MSBSHSE Class 8 Science Chapter 1 Living World and Classification of Microbes

Question 1: Use Whittaker method to classify bacteria, protozoa, fungi, algae, prokaryotic and eukaryotic microbes.

Answer: According to Robert Harding Whittaker, given below are the characteristic features of bacteria, protozoa, fungi, algae, prokaryotic and eukaryotic microbes:

1. Kingdom Monera

• As all the organisms are unicellular, there is absence of multicellular body designs.
• They may have either an autotrophic or heterotrophic mode of nutrition.
• These are prokaryotic cells without well-defined nucleus or cell organelles.
• All types of blue green algae and bacteria are included in this kingdom.

2. Kingdom Protista

• These are unicellular, eukaryotic organisms with a well-defined nucleus enclosed in a nuclear membrane.
• These organisms can be either autotrophic or heterotrophic.
• They have whip-like flagella or pseudopodia or hair-like cilia which helps in locomotion.

3. Kingdom Fungi

• They may be unicellular or multicellular, non-green, heterotrophic and eukaryotic organisms.
• Most of them are saprotrophs and they feed on dead organic matter.
• Some fungi are thread-like and most of the nuclei are present in the cytoplasm.
• Their cell walls are made up of complex and tough sugar called ‘Chitin’.
• Examples- Mushrooms, Baker’s yeast, Penicillium, Aspergillus (Fungus on corn).

4. Kingdom Plantae

• They are mainly multicellular and eukaryotic organisms.
• They are of non-motile nature.
• The plant cells mostly contain chlorophyll pigments and they are an autotrophic mode of nutrition.
• Their cell wall is composed of cellulose and not ‘Chitin’ like that of fungi.

5. Kingdom Animalia

• These organisms are multicellular eukaryotes.
• Absence of cell walls in these organisms.
• Absence of chloroplast in animal cells. They mostly have a heterotrophic mode of nutrition.

Question 2: Complete the five kingdom method of classification using living organism prokaryotes, eukaryotes, multicellular, unicellular, protista, animals, plants, fungi.

Answer:

Question 3: Find out my partner

A	B
Fungi	Chlorella
Protozoa	Bacteriophage
Virus	Candida
Algae	Amoeba
Bacteria	Prokaryotic

Answer:

A	B
Fungi	Candida
Protozoa	Amoeba
Virus	Bacteriophage
Algae	Chlorella
Bacteria	Prokaryotic

Question 4: State whether the following statements are true or false. Explain your statement.

a. Lactobacilli are harmful bacteria.

b. Cell wall of fungi is made up of chitin.

c. Organ of locomotion in amoeba is pseudopodia.

d. Tomato wilt is a viral disease.

Answer: a. Lactobacilli are harmful bacteria.- False

Lactobacilli are not harmful bacteria. They are mostly found in the gastrointestinal tracts of humans and animals. They are an important component of dairy products such as milk, yogurt, ghee, etc.

b. Cell wall of fungi is made up of chitin.- True

c. Organ of locomotion in amoeba is pseudopodia.- True

d. Tomato wilt is viral disease.- True

Question 5: Give answers:

a. State the merits of Whittaker’s method of classification.

b. Write the characteristics of viruses.

c. Explain the nutrition in fungi.

d. Which living organisms are included in the kingdom Monera?

Answer: a. Whitakker ’s method of classification has the following merits:

• Unicellular and multicellular organisms are kept and categorised separately.
• Autotrophic and heterotrophic modes of nutrition are placed in distinct groups.
• Fungi is a separate kingdom because of its mode of nutrition.
• It is more naturally segregated than classified under two kingdoms.
• Prokaryotes are unicellular organisms which are placed in Kingdom Monera.

b. The various characteristics of viruses are:

• They are extremely small in size and simpler than bacteria.
• They are ultra-microscopic, which are visible only with an electron microscope.
• They are considered to be the organisms which live at the edge of living and non-living things.
• They are dependent parasites which cannot survive on their own.
• They require a living organism to multiply as they cannot live on their own. .
• Viruses consist of genetic materials (DNA or RNA) which is surrounded by a protein coat (capsid).
• Viruses are responsible for causing severe fatal diseases in humans, plants, animals, etc.

c. Fungi are called saprophytes because of their mode of nutrition. It is a nutrition mode in which an organism obtains its nutrients from dead or decomposed organic matter.

d. Organisms with the following characteristics are included under the kingdom Monera:

• They have either autotrophic or heterotrophic modes of nutrition.
• There is an absence of nucleus and membrane-bound organelles in these organisms.
• There may either have presence or absence of cell walls
• As they are all unicellular organisms, they include bacteria and blue green algae.

Question 6: Who am I?

a. I don ’t have a true nucleus, cell organelles or plasma membrane.

b. I have nucleus and membrane bound cell organelles.

c. I live on decaying organic matter.

d. I reproduce mainly by cell division.

e. I can produce my replica.

f. I am green, but don ’t have organs.

Answer:

a. I don ’t have a true nucleus, cell organelles or plasma membrane. –Monera

b. I have nucleus and membrane bound cell organelles. –Protozoa

c. I live on decaying organic matter. –Fungi

d. I reproduce mainly by cell division.- Bacteria

e. I can produce my replica. –Viruses

f. I am green, but don ’t have organs. –Algae

Question 7: Draw neat and labelled diagrams.

a. Different types of bacteria

b. Paramoecium

c. Bacteriophage

Answer: Given below are the labelled diagrams:

a. Structure of bacteria and its different types

b.Paramoecium

c. Bacteriophage

Question 8: Arrange the following in ascending order of size Bacteria, Fungi, Viruses, Algae.

Answer: Viruses →Bacteria →Fungi→Algae

MSBSHSE Class 8 Science Chapter 1 Additional Questions

Question 1: What is Biological classification?

Answer: Biological classification is the process of dividing living organisms into groups and subgroups.

Question 2: How many species of living organisms are found on the earth?

Answer: There are around 87 million species of living organisms that are found on the earth which includes both land and sea.

Question 3: What are the different groups of classification of living organisms according to Whittaker?

Answer: Robert Harding Whittaker (1920-1980), an American Ecologist divided living organisms into 5 groups in 1969. These include:

1. Complexity of cell structure

2. Complexity of organisms

3. Mode of nutrition

4. Life style

5. Phylogenetic relationship

Question 4: Name the different categories of living world mentioned by Carl Linnaeus.

Answer: In 1735, Carl Linnaeus divided the living world in two kingdoms –

1. Vegetabilia

2. Animalia

Question 5: Mention the categories of kingdoms by Haeckel.

Answer: In 1866, Haeckel considered three kingdoms of living organisms –

1. Protista

2. Plants

3. Animals

Question 6: What are the different categories of living organisms created by Chatton?

Answer: In 1925 –Chatton created two groups of living organisms namely,

1. Prokaryotes

2. Eukaryotes

Question 7: What are the four kingdoms of living organisms mentioned by Kopland?

Answer: In 1938 Kopland divided living organisms into four kingdoms –

1. Monera

2. Protista

3. Plants

4. Animals

Question 8: In kingdom Monera, what are the different types of bacteria?

Answer: Different types of bacteria and blue green algae are found in the kingdom Monera. Tiny movable rod-like microbes called lactobacilli bacteria are found in this kingdom. These can be observed under a high power of compound microscope.

Question 9: Define Protista.

Answer: Protista are unicellular organisms with a well defined nucleus which are covered in a nuclear membrane. They have pseudopodia or hair-like cilia or whip-like flagella meant for locomotion.

Question 10: Explain the shape of living organisms in the Protista kingdom.

Answer: Living organisms in the Protista kingdom are motile microbes which have an irregular shape, which can be observed under a low power and high power microscope.

Question 11: Give examples of Autotrophs and Heterotrophs in the Protista kingdom.

Answer: Examples of Autotrophs are Euglena, Volvox that contain chloroplast.

Examples of Heterotrophs include Amoeba, Paramoecium, etc.

Question 12: Define Fungi.

Answer: Fungi are non-green, eukaryotic, heterotrophic organisms. They feed mostly upon dead organic matter. Examples- Baker’s yeast, Aspergillus (Fungus on corn), Penicillium, Mushrooms.

Question 13: What is Bacteria? How is it formed?

Answer: Bacteria are unicellular, independent or parasitic organisms. They usually reproduce by simple binary fission. They grow vigorously under favourable conditions and can double their number in a matter of 20 minutes.

Question 14: Define Protozoa. Where are they found?

Answer: Protozoa are unicellular organisms with eukaryotic cell. They are found in soil, fresh water and sea water. Some are also found in the body of other organisms and are pathogenic in nature. These organisms reproduce by simple cell division.

Question 15: Give some examples of Protozoa.

Answer: Some examples of Protozoa include:

1. Amoeba, Paramoecium which freely live in dirty water.

2. Entamoeba histolytica –This causes amoebiasis.

3. Plasmodium vivax –This causes malaria

4. Euglena –autotrophic

Question 16: How do Fungi reproduce?

Answer: Fungi are eukaryotic organisms that reproduce sexually and asexually by cell division or by budding.

Question 17: Give some examples of Fungi.

Answer: Some examples of Fungi include Baker ’s yeast, Candida, Mushroom, etc.

Question 18: Define a virus.

Answer: In microbiology, viruses are organisms that live at the edge of living and non livings. Virus is a long molecule of DNA (DeoxyriboNucleic Acid) or RNA (RiboNucleic Acid) which is surrounded by a protein coat.

Question 19: Where are Viruses found?

Answer: Viruses are extremely tiny, i.e. 10 to 100 times smaller than bacteria and can be viewed only under an electron microscope. They are found mostly as independent particles and multiple rapidly in living organisms.

Question 20: What is Algae? Give examples.

Answer: Algae are unicellular, eukaryotic, and autotrophic organisms which live in water. Some examples include Chlorella, Chlamydomonas, etc.

Question 21: Write the sizes of different microorganisms.

Answer: Given below are the sizes of different microorganisms:

1. Bacteria (size – 1 μm to 10 μm)

2. Protozoa (size –approximately 200 μm)

3. Fungi- (size- approximately 10 μm to 100 μm)

4. Algae- (size- approximately 10 μm to 100 μm)

5. Viruses-( size- approximately 10 nm to 100 nm)

Note:

1 meter = 10⁶ micrometer (μm)

1 meter = 10⁹ nanometer (nm)

Question 22: What is the criteria based on which Whittaker classified living organisms?

Answer: Whittaker’s classification of living organisms was done on the basis of the following criteria:

1. Complexity of cell structure: Prokaryotic and Eukaryotic

2. Complexity of organisms: Unicellular or Multicellular

3. Mode of nutrition: Plants –Autotrophic-Photosynthetic

Fungi- Saprophytic- Absorption from dead organisms

Animals- Heterotrophic and ingestive

4. Life style: Plants –Producers

Animals –Consumers

Fungi –Decomposers

5. Phylogenetic relationship: Prokaryotic to Eukaryotic, unicellular to multicellular

We hope that the above mentioned solutions of “MSBSHSE Class 8 Science Chapter 1 Living World and Classification of Microbes ” will help students build a strong foundation of the different concepts mentioned in the chapter.