Bacteria

They are very small,single-celled micro-organism which have cell wall but do not have an organises nucleus and other structures.

For Example:Lactobacillus,Rhizobium.

Some of the diseases cause by bacteria are cholera,typhoid,tuberculosis,diphtheria etc.

Viruses

They are the smallest micro-organism which can develop only inside the cells of the host organism .

Viruses can reproduce and multiply only inside the cells of other organism .They are the agents of diseases.

The diseases caused by virus are common cold, influenza,measles,polio,chicken pox,small pox etc.

For Example:HIV(Human Immuno deficiency) virus causes AIDS, Common cold virus, Corona (COVID-19)

Bacteria

They are very small,single-celled micro-organism which have cell wall but do not have an organises nucleus and other structures.

For Example:Lactobacillus,Rhizobium.

Some of the diseases cause by bacteria are cholera,typhoid,tuberculosis,diphtheria etc.

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Groups of Micro-organism

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Question 1 What is the name of micro-organism which reproduce only inside the living cells of other organism?

Question 2 What are the major groups of micro-organism?

Question 3 Name any 2 diseases caused by bacteria?

Question 4 Name any 2 diseases caused by virus?

Question 5 Name any 2 diseases caused by algae?

Question 6 Name any 2 diseases caused by fungi?

Question 7 Name any 2 diseases caused by protozoa?

Question 8 What is the full form of HIV?Name the disease caused by HIV?

Question 9 Name any 2 bacteria?

Question 10 Name any 2 virus?

Question 11 Name any 2 fungi?

Question 12 Name any 2 protozoa?

Question 13 Name any 2 algae?

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Contents [<a href="https://classnotes.org.in/class-8/micro-organismfriend-and-foe/groups-of-micro-organism/#">hide</a>]

• <a href="https://classnotes.org.in/class-8/micro-organismfriend-and-foe/groups-of-micro-organism/#Groups_of_micro-organism">1 Groups of micro-organism</a>
• <a href="https://classnotes.org.in/class-8/micro-organismfriend-and-foe/groups-of-micro-organism/#Bacteria">2 Bacteria</a>
• <a href="https://classnotes.org.in/class-8/micro-organismfriend-and-foe/groups-of-micro-organism/#Viruses">3 Viruses</a>
• <a href="https://classnotes.org.in/class-8/micro-organismfriend-and-foe/groups-of-micro-organism/#Protozoa">4 Protozoa</a>
• <a href="https://classnotes.org.in/class-8/micro-organismfriend-and-foe/groups-of-micro-organism/#Algae">5 Algae</a>
• <a href="https://classnotes.org.in/class-8/micro-organismfriend-and-foe/groups-of-micro-organism/#Fungi">6 Fungi</a>

Groups of micro-organism

Micro-organism are classified into 5 major groups:

1)Bacteria

2)Viruses

3)Protozoa

4)Algae

5)Fungi

Bacteria

They are very small,single-celled micro-organism which have cell wall but do not have an organises nucleus and other structures.

For Example:Lactobacillus,Rhizobium.

Some of the diseases cause by bacteria are cholera,typhoid,tuberculosis,diphtheria etc.

Viruses

They are the smallest micro-organism which can develop only inside the cells of the host organism .

Viruses can reproduce and multiply only inside the cells of other organism .They are the agents of diseases.

The diseases caused by virus are common cold, influenza,measles,polio,chicken pox,small pox etc.

For Example:HIV(Human Immuno deficiency) virus causes AIDS, Common cold virus, Corona (COVID-19)

1. The first method advocates the use of mosquito nets and mosquito repellent such as permethrin to prevent mosquitoes from biting.
2. The second form of treatment uses a chemical called Quinine present in the bark of a cinchona tree. A form of drug chloroquine has proven very effective against malaria even though it is not a vaccine.

Methods of preventing malaria are:
(i) Use of insect repellants to prevent mosquito bite.
(ii) Wire-gauzing of "doors, windows and ventilators to check the entry of mosquitoes into the houses.
(iii) Periodic spray of insecticides (e.g.,  D.D.T. and B.H.C) to kill adult mosquitoes as well as spray of kerosene oil or insecticides on ponds, ditches etc. to kill the larvae.
(iv) Introducing larvivorous fishes (e.g., Gambusia, minnows, trouts) in water bodies. These fishes feed on mosquito larvae.

1. “By” is used in the passive voice when the actor needs to know the job.
   Example: “Love addicted” was sung by Vamps.
2. Passive voice is used if it doesn’t need to know the perpetrator work.
   Example: the streets are cleaned everyday
3. Passive voice is used if we don’t know or forget who the perpetrator work.
   Example: The police was murdered.
4. Passive voice is used if we are more interested in the job than the actors who work.
   Example: A new departmental store is being built.
5. Passive voice is used to avoid an awkward sentence or inappropriate with grammar.
   Example: When she arrived home a police arrested her — it’s better: when she arrived home she was arrested (by a police).

The places of subject and object are interchanged i.e. the object shifts to the place of subject and subject shifts to the place of object in passive voice.

Example:

• Active voice: I write a letter.
• Passive voice: I letter is written by me.

Subject (I) of sentence shifted to the place of object (letter) and object (letter) shifted to the place of subject (I) in passive voice.

बस देखने में अत्यधिक पुरानी व खस्ता हालत में थी। उसे देखकर ही लग रहा था कि वह बैठने की हालत में भी नहीं है। इसलिए लेखक ने उसे वयोवृद्ध कहा। उसका तो यह भी मानना था कि अगर हम इस पर सवार होंगे तो इसे कष्ट होगा।

Preparation of soil: Soil is prepared before sowing the seeds. The soil is loosened to increase the absorption of water and manures. Loosening of soil particles adds humus and nutrients in the soil that increases crop yields. Tilling or loosening the soil is done by ploughs which are pulled by a pair of bulls.

Sound needs a material medium like solid ,liquid or gas to travel and be heard because the molecules of solid, liquid and gases carry sound waves from one place to another. Sound cannot travel through vacuum or empty space because vacuum has no molecules which can vibrate and carry sound waves.

The sound is produced by vibrating objects. They travel from one place to another in the form of waves. Hence, the name sound waves.

Periodise refers to dividing history/events into different periods or time frame .We may give example of how James Mill divided Indian History into three distinct periods or phases that is Hindu, Muslims and the British period. 

p⁴ – (p + q)4

= (p²)² – [(p + q)²]²

=[p² - (p+q)²][p² + (p+q)²]

= {[p -(p+q)][p +(p+q)]}[p² + p² + q² + 2pq]

= {[p -p- q)][p +p+q]}[2p² + q² + 2pq]

= { - q)[2p+q]}[2p² + q² + 2pq]