Frank Solutions for Chapter 14 Bacteria, Fungi and their Importance Class 9 Biology ICSE
Exercises
1. Define the following:
(a) Bacteria
(b) Gram negative and Gram positive bacteria.
Answer
(a) Bacteria
(b) Gram negative and Gram positive bacteria.
Answer
(a) Bacteria are a large group of unicellular, prokaryotic microorganisms.
(b) The bacteria which do not get stained with crystal violet and iodine solution are called gram negative bacteria while those bacteria which get stained with crystal violet and iodine solution are called gram positive bacteria.
(b) The bacteria which do not get stained with crystal violet and iodine solution are called gram negative bacteria while those bacteria which get stained with crystal violet and iodine solution are called gram positive bacteria.
2. Explain briefly:
(a) Bacteria is a plant.
(b) Spore formation is a survival technique not a mode of reproduction in bacteria.
(c) Bacteria are our friends and foes both.
(d) Yeast is used in bakeries and breweries.
Answer
(a) Bacteria is a plant.
(b) Spore formation is a survival technique not a mode of reproduction in bacteria.
(c) Bacteria are our friends and foes both.
(d) Yeast is used in bakeries and breweries.
Answer
(a) Bacteria shows the presence of cell wall, hence they are included under plants.
(b) Spore formation helps bacteria to survive during adverse environmental conditions. Hence it is a survival technique.
(c) Bacteria as friends: Bacteria are useful to us in many ways like producing antibiotics, forming curd and cheese, tanning leather, producing various industrial products, nitrogen fixation, digesting cellulose etc.
Bacteria as foes: They are harmful in many ways like causing diseases, bio-weapons , food spoilage etc.
(d) Yeast is used in breweries since the fermentation activity of yeast produces different types of beverages like wine, beer, alcohol toddy etc. In bakeries, when yeast is added to the flour its fermentation results in the production of carbon dioxide which produces soft bread and other bakery products.
(b) Spore formation helps bacteria to survive during adverse environmental conditions. Hence it is a survival technique.
(c) Bacteria as friends: Bacteria are useful to us in many ways like producing antibiotics, forming curd and cheese, tanning leather, producing various industrial products, nitrogen fixation, digesting cellulose etc.
Bacteria as foes: They are harmful in many ways like causing diseases, bio-weapons , food spoilage etc.
(d) Yeast is used in breweries since the fermentation activity of yeast produces different types of beverages like wine, beer, alcohol toddy etc. In bakeries, when yeast is added to the flour its fermentation results in the production of carbon dioxide which produces soft bread and other bakery products.
3. Draw a labelled diagram of a bacterial cell.
Answer
Diagram of a bacterial cell:
4. Write short notes on:
(a) Shape of bacteria
(b) Flagellation in bacteria
(c) Economic importance of yeast
(d) Structure of Rhizopus
Answer
(a) Shape of bacteria - Bacteria show wide variation in their shape, but all cells of a species ahve the same shape. On the basis of shape, bacteria are of following types:
- Coccus bacteria → Spherical shaped
- Bacillus bacteria → Rod-shaped shaped
- Spiral bacteria → Helical shaped
- Vibrio bacteria → Comma shaped
(b) Flagellation in bacteria - Many bacteria are motile and contain one or more flagella. the flagella are made up of flagellin protein and rotate like a propeller of ship to bring about movement of bacteria.
(c) Economic importance of yeast-
- Brewery - The brewing industry depends on the fermentation activity of yeasts. Yeast fermentation produces different types beverages like wine, beer, alcohol, toddy etc.
- Baking - In bakeries during bread making, when yeast is added to the flour its fermentation results in the production of carbon dioxide which produces soft bread.
- Vitamins - Yeast is also used in the preparation of idli and dosa from a mixture of powdered rice and dal.
- Food - Yeast is also used in the preparation of idli and dosa from a mixture of powdered rice and dal.
(d) Structure of Rhizopus - Rhizopus consists of a multicellular body called mycelium, consisting of filaments called hyphae. Their Sporangiophores are usually unbranched.
5. Explain, briefly the role of bacteria in nitrogen fixation.
Answer
Bacteria plays an important role in nitrogen fixation. There are two types of nitrogen - fixing bacteria.
- Symbiotic bacteria: Rhizobium is a symbiotic bacteria living in root nodules of leguminous plant which directly fix atmospheric nitrogen and convert them into nitrites and nitrates and make them available to the plant.
- Free-living bacteria: Bacteria like Azatobacter and Clostridium live inside the soil and fix free nitrogen of the air and convert them into ammonia, amino-acids and proteins.
6. Differentiate between:
(a) Bacteria and Yeast
(b) Gram positive and Gram negative bacteria
(c) Rhizopus and Mucor
(d) Parasitic and Saprophytic bacteria
(a) Bacteria and Yeast
(b) Gram positive and Gram negative bacteria
(c) Rhizopus and Mucor
(d) Parasitic and Saprophytic bacteria
Answer
(a) Difference between Bacteria and Yeast
| Bacteria | Yeast |
| It belongs to kingdom Monera | It belongs to kingdom Fungi |
| It is a prokaryotic organism | It is an eukaryotic organism |
| Its cell wall made is up of carbohydrates, proteins, muramic acid etc | Its cell wall is made up of chitin |
| It shows the presence of slimy capsule on the outside | Slimy capsule is absent |
(b) Difference between Gram positive and Gram negative bacteria
| Gram Positive Bacteria | Gram negative Bacteria |
| The bacteria which get stained with crystal violet and iodine solution are called gram positive bacteria | The bacteria which do not stained with crystal violet and iodine solution are called gram negative bacteria |
(c) Difference between Rhizopus and Mucor
| Rhizopus | Mucor |
| They have rhizoids | They do not have any rhizoids |
| Sporangiophores are usually unbranched | Sporangiophores are oftern branched |
(d) Difference between Parasitic and Saprophytic bacteria
| Parasitic Bacteria | Saprophytic Bacteria |
| These bacteria live in or on the surface of other living organisms and take digested food from their hosts. | These bacteria feed on dead organic matter of plant and animal remains. |
| E.g. Salmonella | E.g. Bacillus |
(a) fungus that gives penicillin.
(b) mould that causes Aspergillosis in human beings.
(c) mould which is known as Red-ring mould.
(d) mould that causes lung mycosis.
Answer
(a) Penicillium notatum
(b) Aspergillus fumigatus
(c) Candida albicans
(d) Aspergillus
(b) Aspergillus fumigatus
(c) Candida albicans
(d) Aspergillus
8. Fill in the blanks:
(a) The cell-wall of fungi is made up of ______.
(b) The fungi are ______ in their mode of nutrition.
(c) Bacteria which cannot live without oxygen is called ______.
(d) Fungi which is edible is ______.
(a) The cell-wall of fungi is made up of ______.
(b) The fungi are ______ in their mode of nutrition.
(c) Bacteria which cannot live without oxygen is called ______.
(d) Fungi which is edible is ______.
Answer
(a) chitin
(b) saprophytic
(c) obligate aerobes
(d) Agaricus campestris
(b) saprophytic
(c) obligate aerobes
(d) Agaricus campestris
9. Match items in Column A with the appropriate items in Column B:
|
Column A |
Column B |
|
Rust |
Bacterial disease |
|
Typhoid |
Nitrobacter |
|
Coenocytic |
Penicillin |
|
Aspergillosis |
Crop disease |
|
Symbiotic |
Rhizopus |
|
Sporangiphore |
Study of fungi |
|
Mycology |
Sporangia |
|
Nitrifying bacteria |
Rhizobium |
|
Antibiotic |
Fungal disease |
Answer
|
Column A |
Column B |
|
Rust |
Crop disease |
|
Typhoid |
Bacterial disease |
|
Coenocytic |
Rhizopus |
|
Aspergillosis |
Fungal disease |
|
Symbiotic |
Rhizopus |
|
Sporangiphore |
Sporangia |
|
Mycology |
Study of fungi |
|
Nitrifying bacteria |
Nitrobacter |
|
Antibiotic |
Penicillin |
10. How are fungi important as food?
Answer
Answer
Fungi are cooked like vegetables or used in pulao or prepared as soups. Some common edible fungi are Agaricus, Ramaria, Clavaria, Morchella. Also yeast is used in preparing idli and dosa from a mixture of powdered rice and dal.
11. Are fungi useful in medical sciences? How?
Answer
Answer
Yes, Many types of antibiotics are obtained from fungi which are used in medical sciences. Today about 25 types of antibiotics are commercially produced from moulds. For example: Penicillin is obtained from the fungus Penicillium notatum. Griseofulvin is extracted from the fungus Penicillium griseofulvum.
12. Name two plant diseases caused by fungi. Also, mention the causal agents.
Answer
Plant Disease Causal agent
Loose smut of wheat Ustilago tritici
Leaf rust of sugarcane Puccinia saccharii
13. Every question has four options. Choose the correct answer:
(i) Which scientist first discovered the bacteria?
(a) Pasteur
(b) Leeuwenhoek
(c) Koch
(d) De Vries
(a) Pasteur
(b) Leeuwenhoek
(c) Koch
(d) De Vries
Answer
(b) Leeuwenhoek
(ii) Bacteriology is the study of
(a) bacteria
(b) virus
(c) fungi
(d) mycoplasms
Answer
(a) bacteria
(a) bacteria
(iii) Which bacteria is rod-shaped?
(a) Coccus
(b) Bacillus
(c) Spirillum
(d) None of these
(a) Coccus
(b) Bacillus
(c) Spirillum
(d) None of these
Answer
(b) Bacillus
(b) Bacillus
(iv) Which disease is caused by bacteria?
(a) Tuberculosis
(b) Aspergillosis
(c) Measles
(d) None of these
(a) Tuberculosis
(b) Aspergillosis
(c) Measles
(d) None of these
Answer
(a) Tuberculosis
(a) Tuberculosis
(v) Which fixes the atmospheric nitrogen?
(a) Nitrobacter
(b) Nitrosomonas
(c) Xanthomonas
(d) Rhizobium
Answer
(a) Nitrobacter
(b) Nitrosomonas
(c) Xanthomonas
(d) Rhizobium
Answer
(d) Rhizobium
(vi) Which bacteria is useful in fermentation of milk?
(a) Hay bacillus
(b) Lactobacillus
(c) Aceto bacillus
(d) Rhizobium
(a) Hay bacillus
(b) Lactobacillus
(c) Aceto bacillus
(d) Rhizobium
Answer
(b) Lactobacillus
(b) Lactobacillus
(vii) Tasteful food for man is
(a) Rhizopus
(b) Penicillium
(c) Amantia
(d) Agaricus
(a) Rhizopus
(b) Penicillium
(c) Amantia
(d) Agaricus
Answer
(d) Agaricus
(d) Agaricus
(viii) Yeast is used in the production of
(a) ethyl alcohol
(b) acetic acid
(c) cheese
(d) curd
(a) ethyl alcohol
(b) acetic acid
(c) cheese
(d) curd
Answer
(a) ethyl alcohol