Q.1) What public health measures can safeguard against infectious diseases?
Ans: Public health measures play a key role in preventing infectious diseases:
- Personal and public hygiene: Clean body, safe drinking water, proper disposal of waste and regular cleaning of water sources.
- Prevention of air-borne diseases: Avoid close contact with infected individuals.
- Control of vectors: Prevent stagnation of water, use mosquito nets, insecticides and larva-eating fish.
- Vaccination and immunisation: Vaccines help build immunity against diseases like polio, tetanus and pneumonia.
Q.2) How has biology helped in controlling infectious diseases?
Ans: Study of biology helped us understand disease-causing organisms, leading to the development of vaccines, antibiotics and effective immunisation programmes.
Q.3) How are the following diseases transmitted?
- Amoebiasis: Through contaminated food and water carried by houseflies.
- Malaria: By bite of infected female Anopheles mosquito.
- Ascariasis: Through contaminated water and food.
- Pneumonia: Through inhalation of droplets from infected individuals.
Q.4) What measures can prevent water-borne diseases?
Ans: Consumption of clean drinking water, proper sanitation, disposal of waste and regular cleaning of water reservoirs can prevent water-borne diseases.
Q.5) What is meant by a ‘suitable gene’ in DNA vaccines?
Ans: A suitable gene is a DNA segment that codes for a specific antigen and stimulates the immune system to produce antibodies.
Q.6) Name the primary and secondary lymphoid organs.
Ans:
- Primary lymphoid organs: Bone marrow and thymus.
- Secondary lymphoid organs: Spleen, lymph nodes, tonsils, Peyer’s patches and appendix.
Q.7) Expand the following abbreviations:
- MALT – Mucosa Associated Lymphoid Tissue
- CMI – Cell Mediated Immunity
- AIDS – Acquired Immuno Deficiency Syndrome
- NACO – National AIDS Control Organisation
- HIV – Human Immunodeficiency Virus
Q.8) Differentiate between:
(a) Innate and Acquired Immunity
Ans: Innate immunity is present from birth and non-specific, whereas acquired immunity develops after exposure to pathogens and is specific with memory.
(b) Active and Passive Immunity
Ans: Active immunity involves production of antibodies by the body, while passive immunity involves transfer of ready-made antibodies.
Q.9) Draw a labelled diagram of an antibody molecule.
Ans: Students should practise drawing a neat diagram showing heavy chain, light chain and antigen-binding sites.
Q.10) What are the routes of HIV transmission?
Ans:
- Unprotected sexual contact
- Transfusion of contaminated blood
- Sharing infected needles
- From infected mother to child
Q.11) How does HIV cause immune deficiency?
Ans: HIV attacks helper T-lymphocytes and macrophages, reducing their number and weakening the immune system.
Q.12) Differentiate between normal and cancerous cells.
Ans: Normal cells show contact inhibition and controlled growth, while cancerous cells lack contact inhibition and divide uncontrollably.
Q.13) What is metastasis?
Ans: Metastasis is the spread of cancer cells from the primary site to distant parts of the body through blood or lymph.
Q.14) List harmful effects of alcohol and drug abuse.
Ans: Alcohol and drugs affect individuals, families and society by causing health problems, violence, reduced productivity and increased risk of infections.
Q.15) Can friends influence alcohol or drug intake? How can one avoid it?
Ans: Yes, peer pressure plays a role. Avoid such company, build self-control, seek family support and engage in healthy activities.
Q.16) Why is it difficult to quit alcohol or drugs once addicted?
Ans: Repeated intake increases tolerance levels, making the body dependent on higher doses, leading to addiction.
Q.17) What motivates youngsters to take drugs and how can it be prevented?
Ans: Curiosity, peer pressure and media influence motivate youngsters. Awareness, counselling, parental support and healthy lifestyle choices can prevent abuse.