Friend and Foe
Q1. Fill in the blanks.
Microorganisms can be seen with the help of
Blue green algae fix nitrogen
directly from air to enhance fertility of soil.
Alcohol is produced with the help of yeast.
Cholera is caused by bacteria.
Carrier of malaria-causing protozoan is female
The bread or idli dough rises because of growth
of yeast cells.
Housefly is the common carrier of
communicable diseases. True
Amoeba lives in colonies. False
Bacteria are also involved in the making of
cheese, pickles and many other food items. True
Polio drops given to children are actually
a vaccine. True
Q3. What causes malaria?
Malaria is caused by protozoa.
Q4. Which mosquito act as carrier of dengue virus?
Ans. Aedes mosquito acts as carrier of dengue virus.
Q5. Name any two diseases that can be prevented by vaccination.
Q6. Give two examples of algae.
Ans. Chlamydomonas and Spirogyra
Q7. Give two examples of protozoa.
Q8. How are cholera and typhoid caused?
Ans. Cholera and typhoid are caused by bacteria.
Q9. Give few of examples of fungi.
Bread mould, Penicillium and Aspergillus
Q10. Who discovered penicillin?
In 1929, Alexander Fleming discovered penicillin.
Q11. Name any two diseases caused by bacteria.
Typhoid and tuberculosis (TB)
Q12. What causes foot and mouth disease of cattle?
Ans. Foot and mouth disease of cattle is caused by a
Q13. Who discovered the vaccine for smallpox?
Ans. Edward Jenner discovered the vaccine for smallpox
Q14. Name any two diseases caused by protozoa.
like dysentery and malaria are caused by protozoans.
Q15. Name some antibiotics.
Streptomycin, tetracycline and erythromycin
Q16. How are meat and fish preserved?
and fish are covered with dry salt to check the growth of bacteria.
Q17. What is fermentation?
Ans. The process of conversion of sugar into alcohol
is called fermentation.
Q18. Why do we boil milk before storing?
boil milk before storing because boiling kills many
Q19. Name one plant disease caused by bacteria and its mode of
Ans. Citrus canker is caused by bacteria and
transmitted through air.
Q20. Why are the antibiotics not effective against colds and the
Antibiotics are not effective against cold and flu as these are caused by viruses.
Q21. Name one plant disease caused by virus and its mode of
Yellow vein mosaic of bhindi (Okra) is caused by virus and
transmitted through insect.
Q22. How can we control plant diseases?
Ans. They can be controlled by the use of certain
chemicals which kill the microbes.
Q23. Name one plant disease caused by fungi and its mode of
Rust of wheat is caused by fungi and transmitted through air and seeds.