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GNDU Question Paper-2022
Bachelor of Computer Application (BCA) (Hons.)
1
st
Semester (Batch 2024-28) (CBGS)
BOTANY: Paper-I-A
(Diversity of Microbes)
Time Allowed: Three Hours Max. Marks:35
Note: Attempt Five questions in all, selecting at least One question from each section. The
Fifth question may be attempted from any section. All questions carry equal marks.
SECTION-A
1. (a) Write about general characteristics of Algae and its classification.4
(b) Write down about the important features of family Chlorophyceae and also give its
examples.
2. (a) Explain about the economic importance of Algae.
3 (b) To which family does Ectocarpus belong? Wite down about some of its salient
features.
SECTION-B
3. (a) Write about general characteristics of Viruses.
(b) Give classification of bacteria on the basis of their nutrition.
4 4. (a) Differentiate between Gram-positive and Gram-negative bacteria. Also draw
labelled diagrams.
(b) Give a generat account of Cyanobacteria
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SECTION-C
5. (a) Write about the economic importance of Ascomycetes.
(b) Explain and draw a well labeled diagram of life cycle of mucor.
6. (a) Give classification of fungi along with examples.
(b) Differentiate between Mastigomycotina and Zygomycotina.
SECTION-D
7. (a) Define a lichen. Discuss the role of each partner.
(b) Mention some features of Cercospora and which disease is caused by it in plants.
(c). Name the fruiting body of Agaricus.
8. (a) Why lichens are considered as pollution indicator?
(b) How fungi are different from plants?
(c) Highlight some of the differences between Basidiomycetes and Deuteromycetes.
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GNDU Answer Paper-2022
Bachelor of Computer Application (BCA) (Hons.)
1
st
Semester (Batch 2024-28) (CBGS)
BOTANY: Paper-I-A
(Diversity of Microbes)
Time Allowed: Three Hours Max. Marks:35
Note: Attempt Five questions in all, selecting at least One question from each section. The
Fifth question may be attempted from any section. All questions carry equal marks.
SECTION-A
1. (a) Write about general characteristics of Algae and its classification.4
(b) Write down about the important features of family Chlorophyceae and also give its
examples.
Ans: Algae are simple, chlorophyll-containing plants that mostly live in water. They are one
of the oldest living organisms on Earth and play a very important role in nature because
they produce a large amount of the oxygen we breathe. Unlike higher plants, algae do not
have true roots, stems, leaves, or vascular tissues (xylem and phloem). Their plant body is
called a thallus, which means it is not divided into different plant organs.
Imagine visiting a pond. The green layer floating on the water or attached to stones is often
made up of algae. Although they look very simple, algae are extremely important because
they are the primary producers in aquatic ecosystems. They prepare their own food
through photosynthesis, using sunlight, carbon dioxide, and water.
General Characteristics of Algae
1. Body Structure
The body of algae is called a thallus.
It has no true roots, stems, or leaves.
They may be unicellular (single-celled), colonial, filamentous, or multicellular.
2. Habitat
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Most algae live in freshwater, marine water, ponds, lakes, rivers, and oceans.
Some grow on moist soil, tree bark, rocks, or even in snow.
3. Nutrition
Algae are autotrophic, meaning they make their own food by photosynthesis.
Chlorophyll helps them capture sunlight.
4. Cell Wall
Most algae have a cell wall made of cellulose.
Some also contain pectin or other substances depending on the group.
5. Reproduction
Algae reproduce in three different ways:
Vegetative reproduction by fragmentation.
Asexual reproduction by spores such as zoospores.
Sexual reproduction by fusion of male and female gametes.
6. Importance
Produce oxygen.
Used as food (e.g., seaweed).
Used in medicines and fertilizers.
Provide food and shelter for aquatic animals.
Classification of Algae
Algae are mainly classified according to the type of pigments, stored food, and cell wall
composition.
Class
Main Pigment
Stored Food
Example
Chlorophyceae (Green
Algae)
Chlorophyll a &
b
Starch
Chlamydomonas, Spirogyra,
Ulothrix
Phaeophyceae (Brown
Algae)
Fucoxanthin
Laminarin
Sargassum, Laminaria
Rhodophyceae (Red
Algae)
Phycoerythrin
Floridean
starch
Gelidium, Polysiphonia
Simple Classification Diagram
ALGAE
│
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┌─────────────────┼──────────────────┐
│ │ │
Green Algae Brown Algae Red Algae
(Chlorophyceae) (Phaeophyceae) (Rhodophyceae)
│ │ │
Chlorophyll a,b Fucoxanthin Phycoerythrin
│ │ │
Spirogyra Sargassum Gelidium
Chlamydomonas Laminaria Polysiphonia
(b) Important Features of Chlorophyceae (Green Algae) with Examples
Chlorophyceae is the group commonly known as green algae. They are called green algae
because they contain a large amount of chlorophyll a and chlorophyll b, the same pigments
found in higher plants. These pigments give them their bright green color.
Most green algae are found in freshwater ponds, lakes, rivers, and slow-moving streams,
although some are also found in the sea and on moist land.
Important Features of Chlorophyceae
1. Green Colour
The green colour is due to the presence of chlorophyll a and chlorophyll b.
2. Plant Body
The body is called a thallus and may be:
Unicellular
Colonial
Filamentous
Multicellular
3. Cell Wall
The cell wall is mainly composed of cellulose.
4. Food Storage
The food produced during photosynthesis is stored as starch, usually inside structures called
pyrenoids.
5. Habitat
Mostly freshwater
Some marine
Some terrestrial in moist places
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6. Reproduction
They reproduce by:
Vegetative reproduction (fragmentation)
Asexual reproduction (zoospores)
Sexual reproduction (fusion of gametes)
7. Reserve Food
Starch is the main reserve food, making them similar to higher plants.
8. Importance
Produce oxygen.
Maintain ecological balance.
Used as food for fish and other aquatic organisms.
Some are used in research and biotechnology.
Examples of Chlorophyceae
1. Chlamydomonas
Unicellular and motile.
Has two flagella for movement.
Found in freshwater.
2. Spirogyra
Filamentous green alga.
Contains spiral-shaped chloroplasts.
Commonly seen as green silky masses in ponds.
3. Ulothrix
Filamentous freshwater alga.
Attached to rocks with a holdfast.
4. Volvox
Forms spherical colonies.
Hundreds of cells live together and move as one colony.
Simple Diagram of Spirogyra
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Spirogyra Filament
┌─────┬─────┬─────┬─────┐
│/////│/////│/////│/////│
│/////│/////│/////│/////│
└─────┴─────┴─────┴─────┘
///// = Spiral Chloroplast
Flow Chart of Chlorophyceae
CHLOROPHYCEAE
│
┌─────────────┼─────────────┐
│ │ │
Green Colour Cellulose Wall Starch Stored
│ │ │
Photosynthesis Protection Pyrenoids
│
Reproduction
┌──────────┼──────────┐
│ │ │
Vegetative Asexual Sexual
(Fragment.) (Zoospores) (Gametes)
Conclusion
Algae are simple, photosynthetic organisms that form the foundation of aquatic
ecosystems. They are essential because they produce oxygen, provide food for aquatic life,
and help maintain ecological balance. Based on their pigments and food reserves, algae are
mainly classified into Chlorophyceae (green algae), Phaeophyceae (brown algae), and
Rhodophyceae (red algae).
Among these, Chlorophyceae is the most familiar group because its members closely
resemble higher plants in having chlorophyll a and b, storing starch, and possessing
cellulose cell walls. Common examples such as Chlamydomonas, Spirogyra, Ulothrix, and
Volvox are frequently studied because they clearly demonstrate the diversity and
importance of green algae. Understanding their characteristics and classification helps
students appreciate their ecological, economic, and biological significance.
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2. (a) Explain about the economic importance of Algae.
(b) To which family does Ectocarpus belong? Wite down about some of its salient
features.
Ans: (a) Economic Importance of Algae
Algae are simple, chlorophyll-containing plants that mostly live in water. They may look like
ordinary green or brown plants floating in ponds, rivers, lakes, or seas, but they are one of
the most useful groups of organisms on Earth. They are called the "primary producers" of
aquatic ecosystems because they prepare food through photosynthesis. Just as trees are
important on land, algae are equally important in water.
Imagine a fish pond without algae. Small aquatic animals would have no food, fishes would
eventually die, and the entire ecosystem would collapse. This shows how important algae
are for maintaining life.
1. Algae as Food
Many algae are rich in proteins, vitamins, carbohydrates, minerals, and essential amino
acids. Therefore, they are used as food by humans and animals.
Some edible algae include:
Ulva (Sea Lettuce)
Porphyra (used in sushi)
Laminaria
Spirulina
Chlorella
Spirulina is especially famous because it contains about 6070% protein, making it one of
the richest natural protein sources. It is commonly used as a health supplement.
Example: Athletes and health-conscious people often consume Spirulina powder or tablets
to improve nutrition.
2. Algae as Food for Animals and Fish
Algae are excellent food for:
Fish
Prawns
Cattle
Poultry
Fish farms often grow microscopic algae because young fish depend on them for food.
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3. Production of Oxygen
Like green plants, algae perform photosynthesis.
Photosynthesis:
Takes in carbon dioxide (CO₂)
Uses sunlight
Releases oxygen (O₂)
Scientists estimate that algae produce about half of the oxygen present in Earth's
atmosphere. This oxygen supports the survival of humans, animals, and other living
organisms.
4. Industrial Uses
Several useful products are obtained from algae.
(i) Agar
Agar is extracted from red algae such as Gelidium and Gracilaria.
Uses:
Preparing culture media in laboratories
Food industry
Ice cream
Jelly
Bakery products
(ii) Algin
Algin is obtained from brown algae such as Laminaria and Macrocystis.
Uses:
Textile industry
Paper industry
Toothpaste
Cosmetics
Medicines
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(iii) Carrageenan
Obtained from red algae like Chondrus.
Uses:
Chocolate milk
Toothpaste
Cosmetics
Pharmaceutical industry
5. Fertilizers
Seaweeds are used as natural fertilizers because they improve soil fertility and supply
minerals like potassium and nitrogen.
Benefits:
Better crop growth
Increased yield
Improved soil quality
6. Medicines
Many algae possess antibacterial, antiviral, antifungal, and antioxidant properties.
Scientists are studying algae for developing medicines against:
Cancer
Diabetes
Viral infections
7. Biofuel Production
Some algae store large amounts of oil.
These oils are converted into:
Biodiesel
Bioethanol
Biogas
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Algal biofuel is considered an environmentally friendly alternative to fossil fuels.
8. Environmental Importance
Algae help in:
Absorbing carbon dioxide
Reducing global warming
Purifying wastewater
Maintaining ecological balance
They also provide shelter to many aquatic organisms.
Diagram: Economic Importance of Algae
ALGAE
│
┌──────────┬──────────┬──────────┬──────────┐
│ │ │ │
Food Oxygen Industries Fertilizer
│ │ │ │
Spirulina Photosynthesis Agar Seaweed manure
Ulva O₂ production Algin
Porphyra Carrageenan
│
Medicines & Biofuel
Conclusion
Algae are extremely valuable organisms. They provide food, oxygen, medicines, fertilizers,
industrial products, and renewable energy. Besides supporting aquatic life, they also play an
important role in protecting the environment and maintaining ecological balance. Because
of these numerous benefits, algae are often called the "green wealth of water."
(b) Family and Salient Features of Ectocarpus
Family
Ectocarpus belongs to the family: Ectocarpaceae
Classification:
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Kingdom: Plantae
Division: Phaeophyta (Brown Algae)
Class: Phaeophyceae
Order: Ectocarpales
Family: Ectocarpaceae
Genus: Ectocarpus
Introduction
Ectocarpus is a small brown alga commonly found in marine (sea) water, although a few
species occur in fresh water. It grows attached to rocks, shells, seaweeds, or other
underwater surfaces.
Its brown color is due to the pigment Fucoxanthin, which hides the green color of
chlorophyll.
Salient Features of Ectocarpus
1. Habitat
Mostly marine.
Found attached to rocks, shells, and seaweeds.
Common in coastal regions.
2. Thallus Structure
The plant body is called a thallus because it is not differentiated into roots, stems, and
leaves.
Characteristics:
Small and filamentous.
Branched.
Multicellular.
Soft and flexible.
3. Holdfast
At the base is a small holdfast.
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Function:
Attaches the plant firmly to rocks.
Prevents it from being washed away by sea waves.
4. Pigments
Contains:
Chlorophyll a
Chlorophyll c
Fucoxanthin (brown pigment)
Fucoxanthin gives the plant its characteristic brown colour.
5. Cell Wall
The cell wall consists mainly of:
Cellulose
Algin
Algin provides flexibility and has many industrial uses.
6. Reserve Food
Food is stored in the form of:
Laminarin
Mannitol
Unlike green plants, it does not store starch.
7. Reproduction
Ectocarpus reproduces in three ways:
(i) Vegetative Reproduction
Occurs by fragmentation.
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The broken pieces grow into new plants.
(ii) Asexual Reproduction
Occurs through spores.
Different spores are produced inside special structures called sporangia.
(iii) Sexual Reproduction
Sexual reproduction usually takes place by isogamy, where two similar-looking gametes fuse
to form a zygote.
Some species may also show anisogamy.
8. Life Cycle
Ectocarpus shows alternation of generations.
This means two generations alternate:
Haploid gametophyte
Diploid sporophyte
Both generations appear almost similar (isomorphic alternation of generations).
Diagram of Ectocarpus
Branches
/\
/ \
/ \
/ \
│ │
│ │
│ │
│ │
│ │
Holdfast
│
Attached to
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Rock
Key Points to Remember
Feature
Ectocarpus
Family
Ectocarpaceae
Group
Brown algae (Phaeophyceae)
Habitat
Mostly marine
Plant Body
Branched filamentous thallus
Pigment
Fucoxanthin
Reserve Food
Laminarin and Mannitol
Cell Wall
Cellulose and Algin
Attachment
Holdfast
Reproduction
Vegetative, Asexual and Sexual
Life Cycle
Isomorphic alternation of generations
Conclusion
Ectocarpus is a simple filamentous brown alga belonging to the Ectocarpaceae family.
Although small in size, it is biologically important because it demonstrates the typical
characteristics of brown algae, including the presence of fucoxanthin, storage of laminarin
and mannitol, attachment by a holdfast, and an isomorphic alternation of generations.
Along with other algae, it contributes significantly to marine ecosystems and has indirect
economic importance through products like algin obtained from brown algae.
SECTION-B
3. (a) Write about general characteristics of Viruses.
(b) Give classification of bacteria on the basis of their nutrition.
Ans: (a) General Characteristics of Viruses
A virus is an extremely small infectious particle. It is much smaller than bacteria and can
only be seen with an electron microscope. Viruses are unique because they are neither
completely living nor completely non-living.
For example, when a virus is outside a living cell, it behaves like a lifeless particle. It cannot
grow, reproduce, or perform any life processes. But once it enters the body of a living
organism, it becomes active and starts multiplying rapidly.
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General Characteristics of Viruses
1. Extremely Small Size
Viruses are the smallest known infectious agents, usually measuring 20300 nanometers
(nm). Thousands of viruses can fit inside a single bacterial cell.
2. Acellular Structure
Viruses are not made of cells. Unlike plants, animals, fungi, and bacteria, they do not have a
cell membrane, cytoplasm, or nucleus.
3. Contain Genetic Material
Every virus contains only one type of nucleic acid:
DNA or
RNA
Unlike living cells, they never contain both DNA and RNA together.
4. Protein Coat
The genetic material is surrounded by a protective protein coat called a capsid. Some
viruses also have an outer lipid envelope.
5. Obligate Parasites
Viruses can reproduce only inside living host cells. Therefore, they are called obligate
intracellular parasites.
6. Cause Diseases
Viruses cause many diseases in humans, animals, and plants.
Examples:
Common Cold
Influenza (Flu)
COVID-19
Polio
AIDS
Hepatitis
7. Host Specific
Many viruses infect only particular organisms or tissues.
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Example:
Rabies virus infects animals and humans.
Tobacco Mosaic Virus infects only plants.
8. Cannot Grow on Ordinary Media
Unlike bacteria, viruses cannot grow on nutrient agar or broth. They require living cells for
multiplication.
9. Rapid Multiplication
Once inside a host cell, viruses make thousands of copies of themselves by using the host
cell's machinery.
Structure of a Virus
Virus Structure
___________________
/ \
/ Protein Coat \
| (Capsid) |
| |
| DNA or RNA Genome |
\ /
\___________________/
Parts:
Capsid → Protects the virus.
DNA/RNA → Carries genetic information.
(b) Classification of Bacteria on the Basis of Their Nutrition
All living organisms need food for energy and growth. Bacteria obtain food in different ways.
Based on their method of obtaining nutrition, bacteria are classified into two major groups:
Bacteria
|
-----------------------
| |
Autotrophic Heterotrophic
| |
----------- -----------------
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| | | | |
Photo- Chemo- Saprophytic Parasitic Symbiotic
trophic trophic
1. Autotrophic Bacteria
Autotrophic bacteria prepare their own food from simple inorganic substances.
They are divided into two types.
(A) Photosynthetic (Phototrophic) Bacteria
These bacteria use sunlight as their energy source to prepare food through photosynthesis.
Examples:
Cyanobacteria (Blue-Green Algae)
Purple Sulfur Bacteria
(B) Chemosynthetic (Chemotrophic) Bacteria
These bacteria prepare food using chemical energy released from the oxidation of inorganic
substances such as ammonia, sulphur, iron, or hydrogen.
Examples:
Nitrosomonas
Nitrobacter
These bacteria play an important role in the nitrogen cycle.
2. Heterotrophic Bacteria
These bacteria cannot prepare their own food. They depend on other organisms for
nutrition.
They are of three main types.
(A) Saprophytic Bacteria
These bacteria obtain food from dead and decaying organic matter.
Importance:
Decompose dead plants and animals.
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Recycle nutrients back into the soil.
Examples:
Bacillus
Pseudomonas
(B) Parasitic Bacteria
These bacteria live inside or on another living organism (host) and obtain food from it.
They often cause diseases.
Examples:
Mycobacterium tuberculosis → Tuberculosis
Salmonella typhi → Typhoid
Vibrio cholerae → Cholera
(C) Symbiotic Bacteria
These bacteria live in close association with another organism, where both organisms
benefit.
Example:
Rhizobium bacteria live in the root nodules of leguminous plants.
The plant provides food and shelter.
The bacteria fix atmospheric nitrogen for the plant.
Summary Table
Feature
Bacteria
Cell Structure
Single-celled (prokaryotic)
Size
Larger (0.55 µm)
Genetic
Material
Both DNA and RNA
Nutrition
Autotrophic or Heterotrophic
Reproduction
Independent cell division (binary
fission)
Living Nature
Completely living organisms
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Key Points for Exam
Viruses are acellular, extremely small, and contain either DNA or RNA enclosed in a
protein coat (capsid).
They are obligate intracellular parasites because they reproduce only inside living
cells.
Viruses cause diseases such as COVID-19, influenza, polio, hepatitis, and AIDS.
Bacteria are classified on the basis of nutrition into Autotrophic and Heterotrophic
bacteria.
Autotrophic bacteria prepare their own food and are of two types: photosynthetic
and chemosynthetic.
Heterotrophic bacteria depend on external food sources and are divided into
saprophytic, parasitic, and symbiotic bacteria.
Saprophytic bacteria act as decomposers, parasitic bacteria cause diseases, and
symbiotic bacteria like Rhizobium help plants by fixing nitrogen.
4 4. (a) Differentiate between Gram-positive and Gram-negative bacteria. Also draw
labelled diagrams.
(b) Give a generat account of Cyanobacteria.
Ans: Gram-positive and Gram-negative bacteria are the two major groups of bacteria.
Scientists classify them based on the Gram staining test, which was developed by Hans
Christian Gram. In this test, bacteria are treated with different stains. Some bacteria remain
purple, while others become pink or red. This difference happens because of the structure
of their cell wall.
Gram-positive Bacteria
Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall. This thick layer
traps the crystal violet stain during the Gram staining process. As a result, these bacteria
appear purple under the microscope.
They do not have an outer membrane, making their cell wall simpler. Many Gram-positive
bacteria produce spores and are usually more sensitive to antibiotics such as penicillin.
Examples: Bacillus, Clostridium, Staphylococcus, and Streptococcus.
Gram-negative Bacteria
Gram-negative bacteria have a thin peptidoglycan layer. They also possess an outer
membrane containing lipopolysaccharides (LPS), which acts as a protective barrier. During
Gram staining, they lose the purple stain and absorb the counterstain (safranin), appearing
pink or red.
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Because of the outer membrane, these bacteria are often more resistant to antibiotics.
Examples: Escherichia coli (E. coli), Salmonella, Pseudomonas, and Vibrio cholerae.
Difference Between Gram-positive and Gram-negative Bacteria
Gram-positive Bacteria
Gram-negative Bacteria
Stain purple
Stain pink/red
Thick peptidoglycan layer
Thin peptidoglycan layer
No outer membrane
Outer membrane present
Simpler cell wall
More complex cell wall
More sensitive to antibiotics
More resistant to antibiotics
No lipopolysaccharide (LPS)
LPS present in outer membrane
Simple Labelled Diagrams
Gram-positive Bacterium
Capsule (optional)
┌─────────────────────┐
│ Thick Peptidoglycan │
│ Cell Wall │
├─────────────────────┤
│ Cell Membrane │
├─────────────────────┤
│ Cytoplasm │
└─────────────────────┘
Gram-negative Bacterium
Capsule (optional)
┌─────────────────────┐
│ Outer Membrane (LPS)│
├─────────────────────┤
│ Thin Peptidoglycan │
├─────────────────────┤
│ Cell Membrane │
├─────────────────────┤
│ Cytoplasm │
└─────────────────────┘
4. (b) Give a general account of Cyanobacteria.
Cyanobacteria are a group of photosynthetic bacteria that are commonly called blue-green
algae. Although they look like algae because of their green color and ability to perform
photosynthesis, they are actually prokaryotic bacteria, which means they do not have a true
nucleus or membrane-bound organelles.
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Cyanobacteria are among the oldest living organisms on Earth, with fossils dating back
more than 3.5 billion years. They played a major role in increasing the amount of oxygen in
Earth's atmosphere through photosynthesis, making life possible for many other organisms.
These bacteria contain the green pigment chlorophyll-a and blue pigment phycocyanin,
which help them prepare food using sunlight. During photosynthesis, they release oxygen
into the atmosphere.
Cyanobacteria are found in many habitats such as ponds, lakes, rivers, oceans, wet soil,
rocks, tree bark, and hot springs. Some species live independently, while others live in
association with plants or fungi.
A special feature of many cyanobacteria is the presence of heterocysts. Heterocysts are
thick-walled specialized cells that carry out nitrogen fixation, converting atmospheric
nitrogen into usable forms for plants. Because of this ability, cyanobacteria improve soil
fertility and are widely used as biofertilizers, especially in rice fields.
Characteristics of Cyanobacteria
They are prokaryotic organisms.
They perform photosynthesis.
They contain chlorophyll-a and phycocyanin pigments.
They reproduce mainly by binary fission, fragmentation, and spores.
Some species possess heterocysts for nitrogen fixation.
They are important producers of oxygen and improve soil fertility.
Examples
Nostoc
Anabaena
Oscillatoria
Gloeocapsa
Importance of Cyanobacteria
Produce oxygen through photosynthesis.
Fix atmospheric nitrogen and increase soil fertility.
Used as biofertilizers in agriculture.
Form the base of many aquatic food chains.
Some species can also cause harmful algal blooms in polluted water.
Simple Labelled Diagram of Cyanobacteria (Anabaena)
Vegetative Cell Vegetative Cell Heterocyst Vegetative
Cell
○ ───────────── ○ ───────────── ⊙ ───────────── ○
↑
Heterocyst
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(Nitrogen Fixation)
Conclusion
Gram-positive and Gram-negative bacteria differ mainly in the structure of their cell wall,
which determines how they react to Gram staining. Gram-positive bacteria have a thick
peptidoglycan wall and stain purple, while Gram-negative bacteria have a thin
peptidoglycan layer with an outer membrane and stain pink. Cyanobacteria are ancient,
oxygen-producing, photosynthetic bacteria that are highly important in nature because they
perform photosynthesis, fix atmospheric nitrogen, and improve soil fertility.
SECTION-C
5. (a) Write about the economic importance of Ascomycetes.
(b) Explain and draw a well labeled diagram of life cycle of mucor.
Ans: Ascomycetes are commonly called sac fungi because they produce spores inside a
small sac-like structure called an ascus. They are one of the largest groups of fungi and are
found almost everywherein soil, water, decaying plants, food, and even inside living
organisms. Some species are extremely useful to humans, while others can be harmful.
Their economic importance can be understood through their beneficial and harmful roles.
1. Useful in Food Industry
One of the most famous members of Ascomycetes is yeast (Saccharomyces cerevisiae).
Yeast is widely used in baking because it produces carbon dioxide gas, which makes bread
soft and fluffy. It is also used in making beer, wine, and other alcoholic beverages through
the process of fermentation.
2. Production of Medicines
Many Ascomycetes produce important antibiotics. The fungus Penicillium is the source of
penicillin, the world's first widely used antibiotic. Penicillin has saved millions of lives by
treating bacterial infections.
3. Industrial Uses
These fungi produce enzymes and organic acids that are used in industries. For example,
Aspergillus niger is used for the commercial production of citric acid, which is added to soft
drinks, candies, and medicines.
4. Role in Agriculture
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Many Ascomycetes decompose dead plants and animals into simpler substances. This
decomposition returns nutrients to the soil, increasing soil fertility and helping plants grow
better.
5. Scientific Research
Yeast is an important model organism used in genetics and molecular biology research
because it grows quickly and is easy to study.
Harmful Effects
Some Ascomycetes cause diseases in plants such as powdery mildew and ergot disease,
reducing crop yield. Others spoil food items like fruits, vegetables, and stored grains. A few
species also produce harmful toxins known as mycotoxins, which can affect human and
animal health.
Conclusion
Ascomycetes play an important role in human life. They help in making food, medicines,
industrial products, and maintaining ecological balance through decomposition. Although
some species cause diseases and food spoilage, their beneficial contributions are much
greater than their harmful effects.
5. (b) Life Cycle of Mucor
Mucor is a common fungus that grows on moist bread, fruits, vegetables, and decaying
organic matter. It belongs to the group Zygomycetes. The body of Mucor consists of thread-
like structures called hyphae, which together form a mycelium. The life cycle of Mucor
includes two methods of reproduction: asexual reproduction and sexual reproduction.
1. Asexual Reproduction
This is the most common method of reproduction.
A special upright hypha grows from the mycelium. It is called a sporangiophore.
At the tip of the sporangiophore, a round structure called a sporangium develops.
Inside the sporangium, many tiny spores (sporangiospores) are produced.
When the spores become mature, the sporangium bursts open.
The spores are carried by wind to suitable places.
If they land on a moist surface with enough food, each spore germinates and forms a
new mycelium.
This process allows Mucor to spread rapidly.
2. Sexual Reproduction
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Sexual reproduction usually occurs when environmental conditions become unfavorable.
Two compatible hyphae of opposite mating types (+ and strains) grow toward each
other.
Their tips swell and form structures called gametangia.
The walls between them dissolve, and the two gametangia fuse.
A thick-walled zygospore is formed.
The zygospore remains dormant during unfavorable conditions.
When conditions become favorable again, the zygospore germinates and produces a
new sporangiophore with a sporangium.
The sporangium releases spores that develop into new mycelia.
Thus, the life cycle is completed.
Well-Labeled Diagram of the Life Cycle of Mucor
ASEXUAL REPRODUCTION
Mature Sporangium
●
(Spores)
│
Sporangium bursts and spores released
│
Wind dispersal
│
Spore lands
│
Germination
│
New Mycelium
│
Sporangiophore
│
New Sporangium
▲
│
(Cycle repeats)
SEXUAL REPRODUCTION
(+) Hypha (-) Hypha
\ /
\ /
\ /
Gametangia fuse
│
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Thick-walled
Zygospore
│
Dormant during bad conditions
│
Germination of zygospore
│
Sporangiophore develops
│
Sporangium
│
Spores
│
New Mycelium
Easy Revision Points
Mucor is commonly known as bread mould.
Body consists of hyphae, forming a mycelium.
Asexual reproduction occurs through sporangiospores formed inside a sporangium.
Sexual reproduction occurs by fusion of + and hyphae, producing a zygospore.
The zygospore survives unfavorable conditions and germinates when conditions
improve.
The life cycle alternates between spore formation, germination, mycelium growth,
and reproduction, ensuring the survival and spread of the fungus.
6. (a) Give classification of fungi along with examples.
(b) Differentiate between Mastigomycotina and Zygomycotina.
Ans: Fungi are a unique group of living organisms that are neither plants nor animals. They
do not have chlorophyll, so they cannot prepare their own food by photosynthesis. Instead,
they absorb nutrients from dead organic matter, living plants, animals, or other organisms.
Because of this, fungi play a very important role in nature by decomposing dead materials
and recycling nutrients back into the soil.
Think of fungi as the "clean-up workers of nature." Whenever leaves, wood, fruits, or
animals die, fungi help break them down into simpler substances. Some fungi are useful in
making bread, cheese, and medicines like penicillin, while others can cause diseases in
plants and humans.
Scientists classify fungi into different groups based on their structure, method of
reproduction, and type of spores they produce.
Classification of Fungi
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KINGDOM FUNGI
│
┌───────────────────┼───────────────────┐
│ │ │
Mastigomycotina Zygomycotina Ascomycotina
│
Basidiomycotina
│
Deuteromycotina
1. Mastigomycotina (Flagellate Fungi)
These fungi produce motile spores called zoospores.
Zoospores have one or two flagella (tail-like structures) that help them swim in
water.
Therefore, these fungi are usually found in water or moist places.
Their cell wall is mainly made of cellulose.
Reproduction occurs by both sexual and asexual methods.
Examples:
Albugo (White rust of mustard)
Phytophthora (Late blight of potato)
Pythium
2. Zygomycotina
These fungi do not produce motile spores.
They produce sporangiospores during asexual reproduction.
During sexual reproduction, they form a thick-walled zygospore, which gives this
group its name.
Mostly found on bread, fruits, and decaying organic matter.
Examples:
Rhizopus (Bread mould)
Mucor
3. Ascomycotina (Sac Fungi)
Sexual spores are called ascospores, formed inside a sac-like structure called an
ascus.
Many members are economically important.
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Examples:
Yeast (Saccharomyces)
Penicillium
Aspergillus
4. Basidiomycotina (Club Fungi)
Sexual spores called basidiospores are produced on a club-shaped structure called
the basidium.
Includes mushrooms and puffballs.
Examples:
Agaricus (Mushroom)
Puccinia (Rust fungus)
Ustilago (Smut fungus)
5. Deuteromycotina (Imperfect Fungi)
Called imperfect fungi because their sexual stage is unknown.
Reproduce only by asexual spores (conidia).
Examples:
Alternaria
Colletotrichum
(b) Difference Between Mastigomycotina and Zygomycotina
Feature
Mastigomycotina
Zygomycotina
Habitat
Mostly aquatic or moist places
Mostly terrestrial (land)
Asexual Spores
Zoospores (motile)
Sporangiospores (non-motile)
Flagella
Present
Absent
Sexual Spore
Oospore
Zygospore
Cell Wall
Mainly cellulose
Mainly chitin
Movement
Spores can swim
Spores cannot swim
Examples
Albugo, Phytophthora, Pythium
Rhizopus, Mucor
Easy Trick to Remember
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Mastigomycotina
M = Moist
M = Motile spores
M = Movement by flagella
Zygomycotina
Z = Zygospore
Z = Zero flagella
Z = Zigzag growth on bread (Rhizopus)
Conclusion
Fungi are essential organisms that help maintain ecological balance by decomposing dead
matter and recycling nutrients. Based on their reproductive structures and spores, fungi are
classified into Mastigomycotina, Zygomycotina, Ascomycotina, Basidiomycotina, and
Deuteromycotina. Among these, Mastigomycotina produce motile, flagellated zoospores
and are mostly found in water or moist habitats, whereas Zygomycotina produce non-
motile sporangiospores and zygospores and commonly grow on land, especially on bread
and decaying organic matter. Understanding these differences makes it easier to identify
different fungal groups and appreciate their importance in agriculture, medicine, food
production, and the environment.
SECTION-D
7. (a) Define a lichen. Discuss the role of each partner.
(b) Mention some features of Cercospora and which disease is caused by it in plants.
(c). Name the fruiting body of Agaricus.
Ans: A lichen is a special living organism formed by the close association of two different
organismsa fungus and an alga (or sometimes a cyanobacterium). This relationship is
called symbiosis because both organisms live together and help each other survive.
Think of a lichen as two friends sharing one house. One friend cooks the food, while the
other builds and protects the house. Alone, they may not survive in difficult conditions, but
together they grow successfully on rocks, tree bark, walls, and even in deserts.
Role of the Fungus (Mycobiont)
The fungus is the main body of the lichen. Its functions are:
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Provides protection to the algal cells.
Absorbs water and minerals from rain and air.
Anchors the lichen firmly to rocks or tree bark.
Prevents the algal cells from drying out.
Role of the Alga (Phycobiont)
The alga is the food producer.
It contains chlorophyll.
Performs photosynthesis using sunlight.
Prepares carbohydrates (food).
Shares the food with the fungus.
Thus, both partners depend on each other:
Fungus → gives shelter, water, and minerals.
Alga → prepares food through photosynthesis.
Importance of Lichens
They are pioneer organisms, meaning they are among the first to grow on bare
rocks.
Help in soil formation by breaking down rocks.
Used as air pollution indicators, because they grow only where the air is clean.
Some lichens are used in medicines, perfumes, and dyes.
Simple Diagram
LICHEN
│
┌──────────┴──────────┐
│ │
Fungus Alga/Cyanobacteria
(Mycobiont) (Phycobiont)
│ │
Provides water, Performs
minerals, shelter photosynthesis
and protection and makes food
└──────────┬──────────┘
│
Both live together happily
and help each other survive
(b) Mention some features of Cercospora and which disease is caused by it in plants.
Cercospora is a fungus that attacks many crop plants and causes serious damage to leaves.
It mainly infects the leaf surface and reduces the plant's ability to prepare food.
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Features of Cercospora
It is a plant pathogenic fungus (causes disease in plants).
It mainly attacks leaves.
Produces long, thin spores (conidia).
Spores spread through wind, rain splash, and irrigation water.
Grows rapidly in warm and humid weather.
Infected leaves develop brown or grey circular spots with darker edges.
Severe infection causes leaves to dry, fall early, and reduce crop yield.
Disease Caused
The most common disease caused by Cercospora is Cercospora Leaf Spot.
Symptoms
Small brown or grey spots appear on leaves.
Spots gradually become larger.
Leaves turn yellow.
Premature leaf fall occurs.
Photosynthesis decreases, resulting in poor plant growth and lower production.
Simple Diagram
Healthy Leaf Cercospora Infection
󷋇󷋈󷋉󷋊󷋋󷋌 󷋇󷋈󷋉󷋊󷋋󷋌
● ●
● ●
Brown Leaf Spots
(c) Name the fruiting body of Agaricus.
The fruiting body of Agaricus is called the Basidiocarp.
Agaricus is the common mushroom. The basidiocarp is the visible part that grows above the
ground and produces spores for reproduction.
Parts of the Basidiocarp
Pileus (Cap): The umbrella-shaped top.
Gills (Lamellae): Thin plates below the cap where spores are formed.
Stipe (Stalk): Supports the cap.
Ring (Annulus): A ring present on the stalk in many species.
Simple Diagram
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_________
/ \
/ Pileus \
/_____________\
||||||||||||| ← Gills (Lamellae)
│
│
Stipe
│
---Ring---
│
Final Revision Points
Lichen: Symbiotic association of a fungus + alga (or cyanobacterium).
Fungus: Provides water, minerals, shelter, and protection.
Alga: Performs photosynthesis and prepares food.
Cercospora: Plant pathogenic fungus causing Cercospora Leaf Spot.
Symptoms: Brown leaf spots, yellowing, early leaf fall, and reduced yield.
Agaricus fruiting body: Basidiocarp, consisting of the cap (pileus), gills, stalk (stipe),
and ring (annulus).
8. (a) Why lichens are considered as pollution indicator?
(b) How fungi are different from plants?
(c) Highlight some of the differences between Basidiomycetes and Deuteromycetes.
Ans: (a) Why are lichens considered pollution indicators?
Lichens are special living organisms formed by a partnership between a fungus and an alga
(or cyanobacterium). The fungus provides water, minerals, and protection, while the alga
prepares food through photosynthesis. Both help each other survive.
Lichens absorb water, minerals, and gases directly from the air because they do not have
roots like normal plants. This makes them extremely sensitive to air pollution. Harmful gases
such as sulphur dioxide (SO₂), nitrogen oxides, and heavy metals easily enter their body
and damage their cells.
Because of this sensitivity, lichens disappear quickly from polluted areas but grow well in
clean environments. Therefore, scientists use lichens as natural pollution indicators
(bioindicators) to measure the quality of air.
For example:
Many lichens present → Air is clean.
Very few or no lichens → Air is polluted.
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Thus, the presence or absence of lichens helps us understand the pollution level without
using expensive machines.
Simple Diagram
Clean Air 󷋇󷋈󷋉󷋊󷋋󷋌
│
Many Lichens Grow
│
Indicates Good Air Quality
Polluted Air 󷫿󷬀󷬁󷬄󷬅󷬆󷬇󷬈󷬉󷬊󷬋󷬂󷬃
│
Lichens Die or Disappear
│
Indicates Poor Air Quality
(b) How are fungi different from plants?
Although fungi and plants may appear similar because they do not move, they are actually
very different.
Plants contain chlorophyll, a green pigment that allows them to prepare their own food by
photosynthesis. Fungi do not contain chlorophyll, so they cannot make their own food.
Instead, fungi obtain nutrients by absorbing food from dead organic matter, living
organisms, or decaying materials. This is called heterotrophic nutrition.
The cell wall of plants is made of cellulose, whereas the cell wall of fungi is made of chitin,
the same material found in the outer covering of insects.
Plants usually have roots, stems, and leaves, but fungi do not. Their body is made of thin
thread-like structures called hyphae, which together form a network known as mycelium.
Plants mainly reproduce through flowers, seeds, or fruits, while fungi mostly reproduce
through spores.
Differences between Fungi and Plants
Plants
Fungi
Contain chlorophyll
No chlorophyll
Make their own food
Depend on other organisms for food
Cell wall made of cellulose
Cell wall made of chitin
Have roots, stems, and leaves
Made of hyphae and mycelium
Reproduce by seeds or flowers
Reproduce mainly by spores
(c) Differences between Basidiomycetes and Deuteromycetes
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Both Basidiomycetes and Deuteromycetes belong to the kingdom Fungi, but they differ
mainly in their method of reproduction.
Basidiomycetes are called club fungi because they produce sexual spores called
basidiospores on a club-shaped structure called a basidium. Common examples include
mushrooms, puffballs, and bracket fungi.
Deuteromycetes are known as imperfect fungi because their sexual stage has not been
discovered. They reproduce only by asexual spores (conidia). Many species are important in
agriculture and medicine, while some cause diseases in plants and humans.
Differences between Basidiomycetes and Deuteromycetes
Basidiomycetes
Deuteromycetes
Sexual reproduction present
Sexual stage absent or unknown
Produce basidiospores
Produce conidia (asexual spores)
Spores formed on basidium
No basidium present
Examples: Mushroom, Puffball
Examples: Alternaria, Trichophyton, Colletotrichum
Simple Diagram
FUNGI
│
┌──────────┴──────────┐
│ │
Basidiomycetes Deuteromycetes
│ │
Basidium Present Basidium Absent
│ │
Basidiospores Conidia (Asexual)
│ │
Mushroom 󷋞󷋟󷋠󷋡󷋢 Imperfect Fungi
Conclusion
Lichens are valuable bioindicators because they react quickly to air pollution and help
scientists assess environmental quality. Fungi differ from plants because they lack
chlorophyll, absorb nutrients from other sources, possess chitin in their cell walls, and
reproduce mainly through spores. Among fungi, Basidiomycetes reproduce sexually by
forming basidiospores on a basidium, whereas Deuteromycetes are called imperfect fungi
because only their asexual stage is known. Understanding these differences helps students
recognize the ecological importance, structure, and reproduction of fungi and appreciate
how certain organisms, such as lichens, can naturally monitor the health of our
environment.
This paper has been carefully prepared for educational purposes. If you notice any mistakes or
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