1. The study of microorganisms is known as microbiology.
2. The bread dough rises because of the production of Carbon dioxide.
3. Pathogens are the microorganisms that cause diseases.
4. Sodium Benzoate and Potassium metabisulfite are two chemical preservatives.
5. Aspergillus is a fungus that causes food poisoning.
B. Match the following.
1. Ringworm- Fungus
2. Clostridium- Food poisoning
3. Anthrax- Cattle
4. Lactobacillus- Curd
5. Methane- Biogas reactor
C. Tick the correct option.
1. The process, that helps the milk to last longer but does not kill all microbes present in it, is known as ----
Ans- Pasteurisation
2. Rust of wheel is caused by----
Ans- Fungus
3. Medicines, containing killed or weakened pathogens are used to prevent infectious diseases, are called----
Ans- Vaccines
4. Which of the following reproduces only inside a host cell----
Ans- Virus
5. A disease, caused by a virus, and spread by an insect is----
Ans- Dengue
D. Answer the following questions in brief.
1. Why are viruses considered as being at the 'borderline' between living and non-living things?
Ans- The viruses considered as being at the 'borderline' between living and non-living things because, when it is prevented in the environment, it acts as non-living but, when it comes in contact with the living environment, it acts as living beings.
2. What is fermentation? How is the process useful in the food and beverage industries.
Ans- It is an anaerobic process through which carbohydrate gets converted into alcohol or acid and carbon dioxide by the yeast.
Due to the production of carbon dioxide and alcohol.
3. ' In the absence of microorganisms the Earth would become a heap of dead plants and animals. Justify this sentence.
Ans- Microorganisms are decomposers. So it decomposes dead plants and animals. But in absence of it, the earth would become a heap of dead plants and animals.
4. Munna observes that the yield of wheat, growing in his field, has reduced in the current year. He gets the soil tested and the report confirms that deficiency of one particular nutrient. Accordingly, he is advised to grow peas after harvesting wheat.
(i) Name the nutrient found insufficient.
Ans- Nitrogen found insufficient in the soil.
(ii) How Do you think growing peas will help in replenishing the soil?
Ans- Pea belongs to a leguminous family plant, which has root nodules, where nitrogen-fixing bacteria Rhizobium is present.
5. Why does it take less time to prepare curd in summers as compared to winters?
Ans- Growth of lactobacillus bacteria is more in summer than winter. So, it takes less time to prepare curd in summer than in winters.
6. How are the following disease transmitted:
(a) Malaria- Mosquito
(b) Common cold- Air
(c) Tetanus- Soil
(d) Typhoid- Contaminated water
7. What are antibiotics? How are they produced? Give two examples of these.
Ans-Antibiotics are the chemicals produced by microorganisms that kill or inhibit the growth of other harmful microorganisms.
They are produced by bacteria and funguses. For ex- Streptomycin and Tetracycline.
E. Answer the following questions.
1. ' Microorganisms are very useful in manufacturing different food items.' Explain the above statement.
Ans- Microorganisms are very useful in manufacturing different food items----
(i) Curd and cheese formation- Lactobacillus helps in the formation of curd. Some other bacteria and fungi also help in making cheese.
(ii) In bakery product- Some fungi like yeast increased the volume of batter and make it fluffy and soft by the process of fermentation.
(iii) Alcoholic beverage- Yeast also converts carbohydrate into alcohol and help in manufacturing alcoholic beverages.
2. Give the reason for the following.
(a) Yeast is added to the batter used to make 'dosas'.
Ans- Yeast by fermentation process produced CO2 and make it fluffy and soft.
(b) It is important to brush one's teeth before going to bed.
Ans- Food particles after decomposition produces acid which causes teeth decay. So, it's important to brush your teeth before going to bed.
(c) Reducing the quantity of salt in the pickle can cause it to go bad soon.
Ans- Salt is a preservative item and it stops the growth of microorganisms and prevents pickle.
(d) When using frozen food items one should take only the required quantities; thawed food should never be refrozen.
Ans- Puffed food indicate spoilage of food which causes food poisoning. Most bacterial spores and a large number of organisms survive and get revitalized, when the food is thawed.
3. How do communicable diseases spread? Suggest ways to prevent the following diseases;
a) Tuberculosis
b) Athlete's foot
c) Cholera
Ans- Communicable diseases spread from one person to another through the air, water, food, and physical contact or insect.
a) Tuberculosis- Vaccination
b) Athlete's foot- Maintaining good personal hygiene
c) Cholera- Proper disposal of waste and using disinfected water.
4. What are pathogens? Name two pathogens each that cause diseases in
(i) plants
(ii) animals
Ans- Disease causing microorganisms are called pathogens.
In plants----
i) Virus- Tobacco mosaic virus
ii) Bacteria- Citrus canker
In animals----
i) Bacteria- Anthrax
ii) Virus- Rabies
5. Mohan bought samosas from a road-side vendor and ate them. After some time he felt nausea and he started vomiting he had severe pain in the abdominal region and suffered from diarrhoea. What could be the reason for his condition? Was is it called? How could it be prevented?
Ans- Eating samosa from road-side vendors is the reason for this condition. It is called food poisoning.
It can be prevented by avoiding eating food from the road-side vendors. The food items must be properly prepared and stored. Always wash your hands and eat fresh food.
6. Which diseases the following children are most likely to suffer from?
(a) Ramu drinks water from a nearby lake. The water is neither boiled nor disinfected.
Ans- Cholera
(b) Ashu does not take a bath every day. He maintains poor personal hygiene.
Ans- Athlete's foot or ringworm
(c) Pulkit has been bitten by an infected street dog.
Ans- Rabies
(d) Sohan is living in an area where the population is very high. He does not use a mosquito net (while sleeping), or insect-repellent creams(while playing) in the open.
Ans- Malaria or dengue
(e) Mohan was with two of his friends who were coughing and sneezing (they were suffering from common cold). One of these friends did not keep a handkerchief in front of his mouth while coughing and sneezing.
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