2nd PUC Biology Question and Answer: Human Health and Disease

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Karnataka 2nd PUC Biology Textbook Answers—Reflections Chapter 8

Human Health and Disease Questions and Answers, Notes, and Summary

2nd PUC Biology Chapter 8

Human Health and Disease

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Question and Answer

Question 1.
What are the various public health measures, which you would suggest as safeguard against infectious diseases?
Answer:
The following public health measures can be taken as safeguards against infectious diseases:

Maintenance of Personal and Public Hygiene:
Keeping the body, surroundings, and environment clean helps prevent infection.
Proper Disposal of Waste and Excreta:
Safe disposal of human and animal waste prevents contamination of water and food.
Clean Drinking Water:
Water should be purified by boiling, filtration, or chlorination to kill harmful microorganisms.
Control of Vectors:
Measures like using mosquito nets, insect repellents, and spraying insecticides help control disease-spreading vectors such as mosquitoes and flies.
Vaccination and Immunization:
People should be vaccinated against common infectious diseases such as measles, polio, tetanus, and hepatitis.
Isolation of Infected Individuals:
Infected persons should be kept isolated to prevent the spread of contagious diseases.
Proper Nutrition:
A balanced diet boosts immunity and helps the body resist infections.
Health Education and Awareness:
Public awareness campaigns about hygiene, sanitation, and preventive care help reduce the spread of diseases.

Question 2.
In which way has the study of biology helped us to control infectious diseases?
Answer:
The study of biology helps us to control infectious diseases in the following ways:

The life cycle of many pathogens has been studied.
Alternate and reservoir hosts of pathogens are identified.
The mechanisms of disease transmission are understood.
Protective measures are suggested against diseases and pathogens based on these studies.
Suitable medicines are developed to treat infectious diseases.
Biology has also enabled the preparation and use of vaccines against many pathogens.

Question 3.
How does the transmission of each of the following diseases take place?

Amoebiasis
Malaria
Ascariasis
Pneumonia

Answer:

a) Amoebiasis:
Transmitted through contaminated food and water containing cysts of Entamoeba histolytica.
b) Malaria:
Transmitted by the bite of an infected female Anopheles mosquito, which carries Plasmodium
c) Ascariasis:
Transmitted through ingestion of food, water, or vegetables contaminated with the eggs of Ascaris lumbricoides (roundworm).
d) Pneumonia:
Transmitted by droplets released from the nose or mouth of an infected person during coughing or sneezing.

Question 4.
What measure would you take to prevent water-borne diseases?
Answer:
The following measures can be taken to prevent water-borne diseases:

Use of safe drinking water – Always drink boiled or filtered water.
Proper sanitation – Dispose of human excreta safely to avoid contamination of water sources.
Maintain personal hygiene – Wash hands with soap before eating and after using the toilet.
Avoid stagnant water – Prevent mosquito breeding by not allowing water to collect near houses.
Proper disposal of waste – Do not dump garbage or sewage into water bodies.
Health education – Create awareness about clean water practices and sanitation.
Vaccination – Get vaccinated against diseases like typhoid and hepatitis A.

Question 5.
Discuss with your teacher what does ‘a suitable gene’ means, in the context of DNA vaccines.
Answer:
In the context of DNA vaccines, ‘a suitable gene’ refers to a specific gene from the pathogen that codes for an antigenic protein — a protein capable of triggering an immune response in the host.
When this suitable gene is introduced into the host’s body through a DNA vaccine, the host’s cells produce the antigen, which stimulates the immune system to recognize and destroy the pathogen if it later infects the body.

Thus, a suitable gene is one that can produce a protective immune response without causing the disease itself.

Question 6.
Name the primary and secondary lymphoid organs.
Answer:

Primary lymphoid organs: Bone marrow and thymus.
Secondary lymphoid organs: Spleen, lymph nodes, tonsils, Peyer’s patches of the small intestine, and appendix.

Question 7.
The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form:

MALT
CMI
AIDS
NACO
HIV

Answer:
a) MALT – Mucosa Associated Lymphoid Tissue
b) CMI – Cell Mediated Immunity
c) AIDS – Acquired Immuno Deficiency Syndrome
d) NACO – National AIDS Control Organisation
e) HIV – Human Immunodeficiency Virus

Question 8.
Differentiate the following and give examples of each:
(a) Innate and acquired immunity
(b) Active and passive immunity
Answer:

(a) Difference between Innate and Acquired Immunity

Feature	Innate Immunity	Acquired Immunity
1. Definition	It is the immunity present at birth and provides the first line of defense.	It is the immunity developed after exposure to antigens or after vaccination.
2. Specificity	Non-specific; acts against all pathogens.	Specific; acts against a particular pathogen.
3. Memory	No immunological memory.	Has memory; gives a stronger response on re-exposure to the same pathogen.
4. Example	Skin, mucous membranes, phagocytic cells.	Immunity developed after infection or vaccination (e.g., measles vaccine).

(b) Difference between Active and Passive Immunity

Feature	Active Immunity	Passive Immunity
1. Definition	Immunity developed in the body due to direct contact with antigen.	Immunity provided by transfer of ready-made antibodies.
2. Duration	Long-lasting, often lifelong.	Short-lived and temporary.
3. Memory	Immunological memory is developed.	No memory is developed.
4. Example	Immunity after vaccination or infection.	Immunity from mother to child through placenta or injection of antibodies (e.g., antiserum).

Question 9.
Draw a well-labelled diagram of an antibody molecule.
Answer:

Question 10.
What are the various routes by which transmission of human immuno-deficiency virus takes place?
Answer:
The Human Immunodeficiency Virus (HIV) can be transmitted through the following routes:

Sexual contact with an infected person.
Transfusion of contaminated blood or blood products.
Sharing of infected needles or syringes (for example, among drug users).
From infected mother to child during pregnancy, childbirth, or breastfeeding.

Question 11.
What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?
Answer:
The AIDS virus (HIV) attacks the immune system, mainly the helper T-lymphocytes (T-helper cells or CD4 cells).

Mechanism:

HIV enters the body and binds to the CD4 receptors on helper T-cells.
The viral RNA is converted into DNA by the enzyme reverse transcriptase.
This viral DNA gets integrated into the host cell’s DNA, taking control of the cell’s machinery.
The infected T-cells start producing new viruses, which destroy the host cells as they are released.
As the number of T-helper cells decreases, the immune system becomes weak and unable to fight off even minor infections.

Hence, the person becomes immuno-deficient, leading to Acquired Immuno Deficiency Syndrome (AIDS).

Question 12.
How is a cancerous cell different from a normal cell?
Answer:
A cancerous cell is different from a normal cell in the following ways:

It loses the property of contact inhibition.
It continues to grow and divide uncontrollably.
It forms masses of cells called tumors.

Question 13.
Explain what is meant by metastasis.
Answer:
Metastasis is the process by which cancerous cells spread from their original site (primary tumor) to distant parts of the body through blood or lymph.

These cells form secondary tumors in other organs, damaging normal tissues.
Metastasis is the most dangerous property of malignant tumors.

Question 14.
List the harmful effects caused by alcohol/drug abuse.
Answer:
The adverse effects of drugs and alcohol abuse are as follows:

Cirrhosis and Fatty Liver:
The liver synthesises fat from alcohol. Excess fat lowers the production of enzymes and proteins, leading to fatty liver and eventually cirrhosis (where liver cells are replaced by fibrous tissue).
Alcoholic Polyneuritis:
Alcohol reduces appetite, leading to deficiency of B-complex vitamins and resulting in inflammation of nerves (polyneuritis).
Heart Diseases:
Continuous alcohol use causes cardiovascular problems, including hypertension and heart failure.
Amnesia:
Leads to partial or total loss of memory.
Ulcer and Pancreatitis:
Regular alcohol intake can cause stomach ulcers and inflammation of the pancreas.
Male Impotence:
Causes loss of sexual drive and defective sperm production (necrospermia).
Foetal Alcohol Syndrome (FAS):
Alcohol abuse during pregnancy leads to abnormal development of the foetus (alcohol embryopathy).
Family and Social Problems:
Alcoholism damages family relationships, lowers moral standards, and leads to accidents, violence, and other antisocial activities.

Question 15.
Do you think that friends can influence one to take alcohol/drugs? If yes, how may one protect himself/herself from such an influence?
Answer:
Yes, friends can influence a person to take alcohol or drugs.

One can protect himself/herself from such an influence by:

Avoiding the experimental use of alcohol or drugs out of curiosity, pleasure, adventure, or excitement.
Staying away from the company of friends who indulge in such activities.
Choosing good friends with healthy habits and positive attitudes.
Developing self-control and confidence to say “No” when offered alcohol or drugs.

Question 16.
Why is that once a person starts taking alcohol or drugs, it is difficult to get rid of this habit? Discuss it with your teacher.
Answer:
Once a person starts taking alcohol or drugs, it becomes difficult to get rid of the habit because these substances create physical and psychological dependence.

They affect the nervous system, producing a feeling of pleasure or relaxation. With repeated use, the body develops tolerance, meaning higher doses are needed to get the same effect. When the person tries to stop, withdrawal symptoms such as anxiety, restlessness, nausea, and depression occur, forcing them to take the substance again.

This cycle leads to addiction, making it very hard to quit without medical help and strong willpower.

Question 17.
In your view what motivates youngsters to take to alcohol or drugs and how can this be avoided?
Answer:
Youngsters are motivated to take alcohol or drugs due to the following reasons:

Curiosity to experience new sensations.
Experimentation for fun or thrill.
Adventure and excitement seeking behaviour.
Peer pressure and desire to fit in with friends.
Family history or unstable and unsupportive family environment.
Frustration and depression due to personal or academic stress.
Relief from pain or emotional distress.
Feeling of independence or rebellion against authority.
Influence of media such as television, movies, newspapers, and the internet, which often glamorize alcohol or drug use.

This can be avoided by:

Building self-confidence and strong willpower.
Choosing good friends and avoiding negative company.
Engaging in healthy activities like sports, reading, or creative hobbies.
Seeking guidance from parents, teachers, or counsellors when facing stress.
Spreading awareness about the harmful effects of alcohol and drugs.

Additional Questions And Answers

Question 1.
What is immunity? Mention its types.
Answer:
Immunity is the ability of the body to resist or fight against disease-causing microorganisms.
There are two types of immunity:

Innate immunity – Present from birth and provides general defence.
Acquired immunity – Developed after exposure to disease or through vaccination.

Question 2.
What is vaccination? How does it help in preventing diseases?
Answer:
Vaccination is the process of introducing a harmless or weakened pathogen into the body to stimulate the immune system to produce antibodies.
It helps the body to develop immunity and memory cells, which protect against future infections by the same pathogen.

Question 3.
What is the difference between a benign tumour and a malignant tumour?
Answer:

Benign tumour: Non-cancerous, does not spread to other parts of the body.
Malignant tumour: Cancerous, spreads to other tissues and organs through metastasis.

Question 4.
Name two diseases caused by protozoa and mention their mode of transmission.
Answer:

Amoebiasis – Transmitted through contaminated food and water.
Malaria – Transmitted by the bite of female Anopheles mosquito.

Question 5.
What is allergy? How is it caused?
Answer:
Allergy is a hypersensitive reaction of the immune system to certain substances called allergens (e.g., pollen, dust, food, etc.).
It occurs when the body produces excessive antibodies (IgE) and releases histamine, causing sneezing, itching, or breathing difficulties.

Question 6.
What are the common symptoms of withdrawal in drug addicts?
Answer:
Common withdrawal symptoms include anxiety, restlessness, muscle pain, nausea, vomiting, sweating, shaking, and depression.

Question 7.
Name any two diseases caused by viruses.
Answer:

AIDS – caused by Human Immunodeficiency Virus (HIV).
Common cold – caused by Rhinovirus.

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