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📚✨ NCERT Solutions for Class 9 Science – 2025–26



📚✨ NCERT Solutions for Class 9 Science – 2025–26

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NCERT Solutions For Class 9 Science Chapter 15 Improvement in Food Resources

 


NCERT Solutions For Class 9 Science Chapter 15 Improvement in Food Resources

Topics and Sub Topics in Class 9 Science Chapter 15 Improvement in Food Resources:

  1. Improvement in Food Resources
  2. Improvement in Crop Yields
  3. Animal Husbandry

In-Text Questions Solved

NCERT Textbook for Class 9 Science – Page 204
Question 1. What do we get from cereals, pulses, fruits and vegetables?
Answer: Cereals give carbohydrates which provide energy.
Pulses give proteins which build our body.
Vegetables and fruits provide vitamins and minerals.

Class 9 Science NCERT Textbook – Page 205
Question 1. How do biotic and abiotic factors affect crop production?
Answer: Factors responsible for loss of grains, during storage and production are:
(a) Biotic factors like rodents, pests, insects, etc.
(b) Abiotic factors like temperature, humidity, moisture, etc.
Combination of both biotic and abiotic factors causes :

  1. infestation of insects
  2. weight loss
  3. poor germination ability
  4. degradation in quality
  5. discolouration
  6. poor market price

Question 2. What are the desirable agronomic characteristics for crop improvements?
Answer: Desirable agronomic characteristics for crop improvements are:
(a) Tallness and profuse branching are desirable characters for fodder crops.
(b) Dwarfness is desired in cereals, so that less nutrients are consumed by these crops.

NCERT Textbook for Class 9 Science – Page 206

Question 1. What are macro-nutrients and why are they called macro-nutrients?
Answer: Macro-nutrients are the essential elements which are utilised by plants in large quantities. Many macro-nutrients are required by the plants for the following functions:

  • As the constituent of protoplasm
  • N, P, S are present in proteins
  • Ca is present in cell wall
  • Mg is important constituent of chlorophyll

Question 2. How do plants get nutrients?
Answer: Plants get nutrients from air, water and soil. There are, sixteen nutrients essential for the growth of plants. Carbon and Oxygen are supplied by water. The remaining thirteen nutrients are supplied by soil.

Class 9 Science NCERT Textbook – Page 207
Question 1. Compare the use of manure and fertilizers in maintaining soil fertility.
Answer: Effects of using manures on soil quality:

  1. The manures enrich the soil with nutrients.
  2. They provide a lot of organic matter (humus) to the soil and thus restores water retention capacity of sandy soils and drainage in clayey soil.
  3. The addition of manures reduces soil erosion.
  4.  They provide food for soil organisms, like soil friendly bacteria.

Effects of using fertilizers on soil quality:

  1. By the continuous use of fertilizers, the soil becomes powdery, dry and rate of soil erosion increases.
  2. By the use of fertilizers, the organic matter decreases which further decreases the porosity of soil and the plant roots do not get oxygen properly,
  3. The nature of soil changes to acidic or basic.

NCERT Textbook for Class 9 Science – Page 208
Question 1. Which of the following conditions will give the most benefits? Why?
(a) Farmers use high-quality seeds, do not adopt irrigation or use fertilizers.
(b) Farmers use ordinary seeds, adopt irrigation and use fertilizer.
(c) Farmers use quality seeds, adopt irrigation, use fertilizer and use crop protection measures.
Answer: In this, (c) Farmers use quality seeds, adopt irrigation, use fertilizer and use crop protection measures.
Use of any quality seeds is not sufficient until they are properly irrigated, enriched with fertilizers and protected from biotic factors. Hence, option (c) will give the most benefits.

Class 9 Science NCERT Textbook – Page 209
Question.1. Why should preventive measures and biological control methods be preferred for protecting crops?
Answer. Diseases in plants are caused by pathogens. To get rid of pathogens, some preventive measures and biological control methods are used as they are simple, economic and minimise pollution without affecting the soil quality.

Question 2. What factors may be responsible for losses of grains during storage?
Answer: The factors responsible for losses of grains during storage are:

  • Abiotic factors like moisture (present in food grains), humidity (of air) and temperature.
  • Biotic factors like insects, rodents, birds, mites, bacteria and fungi.

NCERT Textbook for Class 9 Science – Page 210
Question 1. Which method is commonly used for improving cattle breeds and why ?
Answer: Cross breeding is a process in which indigenous varities of cattle are crossed by exotic breeds to get a breed which is high yielding. During cross breeding, the desired characters are taken into consideration. The offspring should be high yielding, should have early maturity and should be resistant to climatic conditions.

Class 9 Science NCERT Textbook – Page 211
Question 1. Discuss the implications of the following statement:
“It is interesting to note that poultry is India’s most efficient converter of low fibre food stuff (which is unfit for human consumption) into highly nutritious animal protein food”.
Answer: The basic aim of poultry farming is to raise domestic fowl for egg production and chicken meat. These poultry birds are not only the efficient converters of agricultural by-products, particularly cheaper fibrous wastes (which is unfit for human consumption but can be formulated into cheaper diets for poultry birds) into high quality meat and also help in providing egg, feathers and nutrient rich manure. For this reasons, it is said that, “poultry is India’s most efficient converter of low fibre food stuff into highly nutritious animal protein food”.

NCERT Textbook for Class 9 Science – Page 211
Question 1. What management practices are common in dairy and poultry farming?
Answer:

  1. Shelter: Dairy animals and poultry birds require proper shelter, i.e., well designed dairy and hygienic shelter.
  2. Feeding: To get good yield of food product, proper feed is provided to dairy animals and poultry birds.
  3. Caring for animal health: Animal and birds must be protected from diseases caused by virus, bacteria or fungi.

Question 2. What are the differences between broilers and layers and in their management?
Answer: The poultry bird groomed for obtaining meat is called broiler. The egg laying poultry bird is called layer.
The housing, nutritional and environmental requirements of broilers are somewhat different from those of egg layers.
The ration (daily food requirement) for broilers is protein rich with adequate fat. The level of vitamins A and K is kept high in the poultry feeds while layers require enough space and proper lightning.

Class 9 Science NCERT Textbook – Page 213
Question 1. How are fish obtained?
Answer: There are two ways of obtaining fish. One is from natural resources, which is called capture fishing. The other way is by fish farming, which is called culture fishery.

Question 2. What are the advantages of composite fish culture?
Answer:  In composite fish culture, a combination of five or six fish species is used in a single fish pond. These species are selected so that they do not compete for food among them and are having different types of food habits. As a result, the food available in all the parts of the pond is used. For example, Catlas are surface feeders, Rohus feed in the middle-zone of the pond, Mrigals and Common Carps are bottom feeders and Grass Carps feed on the weeds, together these species can use all the food in the pond without competing with each other. This increases the fish yield from pond.

NCERT Textbook for Class 9 Science – Page 213
Question 1. What are the desirable characters of bee varieties suitable for honey production?
Answer:

  1. The variety of bee should be able to collect a large amount of honey.
  2.  The bees should stay in a given beehive for a longer period.
  3. The bees should have capacity of breeding well.
  4. The variety of bee should be disease resistant.

Question 2. What is pasturage and how is it related to honey production?
Answer: The pasturage means the flowers available to the bees for nectar and pollen collection. In addition to adequate quantities of pasturage, the kind of flowers available will determine the taste of the honey.

Questions From NCERT Textbook for Class 9 Science

Question 1. Explain any one method of crop production which ensures high yield.
Answer:  One method used for crop production which ensures high yield is plant breeding. It is the science involved in improving the varieties of crops by breeding plants. The plants from different areas/places is picked up with desired traits and then hybridisation or cross-breeding of these varieties is done to obtain a plant/crop of desired characteristic.
The high yielding crop variety shows the following characteristics:
High yield, early maturation, less water for irrigation, better quality seeds are produced, less fertilizers required, adapts itself to the environmental conditions.

Question 2. Why are manure and fertilizers used in fields?
Answer: They are used to ensure good vegetative growth (leaves, branches and flowers), giving rise to healthy plants, that results in high crop production.

Question 3. What are the advantages of inter-cropping and crop rotation?
Answer:  Advantages of using inter-cropping:

  1. It helps to maintain soil fertility.
  2. It increases productivity per unit area.
  3. Save labour and time.
  4. Both crops can be easily harvested and processed separately.

Advantages of using crop rotation:

  1. It improves the soil fertility.
  2. It avoids depletion of a particular nutrient from soil.
  3. It minimise pest infestation and diseases.
  4. It helps in weed control.
  5. It prevents change in the chemical nature of the soil.

Question 4. What is genetic manipulation? How is it useful in agricultural practices?
Answer: Genetic manipulation is a process of incorporating desirable (genes) characters into crop varieties by hybridisation. Hybridisation involves crossing between genetically dissimilar plants. This is done for production of varieties with desirable characteristics like profuse branching in fodder crops, high yielding varieties in maize, wheat, etc.
Genetic manipulation is useful in developing varieties which shows:

  • Increased yield
  • Better quality
  • Shorter and early maturity period
  • Better adaptability to adverse environmental conditions
  • Desirable characteristics

Question 5. How do storage grain losses occur?
Answer: The factors responsible for loss of grains during storage are:

  1. Abiotic factors like moisture (present in foodgrains), humidity (of air) and temperature.
  2. Biotic factors like insects, rodents, birds, mites and bacteria.

Question 6. How do good animal husbandry practices benefit farmers?
Answer: Good animal husbandry practices are beneficial to the farmers in the following ways:

  1. Improvement of breeds of the domesticated animals.
  2. Increasing the yield of foodstuffs such as milk, eggs and meat.
  3. Proper management of domestic animals in terms of shelter, feeding, care and protection against diseases.
    Which ultimately helps the farmers to improve their economic condition.

Question 7. What are the benefits of cattle farming?
Answer:  Cattle farming is beneficial in the following ways:

  1. Milk production is increased by high yielding animals.
  2. Good quality of meat, fibre and skin can be obtained.
  3. Good breed of draught animals can be obtained.

Question 8.  For increasing production, what is common in poultry, fisheries and bee-keeping?
Answer: Through cross breeding, the production of poultry, fisheries and bee-keeping can be increased.

Question 9.  How do you differentiate between capture fishing, mariculture, and aquaculture?
Answer:
Capture fishing: It is the fishing in which fishes are captured from natural resources like pond, sea water and estuaries.
Mariculture: It is the culture of fish in marine water. Varieties like prawns, oysters, bhetki and mullets are cultured for fishing.
Aquaculture: It is done both in fresh water and in marine water.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

 


NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Topics and Sub Topics in Class 9 Science Chapter 14 Natural Resources:

  1. Natural Resources
  2. The Breath of Life: Air
  3. Water: A Wonder Liquid
  4. Mineral Riches in the Soil
  5. Biogeochemical Cycles
  6. Ozone Layer

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources 1

Page: 193
Question 1. How is our atmosphere different from the atmosphere on Venus and Mars? (SA II – 2013)
Answer: Our atmosphere contains a mixture of many gases like nitrogen (78.08%), oxygen (20.95%), carbon dioxide (0.03%) and water vapor (in varying proportion). Whereas the atmosphere on Venus and Mars is mainly comprised of carbon dioxide. This carbon dioxide constitutes up to 95-97% of the atmosphere on Venus and Mars. It is supposed that due to this reason no life is known to exist on these planets.

Question 2. How does the atmosphere act as a bblanket?(SA II – 2012, 13)
Answer: It is a known fact that, air is a bad conductor of heat and our atmosphere contains mainly the air. Due to this reason, the atmosphere keeps the average temperature of the Earth fairly steady during the day and even during the course of the whole year. The atmosphere prevents the sudden increase in temperature during the daylight hours and during the night, it slows down the escape of heat into outer space.

Question 3. What causes winds ? (SA II – 2012, 13)

Answer: Winds are caused due to unequal heating of atmospheric air. This phenomena can be easily seen near coastal regions during the daytime. The air above the land gets heated faster and starts rising. As this air rises, a region Of low pressure is created and air over the sea moves into this area Of low pressure. The movement of air from one region to the other Creates winds. During the day, the direction of the wind would be from the sea to the land.

Question 4. How are clouds formed ? (SA II – 2013)
Answer:The water evaporates due to heating up Of water bodies and other biological activities. The air also heats and rises. On rising, it expands and cools to form tiny droplets. These droplets grow bigger, expand and form clouds. The collection Of dust and other suspended particles facilitate the process.

Question 5. List any three human activities that you think would lead to air pollution. (SA II – 2013)
Answer: Human activities that would lead to air pollution
(i) Excessive use and burning of fossil fuels like coal and petroleum produces different oxides of nitrogen and sulphur. These are not only dangerous to our respiratory system but also leads to acid rain.
(ii) Incomplete combustion of various fuels forms unburnt carbon particles which lowers the visibility, especially in cold weather when water also condenses Out of air. This is known as smog and is a visible indication Of air pollution.
(iii) Large usage Of automobiles and improperly tuning of engines leads to the formation of carbon monoxide gas and Other oxides of nitrogen which causes lot of respiratory problems.
(iv) Forest fires, excessive mining and ore refining, excessive use of chlorofluorocarbons and excessive industrialisation leads to air pollution.

Page 194:
Question 1. Why do organisms need water ? (SA II – 2012)
Answer: Organisms need water due to the following
(i) All cellular processes take place in a water medium.
(ii) All the reactions that take place within our body and within the cells occur between substances that are dissolved in water.
(iii) Substances are also transported from one part of the body to the other in a dissolved form.
(iv) Water makes up about 70% of body weight Of all living organisms.
(v) It helps in the digestion of food and absorption of nutrients in the blood. Hence, organisms need to maintain the level of water within their bodies in order to stay alive. It helps in maintaining body temperature.
Question 2. What is the major source of freshwater in the city/town/village where you live ?
Answer: The major sources of freshwater in the city (town/ village is the underground water which is mostly taken out with the help of hand pumps or tube wells. The rivers flowing in the nearby areas, lakes and ponds also serve as the source of freshwater.

Question 3. DO you know any activity which may be polluting these water sources?
Answer: There are many activities which cause pollution Of water sources such as :
(i) Dumping of waste from factories, sewage from our towns and cities into rivers or lakes.
(ii) Discharging hot water from cooling towers into the water bodies affect the breeding capacity of aquatic organisms.

Page 196
Question 1. How is soil formed ? (SA II – 2013, 2014)
Answer: The formation of soil takes place in this way :
Over long periods of time, thousands and millions Of years, the rocks at or near the surface of the are broken down by various physical, chemical and some biological processes. The end product of this breaking down is the fine particles of soil. There are many other factors which play a vital role in the formation of soil. These factors are :
(i) The Sun : It causes heating of rocks which causes cracking and ultimately breaking up into smaller pieces.
(ii) Water: It breaks rocks both by freezing and fast flow.
(iii) Wind : It causes erosion of rocks similar to as done by fast flowing water. It also carries sand from one place to the other like water does.
(iv) Living organisms : Lichens and moss plants grow on the rock surface and cause rock surface to powder down and form a thin layer of soil. The roots of big trees sometimes go into cracks in the rocks and as the roots grow bigger, the crack is forced bigger.

Question 2.What is soil erosion ? (SA II 2012)
Answer: The removal of topsoil which is rich in humus and nutrients by flowing water or wind is known as soil erosion. If this process continues further then all soil may get washed away and the rocks underneath may get exposed. It may lead to the loss of all valuable resources because nothing grows as such on the rocks.

Question 3. What are the methods of preventing or reducing soil erosion ? (SA II – 2012)
Answer: The methods of preventing soil erosion are :
(i) Afforestation : Forests reduce erosion as the roots of trees hold the soil in place.
(ii) Shelter belts : Trees planted in lines or hedges around farmland reduce erosion by reducing the speed of the wind.
(iii) Contour ploughing : Farmers plough land so that furrows lie across the natural slope of the land. These furrows trap water and do not allow it to flow down carrying the topsoil.
(iv) Terrace (or step) farming : A terraced hillside is less likely to be eroded than a natural hillside. Here a series of steps formed by horizontal strips supported by walls, catch the descending water. It gives the water sufficient time to percolate into the soil and nourish the crop.
(v) Soil cover : Soil left bare after harvesting a crop is often covered with dried vegetation to prevent erosion. Steep slopes that cannot be ploughed are covered with grass or pasture crops.
(vi) Preventing overgrazing : As the grass has a tendency to bind soil molecules, so even a very little grass on a field prevents erosion of soil. But if the grass is overgrazed, it exposes the soil to erosion.

Page 201
Question 1. What are the different states in which water is found during the water cycle? (SA II – 2011)
Answer: All three different states of water can be seen during the water cycle. These states are :
(i) Gaseous state (In the form Of water vapour which evaporates from the surface water). Liquid state (It is formed by the condensation of water vapour and can be Seen in the form of rain).
(ii) Solid state (It is formed by the freezing Of liquid droplets in the upper layer of atmosphere which can be seen in the form Of snow, hail Or sleet).

Question 2. Name two biologically important compounds that contain both oxygen and nitrogen. (SA II – 2011)
Answer: Proteins and nucleic acids (DNA and RNA).

Question 3. List any three human Which would lead to an increase in the carbon dioxide content of air. (SA II – 2011)
Answer: Three human activities which would lead to an increase in the C02 content of air are :
(i) Respiration : It is the natural process Of release Of C02 by both plants and animals. But this release is neither dangerous nor it has any adverse effect on our environment.
(ii) Combustion of fuels : The various types of fuels are burnt to provide energy for various needs like heating, cooking, transportation and industrial fuels.
(iii) Deforestation : Trees help in the conversion Of C02 into organic compounds such as glucose, starch, etc., by the process of photosynthesis. When these trees are cut non-judiciously, then the level of C02 increases in our environment.

Question 4. What is the greenhouse effect ? (SA II – 2011)
Answer: Some gases prevent the escape of heat from the Earth. An increase in the percentage Of such gases in the atmosphere would cause the average temperatures to increase worldwide and this is called the greenhouse effect.

Question 5. What are the two forms of oxygen found in the atmosphere ? (SA II 2011)
Answer: (i) Elemental oxygen is normally found in the form Of a diatomic molecule (02) in the lower regions Of the atmosphere to the extent of 21 %. It is non-poisonous form Of oxygen.
(ii) But in the upper reaches Of the atmosphere (stratosphere), it occurs in the form of ozone, containing three atoms of oxygen and having the molecular formula 03. It is the poisonous form of oxygen.
Some other forms of Oxygen :
It also Occurs extensively in the combined form in the Earth’s crust as well as also in the air in the form of carbon dioxide. In the crust, it is found as the oxides of most metals and silicon, and also as carbonate, sulphate, nitrate and other minerals. It is also an essential component Of most biological molecules like carbohydrates, proteins, nucleic acids and fats (or lipids).

Question 1. Why is the atmosphere essential for life (SAII – 2011)
Answer: Atmosphere is essential for life because of the following masons :
(i) It keeps the average temperature of the earth fairly steady during the day and even during the course of the whole year.
(ii) It prevents the sudden increase in temperature during the daylight hours.
(iii) It contains all the important gases which are required for sustaining life on earth.
These gases are :
(a) Oxygen for respiration of living organisms and oxidation.
(b) Carbon dioxide for photosynthesis in plants and for making food.
(c) Nitrogen for providing inert atmosphere and making proteins.
(iv) The stratosphere region (16-23 km from the surface of Earth) of atmosphere contains a thick layer of ozone which filters the harmful UV radiation from Sun. If these radiations reach on the surface of Earth, then they may cause cancer in animals and are also harmful for plants.

Question 2. Why is water essential for life ? (SAII – 2011)
Answer: Water is considered essential for life because of the following reasons :
(i) All cellular processes take place in water medium.
(ii) All the reactions that take place within our body and within the cells occur between substances that are dissolved in water.
(iii) Substances are also transported from one part of the body to the other in a dissolved form.
(iv) Water makes up about 70% of body weight of all living organisms.
(v) It helps in the digestion of food and absorption Of nutrients in the blood. Hence, organisms need to maintain the level of water within their bodies in order to stay alive.
(vi) It helps in maintaining body temperature.

Question 3. How are living organisms dependent on the soil? Are organisms that live in water totally independent Of soil as a resource ?
Answer: Living organisms are dependent on the soil in the following ways :
(i) Soil provides a natural habitat for various different organisms (such as bacteria, fungi, algae) which help in improving the quality of the soil. Thus, they maintain the fertility of the soil.
(it) Number of insects, animals like rats, rabbits, etc., build their home in the soil.
(iii) Earthworms perform all their activities in the soil. They maintain fertility also as their excreta is rich in nitrogen.
(iv) Soil provides anchorage and nutrients to the plants for their growth and development.
Yes, all organisms that live in water are totally dependent on soil as a resoure :
The mineral nutrients are present in water in the dissolved form. But their recycling takes place only with the help Of decomposers which are present in the soil beds. Thus, all water bodies has soil beds which contain decomposers for the recycling of nutrients and to convert them into readily absorbable forms.

Question 4. You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?
Answer: Weather observatories collect information regarding the pattern of temperature, speed of wind, air pressure, ocean features and all other features which can affect the weather. This information is collected by remote sensing and weather forecasting satellites. The information collected is then sent to the meteorological departments which prepare a weather report which is displayed on the maps. This information is further transmitted through radio and television.

Question 5. You might have heard about weather report saying ‘depressions’ in the Way of Bengal have caused rains in some areas. We know that many human activities lead to increasing levels of pollution of the air, water bodies and soil. Do you think that isolating these activities to specific and limited areas wcwld help in reducing pollution ?
Answer: Yes, definitely if these activities are isolated to specific and limited areas, then the level of pollution Of the air, water bodies and soil will ‘decrease. For example
(i) If all the sewage discharge, industrial waste is collected and treated properly before diScharging into water bodies, then obviously aquatic life in these water bodies will be affected to a little extent.
(ii) If hot water from the industries (which is used for cooling machines and other devices) is collected at a common place and cooled and aerated properly before discharging into water bodies. Then this will not affect the breeding capacity of aquatic organisms.
(iii) If all the industries and commercial places of a city/town are located in a particular area which is far away from a residential area. Then all diseases resulting from air pollution could be minimised.
(iv) Above all, if we use only biodegradable substances, then they will get decomposed easily and there will be very little pollution of our precious natural resources.

Question 6. Write a note on how forests influence the quality “four air, soil and water resources.
Answer: Forests influence the quality of air, soil and water resources in the following ways :

  1. Influence of forests in controlling the quality of air :
    (a) Forests help in minimising the level of C02 in the atmosphere. This prevents greenhouse effect and global warming.
    (b) Forests reduce environmental temperature which in turn increases the rate of photosynthesis in plants in the surrounding regions.
    (c) Some of the trees has the ability to absorb harmful gases present in the atmosphere, e.g., Jamun trees can absorb compounds of lead easily.
  2.  Influence of forests in controlling the quality of soil :
    (a) The roots of huge trees larger area and prevent erosion of topsoil by holding the soil particles tightly.
    (b) Forests also regulate biogeochemical cycles which are responsible for cycling of nutrients and making them available for the plants in the soil,
    (c) Many of the decomposing bacteria and nitrogen-fixing bacteria live in close association with the roots of the trees.
  3. Influence of forests in controlling the quality of water :
    (a) Forests help in returning pure water back to the surface of earth through rains
    (b) Forests help in maintaining the water cycle as well as water resources of the earth.

NCERT Solutions for Class 9 Science Chapter 13 Why Do We Fall Ill

 


NCERT Solutions for Class 9 Science Chapter 13 Why Do We Fall Ill

Topics and Sub Topics in Class 9 Science Chapter 13 Why Do We Fall Ill:

  1. Why Do We Fall Ill
  2. Health and its Failure
  3. Disease and Its Causes
  4. Infectious Diseases

In-Text Questions Solved

NCERT Textbook for Class 9 Science – Page 178:
Question 1. State any two conditions for good health 
Answer: Two conditions essential for good health are:

  1. State of physical, mental and social well-being.
  2. Better surroundings or -environment.

Question 2. State any two conditions essential for being free of disease.
Answer. The two conditions essential for being free of disease are:

  1. Personal and -domestic .hygiene.
  2. Clean environment and surroundings

Question 3. Are the answers to the above questions necessarily the same or different ? Why ?
Answer: The answer to the above questions are different because a person may be free of disease but his mental, social or economical health may not be good.

Class 9 Science NCERT Textbook – Page 180

Question 1. List any three reasons why you would think that you are sick and ought to see a doctor. If only one of these symptoms were present, would you still go to the doctor? Why or why not?
Answer: The 3 reasons why one would think that he is sick are—(1) headache, (2) cold and cough, (3) loose-motions.
This indicates that there may be a disease but does not indicate what the disease is. So one would still visit the doctor for the treatment and to know the cause of above symptom.
Even in case of single symptom one needs to go to the doctor to get proper treatment.

Question 2. In which of the following case do you think the long-term effects on your health are likely to be most unpleasant?

  • If you get jaundice
  • If you get lice
  • If you get acne.

Why.
Answer: In the above cases, lice and acne are acute problems of our health which can be cured in short duration. But jaundice is the disease that can have most unpleasant effect on our health as it affects the most important organ of our body i.e., liver. This disease is a chronic one.

NCERT Textbook for Class 9 Science – Page 187
Question 1. Why are we normally advised to take bland and nourishing food when we are sick?
Answer: We are advised to take bland and nourishing food when we are sick because our body needs energy to release cells to overcome the infection, the wear and tear of body organ. The nourishing food provides nutrients to our body that will further provide energy and make new cells. No spices in the food makes its digestion process faster, does not release acids in the body that can interfere in the treatment and cure.

Question 2. What are the different means by which infectious diseases are spread?
Answer: The different means by which infectious diseases spread are:
(a) Through air: They are also called air-borne diseases. The air carries bacteria, virus and the diseases that can be caused are: common cold, influenza, tuberculosis etc.
(b) Through food and water: When one eats/drinks contaminated food/water, that contains bacteria, virus, worm etc. it can cause diseases like cholera typhoid, hepatitis.
(c) Through contact: Many diseases spread by contact of infected person with the healthy person. Example, fungal infections, skin diseases, scabies etc.
(d) By sexual contact: Many diseases can be transmitted, example, syphilis, AIDS.
(e) By body fluids: Fluids like blood, semen, mother’s milk, when infected,
can also cause diseases. Example, AIDS.
(f) Vectors: The organism that spreads a disease by carrying pathogens from one place to another is called vector. Example, mosquitoes are vectors that carry pathogens like protozoa.

Question 3. What precautions can you take in your school to reduce the incidence of infectious diseases?
Answer: The precautions that one can take in school to reduce the incidence of infectious diseases are
(a) By using handkerchief while coughing sneezing.
(b) Washing hands before eating tiffins.
(c) Staying at home if anyone suffers from infectious diseases.
(d) Getting vaccinated before the infection affects.
(e) Keeping the school surroundings clean, checking for stagnant water.

Question 4. What is immunisation?
Answer: When the body attains immunity against any disease, due to vaccination. This process is called immunisation.

Question 5. What are the immunisation programmes available at the nearest health centre in your locality? Which of these diseases are the major health problems in your area?
Answer: The immunization programmes available at the nearest health care centres are:

  1. Child immunization programme starts from 0 to 12 years.
  2. Polio eradication programme
  3. H1N1 screening programme
AgeImmunisation

Infant

6 weeks—9 weeks

9-12 months

Polio, B.C.G

D.P.T, tetanus

booster doses, chickenpox, hepatitis A, B etc.

In major areas tuberculosis cases are reported in a large number which is a major concern.

Questions From NCERT Textbook for Class 9 Science

Question 1. How many times did you fall ill in the last one year? What were the illnesses?
(a) Think of one change you could make in your habits in order to avoid any of/ most of the above illnesses.
(b) Think of one change you would wish for in your surroundings in order to avoid any of/most of the above illness.
Answer: The illness was 2-3 times, common-cold, occurred in a year.
(a) One change I would make in my habits in order to avoid the above illness is that I would take proper diet rich in vitamin C and would avoid too cold food.
(b) The surroundings should be neat, and clean,

Question 2. A doctor/nurse/health worker is exposed to more sick people than others in the community. Find out how she/he avoids getting sick herself/himself?
Answer: A doctor/nurse/health worker when exposed to sick people they keep their nose and mouth covered, take care of hygiene, wash hands with soap before drinking water or eating food. They use mask, gloves, etc to avoid the direct contact with the person suffering from infectious diseases.

Question 3. Conduct a survey in your neighbourhood to find out what the three most common diseases are. Suggest three steps that could be taken by your local authorities to . bring down the incidence of these diseases.
Answer:

Common-diseases In neighbourhoodSteps to bring down the diseases spread
1. Malaria

2. Typhoid

3. Cough and cold

1. Clean surrounding

2. Clean drinking water

3. Childhood immunisation

Question 4. A baby is not able to tell bis/her.caretakers that she/he is sick. What would help us to find out
(a) that the baby is sick?
(a) what is the sickness?
Answer:
(a) The symptoms like body temperature, fever, cough, cold, loose-motions, non-stop crying improper or no food intake etc. would help up to find that the baby is sick.
(b) The symptoms could help us to find out the sickness of the body.

Question 5. Under which of the following conditions is a person most likely to fall sick?
(a) When she is recovering from malaria.
(b) When she has recovered from malaria and is taking care of someone suffering from chicken-pox.
(c) When she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chicken-pox.
Why?
Answer: (c) When she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chicken-pox.
As the person is not taking proper diet which is required for her proper health and healing of body.
Her chances of getting chicken-pox also high as her body’s immunity has lowered.

Question 6. Under which of the following conditions are you most likely to fall sick?
(a) When you are taking examinations.
(b) When you have travelled by bus and train for two days.
(c) When your friend is suffering from measles.
Why?
Answer: (c) When your friend is suffering from measles, as it is an infectious disease.

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