Hygiene: A Key to Healthy Life — ICSE Class 9 Biology Important Questions

Answer: (b) Personal hygiene.

Washing one's own hands to keep the body clean and free of germs is a personal-hygiene habit, and it prevents germs from entering the body with food.

Answer: (b) Cholera.

Cholera (like typhoid and dysentery) is a water-borne disease that spreads through drinking water contaminated with the pathogen; safe water and sanitation prevent it.

Answer: (b) Carries germs from filth to food.

Houseflies sit on garbage and faeces and then on our food, mechanically transferring disease-causing germs; this is why food must be covered.

Answer: (b) Providing a supply of safe, disinfected drinking water.

Typhoid is a water-borne disease. Since it spreads through contaminated water, providing clean, disinfected drinking water (and proper sewage disposal) is the most effective preventive measure.

Answer: (a) Covering food keeps flies away, and because flies carry germs onto exposed food, this is exactly the reason food must be covered, so R correctly explains A.

(i) Health: A state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity.

(ii) Hygiene: The science and practice of keeping oneself and one's surroundings clean so as to preserve health and prevent the spread of disease.

Personal hygiene: cleanliness practices carried out by an individual to keep his or her own body healthy. Example: brushing teeth twice a day / bathing daily.

Public (community) hygiene: measures taken by the community or authorities to keep the surroundings clean and healthy for everyone. Example: proper disposal of sewage and supply of safe drinking water.

Healthy teeth are needed to bite and chew food properly for digestion, and to keep the mouth free of infection. If food remains between the teeth, bacteria act on it, producing acids that cause tooth decay (dental caries) and gum disease, and bad breath.

Three ways to keep teeth healthy: (i) brush the teeth at least twice a day, especially after meals and before sleeping; (ii) rinse the mouth after eating and avoid too many sugary or sticky foods; (iii) eat a balanced diet with enough calcium and vitamins, and have regular dental check-ups.

(i) Bathing daily: removes sweat, dirt, oil and germs from the skin, preventing body odour and skin infections.

(ii) Washing hands with soap before meals and after using the toilet: removes germs from the hands and prevents them from entering the body with food, checking diseases like diarrhoea.

(iii) Brushing teeth twice a day and trimming nails: removes food particles and germs from the mouth and from under the nails, preventing tooth decay and the entry of germs into the body.

(Other correct habits include wearing clean clothes, cleaning the hair, and taking regular exercise, rest and balanced food.)

(i) Uncovered drains: carry sewage and breed germs and flies, which contaminate food and spread water-borne and food-borne diseases. Remedy: keep drains covered and provide a proper closed drainage/sewage system.

(ii) Garbage heaps: rotting refuse attracts flies and rats and gives off harmful gases and germs, spreading diseases and foul smell. Remedy: collect waste in covered bins and dispose of it regularly (burning, burying or composting).

(iii) Stagnant water: is the breeding ground of mosquitoes, which spread malaria and dengue. Remedy: drain or fill stagnant water and spray it with oil/larvicide to kill mosquito larvae.

Importance: However clean an individual keeps himself, he cannot stay healthy in dirty, unhealthy surroundings. Public hygiene keeps the whole community's surroundings clean, prevents the breeding and spread of disease-causing organisms, and protects everyone from epidemics. It is a shared responsibility of the people and the local authorities.

Four measures of community hygiene:
(i) Safe drinking water: supplying clean, filtered and disinfected (chlorinated) water prevents water-borne diseases like cholera and typhoid.
(ii) Proper disposal of waste and sewage: collecting and treating refuse and sewage through covered drains prevents contamination of water and soil and stops flies breeding.
(iii) Control of insects and pests: draining stagnant water, spraying, and clearing garbage controls mosquitoes, flies and rats that spread malaria, dengue and other diseases.
(iv) Clean public places and pollution control: keeping streets, markets and parks clean and checking air, water and noise pollution keeps the environment healthy.

Together these measures reduce the incidence of communicable disease and raise the general standard of health of the community.

Communicable (infectious) diseases are caused by pathogens that pass from an infected person or source to a healthy person. They spread in the following ways:

(i) Through air (droplet infection): germs released in coughs and sneezes are breathed in by others. Example: common cold, tuberculosis, influenza. Prevention: cover the mouth and nose while coughing/sneezing, avoid crowded, poorly ventilated places.

(ii) Through water and food: drinking contaminated water or eating food handled with dirty hands or settled on by flies. Example: cholera, typhoid, dysentery. Prevention: drink safe/boiled water, wash hands, keep food covered.

(iii) Through contact: touching an infected person or their articles (towels, combs, clothes). Example: ringworm, scabies, conjunctivitis. Prevention: keep the body and clothes clean, do not share personal articles.

(iv) Through vectors (carriers): insects such as mosquitoes and houseflies carry germs. Example: malaria and dengue (mosquito), typhoid (housefly). Prevention: destroy breeding places of mosquitoes and flies, use nets and dispose of waste properly.

How hygiene helps: Personal hygiene (clean hands, body and food) and public hygiene (safe water, sanitation, pest control) break these routes of transmission, so the pathogens cannot reach a healthy person and the disease does not spread.

(i) Diarrhoea - spread through water and food (water/food-borne). Malaria - spread through a vector (mosquito). Ringworm - spread through contact (sharing articles).

(ii) Children should wash their hands with soap before eating and after using the toilet (and drink only safe/boiled water) to reduce diarrhoea.

(iii) Drain or remove stagnant water around the school (and spray to kill mosquito larvae) so that mosquitoes cannot breed, reducing malaria.

(iv) Sharing towels and combs can transfer germs and fungi from an infected person to a healthy one, spreading contact diseases such as ringworm and lice; using one's own clean articles prevents this.