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BIOLOGY

Did you notice the conversation betweenthe students? What might be Rani'sexplanation to Johny's question?

Given below are extracts on hygiene, fromthe Science diary, prepared by a student.Examine it.

Rani, I am fed up with ourHealth Club convener. I can't

clean the school premises. We needto clean only our classroom, houseand its surroundings, don't we...?

Johny, it is notfair to say like

that.........................................................................

..................

FoodWater

Dysentery

� Mild abdominal pain

� Frequent defaecation

� Blood and mucus in stool

Typhoid

� Headache

� Severe fever

� Abdominal pain, constipation

Cholera

� Diarrhoea, vomiting

� Rice water like stool

� Muscle cramps

bacteria

Pathogens like bacteria,protozoa etc.

bacteria

Illustration-5.1.

Protozoa

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BIOLOGY

Athlet's Foot, Ring worm

When we hear of these diseases we getan impression that these are caused bysome kind of worms. But they arecaused by fungi. Fungi that causeAthlet's foot infection are transmittedfrom the soil to the soft and wet parts ofthe feet. Ring worm spreads throughcontact. It is called ring worm becausethe symptom of the disease manifestsas circular rashes.

Filariasis

� Fever accompanied by chill� Pain and reddishness in the affected

area� Since adult worms live only in the

lymph vessels, the flow of lymph isobstructed. Obstruction of lymphaticvessels leads to extreme swelling ofaffected organs.

Larv

ae o

f Fila

rial

wor

m

bacteria

virus

Air

Tuberculosis

� Continuous dry cough

� Fever

� Blood- tinged sputum

� Chest pain

� Loss of weight

Chicken pox

� Fever, headache

� Red rashes on the body. Theygradually transform into blisters

Prot

ozoa

(Pla

smod

ium

)

Culex mosquito

Anopheles mosquito

Malaria

� Severe fever, chill

� Severe headache

� Burning sensation all over the body

� Fever recurring at regular intervalsIllustration-5.2.

August 20 - A Day for Mosquitoes!

Curiosity arose when I heard about it…On enquiry the matter became clear.The day is observed not for breedingmosquitoes but for creating awarenessabout the menace of mosquitoes. Itwas on this day in 1897 that Sir RonaldRoss affirmed that malaria was spreadby mosquitoes..

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BIOLOGY

How do the circumstances causing thediseases mentioned in the diary arise?Discuss it and note the inferences in theScience diary.

Are only those diseases mentioned in thediary seen nowadays? What are thecontagious diseases widely seen in Keralain recent times? Discuss it with yourfriends and fill up Table 5.1

You might have understood what contagious diseases are. Formulate a practicaldefinition of contagious diseases and write it down.

...........................................................................................................................

Have any of these diseases occurred in your locality? What are the situations prevailingthere that cause their transmission? What are the precautions to be adopted forpreventing the transmission of disease ? Conduct a study, prepare a report and presentit in the class room. Organise appropriate awareness programmes to prevent thetransmission of diseases.

Collect information about the diseasesyou have listed out. Prepare a sciencearticle including the ideas in the collage(Illustration 5.3) given below.

Illustration-5.3.

Dengue feverWhen it recurs

Symptoms of the common viral fever are seenin dengue fever also. Red rashes seen on thechest and face is a major symptom. It becomesmore dangerous when those who haverecovered from the disease are again attackedby another type of dengue virus. Bloodplatelets decrease far below normal count andhence bleeding occurs in various parts of thebody.

Swine Flu

Swine flu, transmitted through air, is

becoming a threat in Kerala. The

causative organism is the virus known

as Influenza A H 1N 1

. Its symptoms

and modes of transmission resemble

those of common cold.

Beware of Rat FeverThe bacteria causing rat feverreach the body from thesurroundings contaminated withthe urine of rat, through woundsor through food and drink. Besidessymptoms of commom fever,reddishness in the eye, difficultyto look at day light, bleeding ininternal organs like kidney, liver,lungs are the symptoms seen.

Rab

id d

og b

ites

,7 h

osp

ital

ized

In C

hitta

rikka

ra p

anch

ayat

, 7 in

clud

ing

a sm

all b

aby

bitte

n by

a ra

bid

dog

soug

ht tr

eatm

ent i

n th

e ho

spita

l.

ChikungunyaJoint pain non -resolving

Initial symptoms of Chikungunya, the viral

disease transmitted by mosquitoes, are

fever with chills, headache, etc. Even

though these subside within a few days,

the subsequent joint inflammation, pain etc.

Malaria returns

Malaria presumed to be

under control, back in Kerala.

Mosquito EradicationThrough Public ParticipationUnder the auspices of Kudumbasreeactivists in Eramala Panchayatmosquito iradication programmes....

Table 5.1

Diseases Mode of TransmissionChikungunya Through mosquito� �

� �

� �

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BIOLOGY

Table-5.2

Disease causing Diseases Mode of Mode of InfectionOrganisms Transmission

Chickenpox

Bacteria

Protozoa

The enzymes producedby them destroy our cells.

Fig-5.2.

Fig-5.1.

Fig-5.4.

Fig-5.3.

VIRUS

They have no cellular mechanism of their own to carry out metabolicreactions. Hence they grow and multiply undertaking the control of thegenetic mechanism of our cell. As a result, virus infected cells arecompletely destroyed.

BACTERIA

After entering the body they multiply by division. Certain toxic substancesare released into our body as a result of metabolic reactions. They eitherdisrupt the rhythm of cellular activities or destroy the cell itself.Consequently symptoms of the disease appear.

PROTOZOA

Like bacteria, these also produce toxins which become harmful to ourbody. The enzymes produced by some species of protozoa destroy theepithelium of the intestine and other organs. Some others attack bloodcells.

FUNGUS

The enzymes released by fungus destroy our cells. They cause manydiseases.

Now you have learnt about certain disease causing microorganisms? How does theirentry (infiltration) into the body cause diseases? Read the given description andcomplete the table.

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BIOLOGY

Bad Habits and DiseasesDo microorganisms alone cause diseases? Are there anyother reasons for the occurrence of diseases? Look atthe poster prepared by the students of the Health Club.

What is the message given by the poster?

...................................................................

Let us observe some of the substances in tobacco thatadversely affect health. Perform the given experiment(Fig.5.6) in the class room.

Note down your observations and inferences.

A

Pet bottle

Hole

Water

Water flows out

CigaretteLid of bottle

C

Light the cigarette and insertit in the hole made in the cap.Now, let the water flow outthrough the hole at thebottom. When the cigaretteis completely burnt, take outthe inserted cloth andobserve. Then wash the clothin soap water and observe.

Moist white cloth

BFig-5.6.

Observation : .......................................................................................................................

Inference : .......................................................................................................................

How many substances that cannot be removed even by washing with soap, do we takein through smoking? These substances contain about four thousand chemical substanceslike tar, nicotin, carbon monoxide, benzopyrin, etc. It has been proved that nearly sixtyof them are carcinogens. We have learnt about bronchitis seen among smokers.Haemoglobin has more affinity to carbon monoxide than to oxygen. So carbon monoxidecombines with haemoglobin to form carboxyhaemoglobin. As it dissociates only veryslowly the capacity of blood to receive oxygen is reduced.

Fill water in the petbottle by closing thehole with the hand.

Insert the cloththrough the mouth ofthe bottle

Fig-5.5.

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BIOLOGY

What are the other ways in which smokingaffects the body? Analyse Figure 5.7 andprepare notes.

What are the other bad habits that causediseases? Examine the given descriptionon the basis of the indicators.

Alcohol and Drugs

Alcoholism is a wide spread bad habit.When alcohol is consumed, it immediatelyreaches the internal environment. It affectsthe nervous system and hinders the co-ordination of muscular activities. As aresult, reflexes slow down and the abilityto take quick decisions in emergency

situations is lost. Alcoholism is the maincause of diseases like hepatitis andcirrhosis.

Use of drugs is another very dangeroushabit. The thing to be noticed here is thatdrugs develop addiction even when takenjust once or twice. Marijuana, cocaine,opium, heroin, morphine, LSD (Lysergicacid diethylamide) etc. are examples ofdrugs. Some of these induce fear, anxietyand hallucination. Some others depressthe nervous system and cause sedation.

The danger of such bad habits is that theyare started for fun but later develop intoaddiction. Hence they are to be totallyavoided.

Indicators

¬ Why is it said that alcohol, drugs etc.disrupt homeostasis?

¬ Why is it said that the possibility ofaccidents is more when peopleintoxicated with alcohol and drug drivevehicles?

¬ Why is it said that alcohol and drugsare to be completely avoided?

Plan and conduct awareness programmesagainst such bad habits.

You have learnt that the use of tobacco,panmasala etc. is a shortcut to cancer. Butsometimes those without any such badhabits too develop cancer. What might bethe reason? Using the given descriptionprepare a notice to be circulated as part ofcancer awareness programmes.

Fig.- 5.7Effects of smoking on the body

Lethargy, nauseaAddiction to nicotin

Vital capacity decreasesCancer may develop

Cholesterol level increases

Secretion of gastric glandsincreases

Blood pressure rises

Production of Adrenalineincreases

Tremor

Inner diameter of theartery decreases. Bloodflow to this partdecreases and hencetissues get damaged

Peristalsis increases

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BIOLOGY

Name-Mumthas

Age-12yrs. Sex-female

Name-Manu

Age- 10yrs. Sex-male

Red blood cell count,haemoglobin content less thannormal

No infection.

Anaemia, difficulty in doingstrenuous work

Blood platelets, vitamin K -Normal

No particular infection.

Excessive bleeding even from verysmall wounds.

Red Blood Cells

Fig-5.8.

Cancer

Cancer is the condition in which cells multiply uncontrollably and destroy other cells byconsuming the nutrients meant for them. Cancer cells are capable of reaching otherparts of the body from their place of origin through blood and lymph, and they can multiplythere. Ultra violet rays, other radiations, carcinogens contained in tobacco and othersubstances, some kinds of virus, etc. can cause cancer.

Genetic DiseasesYou have understood that many diseases are caused by certain factors entering thebody from the surroundings. In contrast to this, is there any possibility of diseases dueto other reasons? Details related to the diseases of Manu and Mumthas are given below.Examine them and find out the peculiarities of their diseases.

Is it clear that these diseases are not due to any infection? What could be the reason?Examine the flow chart (Illustration 5.4) and record the inferences in the Science diary.

↓

↓ ↓

↓

↓

Disorder in the genes

Defective synthesis of one of the proteins whichenables blood coagulation.

Uncontrolled bleeding occurs even from verysmall wounds as blood does not clot.

Haemophilia

Structural deformity occurs in the haemoglobinmolecules of the red blood cells

When the level of oxygen in the blooddecreases red blood cells undergo change inshape and transform into sickle shaped cells.

Sickle Cell Anaemia

Oxygen transport to the tissues is affected.

Illustration-5.4.

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BIOLOGY

Haven’t you understood what the diseases of Manu and Mumthas are?

Such diseases caused by defects in genes are called genetic diseases.

We learned about anaemia last year. What is the reason for it? What are the similaritiesand dissimilarities between that and the anaemia just discussed. Record in Table 5.3.

Keralites are people who are highlyconcerned about personal hygiene. Butmany of them do not give adequateattention to community hygiene. Howdoes this affect health? Read the givendescription, and prepare notes based onthe indicators . Record it in the Sciencediary.

Urinary Tract Infection- UTI

How safe and hygienic are the urinals inour schools and public places? We arereluctant to use such unhygienic urinals.Hence children, especially girls, going outof their houses, develop the habit ofpassing urine only after returning home.This creates a lot of health problems.

While passing urine, pathogens too areflushed out from the urinary bladder,urethra etc.. How do pathogens reach theurinary tract? Certain bacteria in ourintestine come out along with faeces.These bacteria are seen around the anus.They may reach even the kidneys throughthe urethra and the urinary bladder. The

infection caused in the urinary tract bysuch microorganisms is generally knownas Urinary Tract Infection. Through habitslike low intake of water and voluntaryretention of urine we reduce thepossibility of expelling bacteria that maybe present in the urinary tract and urinarybladder. As a result, the inner lining of theurinary bladder becomes inflammateddue to infection. Sometimes this infectionleads to nephritis. Certain species offungi also cause urinary tract infection.

Indicators

¬ How can the situations that causeurinary tract infection be avoided?

¬ Why do women have a greater risk ofUTI than men?

¬ Why is it said that at least 2-3 litres ofwater must be taken every day?

We must remember that it is the duty ofeach and every one of us to keep urinalsand latrines in schools and public placeshygienic. Discuss what can be done in thisregard.

Table-5.3.

Anaemia Sickle Cell Anaemia

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BIOLOGY

Similarly what other health hazards resultfrom the failure in community hygiene?Discuss it with your friends.

...................................................................

Can a person be said to be absolutelyhealthy just because one's body is freefrom diseases? If not, what are the otherfactors that adversely affect the health of aperson?

� strained family relationships

� Job dissatisfaction� ...................................................................�

You know that such problems that affectthe mind, gradually affect physical healthtoo.

We have understood the situations thatlead to the occurrence of diseases and howdiseases are caused by them. Based on thisfill up Illustration 5.5.

Animal DiseasesDo diseases occur only in man? Aren't our domestic animals and birds also affected bydiseases? Haven't we studied about these in the previous classes? Find out whichdiseases affect domestic animals and record them in Table 5.4.

Illustration-5.5.

Table - 5.4.

Disease Causative organisms Symptoms

� Anthrax�

�

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BIOLOGY

Fig - 5.12

Mosaic disease intapioca

Collect more information on suchdiseases, prepare a poster and display itin the class.

Plants and DiseasesYou know that like animals, plants tooare affected by diseases.

What are the microorganisms responsiblefor plant diseases?� Bacteria

� ...................................................................�

Given below are some indications aboutdiseases affecting plants. With the helpof this prepare an illustration in yourScience diary in the model of the one givenat the beginning of this chapter. Moredetails on plant diseases can be collectedfrom agricultural publications, local farmsand the Krishi Bhavan.

Coconut bud rot, koleroga inarecanut, quick wilt in pepper areexamples of fungal diseases-transmission of the disease isthrough wind.

Bunchy top of banana, mosaicdisease in the pea plant and tapiocaare examples of viral diseases- the

disease is transmitted by pests viz., aphids- Once the diseasesets in, cure is impossible.

Wilt disease in brinjal-the leaves suddenly wilt and fall.Production is considerably reduced.This is caused by bacteria- the diseasetransmission is through seeds.

Blight disease in the paddy plant-marks of colour change appear on thesides of the leaves, the leaf tips dry up.This is yet another bacterial diseasethat spreads through seeds.

Is there any other reason than pathogenic invasion for plant diseases? We know thatvarious elements are required for the proper growth of plants. Note them down.

...........................................................................................................................

What are the problems occur to plants due to the deficiency of these elements?

The symptoms of the diseases occurring in plants due to the deficiency of certainelements are given in the table. Analyze Table 5.5 and prepare a note based on theindicators.

...........................................................................................................................

Fig - 5.10

Quickwilt in pepper

Fig - 5.11

Bunchy top of banana

Fig - 5.9Koleroga in arecanut

Patients among Plants too

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BIOLOGY

Indicators

¬ How does the deficiency of magnesiumaffect plants?

¬ How can diseases due to the deficiencyof magnesium, potassium, etc beidentified on the basis of thesymptoms?

Are all nutritional elements required forplants obtained from the soil alone?

In plants diseases due to the deficiency ofcarbon and hydrogen do not occur. Whyis it so?

...................................................................

What are the plant diseases seen in yourlocality? Collect the pictures of the plants

showing such symptoms of diseases anddisplay them in the class room withnecessary descriptions.

We have understood that diseases arecaused due to the disruption ofequilibrium in homeostasis. How can theknowledge we have acquired be madeuseful to our daily life and community?Isn't a collective effort inevitable for this?What are the things each one of us can doto safeguard the well-being of ourcommunity? Prepare an action planthrough discussion with your friends andimplement it.

Elements Major Functions Deficiency Symptoms

Potassium � Protein synthesis � Brown coloured dried spotson leaves

� Enables the opening and � Leaf veins turn yellowclosing of stomata � Purple colour on the lower

surface of leaves

Magnesium � Essential for the � Yellow colour between the veins ofsynthesis of chlorophyll the leaf. This symptom is seen in

� Enhances the activity of mature leaves. Gradually it spreadsrespiratory enzymes on to the tender leaves too.

Table-5.5.

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BIOLOGY

Follow up Activities

1) Suppose you receive a warning about the possibility of spreading of diseases likeDengue fever, Chikungunya etc in your locality. Prepare a guideline on what allthings are to be discussed in the awareness class organised by you against suchdiseases.

2) Smoking, alcoholism, drug addiction etc affect not only the persons using them butthe entire society as well. Note down your opinion evaluating this statement.

3) “There is no chance of plants, the manufacturers of food, getting affected by diseasesdue to undernutrition.” Examine the validity of this statement which Nimmy hasnoted in her Science diary.

=============