give me the questions answers of dav public school sasaram class 8 chapter name microorganism friend and foe
Answers
Answer:
SOLVE ⬇⬇
Explanation:
word for each of the following statements.
(a) Chemicals added to food to prevent growth of microorganisms.
(b) Nitrogen-fixing microorganism present in the root nodules of legumes.
(c) Agent which spreads pathogens from one place to another.
(d) Chemicals which kill or stop the growth of pathogens.
Match the names of scientists given in Column A with the discovery made by them given in Column B.
Microorganisms : Friend and Foe
Name one commercial use of yeast.
Name the process in yeast that converts sugars into alcohol.
In the soil, which nutrient is enriched by blue-green algae (cyanobacteria)?
Why should we avoid standing close to a tuberculosis patient while he/she is coughing?
Polio drops are not given to children suffering from diarrhoea. Why?
Paheli watched her grandmother making mango pickle. After she bottled the pickle, her grand mother poured oil on top of the pickle before closing the lid. Paheli wanted to know why oil was poured? Can you help her understand why?
Short Answer Type Questions
Match the microorganisms given in the Column A to the group to which they belong in Column B.
Microorganisms : Friend and Foe
Classify the following into friendly and harmful microorganisms. Yeast, malarial parasite, Lactobacillus, bread mould, Rhizobium, Bacillus anthracis
Microorganisms : Friend and Foe
While returning from the school, Boojho ate chaat from a street hawker. When he reached home, he felt ill and complained of stomach ache and fell ill. What could be the reason?
What will happen to ‘pooris’ and ‘unused kneaded flour’ if they are left in the open for a day or two?
(a) Name two diseases that are caused by virus.
(b) Write one important characteristic of virus.
Long Answer Type Questions
Observe the Fig.2.1 and answer the questions that follows.
Microorganisms : Friend and Foe
(a) Write the name of the disease.
(b) Name the causative agent of this disease?
(c) How does the disease spread from one plant to another?
(d) Name any two plant diseases and the microbes that cause them.
How do vaccines work?
Observe the set up given in Fig. 2.2 and answer the following questions.
(a) What happens to the sugar solution in A?
(b) Which gas is released in A?
(c) What changes will you observe in B when the released gas passes through it?
Microorganisms : Friend and Foe
Observe the Fig.2.3 and answer the following question
Microorganisms : Friend and Foe
(a) Name the microorganism and the group to which it belongs.
(b) Name the food item on which the organism grows.
(c) Does it grow well in dry or in moist conditions?
(d) Is it safe to eat infected bread?
Give reasons for the following.
(a) Fresh milk is boiled before consumption while processed milk stored in packets can be consumed without boiling.
(b) Raw vegetables and fruits are kept in refrigerators whereas jams and pickles can be kept outside.
(c) Farmers prefer to grow beans and peas in nitrogen deficient soils.
(d) Mosquitoes can be controlled by preventing stagnation of water though they do not live in water. Why?
How can we prevent the following diseases?
(a) Cholera
(b) Typhoid
(c) Hepatitis A