'Prevention is better than cure'. Comment.
Prevention is always better than cures because some diseases cause extensive damage to the body tissues or organs and have a
(i) Negative effect on their capacity to function.
(ii) Permanent or long term debilitating effect.
(iii) Negative mental and psychological effect.
(iv) Financial burden.
Prevention, therefore is easier and effective, than cure of a disease.
Explain any three preventive measures to control microbial infections.
Preventive measures to control microbial infection include
(i) Maintenance of personal and public hygiene by
(a) Proper cleanliness standards and practices.
(b) Proper disposal of waste.
(c) Periodic cleaning of water reservoirs, etc.
(ii) Control or elimination of vectors that transmit diseases by
(a) Checking water stagnation and garbage accumulation.
(b) Using disinfectants or biological methods to check their breeding and spread.
(iii) Proper immunisation by vaccination, wherever available to control or completely eradicate infectious diseases.
In the given flow diagram, the replication of retro virus in a host is shown. Observe and answer the following questions.
(a) Fill in (A) and (B)
(b) Why is the virus called retrovirus?
(c) Can the infected cell survive, while viruses are being replicated and released?
(b) The virus is called retro virus because it does not follow the central dogma of biology (DNA $\rightarrow$ RNA $\rightarrow$ Proteins).
Its genetic material is RNA that is transcribed to DNA using enzyme reverse transcriptase.
(c) Yes, the infected cell can survive, while viruses are being replicated and released.
'Maintenance of personal and public hygiene is necessary for prevention and control of many infectious diseaes. Justify the statement giving suitable examples.
Diseases which are easily transmitted from one person to another, are called infectious diseases.
For prevention and control of such diseases, maintenance of personal and public hygiene is necessary, for this purpose, some common preventive measurer should be taken as follows
(i) Education People should be educated about communicable disease to protect themselves from such diseases.
(ii) Isolation The infected person should be kept isolated to minimise the spread of infection.
(iii) Vaccination People should get vaccination on time to avoid infection.
(iv) Sanitation The sanitation should be improved to avoid infection from polluted water, contaminated food, etc.
(v) Eradication of Vectors The breeding places of vectors must be destroyed and adult vectors should be killed by suitable methods.
(vi) Sterilisation The patient's surroundings and articles of use should be completely sterilised to reduce the chances of infection.
The following table shows certain diseases, their causative organisms and symptoms. Fill the gaps.
| Diseases | Causative organisms | Symptoms |
|---|---|---|
| Ascariasis | Ascaris | __ |
| __ | Trichophyton | Appearance of dry, scaly lesions on various parts of the body |
| Typhoid | __ | High fever, weakness, headache, stomach pain and constipation. |
| Pneumonia | Streptococcus | __ |
| __ | Rhino | Nasal congestion and discharge, sorethroat, cough headache |
| Filariasis | __ | Inflammation in lower limbs |
| Diseases | Causative organisms | Symptoms |
|---|---|---|
| Bacterial Typhoid |
Salmonella typhi | High fever, weakness, stomach pain, constipation, headache and loss of appetite. Intestinal perforation and death may occur in severe cases. |
| Pneumonia | Streptococcus pneumoniae and Haemophilus influenzae | Fever, chills, cough and headache. In severe cases, the lips and finger nails may turn gray to bluish in colour. |
| Viral Common cold |
Rhino viruses | Nasal congestion and discharge, sore throat, hoarseness, cough, headache tiredness. |
| Worms Ascariasis |
Ascaris lumbricoides | Internal bleeding, muscular pain, fever, anaemia and blockage of the intestinal passage. |
| Filariasis | Wuchereria (W. bancrofti and W. malayi) | Chronic inflammation and deformation of the organs and genital organs. |
| Ring worms | Microsporum, Trichophyton and Epidermophyton | Appearance of dry, scaly lesions on various parts of the body such as skin, nails and scalp. |
| Parasitic Malaria |
Plasmodium (P. vivax, P. malariae and $P$. falciparum) | High fever, chills, sweating, fatigue, weakness, loss of appetite. |
| Amoebiasis | Entamoeba histolytica | Constipation, abdominal pain and cramps, stools with excess mucous and blood clots. |