KSEEB Solutions for Class 8 Science Chapter 7 The World of Microbes

Students can Download Science Chapter 7 The World of Microbes Questions and Answers, Notes Pdf, KSEEB Solutions for Class 8 Science helps you to revise the complete Karnataka State Board Syllabus and to clear all their doubts, score well in final exams.

Karnataka State Syllabus Class 8 Science Chapter 7 The World of Microbes

KSEEB Class 8 Science The World of Microbes Textbook Exercise Questions and Answers

I. Four alternatives are given to each of the following incomplete statements/questions. Choose the right answer:

Question 1.
One of the following does not belong to the group
(a) Aspergillus niger
(b) Clostridium tetani
(c) Staphylococcus aureus
(d) Vibrio cholerae
Answer:
(a) Aspergillus niger

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Question 2.
The locomotory structure of amoeba is
(a) cilium
(b) flagellum
(c) pseudopodium
(d) tentacle
Answer:
(c) pseudopodium

Question 3.
Chlorophyll is present in
(a) Chlamydomonas
(b) Mushroom
(c) yeast
(d) Aspergillus
Answer:
(a) Chlamydomonas

II. Fill in the blanks with suitable words:

Question:

  1. _______ was considered as the father of microbiology
  2. Malaria is caused by _______.
  3. Vibrio are _______ shaped bacteria.

Answers:

  1. Louis Pasteur
  2. Plasmodium vivax
  3. comma

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III. Answer the following:

Question 1.
What are microorganisms?
Answer:
The organisms which cannot be seen with our naked’ eyes are called microorganisms.

Question 2.
Explain the structure of a typical bacillus.
Answer:
A bacterium is a prokaryotic cell with an outermost layer called a cell wall and an inner cell membrane called the plasma membrane. The plasma membrane encloses cytoplasm which contains genetic material DNA and ribosomes. There is a layer external to the cell wall called a capsule. The capsule will be thicker if it is pathogenic. In addition, the bacterial cells have flagella which help in movement.

Question 3.
Draw a diagram of a typical bacillus and label the parts.
Answer:
KSEEB Solutions for Class 8 Science Chapter 7 The World of Microbes 1

Question 4.
How can the transmission of cholera be prevented?
Answer:
Cholera can be prevented by avoiding eating and drinking unhygienic food and water, and by vaccinating against cholera.

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Question 5.
What are the vaccines?
Answer:
A vaccine is an agent that resembles a disease-causing micro-organism which is prepared from weakened or killed forms of the microbes or its toxins. Immunity is developed against that particular disease.

KSEEB Class 8 Science The World of Microbes Additional Questions and Answers

I. Answer the following:

Question 1.
What is meant by oil immersion?
Answer:
Oil immersion is a technique used to increase the resolution of a microscope.

Question 2.
Write a short note on Amoebans?
Answer:
Amoeba is included under the kingdom Protistans. It is a free-living protozoan. It has an external membrane called the cell membrane, which encloses cytoplasm and nucleus and organelles like mitochondria and food vacuole, which helps in the food storage and contractile vacuole, which helps in excretion. It moves with the help of pseudopodia.

Question 3.
Explain the structure of Chlamydomonas.
Answer:
Chlamydomonas is a unicellular eukaryotic free-living algae. The cell is ova! in shape and surrounded by a definite cell wall made up of cellulose. The cell has a large cup-shaped chloroplast. The cytoplasm contains the organelle like mitochondria, Golgi apparatus, contractile vacuoles, etc. It moves with the two flagella present on the anterior side of the cell.

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Question 4.
Mention the uses of microorganisms.
Answer:
Most of the microorganisms are useful to us in various ways.

  1. Microorganisms are used in food industry, leather industry, dairy industry, pharmaceuticals, water treatment plants, and even in sewage treatment.
  2. They play a very important role in agriculture.
  3. They are also responsible for the decomposition of dead and decaying substances.

Question 5.
What are the symptoms of cholera? How is it caused? What is the mode of transmission?
Answer:
Cholera is caused by Vibrio cholera It is spread through contaminated water and food. The symptoms are vomiting diarrhea, dehydration, stomach pain, etc.

Question 6.
Write the symptoms of Malaria.
Answer:
Recurring fever, chills, headache, muscle pain, tiredness, nausea, and vomiting are the symptoms of Malawians.

Question 7.
Draw a neat labeled diagram to show the structure of Bacteriophage.
Answer:
KSEEB Solutions for Class 8 Science Chapter 7 The World of Microbes 2

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Question 8.
Draw a neat labeled diagram of HIV.
Answer:
KSEEB Solutions for Class 8 Science Chapter 7 The World of Microbes 3

Question 9.
Draw a neat labeled diagram of Amoeba.
Answer:
KSEEB Solutions for Class 8 Science Chapter 7 The World of Microbes 4

Question 10.
Draw a neat labeled diagram of Chlamydomonas
Answer:
KSEEB Solutions for Class 8 Science Chapter 7 The World of Microbes 5

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II. Fill in the blanks:

  1. The bacteria present in curds is _______.
  2. Louis Pasteur proved that life arises from pre-existing life itself by his famous _______ experiment.
  3. The layer external to the cell wall of a bacteria is called _______.
  4. The viruses which infect bacteria are _______.
  5. HIV causes _______.

Answers:

  1. Lactobacilli
  2. Swan neck flask experiment,
  3. Capsule
  4. Bacteriophage,
  5. Aids

III. Match the following:

A – B
1. Rod-shaped – (a) vibrio
2. Spherical – (b) spills
3. Comma shaped – (c) cocci
4. Spiral shaped – (d) bacillus
Answer:
1 – d,
2 – c,
3 – a,
4 – b

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A – B
1. Edward Jenner – (a) tuberculosis
2. Locus Pasteur – (b) Penicillin
3. Joseph Lister – (c) Rabies
4. Robert Koch – (d) smallpox
5. Alexander Fleming – (e) antiseptics
Answer:
1. d
2. c
3. e
4. a
5. b

IV. Choose the best alternative:

Question 1.
Aspergillus niger belongs to the group
(a) virus
(b) bacteria
(c) fungi
(d) protozoa
Answer:
(c) fungi

Question 2.
The disease spread by the bite of female anopheles mosquitoes is
(a) Malaria
(b) Cholera
(c) Plague
(d) Mumps
Answer:
(a) Malaria

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Question 3.
The genetic material of HIV
(a) DNA
(b) RNA
(c) RTE
(d) DNA and RNA
Answer:
(b) RNA

Question 4.
Which one of the following is not true.
(a) Microbes are invisible to the naked eye.
(b) Microbes can be seen through a microscope
(c) Microbes are never useful
(d) Microbes are seen everywhere
Answer:
(c) Microbes are never useful

Question 5.
The capsule is the covering found in
(a) Protozoan
(b) Virus
(c) Bacteria
(d) Fungi
Answer:
(c) Bacteria

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Question 6.
Bacteria do not have
(a) Mitochondria,
(b) lysosome
(c) chloroplast
(d) all the above
Answer:
(d) all the above

Question 7.
Contractile vacuole found in amoeba helps in
(a) respiration
(b) circulation
(c) digestion
(d) Excretion
Answer:
(d) Excretion

Question 8.
The only single-celled fungus is
(a) Mushroom
(b) yeast
(c) Bread mold
(d) Penicillium
Answer:
(b) yeast

Question 9.
The cup-shaped chloroplast is present in
(a) Chlamydomonas
(b) yeast
(c) Euglena
(d) Bluegreen algae
Answer:
(a) Chlamydomonas

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Question 10.
The bacteria which increases the fertility of the soil is
(a) Chlamydomonas
(b) Rhizobium
(c) Euglena
(d) Aspergillus
Answer:
(b) Rhizobium