7. Human Health and Disease

Class 12 Biology Chapter 7 Human Health and Disease

Chapter 7: Human Health and Disease

Class 12 Biology Chapter 7: Human Health and Disease Exercise Question and Answers :

1. What are the various public health measures, which you would suggest as safeguard against infectious diseases?

Answer : The various public health measures to safeguard against infectious diseases are :

Vaccination : Encourage widespread vaccination to achieve herd immunity and prevent outbreaks of vaccine-preventable diseases.

Vector Eradication : Implement measures to control disease vectors such as mosquitoes and ticks to reduce the transmission of diseases like malaria, dengue, and Lyme disease.

Isolation and Quarantine : Isolate infected individuals to prevent further transmission, and quarantine those exposed to infectious agents to monitor for symptoms.

Maintaining Public and Personal Hygiene : Promote regular handwashing with soap and water, proper respiratory hygiene (covering mouth and nose when coughing or sneezing), and the use of hand sanitizers.

Public Health Education : Disseminate clear and consistent public health messaging to educate the public about preventive measures, symptoms, and the importance of vaccination.

Research and Development : Invest in research and development for vaccines, treatments, and diagnostics to respond effectively to emerging infectious diseases.

2. In which way has the study of biology helped us to control infectious diseases?

Answer : The study of biology has advanced our ability to control infectious diseases significantly. Vaccines and immunization programs, informed by biology, led to the complete eradication of smallpox and the control of diseases like polio, diphtheria, pneumonia, and tetanus. Biotechnology is on the cusp of providing safer, more effective vaccines. Furthermore, the discovery of antibiotics and other drugs has revolutionized the treatment of infectious diseases, saving countless lives. These biological advancements have been instrumental in preventing, managing, and sometimes even eliminating infectious diseases.

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

(a) Amoebiasis (b) Malaria (c) Ascariasis (d) Pneumonia

Answer: The transmission of each of the following mentioned diseases :

Disease	Transmission Route	Mode of Transmission	High-Risk Areas
Amoebiasis	Fecal-oral route	Ingestion of contaminated food or water with cysts	Areas with poor sanitation and limited clean water
Malaria	Vector-borne (through mosquitoes)	Bite of infected female Anopheles mosquitoes	Tropical and subtropical regions
Ascariasis	Fecal-oral route	Ingestion of Ascaris lumbricoides eggs	Areas with poor sanitation and hygiene practices
Pneumonia	Respiratory droplets, direct contact, etc.	Dependent on the specific pathogen causing it	Crowded settings, immunocompromised individuals

4. What measure would you take to prevent water-borne diseases?

Answer : To prevent water-borne diseases:

(i) Ensure clean water sources.

(ii) Purify water.

(iii) Promote good hygiene.

(iv) Educate communities.

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 a pathogen (like a virus or bacterium) that, when inserted into a DNA vaccine, can stimulate an immune response. This gene should code for a critical part of the pathogen, ensuring an effective immune reaction and memory for future protection against the pathogen.

6. Name the primary and secondary lymphoid organs.

Answer : The primary and secondary lymphoid organs are :

Primary Lymphoid Organs

Secondary Lymphoid Organs

(i) Bone Marrow

(ii) Thymus

(i) Lymph Nodes

(ii) Spleen

(iii) Tonsils

(iv) appendix

(v) Peyer’s patches of small intestine

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

(a) MALT (b) CMI (c) AIDS (d) NACO (e) HIV

Answer : The expanded forms of the abbreviations are :

Abbreviation	Expanded Form
(a) MALT	Mucosa-Associated Lymphoid Tissue
(b) CMI	Cell-Mediated Immunity
(c) AIDS	Acquired Immuno Deficiency Syndrome
(d) NACO	National AIDS Control Organization
(e) HIV	Human Immunodeficiency Virus

8. Differentiate the following and give examples of each:

(a) Innate and acquired immunity (b) Active and passive immunity

Answer : (a) The differentiation between Innate and Acquired Immunity are :

Concept	Innate Immunity	Acquired Immunity
Present at Birth	Yes	No
Specificity	Non-specific in nature	Specific in nature
Response Time	Immediate	Delayed (develops over time)
Memory	No memory; no lasting immunity	Develops memory; provides lasting immunity
Examples	Skin, mucous membranes, phagocytes	Antibodies, memory T and B cells
Activation	Always present; doesn't require prior exposure to pathogen	Develops after exposure to specific pathogens or through vaccination

(b)The differentiation between Active and Passive Immunity are :

Concept	Active Immunity	Passive Immunity
Source	Developed by the body's immune response	Acquired from an external source (ready-made antibodies)
Onset	Slow; takes time to develop	Immediate; no waiting period for protection
Duration	Provides long-lasting protection	Offers temporary protection
Examples	Immunity after natural infection or vaccination	Maternal antibodies through breastfeeding, antibodies through medical treatment

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

Answer : The diagram of an antibody molecule :

10. What are the various routes by which transmission of human immuno-deficiency virus takes place?

Answer: HIV infection is typically transmitted through:

(a) Sexual contact with an infected person,

(b) The transfusion of contaminated blood and blood products,

(d) From an infected mother to her child through the placenta.

11. What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?

Answer : The AIDS virus, or HIV (Human Immunodeficiency Virus), causes immune system deficiency through a complex process. After entering the body, HIV infects macrophages and helper T-lymphocytes (TH cells). In macrophages, it replicates and acts as a virus factory. Simultaneously, HIV infects TH cells and produces progeny viruses, which attack other TH cells. This cycle continues, progressively reducing the number of TH cells. As TH cell numbers decline, the immune system weakens, making the infected person susceptible to infections that their body can't overcome. Ultimately, this immune deficiency, characterized by a loss of TH cells, leads to AIDS.

12. How is a cancerous cell different from a normal cell ?

Answer : The cancerous cell different from a normal cell are :

Characteristic	Normal Cells	Cancerous Cells
Growth Regulation	Highly controlled and regulated	Breakdown of regulatory mechanisms
Contact Inhibition	Exhibit contact inhibition, preventing uncontrolled growth	Lack of contact inhibition, leading to uncontrolled cell division
Tumor Types	Benign tumors remain localized and less damaging	Malignant tumors grow rapidly, invade nearby tissues, and cause significant damage
Metastasis	Rarely metastasize	Have the potential to metastasize, forming new tumors in distant locations

13. Explain what is meant by metastasis.

Answer : Metastasis is when cancer cells break away from the original tumor, travel through the bloodstream or lymphatic system, and form new tumors in different parts of the body. It's like cancer spreading to other areas, making it more challenging to treat. Metastasis is a critical aspect of cancer progression, often leading to more severe health issues because cancer cells can affect multiple organs and tissues.

14. List the harmful effects caused by alcohol/drug abuse.

Answer : Harmful Effects of Alcohol Abuse:

(i) Long-term effects in adolescence, potentially leading to heavy drinking in adulthood.

(ii) Damage to the nervous system.

(iii) Liver damage, including the risk of cirrhosis.

(iv) Adverse effects during pregnancy, negatively affecting the fetus.

Harmful Effects of Drug Abuse:

(i) Misuse of narcotic analgesics, anabolic steroids, diuretics, and hormones in sports.

(ii) Side-effects of anabolic steroid use, including masculinization, mood swings, and depression in females.

(iii) Side-effects of anabolic steroid use in males, such as acne, reduced testicle size, kidney and liver dysfunction, and breast enlargement.

(iv )Potential for permanent effects like stunted growth and premature closure of growth centers in adolescents.

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 an individual to take alcohol or drugs. Peer pressure and social influence play significant roles in a person's decision-making, especially during adolescence and young adulthood.

To protect oneself from such influences, one can take the following steps:

(i) Avoid undue peer pressure: Every child has their own choices and personality, which should be respected and nurtured.

(ii) Education and counseling: Educate and counsel them to face problems and stresses, as well as to accept disappointments and failures as a part of life.

(iii) Seek help from parents and peers: Seek help from parents and peers immediately so that they can provide appropriate guidance.

(iv) Look for danger signs: Alert parents and teachers need to identify danger signs through discussion.

(v) Seek professional and medical help: There is a lot of assistance available in the form of highly qualified psychologists, psychiatrists, and de-addiction and rehabilitation programs to help individuals who have unfortunately become involved in drug/alcohol abuse.

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 quit due to addiction. These substances can change the brain's chemistry, creating a strong craving. Over time, the body may need more to achieve the same effect, leading to dependency. Quitting can cause withdrawal symptoms, making it hard to stop. Additionally, social and peer pressure may encourage continued use. Getting rid of the habit often requires support, treatment, and determination to overcome the physical and psychological hold these substances have on a person.

17. In your view what motivates youngsters to take to alcohol or drugs and how can this be avoided?

Answer : Youngsters may be motivated to take alcohol or drugs for various reasons are :

(i) Influence from friends or social groups who engage in substance use.

(ii) A desire to experiment and experience the effects of alcohol or drugs.

(iii) Using substances as a way to cope with stress, anxiety, or emotional problems.

(iv) Growing up in an environment where substance abuse is normalized or accepted.

(v) Exposure to media and pop culture that glamorize substance use.

(vi) Insufficient knowledge about the risks and consequences of alcohol and drug abuse.

To prevent youngsters from taking to alcohol or drugs, several strategies can be employed :

(i) Provide comprehensive education on the risks and consequences of substance abuse from an early age.

(ii) Encourage open and non-judgmental communication between parents, caregivers, and young individuals to address their concerns and questions.

(iii) Promote positive role models and encourage healthy behavior among peers.

(iv) Teach effective stress management techniques and coping skills to deal with life's challenges.

(v) Establish support systems within schools and communities to help young individuals resist peer pressure and find healthier alternatives.

(vi) Ensure access to counseling and mental health services for those who may be struggling with emotional or psychological issues.

(vii) Enforce age restrictions and laws related to the sale and consumption of alcohol and drugs.

(viii) Encourage involvement in sports, hobbies, arts, and other constructive activities that provide a sense of fulfillment and belonging.