Question

8 th science assignment A Fill in the blanks using suitable words.

1 ______ is a structural and functional unit of life.

2 Amoeba is a ________ organism.

3 _________ is a smallest cell.

4 _________ is a central yellow mass of a cell.

5 _________ is said to be a power house of a cell.



Q B Answer the following questions in brief:

1 Which branch of biology deals with microorganism?

2 Name the bacteria that help in converting milk to curd.

3 What do you mean by Bioaugmentation?

4 Name any one biological nitrogen fixer.



Q C Give scientific reasons for the following:

1 Virus is said to be a connecting link between living being and non living

things.

2 Afforestation helps to overcome flood.

3 Overgrazing and deforestation contribute towards soil infertility.

Q D Answer the following questions in detail with the help of diagram.



1 Differentiate between plant cell and animal cell giving four points.

Draw a well labeled diagram of a Plant cell.​

Answer 1

Answer:

1 cell

2 single celled

3 mycoplasma

4 nucleus

5 mitochondria

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1 microbiology

2 lactobacillus

3 Bioaugmentation is the practice of adding cultured microorganisms into the subsurface for the purpose of biodegrading specific soil and groundwater contaminants.

4 Azotobacter, Bacillus, Clostridium, and Klebsiella.

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1 This is because viruses are non-cellular organisms that are characterised by having an inert crystalline structure outside the living cell.

2 Afforestation involves the planting of trees in a drainage basin to increase interception and storage while reducing surface run off. This reduces a river's discharge and so makes it less likely to flood

3 Forests play an important role in maintaining fertility of soil by shedding their leaves which contain many nutrients. Forests are also helpful in binding up of soil particles with the help of roots of vegetation. Therefore, cutting о forests will affect the soil adversely.

Increase in livestock population results in overexploitation of pastures. Due to this, grass and other types of vegetation are unable to survive and grow in the area, and lack of vegetation cover leads to soil erosion. Millions of people in Africa and Asia raise animals on pastures and rangelands that have low carrying capacity because of poor quality or unreliable rainfall Pastoralists and their rangelands are threatened by overgrazing.

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