Hygiene

A fundamental aspect of biology, hygiene refers to the practices and conditions that help maintain health and prevent the spread of diseases. This concept is broadly divided into personal and public hygiene. Personal hygiene involves individual habits such as regular bathing, oral care, and keeping clothes clean, which directly remove germs from our bodies and prevent them from causing infections. It also extends to the careful washing of fruits and vegetables and the consumption of clean, potable water. When individuals neglect these practices, they not only risk their own health but also become carriers of pathogens, contributing to the wider spread of illness within their community.

Public hygiene encompasses the collective measures a society takes to ensure a clean and safe environment for everyone. This includes the proper management of sewage and waste through scientific drainage systems and garbage disposal to prevent soil and water contamination. A critical component is the control of disease-carrying vectors like mosquitoes and houseflies by eliminating their breeding grounds, such as stagnant water and uncovered garbage. Public health authorities also ensure the safety of food and water supplies, implementing chlorination of drinking water and regular inspections of food establishments to safeguard the population from large-scale outbreaks.

Ultimately, the chapter emphasizes that personal and public hygiene are deeply interconnected. Good personal habits reduce the burden on public health systems, while robust public sanitation creates an environment where individuals can more easily maintain their health. This synergy is vital for breaking the chain of infection, which requires a pathogen, a source, a mode of transmission, and a susceptible host. By maintaining high standards of hygiene at both levels, we effectively disrupt this chain, leading to the prevention of communicable diseases and the promotion of overall community well-being, which is the ultimate goal of this biological science.

Multiple choice type

Question 1. 

No urination due to shortage of water in the body is a typical symptom of

1. typhoid
2. malaria
3. dysentery
4. Cholera

Question 2. 

Which one of the following is an unhealthy habit?  

1. Removing wax from inside the ears  
2. Keeping the mouth closed while breathing  
3. Sleeping for only 6-7 hours  
4. Sharing towels with others

Question 3. 

The protozoan that causes malaria is: 

1. Entamoeba histolytica 
2. Euglena 
3. Paramecium 
4. Plasmodium 

Question 4. 

The chemical substance mainly responsible for tooth disorders is 

1. Calcium
2. Chloride 
3. Fluorides 
4. Iodides 

Question 5. 

Typhoid is caused by 

1. Housefly 
2. Bacteria 
3. Virus 
4. None of the above

Question 6. 

The germ causing Hepatitis is transmitted through

1. the bite of a mosquito
2. contamination of food by a housefly
3. personal contact with a patient
4. contaminated water

Very short answer type

Question 1. 

Match Column I with that Which is Most Appropriate in Column II.

Column I	Column II
(a) Mosquito	(i) DDT
(b) Plasmodium	(ii) Dengue
(c) Entamoeba histolytica	(iii) Vector
(d) Aedes mosquito	(iv) Malaria
(e) Insecticide	(v) Dysentery

Ans:

Column I	Column II	Match
(a) Mosquito	(iii) Vector	(a) – (iii)
(b) Plasmodium	(iv) Malaria	(b) – (iv)
(c) Entamoeba histolytica	(v) Dysentery	(c) – (v)
(d) Aedes mosquito	(ii) Dengue	(d) – (ii)
(e) Insecticide	(i) DDT	(e) – (i)

Question 2. 

1.Name the following: Organisms that transmit microbes that cause disease.

2. Name the following:Organisms that cause disease.

3. Name the following: Science of maintaining good health.

Ans:

Here are the names for the given descriptions:

1. Organisms that transmit microbes that cause disease: Vectors
2. Organisms that cause disease: Pathogens
3. Science of maintaining good health: Hygiene (or Public Health)

Question 3. 

Describe the different ways by which the housefly contaminates our food.

Ans:

Houseflies contaminate our food through several highly efficient and unsanitary methods, primarily acting as mechanical vectors that physically transfer pathogens from filthy environments to our meals.

Here are the main ways houseflies contaminate food:

1. External Transfer (Legs and Body Hairs) 

A housefly’s body, legs, and feet are covered in numerous fine hairs and sticky footpads.

• Filth to Food: Flies commonly land on and feed from decomposing matter, sewage, garbage, and animal/human feces. Pathogens (bacteria, viruses, and parasitic worm eggs) from these sources adhere directly to the external parts of the fly’s body.
• Contamination by Contact: When the fly subsequently lands on clean food, a utensil, or a kitchen surface, these microbes are easily scraped or rubbed off, directly contaminating the food through simple contact.

2. Regurgitation (Vomiting) 

Houseflies can only ingest food in liquid form. To feed on solid food (like sugar, cake, or meat), they must first liquefy it:

• “Fly Vomit”: The fly regurgitates (vomits) a liquid mixture of saliva and digestive juices from its crop (a pouch in the digestive tract) onto the solid food.
• Internal Contamination: This liquid helps dissolve the solid food, allowing the fly to sponge it up. Any pathogens carried internally within the fly’s digestive system (which can harbor microbes for days) are deposited directly onto the food in this regurgitated fluid.

3. Defecation (Fly Specks) 

While feeding on a surface, a fly will frequently defecate:

• Fecal Droplets: These small, dark spots, often called “fly specks,” are the fly’s excreted wastes.
• Pathogen Source: Since the fly’s diet is often highly contaminated, these fecal droplets contain concentrated pathogens (including Salmonella and E. coli) that are directly deposited onto the food or preparation surface.

Question 4. 

Suggest any two methods of controlling flies.

Ans:

Flies are pests that spread disease, making their control vital. Two highly effective and distinct methods for controlling fly populations are:

1. Sanitation and Source Elimination 

This is the most fundamental and effective long-term method, focusing on breaking the fly’s life cycle by destroying its breeding sites.

• Remove Decaying Matter: Flies, particularly house flies, breed in wet, decaying organic matter (e.g., animal waste, pet feces, rotting food, and garbage).
• Proper Waste Management: Regularly remove all organic waste and ensure all garbage cans and dumpsters have tight-fitting lids. Cleaning garbage containers frequently prevents material from accumulating and becoming a breeding ground. Eliminating standing water and excessive moisture is also key.

2. Exclusion and Trapping

These methods focus on physically preventing flies from accessing an area or capturing the adult insects.

• Exclusion: Use tight-fitting screens on all windows and doors to create a physical barrier. Keep doors closed, especially during warmer months. Air curtains or fans near doorways can also discourage entry.
• Trapping: Utilize various traps to reduce the adult population:
  • Sticky Traps/Ribbons: These are adhesive surfaces that flies land on and become entangled in.
  • Light Traps: Devices that use UV light to attract flies, either zapping them or trapping them on a glue board.

Question 5. 

List any three effective methods for controlling mosquitoes.

Ans:

Controlling mosquitoes requires an integrated approach that targets different stages of their life cycle. Here are three effective methods:

1. Source Reduction (Elimination of Breeding Sites) :
   • This is the most critical and permanent method, as all mosquitoes require standing water to lay eggs and for their larval and pupal stages.
   • The goal is to empty, cover, or remove any containers that can hold water around homes, such as old tires, buckets, flowerpot saucers, and clogged gutters.
   • For larger, unavoidable bodies of water (like fish ponds or large storage containers), covering them tightly or treating them with larvicides is necessary.
2. Larval Control (Larviciding or Biological Control) :
   • This method targets mosquitoes when they are concentrated and immobile in the water before they emerge as flying adults.
   • Chemical Larvicides: Applying compounds (like Bti, a specific bacterium) to standing water to kill the larvae.
   • Biological Control: Introducing natural predators, such as Gambusia affinis (mosquitofish), into ponds or reservoirs where they feed on the mosquito larvae and pupae.
3. Protection and Barriers (Exclusion and Repellents) :
   • These methods focus on preventing mosquitoes from biting humans.
   • Exclusion: Installing and maintaining tight-fitting screens on all windows and doors to prevent adult mosquitoes from entering homes.
   • Repellents: Using skin repellents (containing DEET or Picaridin) or insecticide-treated bed nets, especially in high-risk areas, to deter biting.

Question 6. 

Name the two common kinds of mosquitoes and the diseases they transmit.

Ans:

Here are two common kinds of mosquitoes and the diseases they are known to transmit:

1. Anopheles Mosquito
   • Disease Transmitted: Malaria
2. Aedes Mosquito
   • Diseases Transmitted: Dengue Fever, Chikungunya, and Zika Virus (it can transmit all three).

Question 7. 

Mention any three ways by which potable water can be contaminated.

Ans:

Potable (safe drinking) water can be contaminated in several ways, often leading to the spread of waterborne diseases. Here are three primary methods of contamination:

1. Improper Sewage and Waste Disposal (Fecal Contamination):
   • This is the most common cause of contamination. If human or animal sewage is not properly treated and disposed of, pathogens (like bacteria, viruses, and parasites) can leach into groundwater sources, reservoirs, or rivers used for drinking water.
   • This includes seepage from septic systems, sewer line leaks, or direct discharge of untreated wastewater.
2. Industrial Discharge and Chemical Leaching:
   • Industrial facilities may illegally or accidentally discharge toxic chemicals, heavy metals (e.g., lead, mercury), or solvents directly into water bodies.
   • Agricultural runoff containing pesticides and herbicides can also contaminate surface water and shallow groundwater.
3. Faulty or Aging Plumbing Infrastructure:
   • Within the distribution system, water can become contaminated if aging pipes crack or leak, allowing untreated groundwater, soil, or contaminants from nearby sewage lines to seep into the potable water supply, especially during periods of low water pressure.
   • Contamination can also occur from leaching if the pipes themselves are made of harmful materials, such as old lead plumbing.

Long answer type

Question 1. 

1.Give suitable explanations for the following : One should breathe by nose and never by mouth. 

2. Give suitable explanations for the following : Hands must be washed before eating food.

3. Give suitable explanations for the following : Eating places must be kept free of flies.

Ans:

Here are suitable explanations for each of the given statements:

1. Breathe by Nose, Never by Mouth 

Breathing through the nose is highly recommended over mouth breathing because the nasal passage performs three crucial functions that protect the lower respiratory tract:

• Filtration: Coarse hairs in the nostrils and a lining of mucus and cilia trap dust particles, pollen, and large pathogens, preventing them from entering the lungs.
• Warming: The extensive network of capillaries in the nasal lining warms the inhaled air, bringing it up to body temperature before it reaches the sensitive lung tissue.
• Moistening: The mucus and moist lining of the nose add moisture to the dry inhaled air, preventing the delicate respiratory lining in the lungs from drying out.

The mouth lacks these protective mechanisms, allowing cold, dry, and unfiltered air to enter the lungs directly.

2. Hands Must Be Washed Before Eating Food 

Washing hands before eating is the most effective way to prevent the transmission of infectious diseases via the fecal-oral route.

• Removal of Pathogens: Hands frequently come into contact with contaminated surfaces (e.g., door handles, money, keyboards) or feces (after using the restroom). These surfaces can harbor invisible pathogens (bacteria, viruses, and parasites) that cause illnesses like diarrhea, cholera, and hepatitis A.
• Preventing Ingestion: By washing hands with soap and water, these microbes are physically removed, preventing their transfer directly from the fingers to the food, and subsequently into the mouth and digestive system.

3. Eating Places Must Be Kept Free of Flies 

Eating places must be kept free of flies because houseflies are significant mechanical vectors that contaminate food with disease-causing pathogens.

• Physical Transfer: Flies land on filth (garbage, decaying matter, feces) and pick up millions of microbes on their hairy legs, sticky footpads, and bodies.
• Food Contamination: When a fly lands on food or utensils, it instantly deposits these microbes. Furthermore, flies often regurgitate (vomit) digestive juices onto solid food to liquefy it, directly injecting internal pathogens onto the food surface.

Question 2. 

How are cockroaches and rats harmful to humans?

Ans:

Cockroaches and rats are significant public health pests that cause harm through the spread of disease, contamination, and triggering allergic reactions.

Harm Caused by Cockroaches

Cockroaches pose harm primarily through mechanical transmission of pathogens and airborne allergens:

• Disease Transmission: Cockroaches frequently crawl through unsanitary environments (sewers, drains, garbage) and pick up pathogens on their bodies, legs, and mouths. They then mechanically transfer these germs to food, dishes, and surfaces. Diseases they can spread include:
  • Salmonellosis (food poisoning)
  • Typhoid Fever
  • Cholera
  • Dysentery
  • Various Gastroenteritis infections
• Allergies and Asthma: The shed skin, droppings, and saliva of cockroaches contain potent allergens. When these particles become airborne, they can trigger allergic reactions and significantly worsen asthma attacks, particularly in children.
• Food Contamination: They feed on and spoil human food, leaving behind droppings and vomit, making the food unsafe for consumption.

Harm Caused by Rats

Rats (rodents) are vectors for some of the most serious diseases and cause significant structural damage:

• Disease Transmission: Rats carry numerous pathogens and often host other vectors, like fleas, which transmit diseases to humans. Diseases associated with rats include:
  • Plague: Transmitted by infected fleas carried by rats.
  • Leptospirosis: Spread through contact with water or soil contaminated by infected rat urine.
  • Hantavirus: Spread via inhalation of dust contaminated with rat droppings, urine, or nesting materials.
  • Salmonellosis (from contaminating food with feces or urine).
• Food Contamination and Consumption: Rats eat and contaminate enormous amounts of food with their feces, urine, and hair, leading to food spoilage and health risks.
• Structural Damage: They have a constant need to gnaw. They cause severe damage to buildings by chewing through wood, plastic, pipes, and electrical wiring. Gnawing on wires is a common cause of electrical fires.

Question 3. 

Name the two types of dysentery and their causative germs and give one main precaution against them.

Ans:

Type of Dysentery	Causative Germ (Pathogen)	One Main Precaution
1. Bacillary Dysentery (Shigellosis)	Bacteria (most commonly Shigella species)	Practice rigorous personal hygiene, especially washing hands thoroughly with soap and water after using the toilet and before preparing or eating food.
2. Amoebic Dysentery (Amebiasis)	Protozoan Parasite (Entamoeba histolytica)	Ensure food and water safety by only drinking boiled or treated water and avoiding raw or unpeeled foods in high-risk areas.

Question 4. 

Mention three symptoms of the disease Hepatitis.

Ans:

Hepatitis is an inflammation of the liver, and the symptoms can vary in severity. Here are three common symptoms:

1. Jaundice (Yellowing of Skin and Eyes) : The inflamed liver cannot effectively process bilirubin (a yellow compound formed from the breakdown of old red blood cells). This buildup of bilirubin in the blood causes the skin and the whites of the eyes to turn yellow.
2. Fatigue and Malaise (Feeling unwell) : Persistent and overwhelming tiredness, along with a general feeling of discomfort, illness, or uneasiness, is a very common symptom as the liver’s function is compromised.
3. Dark Urine and Pale Stool :
   • Dark Urine: Excess bilirubin is excreted by the kidneys, making the urine appear dark (tea or cola-colored).
   • Pale Stool: Bilirubin pigments are normally excreted in the stool, giving it its brown color. If the liver or bile ducts are blocked or inflamed, less bilirubin reaches the intestine, resulting in light-colored or clay-colored feces.