SOUND NOTES CLASS IX FOR SA II

Class 9 CBSE Sound Chapter Notes

 SOUND CLASS 9 NOTES, SOUND IMPORTANT POINTS

Important Notes of Science Class 9 Sound

Production of Sound
Sound is produced due to the vibration of objects. Vibration is the rapid to and fro motion of an object. Vibrating objects are the source of all sounds Irregular, chaotic vibrations produce noise Regular, controlled vibration can produce music All sound is a combination of pure frequencies A stretched rubber band when plucked vibrates and produces sound.

Propagation of Sound
When an object vibrates, the particles around the medium vibrate. The particle in contact with the
vibrating object is first displaced from its equilibrium position
The disturbance produced by the vibrating body travels through the medium but the particles do not
move forward themselves.

A wave is a disturbance which moves through a medium by the vibration of the particles of the
medium. So sound is considered as a wave.Sound waves Require medium for transmission.Sound
waves are called mechanical waves. When a vibrating object moves forward, it pushes and
compresses the air in front of it forming a region of high pressure called compression (C). When the
vibrating object moves backward, it forms a region of low pressure called rarefaction (R).

A vibrating object producing a series of compressions (C) and rarefaction (R)
In these waves the particles move back and forth parallel to the direction of propagation of the
disturbance. Such waves are called longitudinal waves.
Compressions are the regions of high pressure and density where the particles are crowded and
are represented by the upper portion of the curve called crest.
Rarefactions are the regions of low pressure and density where the particles are spread out and
are represented by the lower portion of the curve called trough

Sound is a Mechanical Wave:
Sound requiers medium for its propagation it can travel through solid, liquid and gas but not vaccum. The waves which require a material medium for their propagation are called mechanical waves.

Sound is Longitudnal Wave

The wave in which the particles of the medium oscillate along the direction of propagation of the wave is called a longitudinal wave

Transverse wave
The wave in which the particles of the medium oscillate in a direction perpendicular to the direction of propagation of the wave is called a transverse wave.Light waves are transverse waves.They do not require medium for their propagation.Light can travel through vaccum.


 Pulse: A wave of  short duration which is confined to a small portion of a medium at any given time is known as a pulse.


 Characteristics of a sound wave

Frequency of sound waveThe number of oscillations per unit time is called the frequency of the sound wave.
It is represented by the symbol ٧ (Greek letter nu). Its SI unit is hertz (Hz)

The pitch of a sound depends upon the frequency, higher the frequecy higher will be the pitch and vice versa. 

Time Period:Time taken to complete one oscillation

Time period= 1/f

Amplitude of the Sound: The maximum displacement of particles of the medium from their mean positions during the propagation of a wave is known as amplitude of the wave.The amplitude of sound wave is the height of the crest or tough.It is represented by the letter A.
The SI unit is the same as that of density or pressure.

Velocity:The distance travelled by a wave in one second is called wave velocity.It depends upon the nature of the medium through which it passes. 

v=frequency X Wavelength


Audible Frequency: The human ears can hear only those waves whose freqnecy lies between 20 Hz and 20,000HZ.

Infrasonic Waves:The waves having freqnecy less than 20 Hz are infrasonic


Ultrasonic Waves:The waves having frequency more than 20.000 Hz are ultrasonic waves

Reflection of Sound
Sound gets reflected at the surface of a solid or liquid and follows the laws of reflection.
i) The angle of incidence is equal to the angle of reflection.
ii) The incident ray, the reflected ray and normal at the point of incidence all lie in the
same plane.

 Echo
If we shout or clap near a reflecting surface like tall building or a mountain, we hear the
same sound again. This sound which we hear is called echo. It is caused due to the reflection
of sound.
To hear an echo clearly, the time interval between the original sound and the echo
must be at least 0.1 s.
Since the speed of sound in air is 344 m/s, the distance travelled by sound in 0.I s = 344
m/s x 0.1 s = 34.4 m
So to hear an echo clearly, the minimum distance of the reflecting surface should be
half this distance that is 17.2 m.



Reverberation

Echoes may be heard more than once due to repeated or multiple reflections of sound
from several reflecting surfaces. This causes persistence of sound called reverberation.

In big halls or auditoriums to reduce reverberation, the roofs and walls are covered by
sound absorbing materials like compressed fibre boards, rough plaster or draperies.
Uses Of Multiple Reflection Of Sound
 
i)Megaphones, horns, musical instruments like trumpets, etc. are deigned to send sound by
multiple reflection in a particular direction without spreading in all directions.

ii) Doctors listen to sounds from the human body through a stethoscope. The sound of
heartbeat reaches the doctor’s ears by multiple reflection.

iii) Generally the ceilings of cinema halls and auditoriums are curved so that sound after
multiple reflection reaches all parts of the hall.


Sometimes a curved sound board is placed behind the stage so that sound after multiple
reflection spreads evenly across the hall.

Speed of sound in Different Medium
Sound travels with different speeds in different mediu.The speed of sound also depends u pon the temperature of the medium.Sound travels faster in solids than in air.The speed of sound in solids is much more than the speed of sound in liquids or gases.
Average speed of sound at room temperature is 332 m/s

Application of Ultrasound
They are used to establish ship to ship communication.
They are used to find the depth of a sea.
They are used to diagnose the disease in a human body
They are used to kill bacteria in liquids.
They are used for welding plastics

SONAR
SONAR stands for Sound Navigation and Ranging.It is based on the principle of the reflection of sound wave.The ultrasonic waves from the transmitter of SONAR are sent towards the bottom of the sea whose depth is to be measured.These waves are reflected back from the bottom of the seas and are received by the receiver of the SONAR the transmitter and the receiver are suitably placed on the ship.The time taken by the ultrasonic waves to go from the ship to the bottom of the sea and then  back to the ship is recorded
Time taken by the waves to go from the ship to the bottom of the sea is =t/2.If V is the velocity of wave, the the required distance S is given by.
s= v(t/2)
Human Ear
The ear mainly consists of three basic parts the outer ear, the  middle ear, the the inner ear.Each part of the ear serves a specific purpose in the task of the detecting and interpreting sound.The outer ear serves to collect and channel sound to the middle ear.The middle ear serves to transform the energy of a sound wave into the internal vibrations of the bone structure and ultimately transform these vibrations into a compressional waves in the inner ear.The inner ear serves to transform the energy of a compressional wave with the inner ear fluid into nerve impulses which can be transmitted to the brain.

WHY DO WE FALL ILL? CLASS IX SCIENCE SA II IMPORTANT QUESTIONS AND ANSWERS

WHY DO WE FALL ILL?

(NCERT Chapter Solutions, Extra important Q &A) 
Q1: Define Health? What do you interpret when we say a person is in good health?

Answer: Health is a state of physical, mental and social well being of an individual not merely absence of a disease or infirmity.

When we say a person is in good health, it implies the different body systems and organs of that person function well and as a whole body strike a balance with physical, mental and social environment.




Q2(NCERT): State any two conditions essential for good health.

Answer: Conditions essential for good health are:

1.         Physically fit and healthy.

2.         Cleanliness: habitat should be neat and clean.

3.         Good social and economic conditions.

Q3: What are three dimensions of health? Are they interrelated?

Answer: The three dimensions of health are:

1.         Physical Dimension: A person is disease free, his/her skin is shining, has bright eyes, normal metabolism etc. define the physical dimensions of being healthy.

2.         Mental Dimension:Able to judge his strengths and weaknesses, does not overestimate or underestimate things etc.

3.         Social Dimension: Able to adjust with his/her family members and society, free from interpersonal conflicts etc. 

Q4: Kidneys of a person do not filter urine properly. How does it affect physical, mental and social dimensions of that person?

Answer:  If the kidneys of the person do not filter urine, the toxic substances will start collecting in the body and affect on other organ systems. In such conditions, the brain will not think properly. The person will stay socially isolated, his physical movement will be restricted. 

Q5(NCERT): State any two conditions essential for being free of disease.

Answer: Conditions essential for being free of disease are:

·               Personal Hygiene

·               Community Hygiene

·               Balanced Diet

Q6(NCERT): Are the answers to the above questions (Q2 and Q5) and  necessarily the same or different? Why? 

Answer: Yes the answers to these questions are inter-related. Personal and community hygiene and cleanliness reduces the risk of getting any infection or being unhealthy. Physical exercise keeps the body function normally and prepares it to fight against any disease. 

Q7: What is a balanced diet?

Answer: A balanced diet is one that provides all the required nutrients to the body in correct proportion. It includes the correct proportion of carbohydrates, proteins, vitamins, minerals and roughage in your diet.

Q8(CBSE 2011): A hefty boy of 12 years often picks fights with others. Do you think he is in good health? If so, then explain your answer.

Answer: No the boy is not in good health. His persistent impulsiveness (constant fighting with others) indicates that the boy may have mental and/or social issues. He does not feel empathy when others are hurt. It tells he may be psychologically "unhealthy". 

Q9: (i) How do you define 'disease'?
(ii) (CBSE 2011) State and explain in brief the four major factors, which are the causes of disease. 

Answer: The condition of malfunctioning of the organ system or systems is called disease. In layman terms, disease means "without ease". Disease leads to an abnormal condition in which our body or body organ does not work properly.

Following are the major factors which cause diseases:

1.         pathogens (e.g. virus, bacteria, worms etc.)

2.         environmental factors (e.g. pollutants)

3.         nutritional factors (e.g. malnutrition)

4.         genetic factors (e.g. gene defects)

5.         hormonal imbalances (e.g. insufficient release of insulin causes diabetes)

6.         metabolic factors (e.g. organ failure)

Q10: Is there any difference between 'being healthy' and 'disease free'?

Answer: Yes there is difference between the two. A person may be in poor health but he is not suffering from any disease. Having poor health increases the risk that he may suffer from any disease. In general when we talk think about health, we think at society or community level. When we talk about disease, we think about individual sufferers.

Q11: How do we identify a disease?

Answer: By looking at symptoms and signs.

Q12: What is the difference between symptoms and signs of a disease?

Answer:

Symptoms	Signs
1. Symptoms are the indicators that there is some abnormality in the body.	1. Signs provide information about the possibility of a particular disease.
2. In general, symptoms are the problems which a patient feels or notices.	2. Signs are the indications which the doctors find objectively.
3. e.g. Patient feels hot and body ache which are symptoms.	3. Doctors examines the patient and finds the skin is hot and measures patient's body temperature which are the signs.

Q13(NCERT): 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: Symptoms that make me sick:

·               Cough

·               Fever

·               Constant Headache

Yes I will still visit the doctor if only one of these symptom is present because it makes me uncomfortable and bed-ridden. Ignoring the symptom for a a longer duration may have serious consequences.  

Q14: Based on duration or persistence, how diseases are categorised?

Answer: Based on duration or persistence, diseases are categorised as:

·               Acute Diseases

·               Chronic Diseases

Q15(NCERT): In which of the following case do you think the long-term effects on your health are likely to be most unpleasant?
a. if you get jaundice,
b. if you get lice,
c. if you get acne. Why? 

Answer: (a) Jaundice is a chronic disease in which liver is affected. Jaundice has long-term effects on the body. It will take a long time to recover.

(b) Lice can be treated easily and has short-term effect on our health.

(c) Acnes may exist for longer time but do not have any adverse effect on our health.

Q16: Give examples of Acute diseases.

Answer: Cough, Common Cold, Typhoid, Cholera

Q17: Give four examples of Chronic diseases.

Answer: Elephantiasis, Tuberculosis, diabetes, arthritis etc.

Q18: Differentiate between Acute Diseases and Chronic Diseases.

Answer:  

No.	Acute Diseases	Chronic Diseases
1.	Symptoms lasts for a short period of time.	Symptoms persist for a longer duration and may last lifetime.
2.	Generally sudden onset of disease or injury.	Diseases develop slowly and gradually.
3.	Patient may recover fast after the treatment and is free from symptoms.	Patient does not recover completely. It takes a longer time to get relief.
4.	May not require hospitalization.	May require hospitalization and long duration treatment.
5.	Examples: Influenza, Common Cold, bad throat, a small injury like cut in finger etc.	Examples: Diabetes, Tuberculosis, Arthritis, Heart Diseases etc.

Q19: What are congenital diseases? Give two examples of such disease. 

Answer: Congenital diseases refer to diseases or abnormalities present since birth. It may be due to gene mutations (genetic factor) or environmental factors.
Examples: Colour blindness, Down's syndrome, cleft lip or palate.

Q20: Name a disease which was earlier considered to be chronic but now can be treated in short duration?

Answer: Peptic ulcer.

Q21(NCERT): A baby is not able to tell her/his caretakers that she/he is sick. What would help us to find out
(a) that the baby is sick?
(b) what is the sickness?

Answer: (a) Various symptoms can help us find if baby is sick or not:

1.         constant crying, 

2.         frequent loose motions

3.         disrupted sleep or unusual long sleep

4.         vomiting etc.

 (b) An examination and diagnosis of symptoms and signs of the baby by a doctor will help in identifying the particular disease. 

Q22: What are acquired diseases? 

Answer: The diseases which develop after birth are called acquired diseases. These are classified as:

1.         Communicable or Infectious Diseases: malaria, influenza etc.

2.         Non-communicable Diseases: diabetes, scurvy, high blood pressure

Q23(CBSE 2011): Write few common signs and symptoms of a disease if brain is affected.

Answer: Headache, fits, unconsciousness, vomiting etc.

Q24(CBSE 2011): List any two differences between infectious and non-infectious diseases. Write any one example of each disease.

Answer: 

Infectious Diseases	Non-Infectious Diseases
1. Caused by external factors e.g. pathogens	1. Caused by internal factors e.g. genetic abnormality
2. Diseases can spread unhealthy person to healthy person.	2. Diseases do not spread from infected to healthy person.
3. Infection can spread and infect others via direct contact or medium (air, water, vectors etc.)	3.Infection does not spread through direct contact nor by medium. However it may be hereditary i.e. from parents to offspring.
4. Examples: Malaria, Dengue etc.	4. Examples: Goitre, High Blood pressure, Diabetes

Q25(CBSE 2010): What are infectious agents? What are the different infectious agents?

Answer: The microorganisms which spread the disease from one person to other are called
infectious agents. Different infectious or causative agents or pathogens are:

1.         Viruses

2.         Bacteria

3.         Fungi

4.         Protozoans

5.         Worms

Q26: What is 'germ theory of disease'? Who proposed it?

Answer: Louis Pasteur proposed 'germ theory of disease. Accord to this theory he stated that micro-organisms are the causes of many diseases. It is also called pathogenic theory of medicine.

Q27: What are Koch's Postulates?
Answer:  Robert Koch proposed four postulates to identify the causative agent of a particular disease. These postulates are:

1.         The microorganism or other pathogen must be present in all cases of the disease.

2.         Pathogens can be isolated from the diseased host and grown in pure culture.

3.         Pathogens from the pure culture must cause the disease when inoculated into a healthy, susceptible laboratory animal.

4.         Pathogen must be re-isolated from the new host and shown to be the same as the originally inoculated pathogen

Q28: List the diseases caused by viruses?


Answer: Diseases caused by viruses:

1.         Influenza

2.         Dengue fever

3.         Common Cold

4.         AIDS

5.         Chicken Pox

6.         Measles

7.         Hepatitis

Q29: Give three examples of bacterial diseases.

Answers: Examples of bacterial diseases are:

1.         Tuberculosis

2.         Antrax

3.         Typhoid

4.         Tetnaus

Q30: Give examples of fungal diseases.

Answer: Fungal infections are:

1.         Common skin infections e.g. Ringworm, Athlete's foot

2.         Aspergillus infects lungs

Q31: List three diseases caused by protozoans.

Answer: Diseases caused by protozoans:

1.         Kala-azar (Leishmaniasis)

2.         Malaria

3.         Amoebiasis 

4.         African Sleeping Sickness

Q32: Name the pathogen causes peptic ulcer.

Answer: Helicobacter pylori (bacteria)


Q33: List the diseases caused by worms?

Answer: Elephantiasis, Intestinal infections.


Q34: Name the the protozoan pathogen that causes kala-azar.

Answer: Leishmania


Q35: Name the microbe which causes acne.

Answer: staphylococci (a type of bacteria).


Q36: What is the scientific name of roundworm? Where do we find it commonly in human body? Name the disease caused by it.

Answer: Ascaris lumbricoides. Generally found in human intestine. Ascariasis. 


Q37: Why is it important that we think of these categories of infectious agents?

Answer: Members of each one of these groups – viruses, bacteria, and so on – have many biological characteristics in common. these categories are important factors in deciding what kind of treatment to use. It implies many important life processes are similar in the bacteria group but are not shared with the virus group. As a result, drugs that block one of these life processes in one member of the group is likely to be effective against many other members of the group. But the same drug will not work against a microbe belonging to a different group.


Q38: How do antibiotics (say Penicillin) work on bacteria but not on human beings?

or

Q(CBSE 2011): Define antibiotic? Explain how it is able to control bacterial infections but not viral
infections. 

Answer:  Antibiotics (anti means against, biotic - living) are types of medications that destroy or slow the growth of bacteria. They are often termed as antibacterials. They work against the life processes of bacteria. They commonly block biochemical pathways important for bacteria. Many bacteria, for example, make a cell-wall to protect themselves. The antibiotic penicillin blocks the bacterial processes that build the cell wall. Thus bacteria fail to build their cell-wall, stop multiplying and die out. Human cells don’t make a cell-wall anyway, so penicillin cannot have such an effect on us.


Q39(CBSE 2011): Explain why antibiotics are more effective in curing bacterial diseases than viral diseases.

or

Q: Why taking an antibiotic is not effective in the common cold?

Answer: Antibiotics are effective in curing bacterial and fungal infections (e.g. tuberculosis)  but they are ineffective in viral diseases (like common cold). Antibiotics affect on life processes of bacteria and inhibit their growth. On the other hand virus is just a piece of DNA (or RNA), not a well defined life form. Viruses can reproduce inside host cells. They do not use common biochemical pathways as used by other microbes (bacteria, fungi and parasites). That's why antibiotics are ineffective in viral infections.
It should be noted that despite this limitation, there are now effective anti-viral drugs, for example, the drugs that keep HIV infection under control.


Q40(HOTS): Give two examples of bacterial antibiotics.

Answer: Antibiotics used to kill bacterial infections:

1.         penicillin, ampicillin: inhibits synthesis of cell wall.

2.         streptomycin, tetracycline: prevent protein synthesis in ribosomes.

Q41(HOTS): Give an example of fungal antibiotic.

Answer: polyoxin: inhibits cell wall growth  in fungi.



Q42(NCERT): Why are we normally advised to take bland and nourishing food when we are sick?

Answer: When we are sick, generally it affects on our digestion and we lose appetite. Bland food is low-fibre, non-spicy and easy to digest food. It helps in digestion and provides necessary nourishment. In case of patients suffering from gastrointestinal problems like ulcer, bland diet helps recover from such problems. Bland diet helps in improving the immunity and regeneration of healthy body tissues.
On the other hand oily, spicy and fried food cannot be easily digested by sick patients and this food is not recommended. 


Q43(NCERT): What are the different means by which infectious diseases are spread?

Answer: Infectious diseases can spread through various means like through air, water, by direct and indirect contact, vectors (animals, mosquitos, flies etc.).

1.         Through Air: Spread through sneezing, coughing, open defecation. Air Borne Diseases are common cold, pneumonia, tuberculosis, measles, SARS, chicken-pox.

2.         Through Water: open defecation,  consuming contaminated water, inadequate hand washing. Water borne diseases are cholera, amoebiasis, typhoid etc.

3.         Direct Contact(including sexual contact): By handshaking, kissing, contact with body lesions, sexual contact. e.g. common cold, tuberculosis, chicken pox, warts etc. Sex Transmitted diseases (STD) are Syphilis, AIDS, gonorrhea.

4.         Indirect Contact:  By frequently touching the surfaces of objects used by infected persons e.g. touching door knobs, utensils, clothes, towels, toilets, computer keyboards etc. Examples of diseases spread by Indirect Contact are Flu, TB, Chickenpox, urinal infections etc.

5.         Through vectors: Animals, Flies, Mosquitos etc. carry infecting agent from sick person to healthy person. Vector borne diseases are: rabies, malaria, dengue, yellow fever, dysentery, diarrhea etc.

Q44(MCQ): If a person has persistent cough and breathlessness, most likely which of the following organ is affected

(a) lungs

(b) liver
(c) brain
(d) intestinal tract

Answer: (a) lungs


Q45: What is the alternate name of brain fever? Which vector is responsible for this disease?

Answer:  Japanese encephalitis caused by a virus which enters through mosquito bite.

Q46: Name the vector which causes malaria.

Answer: Female Anopheles mosquito.


Q47: Name the vector which causes dengue, chikengunia and yellow fever.

Answer: Aedes aegypti mosquito


Q48: Name the vector that can cause sleeping sickness.

Answer: Tsetse Fly


Q49: Name the diseases that can spread through housefly.

Answer: Cholera, Typhoid, Dysentry, Diarrhoea, Tuberculosis etc. may spread via houseflies.


Q50: Name the vectors which can cause rabies.

Answer: Most of the animals included humans can be infected and all of them can spread the disease. Dogs, rats, cats, monkeys, squirrels, cattle, wolves, raccoons, bears etc. can spread this disease. In India, mostly it spreads through dog bites and monkey bites. 


Q51(NCERT): 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 or a nurse or a health worker avoids getting sick by taking the following precautions:

·               keep the work place (hospital and surroundings) sterilized.

·               use sterilized equipments and disposable syringes.

·               use hand gloves, masks and wash their hands after examining a patient. 

·               immunized themselves with different vaccinations.

·               keep themselves fit by regular exercise and balanced diet.

·               create awareness among co-workers and educate people about cleanliness, regular exercise and healthy diet.

Q52(NCERT): What precautions can you take in your school to reduce the incidence of infectious diseases?

Answer: To reduce the incidence of infectious diseases, following precautions can be taken in schools:

·               provide clean and safe drinking water

·               proper sanitation and cleanliness in school premises and its surroundings and not to allow any mosquitoes (vector) breeding.

·               encouraging students and their parents to take vaccinations against infectious diseases.

·               encourage students and teaching staff to stay home and seek medical advice when infected.

·               aware students about hygienic practices like wash hands before taking food and after going to washroom. And cover face while sneezing etc.

·               encourage students to adopt healthy eating practices e.g. adopt fruit+salad food breaks.

Q53:What do you mean by immunity?

Answer: The ability of the body to be resistant towards injury, poison or harmful pathogens and their products is called immunity. It is part of the defence reaction in the body.
There are two types of immunity:

·               Natural or Innate immunity.

·               Acquired or Specific immunity

Q54(NCERT): What is immunisation?

Answer: Administering vaccines to prevent the disease is called immunization. Immunisation is a technique to prevent infectious disease. In this technique, vaccines are given in to the people so that they develop temporary or permanent immunity (Artificial Active Acquired Immunity) to fight against a particular disease.  


Q55: What is antigen?

Answer: When a pathogen invades our body, it releases toxins in bloodstream or in tissues. This toxin or foreign protein entering our body is called antigen.


Q56: What are antibodies?

Answer: The proteins produced by our immunity system (lymphocytes, WBCs etc.) to neutralize or detoxify antigens are called antibodies.


Q57: What is colostrum? Why is mothers milk strongly advised to new borns?

Answer:  Colostrum also called first milk is the milk produced by mother in late pregnancy. It is rich in antibodies. New born babies have weak immunity system at birth. Through mother's milks, antibodies are transferred to baby. It persist in the baby’s body for several weeks and provides her passive immunity to fight against many diseases. 


Q58(NCERT): 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: At the nearest health centre various immunization programmes are available, such as:

·               Polio eradication programme

·               Hepatitis vaccination programme

·               Tuberculosis prevention programme

To mothers immunization schedule is given for their new borns:

Recommended Immunisation Schedule

S.No.	Age	Disease	Vaccination
1	At Birth	Hepatitis B	Hep B Vaccine I
2	At Birth	Polio	Oral PV 0 dose
3	Birth to 6 wk	Tuberculosis	BCG
4	4 6 weeks	Hepatitis B	Hep B Vaccine II
5	6 weeks	Diphtheria, Pertussis, Tetanus, Polio	DPT-1, OPV-1
6	10 weeks	Diphtheria, Pertussis, Tetanus, Polio, Hepatitis B	DPT-2, OPV-2, HEP B Vaccine III
7	14 weeks	Diphtheria, Pertussis, Tetanus, Polio	DPT-3, OPV-3, HEP B Vaccine IV
8	24 weeks	Hepatitis B	HEP B Vaccine III
9	9- 12 months	Polio Measles	OPV-4, Measels
10	15 - 18 months	Mumps, Measles, Rubella	MMR
11	18 months	Diphtheria, Pertussis, Tetanus, Polio	DPT BOOSTER-1 OPV-5
12	24 months	Typhoid	Typhoid
12	4 - 5 years	Diphtheria, Pertussis, Tetanus, Polio	DPT BOOSTER-2 OPV-6

Q59(CBSE 2011): (a) What are epidemic and endemic diseases? 
(b) Which organ is affected if a person is suffering from jaundice?

Answer:  (a) A disease or condition which affects a large number of people at the same time is called epidemic. e.g. out break of plague in China in 2009.
Endemic disease is disease or condition that is constantly present in a particular community or localized region. e.g. Hepatitis A, Malaria, Dengue are endemic in India.

(b) Jaundice or hepatitis is a viral disease which affects liver. 


Q60: What do you mean by Phagocytosis?

Answer: WBCs or leukocytes play an important role in defense mechanism of a body. When a foreign body or microbe (e.g. bacterium) enters the blood stream, leukocytes surround the microbe and engulf them. Thus the microbes are destroyed. This process of engulfing and destroying foreign bodies is called phagocytosis.


Q61: Why is it not necessary to give Hepatitis A vaccine to children?

Answer: Hepatitis A, a type of jaundice is caused by a virus. This virus is transmitted through water. In many regions of India, this virus is found in drinking water. By the time the children reach age of five for Hepatitis A vaccination, they already have become immune to this disease. Therefore it is not necessary to give Hepatitis A vaccine to children.
Q62: What are the basic principles involved in medical treatment for diseases?

Answers: The basic principles involved in medical treatments are:

1.         Minimize the impact of disease on human body.

2.         Kill or eliminate disease causing germs.

3.         Help in providing immunity of the body.

Q63: Why it is advisable to breast feed the baby for first few several weeks? 

Or

Why Colostrum is good for infants?

Answer: Infants or babies after birth do not have strong immune system. The colostrum or mother's milk contains many antibodies which provides passive immunity to the babies. Therefore it is advisable to breast feed the baby for first few several weeks.


Q64: How do Skin, Hairs, Saliva  form the first line of defense against diseases?

Answer: Skin, Nose hairs, Saliva act as the first line of defense.
Skin: It forms a physical barrier thus preventing the entry of of microbes.
Hairs: Prevent entering dust particles and germs.
Saliva: It washes away bacterial growth from teeth and mouth.