Download 65 Did you notice the conversation between the students? What

BIOLOGY
Johny, it is not
fair to say like
that....................
............................
.........................
..................
Rani, I am fed up with our
Health Club convener. I can't
clean the school premises. We need
to clean only our classroom, house
and its surroundings, don't we...?
Did you notice the conversation between
the students? What might be Rani's
explanation to Johny's question?
Given below are extracts on hygiene, from
the Science diary, prepared by a student.
Examine it.
Pathogens like bacteria,
protozoa etc.
Food
Water
oa
toz
Pro
bac
ter
ia
bacteria
Typhoid
Dysentery
Cholera
— Mild abdominal pain
— Headache
— Diarrhoea, vomiting
— Frequent defaecation
— Severe fever
— Rice water like stool
— Blood and mucus in stool
— Abdominal pain, constipation
— Muscle cramps
Illustration-5.1.
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BIOLOGY
Tuberculosis
— Continuous dry cough
a
teri
bac
— Fever
— Blood- tinged sputum
— Chest pain
Air
— Loss of weight
vir
us
Chicken pox
— Fever, headache
Protozoa
(Plasmodium )
Larvae of Filarial worm
— Red rashes on the body. They
gradually transform into blisters
Filariasis
— Fever accompanied by chill
Culex mosquito
— Pain and reddishness in the affected
area
— Since adult worms live only in the
lymph vessels, the flow of lymph is
obstructed. Obstruction of lymphatic
vessels leads to extreme swelling of
affected organs.
Malaria
— Severe fever, chill
— Severe headache
Anopheles mosquito
Illustration-5.2.
— Burning sensation all over the body
— Fever recurring at regular intervals
August 20 - A Day for Mosquitoes!
Athlet's Foot, Ring worm
Curiosity arose when I heard about it…
On enquiry the matter became clear.
The day is observed not for breeding
mosquitoes but for creating awareness
about the menace of mosquitoes. It
was on this day in 1897 that Sir Ronald
Ross affirmed that malaria was spread
by mosquitoes..
When we hear of these diseases we get
an impression that these are caused by
some kind of worms. But they are
caused by fungi. Fungi that cause
Athlet's foot infection are transmitted
from the soil to the soft and wet parts of
the feet. Ring worm spreads through
contact. It is called ring worm because
the symptom of the disease manifests
as circular rashes.
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BIOLOGY
How do the circumstances causing the
diseases mentioned in the diary arise?
Discuss it and note the inferences in the
Science diary.
Are only those diseases mentioned in the
diary seen nowadays? What are the
contagious diseases widely seen in Kerala
in recent times? Discuss it with your
friends and fill up Table 5.1
Chikungunya
Joint 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.
Mosquito Eradication
Through Public Participation
Under the auspices of Kudumbasree
activists in Eramala
Panchayat
mosquito iradication programmes....
Chikungunya
Through mosquito
—
—
—
—
—
—
Table 5.1
Collect information about the diseases
you have listed out. Prepare a science
article including the ideas in the collage
(Illustration 5.3) given below.
, is
u
e Ftlhrough airThe
n
i
Swsmitted Kerala. own
in
ran
s kn
flu, t threat the viru mptoms
e
n
i
a
s
i
sy
Sw ming
nism N . Its esemble
a
o
g
c
r
e
1
o
r
b
A H 1 sion
ative
caus fluenza transmis .
ld
f
n
as I odes o mon co
m
m
and of co
e
thos
Beware of Rat Fever
The bacteria causing rat fever
reach the body from the
surroundings contaminated with
the urine of rat, through wounds
or through food and drink. Besides
symptoms of commom fever,
reddishness in the eye, difficulty
to look at day light, bleeding in
internal organs like kidney, liver,
lungs are the symptoms seen.
kara panc
a small b
aby bitten hayat, 7 including
by
sought tr
eatment in a rabid dog
the hospit
al.
When it recurs
Symptoms of the common viral fever are seen
in dengue fever also. Red rashes seen on the
chest and face is a major symptom. It becomes
more dangerous when those who have
recovered from the disease are again attacked
by another type of dengue virus. Blood
platelets decrease far below normal count and
hence bleeding occurs in various parts of the
body.
Mode of Transmission
Rabid d
o
7 h o s p g bites,
i
talized
In Chitta
rik
Dengue fever
Diseases
Malaria returns
ed to be
M al ar ia pr es um
in Kerala.
ck
ba
under control,
Illustration-5.3.
You might have understood what contagious diseases are. Formulate a practical
definition of contagious diseases and write it down.
...........................................................................................................................
Have any of these diseases occurred in your locality? What are the situations prevailing
there that cause their transmission? What are the precautions to be adopted for
preventing the transmission of disease ? Conduct a study, prepare a report and present
it in the class room. Organise appropriate awareness programmes to prevent the
transmission of diseases.
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BIOLOGY
Now you have learnt about certain disease causing microorganisms? How does their
entry (infiltration) into the body cause diseases? Read the given description and
complete the table.
VIRUS
Fig-5.1.
They have no cellular mechanism of their own to carry out metabolic
reactions. Hence they grow and multiply undertaking the control of the
genetic mechanism of our cell. As a result, virus infected cells are
completely destroyed.
BACTERIA
After entering the body they multiply by division. Certain toxic substances
are released into our body as a result of metabolic reactions. They either
disrupt the rhythm of cellular activities or destroy the cell itself.
Consequently symptoms of the disease appear.
Fig-5.2.
PROTOZOA
Fig-5.3.
Like bacteria, these also produce toxins which become harmful to our
body. The enzymes produced by some species of protozoa destroy the
epithelium of the intestine and other organs. Some others attack blood
cells.
FUNGUS
The enzymes released by fungus destroy our cells. They cause many
diseases.
Fig-5.4.
Disease causing
Organisms
Diseases
Mode of
Transmission
Mode of Infection
Chickenpox
Bacteria
Protozoa
The enzymes produced
by them destroy our cells.
Table-5.2
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BIOLOGY
Bad Habits and Diseases
Do microorganisms alone cause diseases? Are there any
other reasons for the occurrence of diseases? Look at
the 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 that
adversely affect health. Perform the given experiment
(Fig.5.6) in the class room.
Note down your observations and inferences.
Pet bottle
Fill water in the pet
bottle by closing the
hole with the hand.
Water
Fig-5.5.
Hole
A
Cigarette
Lid of bottle
Light the cigarette and insert
it in the hole made in the cap.
Now, let the water flow out
through the hole at the
bottom. When the cigarette
is completely burnt, take out
the inserted cloth and
observe. Then wash the cloth
in soap water and observe.
Moist white cloth
Insert the cloth
through the mouth of
the bottle
B
Fig-5.6.
C
Water flows out
Observation : .......................................................................................................................
Inference
: .......................................................................................................................
How many substances that cannot be removed even by washing with soap, do we take
in through smoking? These substances contain about four thousand chemical substances
like tar, nicotin, carbon monoxide, benzopyrin, etc. It has been proved that nearly sixty
of them are carcinogens. We have learnt about bronchitis seen among smokers.
Haemoglobin has more affinity to carbon monoxide than to oxygen. So carbon monoxide
combines with haemoglobin to form carboxyhaemoglobin. As it dissociates only very
slowly the capacity of blood to receive oxygen is reduced.
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BIOLOGY
What are the other ways in which smoking
affects the body? Analyse Figure 5.7 and
prepare notes.
Lethargy, nausea
Addiction to nicotin
Vital capacity decreases
Cancer may develop
Cholesterol level increases
Blood pressure rises
Secretion of gastric glands
increases
Production of Adrenaline
increases
Peristalsis increases
Tremor
Inner diameter of the
artery decreases. Blood
flow to this part
decreases and hence
tissues get damaged
Fig.- 5.7
Effects of smoking on the body
What are the other bad habits that cause
diseases? Examine the given description
on the basis of the indicators.
situations is lost. Alcoholism is the main
cause of diseases like hepatitis and
cirrhosis.
Use of drugs is another very dangerous
habit. The thing to be noticed here is that
drugs develop addiction even when taken
just once or twice. Marijuana, cocaine,
opium, heroin, morphine, LSD (Lysergic
acid diethylamide) etc. are examples of
drugs. Some of these induce fear, anxiety
and hallucination. Some others depress
the nervous system and cause sedation.
The danger of such bad habits is that they
are started for fun but later develop into
addiction. Hence they are to be totally
avoided.
Indicators
¬ Why is it said that alcohol, drugs etc.
disrupt homeostasis?
¬ Why is it said that the possibility of
accidents is more when people
intoxicated with alcohol and drug drive
vehicles?
¬ Why is it said that alcohol and drugs
are to be completely avoided?
Alcohol and Drugs
Plan and conduct awareness programmes
against such bad habits.
Alcoholism is a wide spread bad habit.
When alcohol is consumed, it immediately
reaches the internal environment. It affects
the nervous system and hinders the coordination of muscular activities. As a
result, reflexes slow down and the ability
to take quick decisions in emergency
You have learnt that the use of tobacco,
panmasala etc. is a shortcut to cancer. But
sometimes those without any such bad
habits too develop cancer. What might be
the reason? Using the given description
prepare a notice to be circulated as part of
cancer awareness programmes.
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BIOLOGY
Cancer
Cancer is the condition in which cells multiply uncontrollably and destroy other cells by
consuming the nutrients meant for them. Cancer cells are capable of reaching other
parts of the body from their place of origin through blood and lymph, and they can multiply
there. Ultra violet rays, other radiations, carcinogens contained in tobacco and other
substances, some kinds of virus, etc. can cause cancer.
Genetic Diseases
You have understood that many diseases are caused by certain factors entering the
body from the surroundings. In contrast to this, is there any possibility of diseases due
to other reasons? Details related to the diseases of Manu and Mumthas are given below.
Examine them and find out the peculiarities of their diseases.
Name-Manu
Name-Mumthas
Age- 10yrs.
Sex-male
Blood platelets, vitamin K -Normal
No particular infection.
Excessive bleeding even from very
small wounds.
Age-12yrs.
Sex-female
Red blood cell count,
haemoglobin content less than
normal
No infection.
Anaemia, difficulty in doing
strenuous work
Red Blood Cells
Fig-5.8.
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 which
enables blood coagulation.
↓
Uncontrolled bleeding occurs even from very
small wounds as blood does not clot.
Structural deformity occurs in the haemoglobin
molecules of the red blood cells
↓
When the level of oxygen in the blood
decreases red blood cells undergo change in
shape and transform into sickle shaped cells.
↓
Haemophilia
Illustration-5.4.
Oxygen transport to the tissues is affected.
Sickle Cell Anaemia
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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 similarities
and dissimilarities between that and the anaemia just discussed. Record in Table 5.3.
Anaemia
Sickle Cell Anaemia
Table-5.3.
Keralites are people who are highly
concerned about personal hygiene. But
many of them do not give adequate
attention to community hygiene. How
does this affect health? Read the given
description, and prepare notes based on
the indicators . Record it in the Science
diary.
Urinary Tract Infection- UTI
How safe and hygienic are the urinals in
our schools and public places? We are
reluctant to use such unhygienic urinals.
Hence children, especially girls, going out
of their houses, develop the habit of
passing urine only after returning home.
This creates a lot of health problems.
While passing urine, pathogens too are
flushed out from the urinary bladder,
urethra etc.. How do pathogens reach the
urinary tract? Certain bacteria in our
intestine come out along with faeces.
These bacteria are seen around the anus.
They may reach even the kidneys through
the urethra and the urinary bladder. The
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infection caused in the urinary tract by
such microorganisms is generally known
as Urinary Tract Infection. Through habits
like low intake of water and voluntary
retention of urine we reduce the
possibility of expelling bacteria that may
be present in the urinary tract and urinary
bladder. As a result, the inner lining of the
urinary bladder becomes inflammated
due to infection. Sometimes this infection
leads to nephritis. Certain species of
fungi also cause urinary tract infection.
Indicators
¬ How can the situations that cause
urinary tract infection be avoided?
¬ Why do women have a greater risk of
UTI than men?
¬ Why is it said that at least 2-3 litres of
water must be taken every day?
We must remember that it is the duty of
each and every one of us to keep urinals
and latrines in schools and public places
hygienic. Discuss what can be done in this
regard.
BIOLOGY
Similarly what other health hazards result
from the failure in community hygiene?
Discuss it with your friends.
...................................................................
Can a person be said to be absolutely
healthy just because one's body is free
from diseases? If not, what are the other
factors that adversely affect the health of a
person?
—
strained family relationships
—
Job dissatisfaction
—
...................................................................
—
You know that such problems that affect
the mind, gradually affect physical health
too.
We have understood the situations that
lead to the occurrence of diseases and how
diseases are caused by them. Based on this
fill up Illustration 5.5.
Illustration-5.5.
Animal Diseases
Do diseases occur only in man? Aren't our domestic animals and birds also affected by
diseases? Haven't we studied about these in the previous classes? Find out which
diseases affect domestic animals and record them in Table 5.4.
Disease
Causative organisms
Symptoms
— Anthrax
—
—
Table - 5.4.
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BIOLOGY
Collect more information on such
diseases, prepare a poster and display it
in the class.
Plants and Diseases
You know that like animals, plants too
are affected by diseases.
What are the microorganisms responsible
for plant diseases?
—
Bacteria
—
...................................................................
—
Given below are some indications about
diseases affecting plants. With the help
of this prepare an illustration in your
Science diary in the model of the one given
at the beginning of this chapter. More
details on plant diseases can be collected
from agricultural publications, local farms
and the Krishi Bhavan.
Patients among Plants too
Coconut bud rot, koleroga in
arecanut, quick wilt in pepper are
examples of fungal diseasestransmission of the disease is
through wind.
Bunchy top of banana, mosaic
disease in the pea plant and tapioca
are examples of viral diseases- the
disease is transmitted by pests viz., aphids- Once the disease
sets in, cure is impossible.
Fig - 5.9
Koleroga in arecanut
Fig - 5.10
Quickwilt in pepper
Wilt disease in brinjal-the leaves suddenly wilt and fall.
Production is considerably reduced.
This is caused by bacteria- the disease
transmission is through seeds.
Fig - 5.11
Bunchy top of banana
Blight disease in the paddy plantmarks of colour change appear on the
sides of the leaves, the leaf tips dry up.
This is yet another bacterial disease
that spreads through seeds.
Fig - 5.12
Mosaic disease in
tapioca
Is there any other reason than pathogenic invasion for plant diseases? We know that
various 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 certain
elements are given in the table. Analyze Table 5.5 and prepare a note based on the
indicators.
...........................................................................................................................
74
BIOLOGY
Elements
Potassium
Major Functions
Deficiency Symptoms
— Protein synthesis
— Brown coloured dried spots
— Enables the opening and
— Leaf veins turn yellow
on leaves
closing of stomata
Magnesium
— Purple colour on the lower
surface of leaves
— Essential for the
— Yellow colour between the veins of
synthesis of chlorophyll
— Enhances the activity of
respiratory enzymes
the leaf. This symptom is seen in
mature leaves. Gradually it spreads
on to the tender leaves too.
Table-5.5.
Indicators
¬ How does the deficiency of magnesium
affect plants?
¬ How can diseases due to the deficiency
of magnesium, potassium, etc be
identified on the basis of the
symptoms?
Are all nutritional elements required for
plants obtained from the soil alone?
In plants diseases due to the deficiency of
carbon and hydrogen do not occur. Why
is it so?
...................................................................
What are the plant diseases seen in your
locality? Collect the pictures of the plants
showing such symptoms of diseases and
display them in the class room with
necessary descriptions.
We have understood that diseases are
caused due to the disruption of
equilibrium in homeostasis. How can the
knowledge we have acquired be made
useful to our daily life and community?
Isn't a collective effort inevitable for this?
What are the things each one of us can do
to safeguard the well-being of our
community? Prepare an action plan
through discussion with your friends and
implement it.
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BIOLOGY
Follow up Activities
1) Suppose you receive a warning about the possibility of spreading of diseases like
Dengue fever, Chikungunya etc in your locality. Prepare a guideline on what all
things are to be discussed in the awareness class organised by you against such
diseases.
2) Smoking, alcoholism, drug addiction etc affect not only the persons using them but
the 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 diseases
due to undernutrition.” Examine the validity of this statement which Nimmy has
noted in her Science diary.
=============
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