very short answer questions :

1. What is the principle underlying the use of cyanobacteria in agricultural elds for crop
improvement?

Ans:
Cyanobacteria, like Nostoc and Anabaena, have the ability to x atmospheric nitrogen into a
usable form for plants. This enriches the soil with natural nitrogen, reducing the need for chemical
fertilizers and promoting better crop growth.

2. Suppose you accidentally nd an old preserved permanent slide without a label. In your
e ort to identify it, you place the slide under microscope and observe the following
features:a. Unicellular b. Well-de ned nucleus c. Bi agellate—one agellum lying
longitudinally and the other transversely. What would you identify it as? Can you name
the kingdom it belongs to?

Ans:
The organism is Euglena. It is a unicellular, bi agellate organism with a well-de ned nucleus. One
agellum lies longitudinally, and the other transversely in a groove. It belongs to the Kingdom
Protista

3. How is the ve-kingdom classi cation advantageous over the two-kingdom

classi cation?

Ans:
The ve-kingdom classi cation is better because it groups organisms more accurately based on
cell type, nutrition, and body structure. Unlike the two-kingdom system, it gives separate
kingdoms to fungi, protists, and monerans, which don’t t into just plants or animals.

4. Polluted water bodies have usually very high abundance of plants like Nostoc and
Oscillatoria. Give reasons.
Ans:
Polluted water bodies are rich in nutrients like nitrates and phosphates, which cause excessive
growth of cyanobacteria like Nostoc and Oscillatoria. This is called eutrophication.

5. Are chemosynthetic bacteria autotrophic or heterotrophic?

Ans:
Chemosynthetic bacteria are autotrophic because they make their own food using energy from
chemical reactions.

6. The common name of pea is simpler than its botanical (scienti c) name Pisum sativum.
Why then is the simpler common name not used instead of the complex scienti c/
botanical name in biology?
Ans:
Common names vary by region and can be confusing. Scienti c names like Pisum sativum are
used because they are standardized and universally accepted.

7. A virus is considered as a living organism and an obligate parasite when inside a host
cell. But virus is not classi ed along with bacteria or fungi. What are the characters of
virus that are similar to non-living objects?
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 Ans:
Viruses show non-living features like:
– Inactivity outside host cells
– Lack of cellular structure
– No independent metabolism
– Ability to be crystallized

8. In the ve-kingdom system of Whittaker, how many kingdoms are eukaryotes?

Ans:
Four kingdoms are eukaryotic — Protista, Fungi, Plantae, and Animalia. Only Monera is
prokaryotic.

Short Answer Type Questions:

1. Diatoms are also called ‘pearls of ocean’, why? What is diatomaceous earth?
Ans:
Diatoms are called “pearls of the ocean” because they are abundant, beautiful, and play a major
role in oxygen production in oceans.
Diatomaceous earth is a soft, powdery substance formed from the silica-rich cell walls of dead
diatoms. It is used in ltration, polishing, and insulation.

2. There is a myth that immediately after heavy rains in forests, mushrooms appear in large
numbers and make a very large ring, or circle, which may be several metres in diameter.
These are called ‘Fairy rings’. Can you explain this myth of fairy rings in biological
terms?
Ans:
Fairy rings are formed by the circular growth of underground fungal mycelium. After rain,
mushrooms appear along the outer edge of the circle. The mycelium spreads evenly in all
directions, forming a ring. This natural growth pattern creates the illusion of a magical “fairy ring,”
but it is a result of fungal expansion and nutrient availability in the soil.

3. Neurospora – an ascomycetes fungus – has been used as a biological tool to understand

the mechanism of plant genetics, much in the same way as Drosophila has been used to
study animal genetics. What makes Neurospora so important as a genetic tool?
Ans:
Neurospora is ideal for genetic studies because it is haploid (so mutations are easily visible),
grows quickly, and is easy to culture. It has a well-known genome and helps scientists study gene
function, inheritance, and mutation in a simple, controlled way.

4. Cyanobacteria and heterotrophic bacteria have been clubbed together in Eubacteria of

kingdom Monera as per the “Five Kingdom Classi cation” even though the two are
vastly di erent from each other. Is this grouping of the two types of taxa in the same
kingdom justi ed? If so, why?
Ans:
Yes, the grouping is justi ed because both are prokaryotic — they lack a true nucleus and
membrane-bound organelles. Although cyanobacteria are autotrophic and heterotrophic bacteria
depend on other organisms for food, their similar cell structure and genetics place them in the
same kingdom, Monera.
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5. At a stage of their cycle, ascomycetes fungi produce the fruiting bodies like apothecium,
perithecium or cleistothecium. How are these three types of fruiting bodies di erent
from each other?
Ans:
– Apothecium: Cup-shaped and open, with asci exposed for easy spore release.
– Perithecium: Flask-shaped with a small opening (ostiole); asci are enclosed but open at the top.
– Cleistothecium: Completely closed and spherical; spores are released only when the body
breaks open.

6. What observable features in Trypanosoma would make you classify it under kingdom
Protista?
Ans:
Trypanosoma is unicellular and eukaryotic, has a true nucleus, and moves using a agellum. It
doesn’t t into the plant, animal, or fungal kingdoms and shows parasitic behavior, making it a
protist.

7. Fungi are cosmopolitan. Write the role of fungi in your daily life.
Ans:
Fungi play many roles in daily life:
– Used in making bread, alcohol, and cheese (e.g. Saccharomyces).
– Help decompose organic matter and recycle nutrients.
– Used to make antibiotics like penicillin.
– Edible fungi like mushrooms are part of our food.
– Some fungi cause diseases like athlete’s foot or ringworm.

Long answer questions:

1. Algae are known to reproduce asexually by a variety of spores under di erent

environmental conditions. Name these spores and the conditions under which they are
produced.

Ans:
Algae reproduce asexually through di erent types of spores depending on environmental
conditions such as water, temperature, and nutrients. These spores include:
1. Zoospores – Flagellated, motile spores produced under favorable
conditions, especially in water. Common in green algae like Chlamydomonas.
2. Aplanospores – Non-motile spores formed in unfavorable conditions such
as lack of water. They remain within the parent cell and germinate later.
3. Autospores – Small, non-motile spores that resemble the parent cell and
are released directly. Found in unicellular green algae.
4. Hypnospores – Thick-walled dormant spores that form during extreme
conditions like dryness or cold, helping algae survive until better conditions return.
5. Palmella stage – A temporary stage where algae form mucilage-covered
colonies under stress like dehydration. Seen in Chlamydomonas.

These di erent spore types allow algae to survive and reproduce e ciently under
changing environmental conditions.

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2. Apart from chlorophyll, algae have several other pigments in their chloroplast. What
pigments are found in blue-green, red, and brown algae that are responsible for their
characteristic colours?

Ans:
Algae contain accessory pigments besides chlorophyll that give them distinct colors and help in
photosynthesis at di erent depths and light conditions:
1. Blue-Green Algae (Cyanobacteria):
– Contain chlorophyll a, phycocyanin (blue), and phycoerythrin (red).
– The blue-green color is due to the dominance of phycocyanin.
2. Red Algae (Rhodophyceae):
– Contain chlorophyll a & d, phycoerythrin, and phycocyanin.
– Phycoerythrin dominates, giving them a red appearance and allowing survival in deep
waters.
3. Brown Algae (Phaeophyceae):
– Contain chlorophyll a & c, and fucoxanthin (a brown xanthophyll).
– Fucoxanthin masks the green of chlorophyll, giving them a brown color.

These pigments help algae adapt to di erent light zones in aquatic environments.

3. Make a list of algae and fungi that have commercial value as source of food, chemicals,
medicines, and fodder.

Ans:
Algae and fungi are commercially valuable in food, medicine, industry, and agriculture. Here are
examples:

A. Algae:
• As Food:
– Porphyra (used in sushi)
– Chlorella, Spirulina (nutritional supplements)
• For Chemicals:
– Gelidium, Gracilaria (produce agar)
– Sargassum, Fucus (produce alginates)
– Red algae (source of carrageenan)
• As Fodder:
– Ulva, Sargassum used as cattle feed and manure

B. Fungi:
• As Food:
– Agaricus (button mushroom)
– Morchella (morel mushroom)
• In Medicine:
– Penicillium notatum (produces penicillin)
– Claviceps purpurea (source of ergot alkaloids)
– Streptomyces (produces antibiotics like streptomycin)
• In Industry:
– Saccharomyces cerevisiae (used in baking and brewing)
– Aspergillus niger (produces citric acid)
• As Fodder:
– Candida utilis (used as single-cell protein for animal feed)

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 4. ‘Peat’ is an important source of domestic fuel in several countries. How is ‘peat’ formed
in nature?

Ans:
Peat is a spongy, brownish-black material formed by the partial decomposition of plant matter
in wet, acidic, and anaerobic conditions — mainly in bogs and marshes.

Formation of Peat:
1. Mosses like Sphagnum grow in swampy areas, holding water and creating
an acidic environment.
2. Dead plant material doesn’t fully decompose due to lack of oxygen.
3. Layers of partially decomposed material build up and compress over time.
4. This forms peat, which can later become coal under pressure and time.

Uses of Peat:
– Used as fuel in countries like Ireland and Russia.
– Used in horticulture to improve soil texture.
– Acts as a carbon sink, storing atmospheric carbon.

5. Biological classi cation is a dynamic and ever-evolving phenomenon which keeps

changing with our understanding of life forms. Justify the statement taking any two
examples.

Ans:
Biological classi cation evolves with scienti c discoveries. New tools like microscopy and genetic
analysis have changed how we group organisms.

Examples:
1. From Two-Kingdom to Five-Kingdom Classi cation:
– Earlier, all organisms were placed in either Plantae or Animalia.
– With new knowledge, Whittaker’s Five-Kingdom system (Monera, Protista, Fungi,
Plantae, Animalia) was introduced in 1969 to better classify organisms based on cell type,
nutrition, and body structure.
2. Discovery of Archaebacteria:
– Earlier, all prokaryotes were grouped under Monera.
– Later studies revealed that Archaebacteria are very di erent from typical bacteria.
– This led to the Three-Domain System by Carl Woese: Archaea, Bacteria, and
Eukarya.

Conclusion:
Classi cation systems are revised as we learn more about life forms. It’s a dynamic process that
re ects the progress of biological science.
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