Class 9 science and technology chapter 8 Useful and Harmful Microbes question answer
Class 9 science and technology chapter 8question answer Useful And Harmful Microbes | Useful And Harmful Microbes class 9 exercise answers Maharashtra board
1. Complete the statements using the proper option from those given below. Explain the statements.
(mycotoxins,
budding, rhizobium)
a)
Yeast reproduces asexually by the …………. method.
Answer: Yeast reproduces asexually by the Budding method.
Explanation:
Budding is the asexual method of reproduction in yeast. Upon getting favourable
conditions yeast start growing rapidly with the process of budding.
b. Toxins of fungal origin are called …………. .
Answer: Toxins of fungal origin are called Mycotoxins
Explanation:
Different species of fungi can secrete mycotoxins which is a toxic and harmful
substance. When fungal hyphae absorb the nutrients from the food materials, at
the same time they release the mycotoxins into the food.
c.
Leguminous plants can produce more proteins due to …………. .
Answer: Leguminous plants can produce more proteins due to Rhizobium.
Reason:
Rhizobium is beneficial symbiotic bacterium that lives in the root nodules of
the leguminous plants. Plants are unable to take nitrogen from the air
directly. But these bacteria convert nitrogen into compounds of nitrogen by a
process of biological nitrogen fixation. Plants are able to produce food with
high protein contents due to action of these bacteria.
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2 Write the names of microbes found in following food materials. yoghurt, bread, root nodules of leguminous plants, idli, dosa, spoiled potato curry.
Answer:
Yoghurt
: Lactobacilli
Bread:
Yeast
Root
nodules of leguminous plants : Rhizobium
Idli:
Yeast
Dosa
: Yeast
Spoiled
potato curry: Clostridium.
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3. Identify the odd word out and say why it is the odd one?
a.
Pneumonia, diphtheria, chicken pox, cholera.
Answer: chlolera. ( All others are diseases of
respiratory system.)
b.
Lactobacilli, rhizobia, yeast, clostridia.
Answer:
Clostridia ( All others are useful micro-organisms)
c.
Root rot, rust (tambera), rubella, mozaic.
Answer:
rubella ( Rubella is a viral disease of
human beings. Others are plant diseases. Mosaic is viral disease while root rot
and rust are bacterial diseases.)
4. Give scientific reasons.
a. Foam accumulates on a the surface of ‘dal’ kept for a long time in summer.
Answer:
During
summer months , the surrounding temperature and humidity is conducive for the
growth of bacteria and fungi . These favourable conditions help the rapid
proliferation and growth of these organisms . The dal kept for a long time thus
starts fermenting due to bacterial and fungal contamination . The fermentation
releases carbon dioxide causing foam on the surface of such dal .
b. Why are naphthalene balls kept with clothes to be put away.
Answer:
Naphthalene
balls contains certain toxic chemicals which prevent the silverfish or termite
from spoiling the cloth . The fungal growth is also arrested due to naphthalene
. Since the clothes remain well preserved with naphthalene balls , they are
kept with the clothes during their long term storage .
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5. Write down the modes of infection and the preventive measures against fungal diseases
Answer:
The
fungal diseases such as ringworm and other skin diseases spread through contact
of the patients . The clothes , bed linen , combs , etc. spread the fungal
spores or hyphae and this infects other healthy persons . The preventive
measures include maintaining personal hygiene and preventing the contact with
infected persons.
6.Match the pairs.
|
‘A’ group |
‘B’ group |
|
1. Rhizobium |
a. Food poisoning |
|
2. Clostridium |
b. Nitrogen fixation |
|
3. Penicillium |
c. Bakery products |
|
4. Yeast |
d. Production of antibiotics |
Answer:
1.
Rhizobium – b. Nitrogen fixation
2.
Clostridium – a. Food poisoning
3.
Penicillium – d. Production of antibiotics
4.
Yeast – c. Bakery products
7. Answer the following questions.
a. Which vaccines are given to infants? Why?
Answer:
Infants
have less resistance power to fight against diseases . They should be protected
from infectious diseases . Therefore they are given following vaccinations :
( 1 ) The BCG vaccine is given initially within first eight days after birth. B.C.G. vaccine protects infants against tuberculosis infections .
(
2 ) In third , fourth and fifth months they are given triple vaccine or DPT
which has vaccines against DPT – ( Diphtheria , Pertussis , Tetanus . )
(
3 ) At the same time they are also given oral dose of polio vaccine .
(
4 ) In ninth month babies are given combined MMR vaccine which is to get
protection against Mumps , Measles , Rubella .
(
5 ) School going children are given vaccines against typhoid and cholera .
Sometimes vaccination for prevention of hepatitis is also done .
b. How is a vaccine produced?
Answer:
(1)
For preparing vaccines , in olden days , microbes were injected in the bodies
of horses or monkeys . These laboratory animals used to make antibodies to
defend these microbes . Antibodies are . proteins which can act against the
disease causing germs . These antibodies were extracted from the blood of these
animals and were used as vaccines .
(2)
Now – a – days with the advent of biotechnology , the vaccines are manufactured
in laboratories with the help of bacteria . For this purpose , a detailed study
of the disease – causing germ is undertaken . The genes and the DNA of such
microbes are thoroughly explored . Then based on this information , proteins
which can act against such microbes are synthetically prepared in the
laboratories . The safe vaccine is produced in such a way which can defend the
body against infections .
(3)
Some types of vaccines are prepared from the extracts of germs . These germs or
microbes are deactivated and made dormant . When they are injected in the body
of a person , they initiate the defending action . The body of such vaccinated
person , already develops the antibodies in his or her body . When in future ,
this person is again attacked by similar germs the defence starts immediately
and the person does not become sick .
c. How do antibiotics cure disease?
Answer:-------------------
d. Are the antibiotics given to humans and animals the same? Why?
Answer:
Animals
are also affected by different kinds of diseases . They also catch infections
from bacteria , virus and fungi . Therefore , they are also given antibiotics
by veterinary doctor during their treatment . The bacteria infecting humans are
of different species than the pathogens animals , hence some of the antibiotics
are different . infecting Few , however , are similar to human antibiotics .
e.
Why is it necessary to safely store the pathogens of a disease against which
vaccines are to be produced?
Answer:
(1)
Now – a – days with the advent of biotechnology , the vaccines are manufactured
in laboratories with the help of bacteria . For this purpose , a detailed study
of the disease – causing germ is undertaken. The genes and the DNA of such
microbes are thoroughly explored . Then based on this information , proteins
which can act against such microbes are synthetically prepared in the
laboratories . The safe vaccine is produced in such a way which can defend the
body against infections .
(
2) Some types of vaccines are prepared from the extracts of germs. These germs
or microbes are deactivated and made dormant . When they are injected in the
body of a person , they initiate the defending action . The body of such
vaccinated person , already develops the antibodies in his or her body . When
in future , this person is again attacked by similar germs the defence starts
immediately and the person does not become sick.
8. Answer the following questions in brief.
a. What are ‘broad spectrum antibiotics’?
Answer:
The
antibiotics that are useful against a wide variety of bacteria are called broad
– spectrum,antibiotics . Sometimes there are visible symptoms of the disease
but the pathogen causing the disease cannot be identified . In such condition ,
broad spectrum antibiotics are used . E.g. ampicillin , amoxicillin ,
tetracycline , etc.
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b. What is fermentation?
Answer:
Conversion
of carbohydrates into alcohol and carbon dioxide in absence of oxygen is called
fermentation.
c. Define ‘Antibiotic’
Carbon compounds obtained from some bacteria and fungi which are used to destroy or prevent the growth of harmful microorganisms are called antibiotics.
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