RBSE Solutions for Class 6 Science Chapter 8 Micro-Organisms

Rajasthan Board RBSE Class 6 Science Chapter 8 Micro-Organisms

RBSE Solutions for Class 6 Science

RBSE Solutions for Class 6 Science Chapter 8 Micro-Organisms

RBSE Class 6 Science Micro-Organisms Intext Questions and Answers

Page No 67.

Question 1.
How do we preserve the. left food at home?
Answer:
We preserve the left food at home by keeping it in refrigeration. The temperature inside the fridge is low. Biological activities of micro-organisms became slow at low temperature. So the food stuff does not get spoiled easily when kept in fridge. It is called refrigeration.

Question 2.
What changes occur in bread kept in open and moist place?
Answer:
in bread kept in open and moist place, micro-organisms which are seen on its surface as white coloured threads like structure and black spots.

Question 3.
What happens when food is contaminated by micro-organisms?
Answer:
When food is contaminated by micro organisms then it becomes poisonous.

Question 4.
Is the contamination of food a chemical reaction?
Answer:
Yes, contamination of food is a chemical reaction.

Question 5.
Before one decade, glass syringe and needle were kept in boiling water before using them. Why?
Answer:
They became bacteria-free after heating. This is called sterilization.

Question 6.
Which type of syringes are used in hospitals now a days?
Answer:
Now a days, sterilized needles and syringes are used and they can be used only once.

RBSE Class 6 Science Micro-Organisms Text Book Questions and Answers

Choose the correct option:

Question 1.
Which of the following is a micro organism?
(a) virus
(b) fungi
(c) bacteria
(d) all of these
Answer:
(d) all of these

Question 2.
Which micro-organism possess characters of both-living and non-living?
(a) bacteria
(b) fungi
(c) virus
(d) protozoa
Answer:
(c) virus

Question 3.
Which of these is an antibiotic?
(a) penicillin
(b) insulin
(c) Aldrin
(d) auxin
Answer:
(a) penicillin

Question 4.
Which of these is an unicellular organism?
(a) amoeba
(b) cow
(c) star fish
(d) humans
Answer:
(a) amoeba

Fill in the blanks:

  1. ……………………… can be seen with the help of a microscope.
  2. Food ingredients are prepared by an unicellular organism named ………………………
  3. ……………………… bacteria convert the atmospheric nitrogen into nitrates.
  4. The process of removal of water from food items is called ………………………

Answer:

  1. Micro-organisms
  2. chlorella
  3. Rhizobium
  4. dehydration.

Match the following correctly:

Question 1.
RBSE Solutions for Class 6 Science Chapter 8 Micro-Organisms-6
Answer:

  1. (b)
  2. (a)
  3. (d)
  4. (c)

Short Answer type Questions:

Question 1.
Write name of the different types of micro-organisms?
Answer:
Micro-organisms are of six types. They are –

  • Virus
  • Mycoplasma
  • Bacteria
  • Fungus
  • Protozoa
  • Algae

Question 2.
Explain about micro-organisms which are useful in our life?
Answer:
Useful micro-organisms in our lite are –
1. Production of food stuffs:
Micro organisms are used for the production of curd, cheese, vinegar etc. Yeast is used for making bread and in fermenting the solution used in the preparation of jalebi. Chlorella is used to make soup and other food ingredients: Food ingredients produced by chlorella are used for making ice creams.

2. Preparation of medicines:
Vitamin B12 is prepared from a bacteria named, Clostridium botulinum and another bacteria named Anthracoid bacilli is used for preparing immunological substances. Penicillin, a life saving drug which is used as a vaccine and antibiotic, is prepared from a fungi named penicillium. Penicillin was discovered by Alexander Fleming.

3. Biological nitrogen fixation:
Certain species of bacteria and some other micro organisms convert the atmospheric nitrogen into such compounds that can be absorbed by plants.

4. Humus formation:
Bacteria decompose leaves, dung and other waste material and convert them into humus. This makes soil fertile.

5. In making toothpaste:
A micro organism named Xenthomonas compestris is used to make toothpaste.

Question 3.
What is pasteurization?
Answer:
Now a days, the use of canned food items is increasing. Before packaging milk or other food items in cans or bottles, milk or the food items are heated at 60°C for 30 minutes and then cooled down. This process is repeated 2-3 times and it kills the harmful micro-organisms present in them. This technique of killing germs is called pasteurization. Air is removed from the cans after pasteurized food items are packaged in cans because the micro-organisms cannot grow in the absence of air.

Question 4.
What is food poisoning? Why does It happen?
Answer:
The food contaminated by micro organism when intaked by person, then it may cause food poisoning. Clostridium botulinum, a bacteria that causes food poisoning and the person who eats this food, suffers from vomiting and diarrhea and in some cases it may lead to death. This is called food poisoning. Thus it is necessary that we present food from getting contaminated and poisonous and avoid in taking such food.

Question 5.
Write the harms caused by micro organisms?
Answer:
Following harms are caused by micro organism –

  • Causes disease (both is animals and plants)
  • Spoil food stuffs
  • Causes food poisoning
  • Damages valuable items.

Long Answer Type Questions:

Question 1.
What are micro-organisms? Explain different types of micro-organisms with example?
Answer:
Micro-organisms – Those organisms which can not be seen through unaided eyes and can only be seen through. microscope are called micro-organisms. Types of micro-organisms – Micro-organisms are of six types –

  1. Virus
  2. Mycoplasma
  3. Bacteria
  4. Fungus
  5. Protozoa
  6. Algae.

1. Virus –
They are the minutest structures. They are also called the connecting link – between living and non-living because they possess both living as well as non-living characteristics. In nature, they remain as non-living but once they enter living being. they start growth and multiplication. They cause many diseases in plants and animals.

Example –
Tobacco Mosaic Virus (TMV), Human Immuno Deficiency Virus (HIV) etc.

2. Mycoplasma –
Mycoplasma is the smallest cell which can sieve even through a virus filter. It causes diseases in plants such as little leaf of brinjal and sesame phyllody. They are called the jokers of the plant kingdom.

3. Bacteria –
They are unicellular pro karyotes. Bacteria are found in all places around us.

Example –
E.coli, lactobacillus etc.

4. Fungi –
They are also called fungus or moulds, They are micro-organisms with simple structure and can be unicellular or multicellular. They lack chlorophyll in their cells. So, they cannot prepare their own food. Some fungi obtain food as saprophytes by absorbing nutrients from decaying organic substances.

Example –
mushroom. Some fungi live as parasite on plants and animals. For example – Puccinia graminis tritici (black rust disease) in wheat and Sclerospora graminicola (downy mildew disease) in millet. Some fungi live in. symbiotic relation with algae.

5. Protozoa –
They are unicellular organisms.

Example –
amoeba, paramaecium etc.

6. Algae –
They are micro-organisms having simple structure and may be unicellular or multicellular. Water in ponds, puddles and drains appear green due to the presence of algae.

Example –
chlamydomonas, chlorella (eukaryote. unicellular), spirogyra, ulothrix (eukaryote, multicellular) and blue-green algae (prokaryote, multicellular).

Question 2.
What is food preservation? Write the remedies for preventing contamination of food items?
Answer:
Food preservation –
The process of maintaining the nutrient richness and quality of food and other edible substances is called food preservation. Common methods of food preservation are as follows –
1. Refrigeration – ln process of refrigeration, the temperature is low. Biological activities of micro-organisms become slow at low temperature. So, food stuff does not get spoiled easily when kept in refrigerator.

2. Pasteurization –
Now a days, the use of canned food items is increasing. Before packaging milk or other food items in cans or bottles, milk or the food items are heated at 60°C for 30 minutes and then cooled down. This process is repeated 2 – 3 times and it kills the harmful micro-organisms present in them. This technique of killing germs is called pasteurization.

Air is removed from the cans after pasteurized food items are packaged in cans because the micro-organisms can not grow in the absence of air. The date mentioned on the cans before which the food item must be consumed is known as expiry date. We must always see the expiry date of canned food items before buying them. Such food items must he consumed before their expiry date.

3. Dehydration –
In this, water is removed from food items.

Example –
keeping wheat and pulses in sunlight to remove moisture.

4. Boiling –
liquid food items are boiled to kill micro-organisms present in hein.

Example –
milk, water etc.

5. By using chemicals –
Those substances which help in preserving food items are called preservatives.

Example –
sodium benzoate and potassium metabisulphate are used for the preservation of syrups, squash, ketchup etc.

6. Using salt, sugar, oil and vinegar –
Salt, sugar, oil and vinegar are used in the preservation of meat, pickles, jam, jelly and vegetables.

7. By using disinfectants –
Soaps arc used to wash dirty hands. Phenyl is used to clean dirty toilets and bathrooms and make them bacteria-free.

8. To make bacteria free water –
Chlorine. bleaching powder. potassium permanganate etc. are used. In addition to these, carbonic acid also used as a germicide (substance which kills terms).

Question 3.
Draw diagrams of the following –

  1. Amoeba
  2. Paramecium
  3. Algae
  4. Fungi
  5. Virus
  6. Root nodules of plants belonging to leguminous family.

Answer:
RBSE Solutions for Class 6 Science Chapter 8 Micro-Organisms-1

RBSE Class 6 Science Micro-Organisms Important Question and Answers

Choose the correct options:

Question 1.
The link between the living and non – living among the following is –
(a) Virus
(b) Fungus
(c) Algae
(d) Bacteria
Answer:
(a) Virus

Question 2.
Which of the following is not an example of protozoa –
(a) Amoeba
(b) Paramecium
(c) Euglena
(d) Ulothrix
Answer:
(d) Ulothrix

Question 3.
Which bacteria is found in curd –
(a) Rhizohiuin
(b) Ulothrix
(c) Lactohacillus
(d) None of these
Answer:
(c) Lactohacillus

Question 4.
………… is helpful in converting atmospheric nitrogen into nitrates.
(a) Tobacco Mosaic
(b) Lactohacillus
(c) Ulothrix
(d) Rhizobium
Answer:
(d) Rhizobium

Question 5.
Yellow mosaic disease in lady finger is caused by –
(a) Bacteria
(b) Virus
(c) Algae
(d) Fungus
Answer:

  1. (a)
  2. (d)
  3. (c)
  4. (d)
  5. (b)

Fill in the blanks:

  1. ………………… are useful in the formation of curd paneer. vinegar etc. (Bacteria/Virus)
  2. In the technique of refrigeration the temperature is ………………… (low/high)
  3. The instrument through which micro organisms are easily seen is called ………………… (microscope/telescope)
  4. Some fungus are found as ………………… with algae. (symbiotic/parasitic)
  5. Humus makes the soil ………………… (fertile/unfertile)

Answer:

  1. Bacteria
  2. low
  3. microscope
  4. symbiotic
  5. fertile

Match Column (I) with Column (II):

Question 1.
RBSE Solutions for Class 6 Science Chapter 8 Micro-Organisms-2
Answer:

  1. (c)
  2. (e)
  3. (b)
  4. (a)
  5. (d)

Very Short Answer Type Questions:

Question 1.
What changes occur when bread is kept at moist place?
Answer:
On keeping bread in a moist place some white filament like structures and black spots are seen.

Question 2.
What are the filamentous structures and black spots seen in rotten bread?
Answer:
filamentous structures and black spots seen on rotten bread are the filament and spores of the fungi respectively.

Question 3.
What do you see in the roots of peal gram/moong?
Answer:
Roots of leguminous plants like peal gram/moong contains node like structures.

Question 4.
What are these node like structures found in the roots of pea/gram/moong plants called?
Answer:
These node like structures found in the roots of leguminous plants like gram / pea are called nodules.

Question 5.
What is meant by rhizobium?
Answer:
Rhizobium is helpful in converting make the soil fertile. The main source of nitrogen in plants is their nitrates.

Question 6.
Does the nodes like structure that are found in roots of plants like pea / gram / moong are present in all the roots of other plants?
Answer:
No, nodes like structures are not found in roots of all the plants.

Question 7.
Give two examples of virus.
Answer:

  1. Tobacco Mosaic Virus (TMV)
  2. Human Immuno Deficiency Virus (HIV).

Question 8.
Who is called the joker of plant kingdom?
Answer:
The joker of the plant kingdom is a very small sized micro-organism called myco-plasma. It causes little leaf in lady finger and sea same phyllody.

Question 9.
Give two uses of chlorella.
Answer:

  1. Used in making soups and other food products.
  2. The food products made by chlorella are also used as a ingredient for making ice-cream.

Question 10.
Give the names of two bacteria along with the medicines used in the preparation of medicines.
Answer:

  1. Clostridium botulinum bacteria is used to prepare vitamin B12 medicine.
  2. Penicillium fungi is used to prepare a life saving vaccine called penicillin.

Question 11.
Which micro-organism is used in manufacturing toothpaste?
Answer:
The micro-organism named Xenthomonas compestris is used in the manufacture of toothpaste.

Question 12.
Name the bacteria that causes food poisoning.
Answer:
Clostridium botulinum bacteria

Question 13.
Where do the virus multiply’?
Answer:
The virus multiply in bacteria, plant or animals only.

Question 14.
What is meant by the expiry date written on the canned packets of food items?
Answer:
The date mentioned on the cans before which the food items must be consumed is known as the expiry date.

Question 15.
What are food preservatives?
Answer:
Those substances or chemicals that helps in the preservation of food items are called food preservatives.

Example –
sodium benzoate and potassium metabysulphate. are used in the preservation of squash, ketchup, serbitol etc.

Question 16.
Which instrument is used to see micro-organisms?
Answer:
Micro-organisms can be seen with the help of an instrument called microscope. They can not he seen through unaided eyes.

Short Answer Type Questions:

Question 1.
Why the white filamentous structures and black spots are seen on keeping bread In moist place?
Answer:
Spores of many micro-organisms remain suspended in air. In presence of favorable environment and nutrition, they grow and form filament-like structures.

Question 2.
Which type of structures are seen on spreading drops of pond water on a glass slide and observed under microscope.
Answer:
Many types of micro-organisms are found in a single drop of water that can be seen only with the help of a microscope. So, micro-organism are usually found in air, water, soil, hot water springs, snowy areas, marshy land. This means that they are present everywhere. They are found in various shapes and types.

Question 3.
What is nitrogen cycle?
Answer:
When decomposition of dead animals and plants occur, then nitrogen present in them is released into the atmosphere. This nitrogen is again obtained by plants. In this way, this cycle continues in nature. As a result, the amount of nitrogen in the soil remains constant. The process of conversion of free atmospheric nitrogen into usable compounds and reaching in living beings and then again release of nitrogen in the atmosphere is called nitrogen cycle.

Question 4.
What is rhizobium?
Answer:
The roots of leguininous plants like pea/moong/gram has node like structures. These node-like structures are called root node or nodules. Rhizobium bacteria are present in it. They are helpful in converting atmospheric nitrogen into nitrates.

Question 5.
How nitrates are formed and how are they useful?
Answer:
The bacteria present in the soil (Rhizobium) and blue green algae fix the atmospheric nitrogen and converts them into nitrogenous compounds and forms nitrates. Plants use it from the soil through vascular system. Then the absorbed nitrogen is used to synthesys protein and other nitrogen compounds.

Question 6.
Name the diseases caused by micro organisms in plants and animals.
Answer:

1. Dlseases caused in animals by micro- organisms

  • T.B., Diptheria, Tetanus, Cholera, Malaria, Skin disease, Anthrax, Whooping cough.

2. Diseases caused In plants by micro-organisms –

  • Rust of wheat, yellow mosaic in ladyfinger, citrus canker etc.

Question 7.
Write the remedies for protection against harmful micro-organisms.
Answer:
Proper maintenance of items and prevention can protect against harmful organisms which are as follows:

  1. Cereals, pulses, clothes etc. must be kept in sunlight from time to time.
  2. Cooked day, milk etc. must be kept in cool place.
  3. Oils in pickles and sugar in jams can be used.
  4. Food stuffs can be prevented by using vinegar.
  5. Neem leaves and balls of mercury (parad goli) must be used in grains of paddy and pulses.

Question 8.
What is refrigeration?
Answer:
In process of refrigeration, the temperature is low. Biological activities of micro-organisms became slow at low temperature. So, food stuff does not get spoiled easily when kept in refrigeration. the process of keeping food items at low temperature is called refrigeration. Now a days, farmers and businessmen, use cold storage to keep fruits, vegetables and other food items fresh and preserved.

Question 9.
What is sterilization?
Answer:
The process of keeping syringe and needle of an injection in boiling water to make them germ-free, is called sterilization. Now a days, sterilized needles and syringes are used and they can be used only once. To make the equipment and objects used in an operation germ-free, an instrument named autoclave is used. It works like a pressure cooker. Ultraviolet rays can also be used to make objects germ-free.

Essay type Questions:

Question 1.
Write the names of common methods of food preservation.
Answer:
The process of maintaining the nutrient richness and quality of food and other edible substances is called food preservation. The common methods of food preservation are as follows:

  • Refrigeration
  • Sterilization
  • Pasteurization
  • Dehydration
  • Boiling
  • By using chemicals
  • Using salt, sugar, oil and vinegar
  • By using disinfectants
  • To make bacteria free water.

Question 2.
Make a list of uses and harms caused by micro-organisms in our daily life.
Answer:
List of uses and harms caused by the micro-organisms in our daily life is –

1. Uses caused by micro-organisms

  • Production of food stuff.
  • Preparation of medicines.
  • Biological nitrogen fixation.
  • Humus formation.
  • In making toothpaste.

2. Harms caused by micro-organisms

  • Causes disease.
  • Spoil food stuffs.
  • Causes food poisoning.
  • Damages valuable items.
  • Causes disease in plants and animals both.

Question 3.
Explain biological nitrogen fixation or compound formation of nitrogen. Draw the diagram of root nodules also.
Answer:
Biological nitrogen fixation – Certain species of bacteria and some other micro organisms convert atmospheric nitrogen into such compounds that can be absorbed by plants. This process of convening atmospheric nitrogen into plant usable nitrogen compounds is called biological nitrogen fixation or compound formation of nitrogen.

Example –
Rhizobium bacteria is present in the root nodules of leguminous plants ,such as kidney bean, gram, pea etc. These root nodules are present only in leguminous plants. These rhizobium bacteria are helpful in converting atmospheric nitrogen into nitrates. Nitrates make soil more fertile. Nitrates are

the main source of nitrogen for plants. Nitrogen is an integral constituent of protein. Due to this reason, farmers grow leguminous crops like kidney bean, moth, cluster bean (guar) etc. in one year and cereal crops like millet, sorghum etc. in the next year.
RBSE Solutions for Class 6 Science Chapter 8 Micro-Organisms-5

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