Frank Brothers Solutions for ICSE Class 9 Biology Chapter 14 Bacteria And Fungi Their Importanc

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Question 1:
Answer:
1. Bacteria are a large group of unicellular, prokaryotic microorganisms.
2. 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.
Bacteria are so tiny that we need a microscope to see them. The Gram stain is a special test that helps scientists identify which type of bacteria they are looking at by their color.
Teacher's Tip: Remember "P" for Positive and "P" for Purple - Gram-positive bacteria turn purple!
Exam Tip: When defining Gram-negative and Gram-positive, always mention the specific chemicals like crystal violet and iodine solution.

Question 2:
Answer:
1. Bacteria shows the presence of cell wall, hence they are included under plants.
2. Spore formation helps bacteria to survive during adverse environmental conditions. Hence it is a survival technique.
3. 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.
4. 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.
Bacteria are surprisingly versatile; they can be our best helpers in making food or our worst enemies when they cause sickness. Yeast works like a tiny engine that turns sugar into gas, making bread fluffy and light.
Teacher's Tip: Think of spores as a "biological spacesuit" that protects bacteria from heat or dryness.
Exam Tip: List at least three "friend" uses and two "foe" examples to ensure a complete answer for long-form questions.

Question 3:
Answer:
Diagram of a bacterial cell:
Photosynthetic Apparatus
Flagellum
Basal Granule
Capsule
Ribosomes
Cell Wall
Coiled DNA Molecule
Clear Nucleoplasm
Mesosome
Plasmalemma
Dense Cytoplasm
Each part of a bacteria cell has a special job, like the flagellum which acts like a tail for swimming. The DNA inside is coiled up because bacteria do not have a separate nucleus to hold it.
Teacher's Tip: Imagine the Flagellum as a tiny motor boat's propeller that pushes the bacteria forward.
Exam Tip: Draw the flagellum long and thin, and always label the cell wall as the outermost protective layer.

Question 4:
Answer:
(a) Shape of bacteria - Bacteria show wide variation in their shape, but all cells of a species have the same shape. On the basis of shape, bacteria are of following types:
(i) Coccus bacteria -> Spherical shaped
(ii) Bacillus bacteria -> Rod-shaped shaped
(iii) Spiral bacteria -> Helical shaped
(iv) 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 -
(i) Brewery - The brewing industry depends on the fermentation activity of yeasts. Yeast fermentation produces different types of beverages like wine, beer, alcohol, toddy etc.
(ii) 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.
(iii) Vitamins - Yeast is an important source of vitamin B-complex.
(iv) 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 cell walls are composed of chitin and they have multinucleate cells. They have rhizoids and their sporangiophores are usually unbranched.
Bacteria come in many geometric shapes which scientists use to name them, like the round 'Coccus'. Rhizopus is a type of mold that grows on bread, using its root-like rhizoids to anchor itself.
Teacher's Tip: Use "B" for Bacillus and think of a "B"at (rod-shaped) to remember its shape.
Exam Tip: Use the term "chitin" specifically when describing the cell wall of fungi like Rhizopus.

Question 5:
Answer:
Bacteria plays an important role in nitrogen fixation. There are two types of nitrogen- fixing bacteria.
1. 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.
2. Free- living bacteria: Bacteria like Azotobacter and Clostridium live inside the soil and fix free nitrogen of the air and convert them into ammonia, amino- acids and proteins.
Most plants cannot breathe in nitrogen from the air, so these helpful bacteria act like "translators" to turn it into food. This process is essential for keeping our soil rich and helping crops grow.
Teacher's Tip: Rhizobium is like a roommate for plants - it gets a home and gives back nitrogen in return.
Exam Tip: Clearly distinguish between "symbiotic" (living with plants) and "free-living" (living alone in soil) bacteria.

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Question 6:
Answer:
(a) BACTERIA vs YEAST:
BACTERIA: It belongs to kingdom Monera. It is a prokaryotic organism. Its cell wall made is up of carbohydrates, proteins, muramic acid etc. It shows the presence of slimy capsule on the outside.
YEAST: It belongs to kingdom Fungi. It is an eukaryotic organism. Its cell wall is made up of chitin. Slimy capsule is absent.
(b) GRAM POSITIVE BACTERIA vs GRAM NEGATIVE BACTERIA:
GRAM POSITIVE: The bacteria which get stained with crystal violet and iodine solution are called gram positive bacteria.
GRAM NEGATIVE: The bacteria which do not get stained with crystal violet and iodine solution are called gram negative bacteria.
(c) RHIZOPUS vs MUCOR:
RHIZOPUS: They have rhizoids. Sporangiophores are usually unbranched.
MUCOR: They do not have any rhizoids. Sporangiophores are often branched.
(d) PARASITIC BACTERIA vs SAPROPHYTIC BACTERIA:
PARASITIC: These bacteria live in or on the surface of other living organisms and take digested food from their hosts. E.g. Salmonella.
SAPROPHYTIC: These bacteria feed on dead organic matter of plant and animal remains. E.g. Bacillus.
Comparing these organisms helps us see the subtle differences in how they live and what they are made of. For example, knowing if a bacteria is a parasite or a saprophyte tells us if it lives on living or dead things.
Teacher's Tip: "Saprophyte" starts with "S" just like "Scavenger" because they eat dead things.
Exam Tip: When writing differences in a table, ensure points correspond directly to each other for full credit.

Question 7:
Answer:
(a) Penicillium notatum
(b) Aspergillus fumigatus
(c) Candida albicans
(d) Aspergillus
These are the scientific names for specific types of fungi found in nature and medicine. Penicillium is famous for being the source of the world's first life-saving antibiotic.
Teacher's Tip: Scientific names are always in two parts, like a first and last name for every species.
Exam Tip: Always underline scientific names when you write them by hand to follow standard biology rules.

Question 8:
Answer:
(a) chitin
(b) saprophytic
(c) obligate aerobes
(d) Agaricus campestris
These terms describe key characteristics, like 'obligate aerobes' which are organisms that absolutely must have oxygen to breathe. Agaricus campestris is the common mushroom we often see in fields.
Teacher's Tip: Think of "Aerobes" as "Air-eaters" to remember they need oxygen.
Exam Tip: Pay attention to spelling, especially words like "obligate" and "aerobes."

Question 9:
Answer:
Rust -> crop disease
Typhoid -> Bacterial disease
Coenocytic -> Rhizopus
Aspergillosis -> Fungal disease
Symbiotic -> Rhizobium
Sporangiophore -> Sporangia
Mycology -> Study of fungi
Nitrifying bacteria -> Nitrobacter
Antibiotic -> Penicillin
Matching these terms shows how different biological concepts are connected, like a disease to its cause. For instance, mycology is the specific branch of science dedicated to studying fungi.
Teacher's Tip: Use "Myc-" as a clue; whenever you see "myc", it usually means something related to fungi.
Exam Tip: In match-the-column questions, double-check that every pair is correctly linked before finishing.

Question 10:
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.
Not all fungi are moldy; many are delicious and healthy to eat as mushrooms. They add special flavors and nutrients to dishes from all around the world.
Teacher's Tip: Never eat wild mushrooms unless an expert says they are safe, as some can be very poisonous!
Exam Tip: List at least two examples of edible fungi like Agaricus and Morchella to get full marks.

Question 11:
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.
Antibiotics are powerful medicines that help our bodies fight off harmful bacterial infections. Scientists discovered these by watching how certain fungi naturally kill off bacteria in nature.
Teacher's Tip: Think of Penicillin as the "Grandfather" of all antibiotics because it was discovered first.
Exam Tip: State both the antibiotic name and the fungus it comes from for a complete answer.

Question 12:
Answer:
Plant Disease - Causal agent
Loose smut of wheat -> Ustilago tritici
Leaf rust of sugarcane -> Puccinia saccharii
Just like people, plants can get sick from fungus and bacteria too. These diseases can ruin whole fields of crops if farmers do not protect them.
Teacher's Tip: Smut and Rust are descriptive names based on how the diseased plant looks - dark or reddish-brown.
Exam Tip: Memorize the scientific names of the causal agents carefully for these specific plant diseases.

Question 13:
Answer:
1. (b) Leeuwenhoek
2. (a) bacteria
3. (b) Bacillus
4. (a) Tuberculosis
5. (d) Rhizobium
6. (b) Lactobacillus
7. (d) Agaricus
8. (a) ethyl alcohol
These multiple-choice answers cover famous scientists like Leeuwenhoek and the different roles microbes play. For instance, Lactobacillus is the tiny hero that turns milk into tasty yogurt.
Teacher's Tip: Match the scientist to the discovery: Leeuwenhoek was the first person to see "animalcules" (microbes).
Exam Tip: Read each option carefully because some scientific names can look very similar.