Class 8 | Science | Ch 2 | Microorganisms: Friend and Foe | NCERT Solutions 1. Fill in the blanks. (a) Microorganisms can be seen with the help of a ____________. (b) Blue green algae fix __________ directly from air to enhance fertility of soil. (c) Alcohol is produced with the help of __________. (d) Cholera is caused by __________. Answer: (a) Microscope (b) … [Read more...] about Chapter 2 Microorganisms: Friend and Foe