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 .
2. Tick the correct answer:
(a) Yeast is used in the production of (i) Sugar (ii) Alcohol (iii) Hydrochloric acid (iv) Oxygen
(b) The following is an antibiotic
(i) Sodium bicarbonate (ii) Streptomycin
(iii) Alcohol (iv) Yeast
(c) Carrier of malaria-causing protozoan is
(i) Female Anopheles mosquito (ii) cockroach
(iii) Housefly (iv) Butterfly
(d) The most common carrier of communicable diseases is
(i) Ant (ii) Housefly
(iii) Dragonfly (iv) Spider
(e) The bread or idli dough rises because of
(i) Heat (ii) Grinding
(i) Nitrogen fixation (ii) Moulding
(iii) Fermentation (iv) Infection
3. Match the organisms in Column I with their action in Column II.
Column I Column II
i. Bacteria (a) Fixing nitrogen ii. Rhizobium (b) Setting of curd iii. Lactobacillus (c) Baking of bread
iv. Yeast (d) Causing malaria v. A protozoan (e) Causing cholera vi. A virus (f) Causing AIDS
(g) Producing antibodies
4. Can microorganisms be seen with the naked eye? If not, how can they be seen?
5. What are the major groups of microorganisms?
6. Name the microorganisms which can fix atmospheric nitrogen in the soil.
7. Write 10 lines on the usefulness of microorganisms in our lives.
8. Write a short paragraph on the harms caused by microorganisms.
9. What are antibiotics? What precautions must be taken while taking antibiotics?
1.
(a) Microorganisms can be seen with the help of a microscope. (b) Blue green algae fix nitrogen directly from air to enhance
fertility of soil.
(c) Alcohol is produced with the help of yeast. (d) Cholera is caused by bacteria.
2.
(a) Yeast is used in the production of
(i) Sugar (ii) Alcohol
(iii) hydrochloric acid (iv) oxygen
(b) The following is an antibiotic
(i) Sodium bicarbonate (ii) Streptomycin
(iii) Alcohol (iv) Yeast
(c) Carrier of malaria-causing protozoan is
(i) Female Anopheles mosquito (ii) Cockroach
(iii) Housefly (iv) Butterfly
(d)The most common carrier of communicable diseases is
(i) Ant (ii) Housefly
(iii) Dragonfly (iv) Spider
(e)The bread or idli dough rises because of
(i) Nitrogen fixation (ii) Moulding
(iii) Fermentation (iv) Infection
3.
Column I Column II
i. Bacteria (e) Causing cholera ii. Rhizobium (a) Fixing nitrogen
iii. Lactobacillus (b) Setting of curd iv. Yeast (c) Baking of bread v. A protozoan (d) Causing malaria
vi. A virus (f) Causing AIDS
4. Microorganisms are extremely tiny living beings which are not visible through our naked eyes. To observe these microorganisms, we need to use Microscope.
5. There are five major groups of micro-organisms:
i. Bacteria − A single celled organism mainly responsible for diseases. They can be Spiral, rod shaped, spherical shaped, comma shaped.
ii. Fungi − Fungi are mostly multicellular and responsible for
diseases too. Moulds on bread is a type of fungi.
iii. Protozoa − Protozoa can be unicellular or multicellular. And they are harmful to humans and other organisms Eg: Amoeba and Plasmodium are protozoa.
iv. Virus − Viruses are disease causing microorganisms which can only divide inside a host organism/cell. It can affect plants as well as animals. Eg: HIV virus for humans and TMV virus for plants.
v. Algae − Algae are the only microorganism which are multicellular and has photosynthetic pigments. Algae are also known as precursor of plants Eg: Spirogyra, Chlamydomonas etc.
6. Bacteria like Rhizobium can fix atmospheric nitrogen in the soil and make it to such nitrogenous compound which can be taken up by the plants. Plants use these nitrogenous compounds to make proteins and other important compounds. Eg: Rhizobacteria
and Blue green algae have capacity to fix nitrogen.
7.
1. Microorganisms are used in making of wine, break, pickels and other food products
2. Lactobacillus bacteria is mainly used at homes to make curd from milk
3. Yeast is a microorganism which is used at home to make batter for fermented food.
4. Various fungi are the one responsible for decaying the waste in the nature, they obtain nutrients from the dead and decompose the waste.
8. Microorganisms are responsible for various diseases in humans and plants. Diseases caused by bacteria are tuberculosis, cholera, typhoid, etc. Various viruses are responsible for foot and mouth disease in cattle. In plants productivity of wheat, rice, apple, sugarcane etc can all be reduced because of the microorganisms. Microbes present in our body produces harmful substances which will harm the body cells. Microbes also spoil our food and other materials.
9. Antibiotics are the drugs or medicine which we take to kill disease causing microorganisms. Antibiotics are produced from the microorganisms. There are separate antibiotics which kills bacteria, fungus and other organisms.
Eg: penicillin, Tetracycline, Streptomycin and so on. Precautions:
1. Antibiotics should be consumed under the supervision of a qualified doctor
2. The course of antibiotics should be completed as described in the prescription.
3. Correct dosage of antibiotics is important. High dosage or low dosage of antibiotic can cause harm to th