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

Karnataka Board Class 8 Science Chapter 7 The World of Microbes

KSEEB Class 8 Science Chapter 7 Textual Questions & Answers

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

Question 1.
One of the following does not belong to the group
(1) Aspergillus Niger
(2) Clostridium tetani
(3) Staphylococcus aureus
(4) Vibrio cholera.
Answer:
1. Aspergillus Niger

Question 2.
The locomotory structure of amoeba is
(a) cilia
(b) flagella
(c) pseudopodia
(d) tentacle
Answer:
pseudopodia

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

II. Fill in the blanks.

Question 1.
……………….. was considered the father of microbiology.
Answer:
Louis Pasteur

Question 2.
Malaria is caused by ……………
Answer :
Plasmodium

Question 3.
Vibrio is ……………. shaped bacteria.
Answer:
comma.

III. Answer the following:

Question 1.
What are micro-organisms?
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 that has an outermost layer called a cell wall and an inner cell membrane called the plasma membrane. The plasma membrane encloses the cytoplasm which contains the genetic material of a bacterium that is not enclosed by a nuclear membrane. There is a layer external to the cell wall called the capsule the capsule will be thicker if it is pathogenic (disease-causing bacteria). In addition, the bacterial cells have flagella which help in movement.

Question 3.
Draw a diagram of a typical bacillus and label the parts.

Question 4.
How can the transmission of cholera be prevented?
Answer:
Cholera can be prevented by

1. Avoid being close to infected people
2. Do not touch the nose and eye with contaminated hands.

Question 5.
What are the vaccines?
Answer:
A Vaccine is an agent that resembles a disease-causing micro-organism which is often made from weakened or killed forms of the microbe or its toxins by the immunity is developed against a particular disease.

KSEEB Class 8 Science Chapter 7 Additional Questions & Answers

Question 1.
What are micro-organisms? Give example.
Answer:
The organisms which cannot be seen with our naked eyes are called microorganisms.
Ex: Virus, Bacteria, unicellular organisms.

Question 2.
What is oil immersion?
Answer:
Oil immersion is a technique used to increase the resolution of a microscope

Question 3.
Who established the theory of biogenesis?
Answer:
Louis Pasteur established the theory of biogenesis.

Question 4.
Name the different shapes of bacteria.
Answer:
The different shapes of bacteria are
Bacillus – Rod-shaped bacteria
Cocci – Spherical shaped bacteria
Vibrio – Comma shaped bacteria
Spirilli – Spirally coiled shaped bacteria.

Question 5.
What is meant by bacteriophage?
Answer:
A group of viruses which infect bacteria. These are called bacteriophages. Bacteriophage is a virus.

Question 6.
Draw a neat labelled diagram of bacteriophage.

Question 7.
Explain the structure of bacteriophage.
Answer:
A bacteriophage has a head region containing the genetic material. The genetic material of a bacteriophage is DNA. The collar region contains a protein sheath.

Question 8.
Draw a neat labelled diagram Amoeba.
Answer:

Question 9.
Explain the structure of amoeba.
Answer:
Amoeba is included under the kingdom Protista. It is a protozoan. Amoeba has an external membrane called the cell membrane organelles like mitochondria and vacuole is found in the cytoplasm. The cell membrane allows materials to diffuse in and out of the cell.
Amoeba moves with the help of pseudopodia food are digested in the food vacuole contractile vacuole helps in excreting excess water and wastes.

Question 10.
Draw a neat labelled diagram of Chlamydomonas.
Ans.

Question 11.
Explain the structure of Chlamydomonas.
Answer:
Chlamydomonas is a unicellular free-living algae. The cell is oval 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 complex contractile vacuoles etc. It moves with help of flagella.

Question 12.
List the uses of microorganisms.
Answer:3

Uses of Microorganisms are,

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

Question 13.
Write short on harmful microorganisms.
Answer:

Some microorganisms are harmful too.

1. They Spoil food
2. They also cause diseases in plants and animals

Question 14.
Mention the symptoms of Influenza. How is it caused? What is made of transmission?
Answer:

1. Influenza is caused by the influenza virus
2. It is spread through Air, Contaminated handkerchiefs.
3. The symptoms are chills, fever, sore, throat, cough, muscle pains, severe headache.

Question 15.
Mention the symptoms of cholera. How did it cause? What is made of transmission?
Answer:

1. Cholera is caused by Vibrio cholera
2. It is spread through contaminated water and food
3. The symptoms are vomiting, diarrhea, dehydration, stomach pain.

Question 16.
Mention the symptoms of Malaria. How is it caused? What is made of transmission?
Answer:

1. Malaria is caused by plasmodium viva x.
2. It is spread through the bite of female anopheles mosquitoes.
3. The symptoms are recurring fever, chills, headache, muscle pain, tiredness, stomach pain, nausea, vomiting.

Question 17.
What are the symptoms of Aspergillosis? How is it caused? What is made of transmission?
Answer:

1. Aspergillosis is caused by Aspergillus Niger
2. It is spread by inhaling spores of aspergillus Niger
3. The symptoms are cough, fever, chest pain, and difficulty in breathing.

KSEEB Solutions for Class 8 Science