers.
5. The Red Data Book is the only source as a book, which keeps a record of all the endangered animals and plants.
6. The term migration means the phenomenon of movement of a species from its own habitat to some other habitat for a particular time period every year for some specific purposes like breeding or to overcome unfavourable conditions.

Question 6.
In order to meet the ever-increasing demand in factories and for shelter, trees are being continually cut. Is it justified to cut trees for such projects? Discuss and prepare a brief report.
Answer.
Of course, to meet the ever-increasing demand in factories and for shelter, trees are being continually cut, which is hot justified at all. If one tree is cut, at least five trees should be grown so that the reforestation process may remain continuous.

But, if trees are cut blindly and no trees are planted then the earth may face global warming, no rainfall, climatic change, soil erosion, and desertification, etc. So, cutting trees for any reason at all is not justified.

Question 7.
How can you contribute to the maintenance of the green wealth of your locality? Make a list of actions to be taken by you.
Answer.
For the contribution to maintain of green wealth in my locality, the different actions to be taken are:

1. not to allow anybody to cut any trees;
2. always try to plant saplings in the residing area;
3. never ever show the neglection to water the plants;
4. always trimming the plants from time to time for their better growth.

Question 8.
Explain how deforestation leads to reduced rainfall.
Answer.
Deforestation leads to the accumulation of CO₂ in the atmosphere which results in global warming as CO₂ traps the heat of the sunrays. The increase in temperature on earth will disturb the water cycle and reduce rainfall, causing drought in the region.

Question 9.
Find out about national parks in your state. Identify and show their location on the outline map of India.
Answer.
Do yourself.

Question 10.
Why should the paper be saved? Prepare a list of ways by which you can save paper.
Answer.
Manufacturing paper needs trees. By cutting trees, deforestation is caused which disturbs the balance in nature. If the paper is saved or recycled, many trees can be saved. Paper can be saved by recycling. Paper can be recycled.5-7 times and can be used. If everyone who uses paper, could save at least one sheet of paper in a day, we can save many trees in a year.

We should save and reuse the used paper and recycle it. By following these steps we can save not only the trees but also the energy and water needed for manufacturing paper.

Question 11.
Complete the word puzzle:
Down
1. Species on the verge of extinction.
2. A book carrying information about endangered species.
5. Consequence of deforestation.
Across
1. Species which have vanished.
3. Species found only in a particular habitat.
4. Variety of plants, animals, and microorganisms found in an area.
Answer.

We hope the NCERT Solutions for Class 8 Science Chapter 7 Conservation of Plants and Animals help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 7 Conservation of Plants and Animals, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 8 Science Chapter 6 Combustion and Flame are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 6 Combustion and Flame.

NCERT Solutions for Class 8 Science Chapter 6 Combustion and Flame

NCERT TEXTBOOK EXERCISES

Question 1.
List conditions under which combustion can take place.
Answer.
Conditions under which combustion can take place are as follows :

1. The presence of air (oxygen).
2. The ignition temperature should be reached.
3. A source of inflammable substance.

Question 2.
Fill in the blanks:

1. Burning of wood and coal causes………….of air.
2. A liquid fuel, used in homes is…………..
3. Fuel must be heated to its………… before it starts burning.
4. Fire produced by oil cannot be controlled by……………..

Answer.

1. pollution
2. Kerosene
3. ignition temperature
4. water.

Question 3.
Explain how the use of CNG in automobiles has reduced pollution in our cities.
Answer.
CNG is a clean fuel. It produces harmful products in a very small amount. That is why pollution in our cities has reduced.

Question 4.
Compare LPG and wood as fuels.
Answer.

Question 5.
Give reasons:

1. Water is not used to control fires involving electrical equipment.
2. LPG is a better domestic fuel than wood.
3. Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.

Answer.

1. Water is not used to control fires produced by .electrical equipment because water is a conductor of electricity and may cause electrocution or electric shock.
2. LPG is a substance which is readily available. It is cheaper and bums easily in the air at a moderate rate. It produces a large amount of heat and does not leave behind any undesirable substance.
3. Paper catches fire easily, but when it is wrapped around an aluminium pipe and heat is supplied then in the presence of aluminium pipe, the ignition temperature of the paper does not reach, because heat given to it is passed to the aluminium pipe which lowers the temperature of the paper. That is why the paper does not catch fire.

Question 6.
Make a labelled diagram of a candle flame.
Answer.

Fig. 6.1. Different zones of a candle flame

Question 7.
Name the unit in which the calorific value of a fuel is expressed.
Answer.
The calorific value of a fuel is expressed in kilojoules per kg (kJ/kg).

Question 8.
Explain how CO₂ is able to control fires.
Answer.
CO₂, being heavier than oxygen, covers the fire like blanket and also brings down the temperature of fuel. Since the contact between the fuel and oxygen is cut off, the fire comes under control.

Question 9.
It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain.
Answer.
Green leaves contain a lot of water. So, when we try to burn green leaves, water present in the leaves cools the combustible materials (leaves), so that their temperature is brought below their ignition temperature. This prevents the burning of green leaves.

On the other hand, dry leaves do not contain any water. So when a burning process starts, their temperature is raised drastically above their ignition temperature and the leaves catch fire easily.

Question 10.
Which zone of a flame does a goldsmith use for melting gold and silver and why?
Answer.
A goldsmith uses the outermost zone of a flame for melting gold and silver because it is the hottest zone of the flame (temperature ≈ 800°C) and is non-luminous in nature.

Question 11.
In an experiment, 4.5 kg of fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the calorific value of the fuel.
Answer.
The calorific value of the fuel:
Calorific value = heat produced/amount of fuel = 1,80,000 kJ/4.5 kg = 40,000 kJ/kg

Question 12.
Can the process of rusting be called combustion? Discuss.
Answer.
Yes, the process of rusting can be called combustion, in fact, slow combustion because rusting also takes place in the air (O₂) in the presence of humidity.

Question 13.
Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in a shorter time?
Answer.
The water of Ramesh’s beaker will get heated in a shorter time because the outermost part of the flame is the hottest.

We hope the NCERT Solutions for Class 8 Science Chapter 6 Combustion and Flame help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 6 Combustion and Flame, drop a comment below and we will get back to you at the earliest

NCERT Solutions for Class 8 Science Chapter 5 Coal and Petroleum are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 5 Coal and Petroleum.

NCERT Solutions for Class 8 Science Chapter 5 Coal and Petroleum

NCERT TEXTBOOK EXERCISES

Question 1.
What are the advantages of using CNG and LPG as fuels?
Answer.
The advantages of using CNG and LPG as fuels are as follows:

1. These are clean fuels.
2. These are low-cost fuels.
3. These are available easily.
4. These can be used directly for burning in homes and factories where it can be supplied through pipes.

Question 2.
Name the petroleum product used for surfacing roads.
Answer.
A petroleum product ‘Bitumen’ is used for surfacing of roads.

Question 3.
Describe how coal is formed from dead vegetation. What is this process called?
Answer.
About 300 million years ago, the earth was having dense forests in low-lying wetland areas. Due to earthquakes and volcanic eruptions, these forests got buried under the soil. As more soil deposited over them, they were compressed.

The temperature also raised as they sank deeper and deeper. Due to high temperature and lack of oxygen, dead plants inside the earth got slowly converted to coal. As coal contains mainly carbon, the slow process of conversion of dead vegetation into coal is called carbonization.

Question 4.
Fill in the blanks:
(a) Fossil fuels are.…….,…………. and………..
(b) Process of separation of different constituents from petroleum is called………………
(c) Least polluting fuel for a vehicle is……………
Answer.
(a) coal, petroleum, natural gas
(b) refining
(c) CNG.

Question 5.
Tick True/False against the following statements:
(a) Fossil fuels can be made in the laboratory.   (T/F)
(b) CNG is more polluting fuel than petrol.   (T/F)
(c) Coke is almost pure form of carbon.  (T/F)
(d) Coal tar is a mixture of various substances.   (T/F)
(e) Kerosene is not a fossil fuel.  (T/F)
Answer.
(a) False
(b) False
(c) True
(d) True
(e) False.

Question 6.
Explain why fossil fuels are exhaustible natural resources.
Answer.
Fossil fuels are present in nature in limited quantity and are being exhausted abundantly by us. That is why fossil fuels are called exhaustible natural resources.

Question 7.
Describe characteristics and uses of coke.
Answer.
Coke is a tough, porous, and black substance. It is an almost a pure form of carbon. “Coke is obtained by heating soft coal in the absence or little supply of air”.
It is used in the manufacture of steel and in the extraction of many metals.

Question 8.
Explain the process of the formation of petroleum.
Answer.
Petroleum is formed from organisms living in the sea. When these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years, they were transformed into petroleum and natural gas under the absence of air and the presence of high temperature and pressure.

Question 9.
The following table shows the total power shortage in India from 1991-1997.
Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.
Answer.

We hope the NCERT Solutions for Class 8 Science Chapter 5 Coal and Petroleum help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 5 Coal and Petroleum, drop a comment below and we will get back to you at the earliest

NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals.

NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals

NCERT TEXTBOOK EXERCISES

Question 1.
Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen
Answer.
(a) Zinc.

Question 2.
Which of the following statements is correct?
(a) All metals are ductile.
(b) All non-metals are ductile.
(c) Generally, metals are ductile.
(d) Some non-metals are ductile.
Answer.
(c) Generally, metals are ductile.

Question 3.
Fill in the blanks.

1. Phosphorus is a very ……… non-metal.
2. Metals are ……….. conductors of heat and
3. Iron is …….. reactive than copper.
4. Metals react with acids to produce ………………. gas.

Answer.

1. reactive
2. good, electricity
3. more
4. hydrogen.

Question 4.
Mark T’ if the statement is true and ‘F’ if it is false.
(a ) Generally, non-metals react with acids. [   ]
(b) Sodium is a very reactive metal. [    ]
(c) Copper displaces zinc from zinc sulphate solution. [   ]
(d) Coal can be drawn into wires. [    ]
Answer.
(a) F
(b) T
(c) F
(d) F.

Question 5.
Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties.

Answer.

Question 6.
Give reasons for the following.

1. Aluminium foils are used to wrap food items.
2. Immersion rods for heating liquids are made up of metallic substances.
3. Copper cannot displace zinc from its salt solution,
4. Sodium and potassium are stored in kerosene.

Answer.

1. It maintains the temperature of food items intact as it is a good conductor of heat.
2. Metals are good conductors of electricity. That is why immersion rods are made up of metals.
3. It is because copper is less reactive than zinc.
4. It is because sodium and potassium react vigorously when coming in contact with air or water.

Question 7.
Can you store the lemon pickle in an aluminium utensil? Explain.
Answer.
Aluminium is a metal. Metals are more reactive to acids. That is why acidic foodstuffs like lemon pickles must not be stored in aluminium utensils.

Question 8.
Match the substances given in Column A with their uses given in Column B.

Answer.

Question 9.
What happens when
(1) Dilute sulphuric acid is poured on a copper plate?
(2) Iron nails are placed in copper sulphate solution?
Write word equations of the reactions involved.
Answer.

1. Copper sulphate is formed and hydrogen gas is released.
   Copper + dil. sulphuric acid → Copper sulphate + Hydrogen (gas)
2. Brown coating is deposited on the iron nails. This is because of the displacement of copper from copper sulphate solution by iron.
   Iron + Copper sulphate (solution) → Iron sulphate (solution) + Copper

Question 10.
Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(1) How will she find the nature of the gas?
(2) Write down word equations of all the reactions taking place in this process.
Answer.

1. She will bring a wet litmus paper in contact with the gas. If the gas turns wet blue litmus paper into red, the gas will be acidic.
   1. Carbon + Oxygen → Carbon dioxide.
   2. Carbon dioxide + Water → Carbonic acid.

Question 11.
One day Reeta went to a jeweller’s shop with her mother. Her mother gave old gold jewellery to the goldsmith to polish. The next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?
Answer.
In polishing, the jeweller put the gold jewellery in a mild acidic solution, which in reaction with acid goes into the solution. So, in this process, a certain amount of gold is lost to the acidic solution.

We hope the NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals, drop a comment below and we will get back to you at the earliest