Microorganisms: Friend and Foe Class 8 Worksheet with Solved in Pdf
Microorganisms: Friend and Foe Class 8 Worksheet: In this page we have included Microorganisms: Friend and Foe Chapter from Grade 8 Worksheet with solution.
Worksheet for chapter 2: – Microorganisms: Friend and Foe ?
The following questions are important for your exams for 1 mark 2 mark or 5 marks. First solve the questions on your own and then saw the solution for understanding it better.
Practice worksheet for class 8
1.) Fill in the blanks.
- Microbes are small in
- Disease like dysentery and malaria are caused by protozoa.
- Curd is formed by Lactobacillus
- Female Aedes mosquito act as carrier of dengue
2.) Answer in one sentence.
A.) Define
Answer:- Virus is a simple microorganism that infects cells and may cause disease.
B.) Define
Answer :- The process of conversion of sugar into alcohol is called fermentation.
C.) What do you mean by antibiotic?
Answer:- The medicine that fight bacterial infection in people and animals is known as antibiotic.
D.) Define
Answer:- The pathogen is defined as an organism causing disease.
E.) Name any two preservatives.
Answer:- a.Sodium benzoate , b. Sodium metabisulphite
3.) Choose the correct answer.
A.) Nitrogen fixing bacteria is
- Rhizobium
- E coli
- Azatobacter
- Pseudomonas
Answer:- Rhizobium
B.) Tuberculosis and typhoid are
a.Fungal disease
b.Bacterial disease
c. Viral disease
d.None of these
Answer:- b. Bacterial disease
C.) Examples of communicable disease are
a. Diabetes
b. Cholera
c. Cancer
d. Tuberculosis
Answer:- Both b) and d)
D.) Robert Koch discovered
a.) Bacillus coagulans
b.) Bacillus anthracis
c.) Bacillus Thuringiensis
d.) Bacillus megaterium
Answer:- b) Bacillus anthracis
3.) Write notes on :-
A.) Pasteurisation.
Answer:-
- Pasteurisation was discovered by Louis Pasteur.
- Pasteurisation is a process used to kill
- Pasteurisation kills harmful organisms such as typhoid fever, tuberculosis,brucellosis.
- Pasteurisation is a process of food
- Storage of milk is done pasteurisation in this the milk is heated to about 70°C for 15 to 30 seconds and then suddenly chilled and stored.
B.) Nitrogen Fixation.
Answer:-
- In nitrogen fixation process, nitrogen is converted into ammonia by certain bacterial species like Rhizobium, Azatobacter,etc.
- Role of nitrogen fixing bacteria is to provide nutrition to the
- Nitrogen fixing bacteria are Rhizobium, Azatobacter, Cyanobacter,etc.
- Some bacteria present in the soil fix nitrogen from air and converts into nitrogenous
- Nitrogenous compunds are ammonia, nitric acid, hydrogen cyanide
C.) Types of preservation.
a.) Chemical method:-
- Salts and edible oils are common preservatives to check growth of
b.) Preservation by common salt:-
- Common salt has been used to preserve meat and
C.) Preservation by sugar:-
- Jams, jellies are preserved by
d.) Preservation by oils and vinegar:-
- Pickels are commonly preseeved by oils or vinegar to check the growth of microorganisms.
D.) Communicable disease.
- Communicable disease are the disease that spread from one person to other
- Communicable disease are spread through air, water, food or sexual
- Communicable disease are caused by microorganisms such as bacteria, viruses, parasites and
- Example of communicable disease are Tuberculosis , Cholera, Chicken pox, HIV, Hepatitis A,B and C
Microorganisms Friend and Foe Class 8 Worksheet