bio notes for std 9th

Why do we fall ill?

Q: What is health?

Ans:-Health is a state of well being to function well physically, mentally and socially.

Q: What is disease (dis- ease)?

Ans:-When an individual is not at ease which means if he is not feeling easy either physically or mentally, we can say that he is suffering from a disease .There may be several factors for the occurrence of disease.

 Q: What could be he possible factors for a disease to occur?

Ans:-There could be several possible factors for a disease to occur. They are as follows:

*Attack of Pathogens.

*Improper Hygiene (Both personal as well as community)

*Improper Food Habits.

* Genetic Disorders.

*Hereditary Factors.

*Hormonal Disorders.

Q: How can a disease be identified by a doctor?

Ans:-A disease is most primarily identified by its symptoms. It is suggested to carryout some pathological tests for confirmation of disease. On the basis of the pathological reports, the diagnosis for a particular disease is made and an appropriate treatment that includes the medication are followed.

Q: Differentiate between acute and chronic diseases?

Acute Diseases	Chronic Diseases
The disease that lasts for short period of time are acute diseases.	The diseases that can last for a longer period of time are chronic disease.
It generally occurs due to attack of pathogens.	It may be caused due to an infection, genetic factor , hereditary diseases or hormonal problems
These diseases will no cause major affect on our general health or any particular organ of our body.	These diseases can have very drastic long term affect on an individual health and may affect any of he organs.
E. g-Common cold, Cough, Viral Fever.	E.g.-Elephantiasis, Diabetes Peptic Ulcers.

Q: What is peptic ulcer? Name the microorganisms responsible or it?

Ans: - Peptic ulcer is a condition that occurs in the stomach of an individual which causes acidity related pain and bleeding in the stomach and duodenum. This condition occurs due to improper food habit and lifestyle. Peptic ulcers are caused due to a bacterium “Helicobacter Pylori”     

Q: Who discovered the bacterium responsible for peptic ulcer?

Ans: - Robin warren and Barry Marshall discovered the bacterium responsible for peptic ulcer.

Q:Name some diseases caused by common pathogens?

Ans:-                                                                

Type	Disease Caused
Viruses	Common cold, Influenza (flu), Dengue Fever, AIDS, Measles, Rabies, Poliomyelitis.
Bacteria	Typhoid, Cholera, Tuberculosis, Anthrax, Acne, Whooping Cough, Tetanus, Leprosy.
Fungi	Many common skin infections.
Protozoan’s	Malaria(Plasmodium),Kala –azar (Leishmania), Amoebiasis (Amoeba),Sleeping Sickness (Trypanosoma)
Worms	Elephantiasis, Intestinal worm infections like arcariasis, Filariasis.

            

Q: It has been found that a particular drug acts against many members of the same group while it does not work against a microbe belonging to others group. Justify.

Ans. This is because the drug blocks the common life processes present in one particular group of similar organisms (say bacteria) and hence all of them may be killed by just one drug while the other group of organisms (say viruses) cannot be killed by the same drug.

It is further made clear by the following examples of antibiotic functioning. Antibiotics commonly block the pathways of bacteria which are very essential for their growth and survival. Most of the bacteria form cell wall around them for their protection. The antibiotics penicillin blocks he bacterial biochemical pathways that builds the cell wall. When the bacteria are unable to form its protective covering / cell wall in the presence of antibiotic, they die ultimately.

Similarly, many antibiotics work against many species of bacteria rather than simply working against one.

 Q: What are antibiotics?   

Ans. The antibiotics are chemical substance derivable from a microbe that kills microbes and cures infections. Examples-Penicillin, Ampicillin, tetracycline etc.

Q: Who discovered antibiotics for the first time?

Ans. Sir Alexander Fleming discovered antibiotics for the first time in the year 1929.

Q: Why antibiotics do not work against viral infections?

Ans. Since , the viruses do not use the pathways which are followed by the bacteria or the fungi against which the antibiotics are effective so during any viral infection like common cold or flu , taking antibiotics does not reduce the severity or the duration of the disease but kills the symbiotic bacteria present in our intestine . But if we get viral infection along with a bacterial one, taking antibiotics will help.

Q: What are communicable diseases?

Ans. The diseases which can be communicated or transferred from an infected person o a health person through some infections agents are called communicable disease.

The study of transmission of diseases is called epidemiology.

Q: What are the means of spread of “communicable disease”?

Ans. Means of spread of communicable disease are:-

·       Through Air-These diseases are called airborne disease. E.g.-Common cold, Pneumonia, Tuberculosis etc.

·        Through contaminated food and water:-

Many microorganisms spread through contaminated food and water. These diseases get transmitted through water and hence are called water borne diseases. E.g. -Cholera, Diarrhea etc.

·       Through Sexual Contact:-

The diseases spread through sexual contact are known as sexually transmitted diseases (STD’s).E.g.-AIDS, Syphilis, gonorrhea etc. The pathogens that can cause some STD’s are transmitted during sexual contact. These diseases do no spread through casual physical contact.

·       Through vectors and carriers-

There are certain animals like insects which carry the infecting agents from a sick person to a healthy host. Such intermediatary animals are called vectors or carriers. E.g.-Malaria, Jaundice.

Q: How the HIV virus spread?

Ans. The HIV virus (Human Immuno Deficiency Virus) can spread through:

·       Blood transfusion- If an infected person donates his or her blood to a healthy person, and then he/she may also suffer from AIDS.

·       From an infected mother to her baby during pregnancy.

·       Breast Feeding – If a mother is infected, she may pass HIV virus to her baby.

·       Through Sexual Contact

·       By sharing the needles in hospital and razor in a saloon.

Q: How does the HIV infection affect human health?

Ans.HIV infection damages the functioning of the immune system and he body can no longer fight with even minor infections. A small cold and cough can turn into pneumonia and a minor gut infection can give rise to major diseases like diarrhea which may cause major blood loss and ultimately death. The body of an individual suffering from aids becomes a storehouse of multiple diseases and finally causing the death of a person. Hence, it is called a “syndrome”.

Q: How can you say that the microbes show organ specific and tissue specific manifestation?

Ans. The occurrence of he different microorganisms and exhibiting their effects in the different parts of the body of an individual are based on their evolution.

For instance, in an airborne disease, it is the lung which gets affected by the pathogens entering our body via nose or even mouth, resulting in cough and breathlessness. On the other hand, a gut infection may be caused due to the consumption of polluted water which mar result in jaundice as the causative organisms enters the body through the mouth and may migrate to the liver.

If the brain gets targeted by Japanese Encephalitis through mosquito bites, it will show the effects of headache, vomiting and even the fits of unconsciousness.

Q: What is the principle of treatment of any disease?

Ans. Diseases are caused by specific pathogens. It is therefore essential to pinpoint causative organisms or the targeted organ of the body. The first step of any treatment is to reduce the agent of the disease. Symptomatic treatment may not remove the microbes completely out of the body. Hence, we need to kill the microbe by using specific drug for specific pathogens which will block the biochemical pathways of the pathogen and eliminate it.

Differentiate between a disease free and a healthy person.

Disease Free	Healthy person
It is the state of absence of discomfort in any par of the body.	It is a state of complete physical, mental, and social well being.
A disease free person can be healthy or unhealthy.	A healthy person will be disease free.
Performance of disease free person depends upon his environment.	Healthy person is energetic and able o perform as per the requirements.

Q: How can we prevent the diseases?

Ans. There are two ways o prevent diseases:-

*General                                                              *Specific

           

* The general way of preventing disease is to prevent its exposure to infected microbes that are living in well erated houses, drinking safe water, eliminating vectors by maintaining public hygiene.

* The specific approach to prevent diseases is to have effective immunization programs that would develop specific resistance in the body to fight microbes that enter our body anytime there after.

Q: What are vaccines?

Ans. Vaccines can be defined as dead or weakened microbes which are not able to cause the disease but simulate the production disease. The vaccine has been derived from the Latin word vacca meaning cow pox.

Q: Who discovered vaccine for the first time?

Ans. Edward Jenner, a British physician discovered the first vaccine against small pox.

Q: What is immunization?

Ans. Immunization also called vaccination or Inoculation is the method of stimulating resistance in the human body to specific disease using microbes (bacteria or viruses) that have been modified or killed.

These treated microorganisms do not cause the disease but rather trigger the body’s immune response to build a defense mechanism that continuously guards against the disease.

Q: 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.

Ans: The following precautions must be taken by a doctor/ nurse/ health-worker:

(I) wear a mask when in contact with a diseased person.

(ii) Keeping yourself covered while moving around an infected place.

(iii) Drinking safe water.

(iv) Eating healthy and nutritious food.

(v) Ensuring proper cleanliness and personal hygiene.

Question 3:

Q: 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.

Ans:

Three most common diseases are:

(I) Tuberculosis

(ii) Typhoid

(iii) Jaundice

Steps to be taken to bring down the incidence of these diseases are:

(I)Proper disposal of sewage.

(ii) Ensuring supply of safe drinking water.

(iii) Providing a clean environment and preventing mosquitoes from breeding.

Q: 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?

Ans:

(c)A person is more likely to fall sick when she is on a four day fast after recovering from malaria and is taking care of someone who is suffering from chicken pox. This is because she is fasting during recovery, and her immune system is so weak that it is not able to protect its own body from any foreign infection. If she is taking care of someone suffering from chicken pox, then she has more chances of getting infected from chicken pox virus and will get sick again with this disease.

Q: 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?

Ans:

(c)You are more likely to fall sick when your friend is suffering from measles. This is because measles is highly contagious and can easily spread through respiration i.e., through air. Thus, if your friend is suffering from measles, stay away from him otherwise you might easily get infected with the disease.

Q: 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?

Ans:

(a) The baby is sick can be determined by his/her behavioral changes such as constant crying of baby, improper intake of food, frequent mood changes, etc.

(b) The sickness is determined by symptoms or indications that can be seen in the baby. The symptoms include vomiting, fever, loose motion, paleness in the body, etc.