Class 12 Biology Chapter 8 Human Health and Disease

Chapter 8

 Human Health and Disease 



Q1. What are the various public health measures, which you would suggest as safeguard against infectious diseases?

Answer: The various public measures are-
  • Maintainance of personal and public hygiene
  • Isolation
  • Vaccination
  • Vector Eradication.

    

 Q2.  In which way has the study of biology helped us to control infectious diseases?

Answer: The study of biology has helped us to control infectious diseases –
  • Give information to fight against infectious diseases.
  • Measures to control the transmission of various diseases.
  • To know the life cycle of various parasites and pathogens.
  • Help to eradicate diseases by various vaccine and drugs.



Q3.  How does the transmission of each of the following diseases take place?

a) Amoebiasis
Answer:  Causative Organism- Entamoeba histolytica

Mode of transmission- by means of contaminated water and food.


b) Malaria
Answer: Causative Organism- Plasmodium sp.

Mode of transmission- by bite of Female anopheles mosquito.


c) Ascariasis
Answer: Causative organism- Ascaris lumbricoides

Mode of transmission- By contaminated food and water


d) Pneumonia
Answer: Causative organism- Streptococcus pneumonia

Mode of transmission- By sputum of infected person





Q4. What measure would you take to prevent water-borne diseases?
Answer: The measures taken to prevent water borne diseases are-
  • Proper disposal of sewage
  • Periodic cleaning
  • Drinking water should be boiled

Q5. Discuss with your teacher what does ‘a suitable gene’ means, in the context of DNA vaccines.
Answer:  A suitable gene means a particular DNA fragment can be introduced into the host’s cell in order to produce particular proteins. This protein destroys the specific-disease causing organism present in the host body and gives immunity.


Q6. Name the primary and secondary lymphoid organs.
Answer: Bone marrow and thymus are the primary lymphoid organs whereas spleen, tonsils, lymph nodes, appendix and Peter’s patches of small intestine.


Q7. The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form:


a) MALT
Answer: Mucosa Associated Lymphoid Tissue

b) CMI
Answer: Cell mediated immunity

c) AIDS
Answer: Acquired Immuno Deficiency Syndrome

d)NACO
Answer: National AIDS Control Organization

e) HIV
Answer: Human Immuno Deficiency



Q8. Differentiate the following and give examples of each:

a) Innate and acquired immunity
AnswerInnate Immunity
  • It is present in an individual from the time of birth.
  • It is non-specific kind of defense mechanism
  • It is accomplished by applying different barriers helps in preventing the entry of pathogens into our body.
  • It is not characterized by memory.

Acquired immunity
  • It is acquired when pathogen encounters for the first time produces a primary response.
  • It is pathogen specific kind of defense mechanism.
  • It is accomplished by producing primary and secondary responses.
  • It is characterized by memory.



b) Active and Passive immunity
Ans: Active immunity
  • In active immunity, body generates its own antibodies against antigens.
  • It is slow and takes time to give its full  effective response
  • Injecting the microbes by immunization is an example of active immunity.

Passive immunity
  • In passive immunity, ready-made antibodies are directly injected to protect the body against foreign antigens.
  • It is fast and gives immediate response.
  • The foetus gets some antibodies from their mother through placenta during pregnancy.



Q9. Draw a well-labelled diagram of an antibody molecule.

 

Q10. What are the various routes by which transmission of human immunodeficiency virus takes place?

Answer: The various routes by which transmission of human immunodeficiency virus takes place are-
  • Sexual contact with infected person
  • Transfusion of contaminated blood and blood products
  • By sharing infected needles during injection of drugs.
  • Child born to an HIV infected mother



Q11. What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?

Answer. The causative agent of AIDS is Human Immuno Deficiency virus which is a retrovirus having RNA as a genome.  After getting into the human body, the HIV virus enters and attacks the macrophages where it replicates its viral genome to create viral DNA by an enzyme reverse transcriptase. The viral DNA integrates with the host DNA and synthesizes virus particles. At the same time, HIV getting into the helper T-lymphocytes, replicates and generates virus progenies. The newly formed virus progenies released into the blood, invading other healthy helper T-lymphocytes present in the body. Due to decrease in the amount of Helper T-lymphocytes, the person begins to suffering from infectious disease.



Q12. How is a cancerous cell different from normal cell?

Answer Normal cell
  • Normal cell shows the contact inhibition property.
  • The growth and differentiation of the normal cell is controlled.
  • At a particular location, cells remain confined.

Cancerous cell
  • Cancerous cell does not show contact inhibition property.
  • These cells grow quickly, invading the surrounding normal cells.
  • At a particular location, cells do not remain confined.



Q13. Explain what is meant by metastasis.

Answer: The cells of malignant tumor grow rapidly and attacking the surrounding normal cells. The cells of such tumors sloughed off and gets into the bloodstream. Through blood, these cells reach distant sites where they starts new tumor. This property is known as metastasis.



Q14. List the harmful effects caused by alcohol/ drug abuse.

Answer: 

The harmful effects of alcohol are-
  • Excessive use of alcohol can cause damages to the liver and the nervous system.
  • It also affects academic performance due to unexplained absence in college or school.
  • Lack of concern  in personal hygiene
  • Depression, withdrawal, isolation, fatigue, aggressive
  • Worse relationship with family and friends
  • Changes in sleeping and eating habits

The harmful effects of drug
  • Overdoses of drugs lead to coma  and death due to cerebral hemorrhage, and respiratory failure
  • Transmission of HIV due to the sharing of same needles while injecting.
  • Frustrated, violence and reckless behavior



Q15. 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:  list some points by discussing with your friends, relatives and teachers.



Q16. 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:  The repeated use of drugs or alcohol increases the tolerance level of the body’s receptors which lead to greater intake and addiction.



Q17. In your view what motivates youngsters to take to alcohol or drugs and how can this is avoided?

Answer:  Curiosity or in the need of excitement, experimentation and adventures motivate the youngsters towards the use of alcohol and drugs. Some youngsters consume alcohol to overcome pressure, frustration and depression. Television, movies, newspaper, is responsible for this perception. Other reasons such as unstable or unsupportive family structure and peer pressure are responsible for the consumption of alcohol and drugs.

Prevention
  • Avoid undue peer pressure
  • Educating and counseling his/ her to face problems and stress.
  • Seeking help from parents and peers
  • Parents need to identify the danger sign of their children



 Dipshikha Das





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