Write 10 lines on the usefulness of microorganisms in our lives.
Solution and Explanation
Microorganisms are too small to be seen through naked eyes. However, they are vital to plants and the environment.
Importance of microorganisms:
- They are used in winemaking, baking, pickling and other food making processes.
- Alcoholic fermentation by yeast is widely used in the preparation of wine and bread.
- A bacterium lactobacillus promotes the formation of curd.
- Microbes are used to reduce pollution.
- They are used to increase the soil fertility by fixing the atmospheric nitrogen.
- Microbes are also useful in preparing many medicines and antibiotics.
- Certain microbes are also used in the biological treatment of sewage and industrial effluents.
Top Questions on Microorganisms and Us
Questions Asked in CBSE Class VIII exam
- What are the two different ideas about why so few animals were killed in the tsunami? Which idea do you find more believable?
- CBSE Class VIII
- The Tsunami
Look at picture 1 and recall the opening lines of the original song in Hindi. Who is the singer? Who else do you see in this picture?
- CBSE Class VIII
- Glimpses of the past
- In the following situations identify the agent exerting the force and the object on which it acts. State the effect of the force in each case.
1. Squeezing a piece of lemon between the fingers to extract its juice.
2. Taking out paste from a toothpaste tube.
3. A load is suspended from a spring while its other end is on a hook fixed to a wall.
4. An athlete making a high jump to clear the bar at a certain height.- CBSE Class VIII
- Contact Forces
Fill in the blanks using the correct form of the verbs in brackets.
My little sister is very naughty. When she ____ (come) back from school yesterday, she had _____(tear) her dress. We _____(ask) her how it had _____(happen). She ______(say) she _____ _____ (have, quarrel) with a boy. She _____ _____ (have, beat) him in a race and he _____ ____ (have, try) to push her. She _____ ____ (have, tell) the teacher and so he _____ _____ (have, chase) her, and she _____ _____ (have, fall) down and _____ _____ (have, tear) her dress.
- CBSE Class VIII
- The Best Christmas Present in the world
- Simplify.
(i) (x2– 5) (x + 5) + 25
(ii) (a2+ 5) (b3+ 3) + 5
(iii) (t + s2) (t2 – s)
(iv) (a + b) (c – d) + (a – b) (c + d) + 2 (ac + bd)
(v) (x + y) (2x + y) + (x + 2y) (x – y)
(vi) (x + y) (x2– xy + y2)
(vii) (1.5x – 4y) (1.5x + 4y + 3) – 4.5x + 12y
(viii) (a + b + c) (a + b – c)- CBSE Class VIII
- Multiplying a Polynomial by a Polynomial