Selina Solutions for Class 9 Biology Chapter 15 - Hygiene

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1. Fill in the blanks
   1. Cleanliness, rest and sleep, and physical exercise are a part of ________ hygiene
   2. One must always breathe by the _______ and never by the ________
   3. Fresh air brings __________ into the living rooms.
   4. One must never put a sharp-pointed object into the _______ it may rupture the ______
   5. For adults 6-7 hours of continuous undisturbed _______ is sufficient.
   6. The municipal bodies must ensure the supply of clean germ-free ________ and an efficient _________ disposal.

   Solution:

   1. Personal
   2. Nose, mouth
   3. Oxygen
   4. Ear, eardrum
   5. Sleep
   6. Drinking water, sewage
2. List any three advantages of a daily bath.Solution:

   The three advantages are as follows:

   • It keeps the skin clean and germ-free
   • Eliminates body odours given out by perspiration
   • Keeps the sweat pores open
   • To keep the body warm
3. Tick-mark the correctly matched pairs of certain animals and the related diseases/habits.
   1. Culex ____________ yellow fever
   2. Aedes ____________filarial
   3. Anopheles _________malaria
   4. Gambusia _________ eat up mosquito larvae
   5. Rat flea ___________diarrhea
   6. Cockroaches ________breed in man-holes

   Solution:

   Culex ____________ yellow fever	–
   Aedes ____________filarial	–
   Anopheles _________malaria
   Gambusia _________ eat up mosquito larvae	✅
   Rat flea ___________diarrhea	–
   Cockroaches ________breed in man-holes	✅

4. Mention if the following statements are true (T) or false (F)
   1. Contamination means entry of germs by insect bite T/F
   2. Sewage is the commonest source of contamination of water in the cities T/F
   3. Cholera is marked by acute diarrhea and no urination T/F
   4. Typhoid is caused by a type of worm T/F
   5. Mosquitoes are the source of dysentery germs T/F

   Solution:

   1. The statement is false. Contamination means the entry of germs into drinking water or edible foods.
   2. The statement is true.
   3. The statement is true.
   4. The statement is false. Typhoid is caused by a bacteria
   5. The statement is false. Dysentery can be caused by bacteria or protozoans.

Multiple Choice Type

1. No urination due to shortage of water in the body is a typical symptom of
   1. Typhoid
   2. Malaria
   3. Dysentery
   4. Cholera

   Solution:

   d)Cholera

   It is because urea accumulates in the blood, which is highly poisonous and fatal.

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 6-7hours
   4. Sharing towels with others

   Solution:

   d)Sharing towels with others

   Trachoma and conjunctivitis are two common eye diseases caused by sharing towels and others.

3. The protozoan that causes malaria is:
   1. Entamoeba histolytica
   2. Euglena
   3. Paramecium
   4. Plasmodium

   Solution:

   d)Plasmodium

   Malaria is caused by the protozoan Plasmodium

4. The chemical substance mainly responsible for tooth disorder is
   1. Calcium
   2. Chloride
   3. Fluorides
   4. Iodides

   Solution:

   c) Fluorides

   Presence of fluorides in drinking water causes tooth disorders.

5. Typhoid is caused by
   1. Housefly
   2. Bacteria
   3. Virus
   4. None of the above

   Solution:

   (b) Bacteria

   Typhoid is caused by Salmonella typhi, a bacterium.

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

   Solution:

   (d) Contaminated water

   Hepatitis A is infectious hepatitis transmitted through contaminated water.

Very short answer type

1. Match Column I with that which is most appropriate in Column II.
   

   Column I	Column I
   Mosquito	DDT
   Plasmodium	Dengue
   Entamoeba histolytica	(Vector
   Aedes mosquito	Malaria
   Insecticide	Dysentery

   Solution:

   Aedes mosquitoDengue

   Column I	Column I
   Mosquito	Malaria
   Plasmodium	Vector
   Entamoeba histolytica	Dysentery
   Insecticide	DDT

2. Name the following:
   1. Organism that transmits microbes that cause disease.
   2. Organisms that cause disease.
   3. Science of maintaining good health

   Solution:

   1. An organism that transmits microbes that cause disease – Vectors
   2. Organisms that cause disease – Pathogens
   3. Science of maintaining good health – Hygiene
3. Describe the different ways by which the housefly contaminates our food.Solution:

   The different ways by which housefly contaminates food are:

   • Pouring saliva out – Food gets moist when housefly regurgitates on food or pours its saliva as a result pathogens get discharged on them causing the food to get contaminated.
   • Hairy body and legs pick up filth – Spiny or hairy legs and body tend to pick up dirt containing germs from germ-infested places such as faecal matter, rotten material, infected wound. When these carriers/flies rest on our food, they rub their legs continuously dropping the particles of dirt on the food, causing it to get contaminated.
   • Excreta – it deposits its excreta while it feeds, thus contaminating human food.
   • Direct transmission of germs – houseflies directly transmit pathogens in some cases. In case of eye disease trachoma, pathogens are transmitted from an infected person to a healthy person, when a fly settled on an infected eye of a person sits on the eyes of a healthy person.
4. Suggest any two methods of controlling flies.Solution:

   The two methods of controlling flies are:

   • Elimination of breeding places
   • Spraying with DDT and other insecticides
5. List any three effective methods for controlling mosquitoes.Solution:The effective methods for controlling mosquitoes are:
   • Elimination of breeding places for mosquitoes
   • Spraying with DDT other insecticides
   • Avoidance – food should be protected by covering it
6. Name the two common kinds of mosquitoes and the diseases they transmit.Solution:The two common kinds of mosquitoes and the diseases they transmit are as follows:
   

   Mosquito	Disease it transmits
   Anopheles	Malaria
   Aedes	Dengue

7. Mention any three ways by which potable water can be contaminated.Solution:Potable water can be contaminated in the following three ways:
   • Urination and defecation near water bodies such as ponds, lakes and rivers
   • Sewage disposed improperly
   • Contamination of water bodies by the drainage of animal washings and wastes from poultries and dairies

Long Answer Type

1. Give suitable explanations for the following:
   1. One should breathe by nose and never by mouth.
   2. Hands must be washed before eating food
   3. Eating places must be kept free of flies

   Solution:

   1. It is because nostrils have hair and mucous that traps dust and microbes entering while breathing causing it to become purified and hence ensuring the respiratory passage is dust-free and germ-free.
   2. Everything around us mostly has microbes which are not visible to us. The furniture, books, public transport etc all of these objects inhabit germs which can be picked up by us once we get in touch with these objects. These germs are then transmitted to the different parts of the body, through the water we drink or through the food we eat. Hence it becomes a necessity to wash hands thoroughly before consuming food so as to stay at bay from the diseases that could be spread through these germs/vectors.
   3. Eating places must be kept free of flies as flies carry bacteria and germs that cause various diseases.
2. How are cockroaches and rats harmful to humans?Solution:

   Cockroaches and rats are harmful to humans in the following ways:

   • Rats consume grains and other food products. They carry pathogens. Rat-fleas is a pathogen that inhabits on the skin of the rat and carries the plague germs
   • Cockroaches are known to perish food, cloth and paper. They carry viruses especially carcinogens.
3. Name the two types of dysentery and their causative germs and give one main precaution against them. Solution:The table below depicts the two types of dysentery, their causatives and precautions:
   

   Type of Dysentery	Causative	Precaution
   Bacillary	Bacterium – Shigella	Consume safe(boiled) drinking water
   Amoebic	Protozoan – Entamoeba histolytica	Always check for food and water contamination before consumption.

4. Mention three symptoms of the disease Hepatitis.Solution:

   The three symptoms of Hepatitis disease are as follows:

   • Body ache
   • Eyes turn yellowish, due to the bile pigments – urine turns to deep yellow
   • Enlargement of liver

Selina Solutions for class 9 Biology Chapter 15 – Hygiene

ICSE Class 9 Biology Chapter 15 – Hygiene chapter is classified under Unit – VI of Biology textbook – Health & Hygiene. Health refers to the normal and healthy state of the body in all the three aspects namely – physical, mental and social wellness while Hygiene pertains to the conditions and practices in order to maintain health and prevent any chance of diseases.

The chapter discusses the importance of health and the various methods through which one can adopt a healthy lifestyle thereby maintaining personal and social hygiene. Diseases can be acquired from an unhealthy/polluted environment hence it is essential to spread awareness about the various diseases and the carriers of these diseases. Through this chapter, students become aware of the hygienic habits and practices at the basic level so as to inculcate these values in their lives.

The chapter covers the following types of questions:

• Multiple-choice questions
• State whether true/false
• Fill ups
• Match items in Column I & II
• Short answer type questions
• Long answer type questions

List of subtopics covered in Chapter 15 – Hygiene

List of Exercise

Selina Solutions for class 9 Biology Chapter 15 – Hygiene

The chapter draws the attention of the students towards one of the most important and persistent problems in our society today, Hygiene and health. Health is one of the most important aspects of healthy living today in order to avoid all the major medical ailments. Along with giving importance to personal health and hygiene, one should also take an interest in social hygiene to promote healthy living.

Students through this unit learn about the general idea of personal hygiene, public hygiene and sanitation. It takes students through simple personal hygienic habits which can be adapted at the basic level and slowly approach social hygiene and sanitation. It also sheds light upon the control of vectors(disease-carriers) – different modes of transmission of diseases by the vectors by agents such as mosquitoes, cockroaches, rats etc.

Finally, it also enlightens about the ways in which water is contaminated and the different water-borne diseases. Hence the chapter requires a focus not only from the examination perspective but also because it concerns the students at the personal level to adapt these habits in their daily routine and serve as responsible citizens.

Key Features of Selina Solutions for class 9 Biology Chapter 15 – Hygiene

• The free tool, readily available
• Trusted as prepared by a team of experts with extensive knowledge
• Framed in accordance with the latest ICSE syllabus for class 9
• Use of a coherent language
• Use of tables wherever necessary to enable easy remembrance of concepts