Exercise
Fill in the
blanks
blanks
(a) Microorganisms can be seen with the help of a _ microscope _.
(b) Blue green algae fix __nitrogen _ directly from air to enhance
fertility of soil.
fertility of soil.
(c) Alcohol is produced with the help of _ yeast_.
(d) Cholera is caused by _ bacteria_.
2) Tick the
correct answer
correct answer
(a) Yeast is used
in the production of
in the production of
(i) Sugar
(ii) Alcohol
(iii) Hydrochloric
acid
acid
(iv) Oxygen
ANSWER- i) sugar
(b) The following
is an antibiotic
is an antibiotic
(i) Sodium bicarbonate
(ii) Streptomycin
(iii) Alcohol
(iv) Yeast
ANSWER:-(ii) Streptomycin
c)Carrier of
malaria-causing protozoan is
malaria-causing protozoan is
(i) female
Anopheles mosquito
Anopheles mosquito
(ii) cockroach
(iii) housefly
(iv) butterfly
ANSWER:-(i)
female Anopheles mosquito
female Anopheles mosquito
d)The most common
carrier of communicable diseases is
carrier of communicable diseases is
(i) ant
(ii) housefly
(iii) dragonfly
(iv) spider
ANSWER:-(ii) housefly
e) The bread or
idli dough rises because of
idli dough rises because of
(i) heat
(ii) grinding
(iii) growth of
yeast cells
yeast cells
(iv) kneading
ANSWER:-(iii) growth of
yeast cells
yeast cells
f) The process of
conversion of sugar into alcohol is called
conversion of sugar into alcohol is called
(i) nitrogen
fixation
fixation
(ii) moulding
(iii)
fermentation
fermentation
(iv) infection
ANSWER:-iii) fermentation
3) Match the
organisms in Column I with their action in Column II.
organisms in Column I with their action in Column II.
Column I. Column II
(i) Bacteria a)
Fixing nitrogen
Fixing nitrogen
(ii) Rhizobium b)
Setting of curd
Setting of curd
(iii) Lactobacillus. (c) Baking of bread
(iv) Yeast d)
Causing malaria
Causing malaria
(v) A protozoan (e)
Causing choler
Causing choler
(vi) A virus f)
Causing AIDS
Causing AIDS
(g)
Producing antibodies
Producing antibodies
ANSWER:-
i———e
ii———a
iii———b
iv———c
v———–d
vi———-f
4) Can
microorganisms be seen with the naked eye? If not, how can they be seen?
microorganisms be seen with the naked eye? If not, how can they be seen?
ANSWER:-Micro-organisms
are too small to be seen through naked eyes. They can be seen with the help of
a magnifying glass or microscope.
are too small to be seen through naked eyes. They can be seen with the help of
a magnifying glass or microscope.
5) What are the
major groups of microorganisms?
major groups of microorganisms?
ANSWER:-There
are five major groups of micro-organisms:
are five major groups of micro-organisms:
(i) Bacteria − They are single celled
disease -causing micro-organisms. They can be spiral or rod- shaped.
disease -causing micro-organisms. They can be spiral or rod- shaped.
(ii) Fungi − They are mostly multicellular
disease-causing microbes. Bread moulds are common
examples of fungi.
disease-causing microbes. Bread moulds are common
examples of fungi.
(iii) Protozoa − They mainly include
organisms such as Amoeba, Plasmodium,etc. They can be unicellular ormulticellular.
organisms such as Amoeba, Plasmodium,etc. They can be unicellular ormulticellular.
(iv) Virus −Viruses are disease-causing
microbes that reproduce only inside the host organism.
microbes that reproduce only inside the host organism.
(v) Algae − They include multicellular,
photosynthetic organisms such as Spirogyra, Chlamydomonas,
etc.
photosynthetic organisms such as Spirogyra, Chlamydomonas,
etc.
6) Name the
microorganisms which can fix atmospheric nitrogen in the soil.
microorganisms which can fix atmospheric nitrogen in the soil.
ANSWER:-Bacteria
such as Rhizobium and certain blue- green algae present in
the soil can fix atmospheric nitrogen
such as Rhizobium and certain blue- green algae present in
the soil can fix atmospheric nitrogen
7) Write 10 lines
on the usefulness of microorganisms in our lives.
on the usefulness of microorganisms in our lives.
ANSWER: –Importance of micro-organisms:
Lactobacillus is
used to form curd from milk.
used to form curd from milk.
Rhizobiums present
in the roots of pulse plants fix nitrogen from air and supply nitrogen
compounds to the pulse plants. They are used in winemaking, baking, pickling,
and other food making processes.
in the roots of pulse plants fix nitrogen from air and supply nitrogen
compounds to the pulse plants. They are used in winemaking, baking, pickling,
and other food making processes.
Microbes also play
an important role in the
preparation of medicines. Antibiotics are chemicals
produced by micro-organisms to kill bacteria.
an important role in the
preparation of medicines. Antibiotics are chemicals
produced by micro-organisms to kill bacteria.
Alcoholic
fermentation by yeast is widely used in the preparation of wine and bread.
fermentation by yeast is widely used in the preparation of wine and bread.
Bacteria present in
our intestine helps in proper digestion and release Vitamin B which is absorbed
by intestine.
our intestine helps in proper digestion and release Vitamin B which is absorbed
by intestine.
Yeast is used in
making idlis, bread, pastries and cakes.
making idlis, bread, pastries and cakes.
8) Write a short
paragraph on the harms caused by microorganisms.
paragraph on the harms caused by microorganisms.
ANSWER:-Micro-organisms cause diseases in animals.
For example, in humans, bacteria cause diseases such as tuberculosis, cholera,
typhoid, etc. In cattle, the foot and mouth disease is caused by a virus. Also,
several microbes cause diseases in plants. For
example, the productivity of wheat, orange, apple,
etc. is reduced due to microbial diseases in plants. Certain microbes, on
entering into our body, produce toxic
substances. This leads to food poisoning. Some micro- organisms such as fungus
spoil our food.
For example, in humans, bacteria cause diseases such as tuberculosis, cholera,
typhoid, etc. In cattle, the foot and mouth disease is caused by a virus. Also,
several microbes cause diseases in plants. For
example, the productivity of wheat, orange, apple,
etc. is reduced due to microbial diseases in plants. Certain microbes, on
entering into our body, produce toxic
substances. This leads to food poisoning. Some micro- organisms such as fungus
spoil our food.
9) What are
antibiotics? What precautions must be taken while taking antibiotics?
antibiotics? What precautions must be taken while taking antibiotics?
ANSWER:-Antibiotics
are medicines produced by certain micro- organisms to kill other disease-causing micro- organisms.
are medicines produced by certain micro- organisms to kill other disease-causing micro- organisms.
Precautions to be taken while using antibiotics:
(i) Antibiotics
should be taken under the supervision of a well qualified doctor.
should be taken under the supervision of a well qualified doctor.
(ii) Course
(intake) of antibiotics should be completed as per the prescription given by
the doctor.
(intake) of antibiotics should be completed as per the prescription given by
the doctor.
(iii) Antibiotics
should be taken in the right amount and at the right time. A wrong dose of
antibiotics makes the drug ineffective. Also, excessive
consumption of drugs may kill the useful bacteria present in our body.
should be taken in the right amount and at the right time. A wrong dose of
antibiotics makes the drug ineffective. Also, excessive
consumption of drugs may kill the useful bacteria present in our body.