Micro-organisms friend and foe — Science STD 8 — Question

Name the star which remains fixed at the same place in the sky in the North.

Which synthetic fibre contains the organic group similar to those which give fruits their sweet smell?

Name two animals which produce embryos that grow into larvae before transforming into adults.

X is a human activity which will cause an increase in temperature of earth’s atmosphere leading to global warming. It can cause soil erosion making the soil infertile and lead to desertification. It can cause decrease in rainfall but increase the flooding of rivers. It can also affect water cycle and lead to the extinction of many wild species. What is X?

State the function of male sex hormone ‘testerone’.

How does a sound making object differ from one that is silent?

Which of the two is a thermosetting plastic: PVC or bakelite?

Name any four places in India where petroleum is found.

The use of excessive fertilizers in the fields lead to the deficiency of an important substance in the water of a nearby lake. Name the substance.

One student says that water exerts pressure on the bottom of the bucket but another student says that water exerts pressure on the sides of the bucket. What would you like to say?