MSBSHSE Class 9 Science Chapter 8 Useful and Harmful Solutions

MSBSHSE Class 9 Science Chapter 8 Useful and Harmful Microbes Solutions are used by the students as reference material in order to study for the Class 9 Science examination of MSBSHSE. They contain step-by-step solutions with detailed explanations, so that the students can easily understand the basic concepts of the chapter, Useful and Harmful Microbes. Students may be familiar with different types of microbes, which are all around the atmosphere but cannot be seen with naked eyes, This chapter, explains how they are related to everyday life. Useful micro-organisms: Lactobacilli, Rhizobium, Yeast, Harmful micro-organisms: Clostridium and others are the topics discussed in this chapter.

To learn the subject most efficiently, students can practise these MSBSHSE Class 9 Solutions of Science Chapter 8 Useful and Harmful Microbes. These solutions prepared after thorough research includes the questions from the textbook and so helps the students to get more familiar with the exam questions. The well designed comprehensive content is easy to understand and covers the topics according to the latest Maharashtra State Board Syllabus for Class 9. The solutions to the questions listed here are designed to help students do well academically. So, solving these questions for practice helps students to answer the exams more confidently.

Maharashtra Board Class 9 Science Chapter 8- BYJU’S Important Questions & Answers

1. What are Lactobacilli?

Answer: A minute and rectangular in shape bacteria (blue rod-shaped organism) that are anaerobic bacteria that can produce energy without the use of oxygen are called Lactobacilli.

2. How is yoghurt made from milk? What exactly happens in this process?

Answer: The lactobacilli converts the lactose, that is the sugar in the milk, into lactic acid via the process known as fermentation. Following this, the pH of milk reduces, resulting in the coagulation of milk proteins. This also separates the milk proteins from the other milk constituents. This is what occurs when milk is changed to yoghurt. Yoghurt has specific sour taste because of lactic acid and the low pH helps to destroy the harmful microbes found in the milk.

3. What are some of the milk products obtained by fermentation of milk?

Answer: There are several milk products that can be obtained by fermentation of milk. They include ghee, yoghurt, cheese, buttermilk, shrikhand and more.

4. What are some of the uses of Lactobacilli?

Answer: Given here are some of the uses of Lactobacilli:

  • Lactobacilli fermentation is used to produce cider, cocoa, vegetable pickles and so on on a large scale
  • Along with some other microbes, Lactobacilli are used to treat abdominal infection
  • Lactobacilli is used to ferment leavened fodder given to domestic cattle such as cows and buffalos
  • Lactobacilli fermentation process is useful to manufacture wine and certain kinds of breads

5. Write the names of microbes found in the following food materials.

(yoghurt, bread, root nodules of leguminous plants, idli, dosa, spoiled potato curry.)

Answer: Given are the microbes present in the following food materials

Yoghurt- Microbe found in it is Lactobacillus

Bread- Saccharomyces is the microbe found in it

Root nodules of Leguminous plants- The microbe found is Rhizobium

Idli- Lactobacillus is found in it

Dosa- Microbe is Lactobacillus

Spoiled potato curry- Clostridium is one of the microbes found

6. Identify the odd one out from Pneumonia, diphtheria, chicken pox, cholera. Why is it the odd one out?

Answer: Chicken pox is the odd one out as it is a viral disease, whereas the rest are all bacterial diseases.

7. Root rot, rust (tambera), rubella, mozaic. Which amongst these is the odd one out. State the reason.

Answer: Rubella is the odd one out. Root rot, rust (tambera) and mozaic are all names of plant disease, while rubella is a human disease.

8. Which is the odd one from Lactobacilli, rhizobia, yeast and clostridia? Why?

Answer: From this list, Rhizobia is the odd one out. Lactobacilli, Yeast and Clostridia are all bacterias associated with human food products, while Rhizobia is a bacteria related to plants.

9. Foam accumulates on the surface of ‘dal’ kept for a long time in summer. What is the scientific reason for this?

Answer: Food stuff that is kept for a longer time in the summer is favourable for the growth of microbes, which releases some gas as it’sby-product. This gas creates foam on the surface of food stuffs that have more water content, such as dal.

10. Give scientific reason for why naphthalene balls are kept with clothes to be put away.

Answer; Naphthalene balls are kept with clothes to protect them from insects. However, over a period of time, they disappear without leaving any residue as a result of the sublimation process.

11. Write down the modes of infection and the preventive measures against fungal diseases.

Answer: The mode of infection for fungal diseases are contact with an infected person, or even his or her belongings, such as clothes. Meanwhile, certain precautions have to be taken against fungal diseases, They include personal hygiene along with avoiding contact with the infected person.

12. Match the pairs:

Rhizobium Food poisoning
Clostridium Nitrogen fixation
Penicillium Bakery products
Yeast Production of antibiotics


Rhizobium Nitrogen fixation
Clostridium Food poisoning
Penicillium Production of antibiotics
Yeast Bakery products

13. Which vaccines are given to infants? Why

Answer: Immune systems of the children are not yet developed and also their stomachs produce a lesser amount of acid, thus making it easier for the bacteria and viruses to multiply, thus making the child more prone to sickness. To avoid this, children are given vaccines as an infant. Vaccines help the immune system to recognize and fight against infectious diseases. Some of the vaccines given include Oral Polio Vaccine (OPV), Hepatitis B, Rota V and more.

14. How is a vaccine produced?

Answer: Some dead or weakened microorganisms that are introduced into the body so that it stimulates the body to produce antibodies that can help the immune system to fight against diseases are known as vaccines. Vaccines protect the bodies from diseases for a long time.

15. How do antibiotics cure disease?

Answer: Antibiotics are the carbon compounds got from some bacteria and fungi in order to destroy or prevent the growth of harmful micro-organisms. Antibiotics act against bacteria and some are even known to destroy protozoa. Antibiotics that are useful against a wide variety of bacteria are known as broad spectrum antibiotics. Examples for this include tetracycline, amoxicillin, ampicillin and more. In the scenario, when the pathogen is not identified but the symptoms prevail, broad spectrum antibiotics are used. Meanwhile, if the pathogenic micro-organism is known, then narrow-spectrum antibiotics are used. Examples for narrow spectrum antibiotics are erythromycin, gentamycin, penicillin and so on.

16. Define antibiotic.

Answer: Antibiotics, a discovery of the 20th century are carbon compounds that are obtained from some bacteria and fungi so as to destroy and prevent the development of harmful micro-organisms. It has brought about a revolution in the field of medicine.

17. Why are useful microbes like lactobacilli added to eatables?

Answer: Eatables in which lactobacilli microbes are added are healthy for the reason that they kill the harmful bacteria like clostridium in the alimentary canal, thus improving immunity.

18. What is symbiosis?

Answer: Symbiosis is a mutually beneficial relationship, where rhizobia that exists in the root nodules get energy in the form of carbohydrates from the plants and in exchange supply nitrates, nitrites and amino acids to that plant.

19. What is the benefit of Rhizobium to Farmers?

Answer: As a result of the nitrogenous compounds made available by Rhizobium, beans and pulses are rich in protein. Now, the leftover roots and other plant parts are thrown in farm soil, after harvesting a leguminous crop, so as to maintain its bacterial population. This, in turn, brings down the use of chemical fertilizers as well as reduce adverse effects caused by it. This further helps to cut down the expenses of fertilizers, going on to benefit the farmers.

20. What is called ‘rhizobial inoculation’?

Answer: Currently, rhizobial solution or powder is coated over seeds before sowing them. Then, after the sowing, the rhizobia enter the plantlets. This process is known as ‘rhizobia inoculation’. This experiment helps in the supply of nitrogen to cereal and more crops, other than leguminous crops.

21. What is a yeast?

Answer: A heterotrophic fungal microbe found on carbon compounds, Yeast is a eukaryotic type of cell with 1500 various species in existence. It is a unicellular fungus.

22. What is fermentation?

Answer: Take a solution of dry yeast, with sugar and water. You will see that yeast converts the carbohydrates in this solution into alcohol and carbon dioxide, in the process of getting nutrition. This process is known as fermentation.

23. What is used to ferment Molasses?

Answer: A yeast known as Saccharomyces is used to ferment molasses. The alcohol formed as a primary product in this process is ethanol (C2H5OH), while ester and other alcohols are the secondary products.

24. What is used for making wines?

Answer: Glucose and Fructose are the sugars found in the grape juice, which are further fermented using yeast so as to manufacture alcohol that is later used to produce wines.

25. What is the use of yeast Yarrowia lipolytica?

Answer: Yarrowia lipolytica is a yeast and it is used to absorb the toxins that are released during the manufacture of palm oil and the heavy metals along with the minerals, which are released in some other industrial processes.

26. Find the uses of Saccharomyces cerevisiae.

Answer: To absorb a pollutant and arsenic, Saccharomyces cereviceae is used.

27. What is Alcanivorax bacteria used for?

Answer: Alcanivorax bacteria is used to clean the oil spills in oceans.

28. What does the National Institute of Virology do?

Answer: Originated in 1952, the National Institute of Virology in Pune with the support of the World Health Organization is responsible for the research related to diseases such as jaundice, measles, fever and diseases of the lungs.

29. What is a penicillin?

Answer: A group of antibiotics that is obtained from Penicillium, a fungus and used for controlling the infections that are caused by bacteria like Staphylococci, Clostridia, Streptococci, and so on are called Penicillin. Medicines that have penicillin in it are useful to treat a few bacterial infections of the ear, nose, throat and skin along with diseases such as scarlet fever and pneumonia.

30. What are the precautions before taking antibiotics?

Answer: Given below are the precautions to follow before taking antibiotics:

  • Take the antibiotics or purchase it only if it has been prescribed by the doctor
  • Avoid taking antibiotics on your own for common diseases such as throat infection, cold, influenza and so on
  • Continue taking the antibiotics for the prescribed time period, even if the illness has been cured before the antibiotics are over
  • Never give suggestions to other people on which antibiotic to use

31. Who discovered the life saving antibiotics, penicillin?

Answer: A professor of Microbiology at St Mary’s Hospital, Alexander Fleming, on 3 September 1928, made an interesting observation in one of the Petri dishes in his laboratory, which on further study led to the first accidental discovery of penicillin.

32. How do ants, wasps and other insects obtain food?

Answer: Ants grow fungi in their anthill or termitarium, from which they obtain food, while a few species of other insects and wasps lay their eggs in the fungal bodies developing on trees, so as to ensure a food for their larvae.

33. What is the reason that gunny bags, leather items like shoes, purses, belts, etc. on which fungi have grown do not last long and even wooden items also get spoilt?

Answer: In the presence of sufficient moisture, the microscopic spores of fungi found in the air germinate on gunny bags, wooden items, cotton fabric, leather and so on. The fibres of the fungus (fungal hyphae) dig deep into the material to obtain nutrition and to reproduce. Hence, the gunny bags and leather items become weak and do not last long and even wooden items get spoilt fast.

34. Sometimes, you may notice a black powder or white discs floating on the pickle or murabba, when a jar is opened after a long time. What exactly is this? Why are such food items not good to eat?

Answer: There are many species of fungi that are found on food items such as murabba,sauce, pickles, chutney, jam and so on, which make use of the nutrients in these food items to develop and reproduce. In the process of this activity, these fugi release certain poisonous chemicals known as mycotoxins, into the food. Hence, the food becomes poisonous so the food items on which fungi have developed are not to be eaten.

35. What is Clostridium?

Answer: Clostridium is the rod-shaped bacteria that spoils the cooked food. They generate bottle-shaped endospores in adverse conditions. Meanwhile, these bacteria cannot withstand the normal oxygen level of the air as they grow in anaerobic conditions.

36. Do only the Clostridium bacteria cause illness ?

Answer: No. There are also other kinds of micro-organisms such as bacteria, viruses, protozoa and fungi, which caused various diseases that have affected humans.

37. Who found the cause for food poisoning?

Answer: Earlier, belief was that some bacteria of the bacillus type caused the meat to get spoiled, even if the exact type of bacillus was not identified. However, it was Van Ermengem who proved that the anaerobic bacterium, Clostridium botulinum was the main cause for food poisoning.

38. What was the case of Swine flu or Bird flu? What are the preventive measures to be taken?

Answer: The mode of infection for these virus prone diseases Swine flu or Bird flu is contact with infected birds and animals. Personal hygiene and properly cooked meat are some of the preventive measures to be taken as a precaution against the infection.

39. What is the cause of malaria? How to prevent it?

Answer: The main mode of infection for this bacterial disease malaria, is the mosquito bite and unclean surroundings. Main steps that need to be taken to prevent this is to keep the surroundings clean, prevent stagnation of water and to control mosquitoes.

40. How is pneumonia spread? Preventive measures to take.

Answers: The main mode of infection for the bacterial infection, pneumonia is from the droplets spread in air by the infected person. Some of the preventive measures to be taken include vaccination and avoiding contact with the infected person.

In the meantime, students can prepare most effectively for the exams with the help of additional study materials such as the sample papers, syllabus and Maharashtra State Board books PDF free downloadand more. Stay tuned and get more information at BYJU’S.

Frequently Asked Questions on Maharashtra State Board Solutions for Class 9 Science Chapter 8 Useful and Harmful Microbes

Maharashtra State Board Class 9 Science Solutions Chapter 8: Where Can I access them?

We have provided the solutions as a scrollable PDF, and we have also mentioned the clickable link for the students to access. Also find these questions and the solutions online on our webpage, as well.

Why should I solve Maharashtra State Board Class 9 Science Solutions Chapter 8?

These Maharashtra State Board Class 9 Science Solutions Chapter 8 are the perfect guide for those students who are preparing for the Class 9 final exams. These solutions include topics that lays the foundation for the questions likely  asked in the board exams, as well. Preparing with the help of these solutions help students to ace the exams.

What are the concepts covered in these solutions?

This chapter discusses about how different types of microbes are related to everyday life. Useful micro-organisms: Lactobacilli, Rhizobium, Yeast, Harmful micro-organisms: Clostridium and others are some other topics dealt with in this chapter.

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