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Exercise Questions (1)fill in the blanks (a) Microorganisms can be seen with the help of a ____________. (b)Blue green algae fix __________ directly from air and enhance fertility of soil. (c) Alcohol is produced with the help of _____________. (d)Cholera is caused by ____________. Solutions:a-microscope b-Nitrogen c-yeast d-bacteria

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Khushi Rawat 4 years, 1 month ago

Exercise Questions 1. Fill in the blanks. (a) Microorganisms can be seen with the help of a ____________. (b) Blue green algae fix __________ directly from air and enhance fertility of soil. (c) Alcohol is produced with the help of __________. (d) Cholera is caused by __________. Soln: a) Microscope b) Nitrogen c) Yeast d) Bacteria- Vibrio cholera 2. Tick the correct answer. (a) Yeast is used in the production of (i) sugar (ii) alcohol (iii) hydrochloric acid (iv) oxygen (b) The following is an antibiotic (i) Sodium bicarbonate (ii) Streptomycin (iii) Alcohol (iv) Yeast (c) Carrier of malaria-causing protozoan is (i) female Anopheles mosquito (ii) cockroach (iii) housefly (iv) butterfly (d) The most common carrier of communicable diseases is (i) ant (ii) housefly (iii) dragonfly (iv) spider (e) The bread or idli dough rises because of (i) heat (ii) grinding (iii) growth of yeast cells (iv) kneading (f) The process of conversion of sugar into alcohol is called (i) nitrogen fixation (ii) moulding (iii) fermentation (iv) infection Soln: a) (ii) alcohol b) (ii) Streptomycin c) (i) female Anopheles mosquito d) (ii) housefly e) (iii) growth of yeast cells f) (iii) fermentation 3. Match the organisms in Column A with their action in Column B. AB(i) Bacteria(a) Fixing nitrogen(ii) Rhizobium(b) Setting of curd(iii) Lactobacillus(c) Baking of bread(iv) Yeast(d) Causing malaria(v) A protozoan(e) Causing cholera(vi) A virus(f) Causing AIDS(g) Producing antibodies Sol:- AB(i) Bacteria(e) Causing cholera(ii) Rhizobium(a) Fixing nitrogen(iii) Lactobacillus(b) Setting of curd(iv) Yeast(c) Baking of bread(v) A protozoan(d) Causing malaria(vi) A virus(f) Causing AIDS 4. Can microorganisms be seen with the naked eye? If not, how can they be seen? Soln: Microorganisms cannot be seen by the naked eye because they are very small. They can be seen by using a microscope. 5. What are the major groups of microorganisms? Soln: Major group of microorganisms are as follows Bacteria Fungi Protozoans Algae Viruses 6. Name the microorganisms which can fix atmospheric nitrogen in the soil. Soln: Rhizobium 7. Write 10 lines on the usefulness of microorganisms in our lives. Soln: Uses of microorganisms are listed below They are helpful in cleaning up of the environment. For example, the organic wastes (vegetable peels, remains of animals, faeces, etc.) are broken down into harmless and usable substances by bacteria. Curd contains several microorganisms. Of these, the bacterium, Lactobacillus promotes the formation of curd. It multiplies in milk and converts it into curd. Bacteria are also involved in the making of cheese, pickles and many other food items. Bacteria and yeast are also helpful for fermentation of rice idlis and dosa batter. Yeast reproduces rapidly and produces carbon dioxide during respiration. Bubbles of the gas fill the dough and increase its volume. This is the basis of the use of yeast in the baking industry for making breads, pastries and cakes. Microorganisms are used for the large scale production of alcohol, wine and acetic acid (vinegar). Antibiotics are being produced from bacteria and fungi. Microorganisms are helpful in producing vaccines against disease-causing agents. Some bacteria (Fig. 2.7) are able to fix nitrogen from the atmosphere to enrich the soil with nitrogen and increase its fertility. Microorganisms decompose dead organic waste of plants and animals to convert them into simple substances. These substances are again used by other plants and animals. Thus, microorganisms can be used to degrade the harmful and smelly substances and thereby clean up the environment. 8. Write a short paragraph on the harmful effects of microorganisms. Soln: Microorganisms cause diseases in plants and animals Ex; Cholera in humans is caused by bacteria called Vibrio cholera. In animals, the virus causes foot and mouth diseases. Microorganisms spoil the foods by decomposing the food material. Some microorganisms spoil leather and clothes. Microorganisms are responsible for food poisoning. 9. What are antibiotics? What precautions must be taken while taking antibiotics? Soln: Chemical agents that kill or stop the growth of disease-causing microorganisms are called antibiotics. Antibiotics should be taken only on the advice of a qualified doctor. Also, one must complete the course prescribed by the doctor.

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In which direction does the atmospheric pressure acts in the below figure? 1 point downward upward both directions

Posted by Gbs Reddy 4 years, 1 month ago

CBSE > Class 08 > Science

1 answers

Yuvraj Yadav 4 years, 1 month ago

I don't the answer

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What types of organs

Posted by Sahil Alvi 4 years, 1 month ago

CBSE > Class 08 > Science

3 answers

Harnoor Singh Kamboj 4 years, 1 month ago

Ch 2 microorganism all questions answer soluid

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Harnoor Singh Kamboj 4 years, 1 month ago

Microorganisms

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Mannat Verma 4 years, 1 month ago

Igtegumentary Skeletal Muscular Urinary Digestive

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What is Irrigation method

Posted by Shreya Bagry 4 years, 1 month ago

CBSE > Class 08 > Science

1 answers

Mannat Verma 4 years, 1 month ago

Irrigation is the process of applying water to soil, primarily to meet the water needs of growing plants. Water from rivers, reservoirs, lakes, or aquifers is pumped or flows by gravity through pipes, canals, ditches or even natural streams. ... The three main methods of irrigation are surface, sprinkler and drip/micro.

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What are the major grops of microorganisms?

Posted by Khanak Paliwal 4 years, 1 month ago

CBSE > Class 08 > Science

5 answers

Khanak Paliwal 4 years ago

Thanks

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Pavitra Patel 4 years, 1 month ago

Bacteria, fungi ,algae, protozoa,viruses

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Abhijith Reddy 4 years, 1 month ago

Bacteria. Fungi. Protozoa. Algae

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Khushee Bhogayta 4 years, 1 month ago

Alage Fungi Protozoa Bacteria Viruses

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Logith Arun 4 years, 1 month ago

Algae, fungi, protozoa, bacteria.

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What is drip irrigation system?

Posted by Gideon Ganta 4 years, 1 month ago

CBSE > Class 08 > Science

2 answers

Shreya Dubey 4 years, 1 month ago

In this system, the water falls drop by drop directly near the roots.So it is called drip system

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Ronak Choudhary 4 years, 1 month ago

Dirp irrigation is the process in which water go drop by drop in the roots of the plant

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Write different ways of storing crop production?

Posted by Aditi Katre 4 years, 1 month ago

CBSE > Class 08 > Science

1 answers

Khushee Bhogayta 4 years, 1 month ago

Storing in mills and silos.

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In which season kharif crop is harvested?

Posted by Yashica Shree Shree 4 years, 1 month ago

CBSE > Class 08 > Science

5 answers

Kavya Dixit 4 years, 1 month ago

During Rainy season

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Rajni Maheshwari 4 years, 1 month ago

Rainy season is most suitable season for harvesting Rabi crops.During this period the crops are ready to cut and then

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Pavitra Patel 4 years, 1 month ago

In rainy season kharif crop is harvested and in the month of june to September

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Khushee Bhogayta 4 years, 1 month ago

June to October

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Preetam Lamani 4 years, 1 month ago

In rainy season kharif crop harvested

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How the water get ice

Posted by Yash Shukla 4 years, 1 month ago

CBSE > Class 08 > Science

3 answers

Khushee Bhogayta 4 years, 1 month ago

Due to coolnrss

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Pratik Rathod 4 years, 1 month ago

Due to the process of freezing

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Vaibhav Parmar 4 years, 1 month ago

Windowing

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For growing crops we need

Posted by Insha Momin 4 years, 1 month ago

CBSE > Class 08 > Science

3 answers

Sushree Sahoo 4 years, 1 month ago

For growing crop we need field seed nutrients sunlight temperature and water

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Pratik Rathod 4 years, 1 month ago

A good felid is neccesary

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Yash Shukla 4 years, 1 month ago

All thing that need to grow seed

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What is formula of water

Posted by Rajesh Kumar 4 years, 1 month ago

CBSE > Class 08 > Science

5 answers

Sushree Sahoo 4 years, 1 month ago

H2o is the formula of water

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Riya Patel 4 years, 1 month ago

H2o

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Kavya Dixit 4 years, 1 month ago

H2O

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Jeevana Dharma 4 years, 1 month ago

H2o

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Rajesh Kumar 4 years, 1 month ago

H2o

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The charge acquired by a glass rod when it is rubbed with silk is................... A)positive charge B) negative charge C)both

Posted by Anshika Aggarwal 4 years, 1 month ago

CBSE > Class 08 > Science

1 answers

Akanksha Patel 4 years, 1 month ago

after rubbing, the glass rod becomes positively charged and the silk gets negative charge

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What is Cell Meambrane

Posted by Shivam Thakkar 4 years, 1 month ago

CBSE > Class 08 > Science

2 answers

Sia ? 4 years, 1 month ago

The cell membrane is a biological membrane that separates the interior of all cells from the outside environment which protects the cell from its environment. The cell membrane consists of a lipid bilayer, including cholesterols that sit between phospholipids to maintain their fluidity at various temperatures.

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Vizzy Viz 4 years, 1 month ago

The outer covering of cell which protects it from being damaged is known as cell membrane. Cell membrane is also known as plasma membrane

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Distinguish between metals and non - metals on the basic of yheir physical properties

Posted by Kusuma S 4 years, 1 month ago

CBSE > Class 08 > Science

1 answers

Sia ? 4 years, 1 month ago

Metals	Nonmetals
Metals are very hard except for sodium.	Non metals are soft except for diamonds.
Metals are generally malleable and ductile.	Non metals are generally brittle and can break down into smaller pieces.
They are shiny and lustrous.	They are not shiny and are non lustrous except iodine.
They are electropositive in nature.	They are electronegative in nature.
Metals are good conductors of heat and electricity.	Non metals are generally bad conductors of heat and electricity except graphite.
They are used in machinery. Example: Copper, silver, gold etc.	They have medicinal and chemical uses. Example: carbon, oxygen, sulphur etc.

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Under the effect of which hormone does mammary glands develop? (A) testosterone (b)estrogens (c) thyroxine (d) adrenaline

Posted by Saniya Shaikh 4 years, 1 month ago

CBSE > Class 08 > Science

1 answers

Manisha Gundlur 4 years, 1 month ago

Growth hormone, secreted from the pituitary gland, is an important global regulator of mammary gland development, but current evidence suggests that its effect on the mammary gland is mediated largely, or even entirely, through IGF1 whose production it stimulates in the stroma

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Which infection is caused by algae

Posted by Aasma Singla 4 years, 1 month ago

CBSE > Class 08 > Science

5 answers

Ramkanya Suthar 4 years, 1 month ago

Systemic chlorellosis,

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Aasma Singla 4 years, 1 month ago

Thanks ???

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Shree Varshita Ainapur 4 years, 1 month ago

kshitij mahindrakar class

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Roshni Gaha 4 years, 1 month ago

Systemic chlorellosis, an emerging infection in humans caused by algae.

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Aasma Singla 4 years, 1 month ago

Pls tell

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What is green house gas

Posted by Somya Giri 4 years, 2 months ago

CBSE > Class 08 > Science

1 answers

Priya Siddappa 4 years, 1 month ago

A greenhouse gas is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone.

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What is meaning of science

Posted by Swarna Kumari 4 years, 2 months ago

CBSE > Class 08 > Science

2 answers

Sia ? 4 years, 2 months ago

the intellectual and practical activity encompassing the systematic study of the structure and behaviour of the physical and natural world through observation and experiment.

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Yash Shukla 4 years, 1 month ago

I am science

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From the given v-t graph it can be inferred that the object is

Posted by J.G.Niveditha2007 J.G.Niveditha 4 years, 2 months ago

CBSE > Class 08 > Science

2 answers

Chandan Pilli 4 years, 2 months ago

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Magesh Kanth 4 years, 2 months ago

What is royan

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_ is the process of heat and cold treatment for preserving milk

Posted by B. Parnika B. Parnika 4 years, 2 months ago

CBSE > Class 08 > Science

3 answers

Akanksha Patel 4 years, 1 month ago

The process is called pesturisation

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Aasma Singla 4 years, 1 month ago

Pasteurization

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Siriya Palle 4 years, 2 months ago

Pasteurization

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_ are preserved by the use of oil and vinegar

Posted by B. Parnika B. Parnika 4 years, 2 months ago

CBSE > Class 08 > Science

2 answers

Aasma Singla 4 years, 1 month ago

Pickling

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Siriya Palle 4 years, 2 months ago

Picking

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_ are preserved by the use of oil and vinegar.

Posted by B. Parnika B. Parnika 4 years, 1 month ago

CBSE > Class 08 > Science

1 answers

Sia ? 4 years, 1 month ago

Use of oil and vinegar prevents spoilage of pickles because bacteria cannot live in such an environment. Vegetables, fruits, fish and meat are often preserved by this method.

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What happens when a metal placed above hydrogen in the reactivity series reacts with a dilute acid? Explain with the help of an example.

Posted by Sidhee Mishra 4 years, 2 months ago

CBSE > Class 08 > Science

0 answers

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Karif crops name please tell

Posted by Anjali Yadav 4 years, 2 months ago

CBSE > Class 08 > Science

5 answers

Shreya Dubey 4 years, 1 month ago

The crops that are sown in rainy season are called Kharif crops.It is sown in monsoon season (June/July) and harvested in (September/October) For example:- Rice , Maize , etc.

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Sushree Sahoo 4 years, 1 month ago

Kharif crops are wheat maize etc

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Jeevana Dharma 4 years, 1 month ago

Wheat paddy rice maize

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Gargi Agnihotri 4 years, 2 months ago

Paddy and maize

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Hari Dharshini 4 years, 2 months ago

Rice,maize