CBSE Class 8 Science Cell Microorganisms Assignment

Chapters – Cell, Microorganisms and Coal and Petroleum

(I) Choose the correct option:

(i) Which of the following is an antibiotic?

(a) sodium bicarbonate (b) streptomycin

(c) alcohol (d) yeast

(ii) The bread dough rises because of:

(a) heat (b) grinding

(c) growth of yeast cells (d) kneading

(iii) The major component of natural gas is:

(a) nitrogen (b) ethane

(c) water vapour (d) methane

(iv) Which of the following is a prokaryotic cell?

(a) bacteria (b) blue-green algae

(c) both of them (d) None of them

(II) Draw neat and labeled diagrams of:

(a) Cells of onion peel

(b) Cells of human cheek

(III) Give reasons for the following:

(a) We should use fossil fuels only when absolutely necessary.

(b) Viruses are said to lie on the border line dividing the living things from non-living things.

(IV) Value based:

(a) Amoeba is a single cell which can change its shape. A white blood cell present in human blood is another example of a single cell which can also change its shape. What is the difference between them?

(b) PCRA advises regular maintenance of the vehicle. How does it help in saving fuel?

(V) HOTS:

(a) Explain the chemical change brought about by lactobacillus bacteria in changing milk to curd.

(b) Explain how natural gas is utilized in manufacturing of fertilizers.