Where Mindful Learning Begins
Where Mindful Learning Begins
Class 9 Science NCERT question answers for Chapter 12, Patterns in Life: Diversity and Classification, covering every Think It Over, Activity, Pause & Ponder, Revise Reflect Refine and Journey Beyond question (CBSE 2026-27) and the reasoning for every answer. Read your Class 9 Science chapter 12 notes first, then check your answers here.
Patterns in Life explains how scientists organise the huge variety of living things, and these Class 9 Science Chapter 12 Diversity and Classification NCERT solutions cover Whittaker's five kingdom classification, classes of plants (algae, bryophytes, pteridophytes, gymnosperms and angiosperms), animal phyla, binomial nomenclature, biodiversity and fossils, with the reasoning behind every activity and question.
Last updated 20 October 2026 · Reviewed by Suchita Arora, 13+ years teaching CBSE Maths & Science
Patterns in Life: Diversity and Classification explores the variety of living organisms on Earth — biodiversity — and the systematic way scientists organise it. It traces classification from Aristotle's habitat-based grouping to Whittaker's five kingdoms (Monera, Protista, Fungi, Plantae, Animalia), examines the groups within Plantae and the phyla within Animalia, and introduces the classification ladder (Kingdom, Phylum, Class, Order, Family, Genus, Species) along with binomial nomenclature. It closes with fossils as evidence of changing biodiversity and the human-driven threats facing it today. Every question is solved here, section by section, as complete Class 9 Science Chapter 12 NCERT solutions with answers.
India as a biodiversity hotspot, endemic species, and why classifying Earth's millions of organisms makes them easier to study.
Monera, Protista, Fungi, Plantae and Animalia — and the classes and phyla within Plantae and Animalia that build on them.
The Kingdom-to-Species hierarchy, binomial nomenclature, fossils as evidence, and the threats facing biodiversity today.
Meaning: biodiversity is the enormous variety of living organisms on the Earth.
It includes microscopic bacteria and algae, giant trees, insects, jellyfish, eagles and all other life forms.
They live in countless habitats, from the snow-clad Himalayas to the coral reefs of the Andaman Sea.
Importance: every organism has a role in keeping nature stable.
1. Algae in the oceans release most of the oxygen we breathe.
2. Fungi and bacteria decompose fallen leaves and make the soil fertile.
3. Birds, bees and bats pollinate flowers, and plants make food for nearly all life.
Step 1: organisms share some features and differ in others.
Step 2: scientists group organisms on the basis of shared characteristics and evolutionary relationships. This is classification.
Step 3: this gives an organised system, like books arranged in a library.
Step 4: it helps us to understand how organisms are related, how they function, and how they interact.
Step 5: it also helps in ecosystem management, conservation of biodiversity and sustainable farming.
Basis of classification of living organisms:
1. External features, such as shape, size and body organisation.
2. Mode of nutrition, autotrophic or heterotrophic.
3. Internal structures, such as skeleton, organs and tissues.
4. Cell structure: unicellular or multicellular, prokaryote or eukaryote, cell wall present or absent.
5. Ecological role: producer, consumer or decomposer.
6. Reproduction: asexual and/or sexual.
7. Genetic similarity (DNA).
For plants: body differentiation, vascular tissue (xylem and phloem), seeds, and flowers and fruits.
For animals: notochord (present or absent), level of body organisation, symmetry, skeleton and body cavity.
Step 1: classification helps farmers to identify organisms correctly, such as crop varieties, pests and diseases.
Step 2: some insects protect crops (pollinators and predators of pests) while others damage them. We can protect the useful ones and control the harmful ones only when we can identify them.
Step 3: the causes of crop diseases (bacteria, fungi, viruses) can be identified and treated properly.
Step 4: related crops and varieties share useful features, such as drought tolerance, pest resistance and growth in poor soil. Farmers can choose and conserve suitable varieties.
Step 5: diverse crop varieties reduce the risk of crop failure and strengthen food security.
Note: these are sample observations. Check them against Fig. 12.2 in your book.
Table 12.1: observation table
| Organism | Where seen | When active | Visible feature |
|---|---|---|---|
| Peacock | Tree or ground | Day | Feathers, long tail |
| Monkey (langur) | Tree | Day | Hair, long tail |
| Crow | Flying high in air, tree | Day | Feathers, beak, wings |
| Dragonfly / butterfly | Flying near the ground | Day | Wings, six legs |
| Spotted deer, rabbit | Forest floor | Day | Hair, four legs |
| Tiger | Forest floor | Day and night | Stripes, fur |
| Bat | Flying high in air | Night | Wings, hair |
| Owl | Tree | Night | Feathers, large eyes |
| Frog | Water, near water | Night | Moist skin, no tail |
| Firefly | Flying near the ground | Night | Wings, glows |
Table 12.2: grouping the same organisms in different ways
| Criterion | Organisms that fit | Feature that helped |
|---|---|---|
| Carnivore | Tiger, leopard, owl, snake | Eating habits |
| Herbivore | Spotted deer, rabbit | Eating habits |
| Can fly | Crow, owl, bat, dragonfly, butterfly | Wings |
| Active at night | Bat, owl, frog, firefly | Time of activity |
| Covered with feathers | Peacock, crow, owl | Body covering |
| Without a backbone | Dragonfly, butterfly, firefly | Internal structure |
Conclusion: the same organism fits into different groups when the criterion changes. For example, the owl is a carnivore, a bird, and active at night.
So we need a scientific criterion for grouping. This leads to the idea of classification.
Step 1: scientists group the species on the basis of their shared features. This is classification.
Step 2: each species gets a scientific name (binomial name), so every scientist can identify it.
Step 3: they record the species in lists and tables by group, habitat and food, and compare new finds with the known species.
1. size of the body and of the beak,
2. shape and colour of the beak and of the casque (the growth on top of the beak),
3. colour of the feathers, throat and face,
4. the habitat part of the forest, the type of fruit they eat and their calls.
Step 1: hornbills nest only in cavities of large old trees, so they would have no place to nest.
Step 2: the trees also give fruits, so their food would reduce.
Step 3: the number of hornbills would fall and some species could even become extinct.
Step 4: the plants whose seeds they spread would also be affected, and the food web of the forest would be disturbed.
Criteria from the concept map:
1. Cell type: prokaryotic (no true nucleus) or eukaryotic (true nucleus).
2. Level of organisation: unicellular or multicellular.
3. Cell structure: cell wall present (chitin or cellulose) or absent.
4. Mode of nutrition: autotrophic or heterotrophic.
5. Ecological role: producer, consumer or decomposer.
Comparison with the criteria given: all four given criteria (cell type, cell structure, level of organisation and mode of nutrition) are the same as in my list.
The map shows one more: the ecological role, which follows from the mode of nutrition.
Observations: (sample)
1. Bacteria are very tiny single cells. They are seen as rods, spheres or spirals, and need high power to see.
2. Cyanobacteria are bigger single cells that are green-blue in colour. They often lie one after another in threads (filaments).
3. No well-defined nucleus is seen in any of them.
4. The slides match Fig. 12.6.
This confirms that bacteria and cyanobacteria are unicellular prokaryotes, so they are placed in Kingdom Monera.
Observations: (sample)
1. Yes. Many tiny organisms are seen moving in the drop.
2. Some are slipper-shaped and move by cilia (Paramecium).
3. Some change their shape and move by pseudopodia (Amoeba).
4. Some are green and spindle-shaped with a flagellum, and swim (Euglena).
Identification: I identified them by comparing their shape and movement with Fig. 12.7.
This confirms that Protista are single-celled eukaryotes that live in water and move in different ways.
Precautions: wear a lab coat, mask and gloves, because the infusion smells bad, and discard it after autoclaving.
Observations: (sample)
1. The bryophyte (moss) has a small, soft, green body in the form of a mat.
2. It has tiny leaf-like parts on a thin stem-like part. Root-like threads (rhizoids) are attached to the soil.
3. The leaf-like parts are very thin and small. They soak up the water drop at once.
Difference from the usual leaves:
1. Usual leaves are true leaves with veins (vascular tissue). Moss leaves have no veins.
2. Usual leaves are on a plant with true roots and a stem. Mosses have only rhizoids.
3. Moss leaves absorb water directly, but usual leaves get water from the roots through the stem.
Comparison:
| Feature | Fern stem | Sunflower stem |
|---|---|---|
| Xylem and phloem | Present | Present |
| Arrangement of vascular tissue | Simple, in the centre of the stem | Many vascular bundles arranged in a ring |
| Plant group | Pteridophyta | Angiosperm (higher plant) |
Observations:
1. Both stems have xylem (for water) and phloem (for food).
2. The vascular tissue of the fern is simpler and less organised.
3. In the sunflower the vascular bundles are better developed and arranged in a ring.
Discussion: both groups have xylem and phloem, so both can carry water and food to all parts. The difference is mainly in the arrangement.
Step 1: collect leaves and look at their veins (venation).
Step 2: group them:
| Group | Venation | Leaf shape | Examples |
|---|---|---|---|
| Monocots | Parallel | Long and narrow | Grass, wheat, maize, banana |
| Dicots | Net-like (reticulate) | Broad | Mango, peepal, rose, sunflower |
Step 3: adaptation:
1. The narrow, parallel-veined leaves of grasses and cereals bend with strong winds without tearing, and the parallel veins carry water along the length of the leaf.
2. The broad leaves with net-like veins in dicots give a large area to catch sunlight, and the veins spread water and food to every part.
3. Different leaf sizes and shapes help plants to survive in the sun, shade, dry or wet places, as they control the water loss and light capture.
| Plant group | Advantages for survival | Exceptions / challenges |
|---|---|---|
| Thallophyta | Simple body (thallus) takes in water, nutrients and gases directly from the surroundings. Suited to life in water, and spreads easily in water. | Cannot live on land. Needs water or moist places. |
| Bryophyta | First plants to colonise land. Body is suited to moist land and shady places. | Always needs moisture. No vascular tissue and no true root, stem and leaves. Needs water for reproduction (male cells swim). |
| Pteridophyta | Live on land. True roots, stems and leaves. Xylem and phloem carry water and food to all parts, so plants can grow tall. | Reproduction does not take place without water. No seeds. |
| Gymnosperm | Needle-like leaves reduce water loss. Water is not needed for fertilisation. Seeds protect the embryo and give it food, so they can live in cold and dry places. | Seeds are not covered in fruits, so they are exposed on cones. |
| Angiosperm | Flowers attract pollinators. Seeds are enclosed in fruits, which protect them and help in dispersal by animals, wind and water. Most complex body, so they live in the widest range of habitats. | Depend on pollinating agents. Complex processes and complex tissues. |
Pattern: from algae to angiosperms, plants evolved transport tissues, seeds, flowers and fruits, which reduced their dependence on water.
Step 1: yes. Similar features in organisms suggest that they evolved from common ancestors.
Step 2: example: all mammals have hair and mammary glands, so they may have come from a common ancestor.
Step 3: the more features they share (even at DNA level), the more closely related they are.
Step 1: a single cell has all the cell parts (organelles) needed for life. Different parts of the same cell do different jobs.
Step 2: for example in Amoeba, the pseudopodia catch food, the food vacuole digests it, and the contractile vacuole removes the extra water.
Step 3: gases and wastes pass in and out through the cell surface by diffusion, because the cell is small.
Step 4: in a multicellular organism, there is division of labour. Groups of cells become specialised for one function, so billions of cells are needed.
Features of pteridophytes that reduce dependence on water:
1. True roots absorb water from the soil.
2. Xylem and phloem carry water and food to all parts, so the plant can live on land away from water.
Why they still need moist conditions: they reproduce with water, as the male cells swim to the female cells. Also they have no seeds.
(Bryophytes also live on land but are even more dependent on moisture.)
Step 1: in a tall plant, water and minerals must travel a long way from the roots to the top.
Step 2: simple diffusion is too slow over such a distance.
Step 3: xylem carries water and minerals upwards, and phloem carries food from the leaves to all parts.
Step 4: xylem also gives support to the tall stem.
Seeds:
1. They protect the embryo and give it stored food.
2. Water is not needed for fertilisation in seed plants, so they can grow in dry and cold places also.
Fruits:
1. They protect the seeds.
2. They help in spreading the seeds to new places by animals, birds, wind or water.
Result: plants with seeds and fruits survive in many more places, so angiosperms are the most diverse plant group.
Step 1: the hard external skeleton (exoskeleton) protects the soft body from enemies and injury.
Step 2: it reduces water loss, so the beetle can live in dry places.
Step 3: it supports strong muscles, so it can move fast and fly.
Compare: an earthworm has no such covering, so it needs moist soil.
Step 1: no. Biodiversity is not only the number of kinds of organisms.
Step 2: it also includes the variety of habitats and ecosystems (forest, desert, coral reef).
Step 3: it includes the genetic variation within a species (like crop varieties).
Step 4: it includes the interconnections among organisms (food webs, pollination, decomposition) which keep the ecosystem healthy.
Features to observe:
1. Cell type: does it have a true nucleus? (prokaryote or eukaryote)
2. Level of organisation: unicellular or multicellular.
3. Cell wall: present or absent.
4. Mode of nutrition: autotrophic (green, chloroplasts) or heterotrophic.
5. Movement, body shape and mode of reproduction.
Why: these basic features decide the kingdom first. Then the finer features decide the lower groups. Similar features show relationship with known organisms.
Step 1: DNA carries the instructions for growth and function in every cell.
Step 2: organisms with similar DNA are closely related and have a common ancestry.
Step 3: DNA shows relationships that cannot be seen from outside, even in microscopic organisms.
Example: DNA studies led to the three domain system (Bacteria, Archaea, Eukarya), showing that microscopic life is more diverse than we thought.
Step 1: climate change alters temperature and rainfall, so habitats change (melting glaciers, bleaching of corals, droughts).
Step 2: many species cannot adapt or move quickly enough, so their numbers fall or they become extinct.
Step 3: species of cold or narrow habitats (like those on mountains) are the most affected.
Step 4: when one species declines, the species that depend on it also decline.
Step 1: yes. These patches are lichens.
Step 2: a lichen is a symbiotic association of two organisms: an autotrophic alga and a heterotrophic fungus.
Step 3: the fungus gives protection, and the alga does photosynthesis and gives food.
Step 4: lichens change colour with air pollutants, so they are natural bioindicators of air quality. Patches mean the air is clean.
Uses: as a spice (patthar ke phool), medicines and dyes. Some are poisonous, so they must be identified properly.
Changes seen in the fern:
1. It has true roots, stems and leaves. Thallophytes have only a thallus, and bryophytes have only rhizoids.
2. The body is more differentiated, with the leaf (frond) clearly seen.
3. It has vascular tissue (xylem and phloem) to carry water and food.
Step 1: cut a thin cross section of the stem of a fern.
Step 2: stain it with safranin and look at it under a microscope. (Or use a permanent slide.)
Step 3: if we see the xylem and phloem, then the explanation is correct.
Result: the section shows vascular tissue. Xylem transports water and phloem transports food (Fig. 12.11b).
Step 1: no, sponges would not survive on land.
Step 2: water flows through their pores and brings food and oxygen to each cell, and carries the waste away. On land this would stop.
Step 3: they have no tissues or organs, and no covering to stop the loss of water, so the body would dry up.
Step 4: they are fixed, so they cannot move to find food or water.
Hypothesis (limitations):
1. Food and waste use the same opening, so they may get mixed.
2. The animal cannot take in new food till the waste is thrown out. So feeding is not continuous.
3. Food moves in one direction only partly, so digestion and absorption are less efficient.
4. There are no separate parts of the gut for separate jobs, so the body size is limited.
Observation: an earthworm moves by contracting and relaxing its muscles in different segments, one after another.
Advantages of segmentation:
1. More flexibility in the body.
2. More precise control of movement, as each segment can move separately.
3. If one segment is damaged, the others can still work.
4. Segments can be specialised for different jobs, and the body can grow by adding segments.
Advantages of the outer covering (exoskeleton):
1. It protects the body from enemies and injury.
2. It reduces water loss.
3. It supports powerful muscles.
Result: arthropods can survive in dry and exposed environments.
They create physical, biological and chemical barriers:
1. Physical barrier: mangrove forests reduced the damage of the 1999 super cyclone in Odisha. Villages with more mangroves were less destroyed.
2. Biological barrier: in the Western Ghats, the rich diversity of animals acts as a barrier against Kyasanur Forest Disease (Monkey Fever). Many animals are hosts in which the virus cannot grow.
3. Chemical barrier: diverse microorganisms in forest soils and roots absorb or break down pollutants. Mangrove soils trap sediments and heavy metals.
Result: water quality is better, and the damage from storms, diseases and pollution is lower.
Fig. 12.17 shows the classification of the tiger and the pea plant:
| Level | Tiger | Pea plant |
|---|---|---|
| Kingdom | Animalia | Plantae |
| Phylum | Chordata | Magnoliophyta |
| Class | Mammalia | Magnoliopsida |
| Order | Carnivora | Fabales |
| Family | Felidae | Fabaceae |
| Genus | Panthera | Pisum |
| Species | P. tigris | P. sativum |
Inference:
1. Classification follows a step-by-step order, from very broad groups (kingdom) to smaller and more specific ones (species).
2. At each lower level, the organisms share more common features, and there are fewer organisms.
3. Every lower group is a part of the group above it.
4. It works like an address, which helps to identify, compare and study organisms exactly.
Step 1: new tools and knowledge give new information about organisms, such as microscopes, staining techniques and DNA studies.
Step 2: so the old system is changed. Aristotle (habitat) → two kingdom → three kingdom → four kingdom → five kingdom → three domain system.
Step 3: Aristotle’s system worked for his time. Microscopes showed microorganisms, so the system had to change.
Yes, it shows how science works: science evolves and progresses as we learn new things. Classification is an ongoing process of reasoning and change.
To save the habitat (phumdis):
1. Protect the Loktak lake and the Keibul Lamjao National Park from encroachment and pollution.
2. Control the water level and the flow in the lake, as this affects the phumdis.
3. Stop the dumping of sewage and waste, and the removal of the phumdis.
To save the Sangai:
1. Strictly stop hunting and poaching.
2. Count the deer regularly, and breed them in captivity for release.
3. Involve the local community, and make people aware of its importance.
Insects belong to Arthropoda, which has jointed appendages (legs) and a hard external skeleton.
Check the options:
(i) bilateral symmetry is present in earthworms also, so it does not confirm an insect.
(ii) jointed legs are present in insects, but an earthworm has no legs. This confirms an insect.
(iii) a cylindrical body is a feature of the earthworm.
(iv) arthropods are segmented, and earthworms are very segmented. This does not confirm.
Sponges are multicellular and heterotrophic. Their cells have no cell wall.
(i) wrong. They have mitochondria, as all eukaryotic cells have.
(ii) wrong. They cannot photosynthesise, as they depend on other organisms for food.
(iii) correct. Animal cells have only a cell membrane, with no cell wall.
(iv) wrong. A cell wall is present in plants and fungi.
Let the two animals be a cockroach and a sparrow.
| Feature | Cockroach | Sparrow |
|---|---|---|
| Backbone | Absent | Present |
| Legs | Six jointed legs | Two legs |
| Body covering | Hard exoskeleton | Feathers |
| Wings | Thin wings | Wings, with feathers |
| Group | Arthropoda (non-chordata) | Chordata, Vertebrata (Aves) |
How the features help:
1. The notochord or backbone divides animals into non-chordata and chordata.
2. The cockroach has jointed legs and an exoskeleton, so it goes in Arthropoda.
3. The sparrow has a backbone, feathers and wings, so it goes in Vertebrata, class Aves (birds).
Step 1: cellular organisation (cell type and number of cells) is present in all organisms, so it is a fundamental feature.
Step 2: it divides life into big groups: prokaryote or eukaryote, and unicellular or multicellular. These decide the kingdom.
Step 3: xylem and phloem are found only in some plants (pteridophytes, gymnosperms and angiosperms). They cannot classify bacteria, protists, fungi or animals.
Step 4: classification starts with the basic features that are common to many organisms, and then moves to the finer features. Vascular tissue is a finer feature used only within Plantae.
Observations: single-celled, well-defined nucleus (eukaryote), many cilia for movement.
Group: Kingdom Protista.
Reasons:
1. Protista are unicellular eukaryotes, as the slide organism is.
2. Cilia are used for movement by protists like Paramecium.
3. A well-defined nucleus rules out Monera, and a single cell rules out Fungi (mostly multicellular), Plantae and Animalia.
Step 1: every species has a role in the ecosystem: producers make food, consumers feed on others, and decomposers recycle nutrients.
Step 2: pollinators and seed dispersers help plants to reproduce.
Step 3: in a diverse ecosystem, there are many food chains. If one species declines, others can take its place.
Step 4: when a species disappears, those that depend on it also decline. Less diversity means less stability.
Result: more diversity gives greater balance and stability.
Unicellular organisms include bacteria, Amoeba, Euglena, yeast and Chlamydomonas.
Problems if they were all in one kingdom:
1. Bacteria have no true nucleus, but the others have a true nucleus. These are very different cells.
2. Some are autotrophic (Euglena) and some heterotrophic (Amoeba).
3. Yeast has a chitin cell wall, but Amoeba has no cell wall.
4. The kingdom would have organisms with very different features, so it could not show their relationship.
This is why Monera, Protista and Fungi are separate kingdoms.
Reasons:
1. Viruses are acellular. They have no cell membrane, cytoplasm or organelles.
2. The five kingdoms are based on cell type, cell wall, level of organisation and nutrition. A virus cannot be judged on any of these.
3. They are inactive outside a host cell. They can reproduce only inside a living host cell.
4. They do not carry out the life processes (like nutrition and growth) on their own.
My decision: I would keep the viruses outside the five kingdoms, in a separate group of acellular entities.
Justification:
1. A kingdom is a group of cellular organisms, and viruses have no cells.
2. They show life features only inside a host, so their position between living and non-living is not clear.
3. Putting them in a kingdom would mean changing the criteria of the kingdoms.
What it shows: the classification is not final. It has changed with new knowledge, from two kingdoms to five kingdoms and to three domains, and it will change again.
(Any other decision is accepted if it is justified with the criteria.)
Features that prevent the fitting:
1. No cellular organisation, so cell type (prokaryote or eukaryote) cannot be used.
2. Neither unicellular nor multicellular, and no cell wall.
3. No mode of nutrition of their own, as they do not feed.
4. They cannot live and reproduce independently, only inside a host.
Limitations of classification:
1. A classification depends on the criteria chosen by us and on the knowledge of the time.
2. Organisms that lie on the border do not fit neatly.
3. So the systems have to be revised when new knowledge comes.
Key features:
| Feature | Bryophytes | Pteridophytes |
|---|---|---|
| Body | Slightly differentiated, no true root, stem or leaves | True roots, stems and leaves |
| Root-like parts | Rhizoids | True roots |
| Vascular tissue | Absent | Present (xylem and phloem) |
| Flowers and seeds | Absent | Absent |
| Water for reproduction | Needed | Needed |
| Habitat | Moist, shady places | Land, but moist |
Explanation: both lack flowers and seeds, but they differ in body differentiation and vascular tissue. These features are more fundamental, so the two are placed in different groups.
Class is a higher level than the genus. Order of ranks: Kingdom → Phylum → Class → Order → Family → Genus → Species.
Step 1: every lower group is a part of the group above, so a genus has fewer members than a class.
Step 2: at each lower level, organisms share more features.
Example: class Mammalia has tigers, humans and bats, but the genus Panthera has only the tiger, lion and a few others, and they are very alike.
Locomotion and autotrophic nutrition alone are not enough, because animals show locomotion and plants are autotrophic.
Characters that identify Protista:
1. It is unicellular (single-celled).
2. It is eukaryotic, with a true nucleus.
3. It has no cell wall, or has a cellulose cell wall.
Example: Euglena is unicellular, moves with a flagellum, and photosynthesises.
Identification key for a unicellular fungus:
1. The cell is eukaryotic (has a true nucleus).
2. It has a cell wall made of chitin.
3. It has no chlorophyll, and it is heterotrophic, absorbing food from the surroundings.
Reason: protists have no cell wall or a cellulose wall, so a chitin cell wall puts it in Fungi.
Example: yeast is unicellular, but it is kept in Fungi because of its chitin cell wall.
| Organism | Key observations |
|---|---|
| P | Microscopic; no true nucleus; rigid cell covering; survives high salinity and temperature |
| Q | Multicellular; filamentous body; cell wall present; no chlorophyll; grows on dead organic matter |
| R | Unicellular; true nucleus; contractile vacuole present; moves using flagella; shows photosynthesis in light but heterotrophic in the absence of light |
| S | Multicellular; well-differentiated tissues; backbone present; aquatic respiration during early life stage |
| T | Acellular; contains genetic material; remains inactive outside a host cell |
Organism: Q.
Observation: it is multicellular and filamentous, has a cell wall, has no chlorophyll, and grows on dead organic matter.
This matches fungi, which have a mycelium of filaments and feed by absorbing from dead matter (saprophytes).
Organism: P.
Characteristic: it has no true nucleus, so it is a prokaryote.
Its tiny size and its survival in high salinity and temperature are also typical of bacteria and archaea.
1. Level of organisation: R is unicellular, and Q is multicellular.
2. Cell wall and body: R has no cell wall and moves with a flagellum. Q has a cell wall and a filamentous body.
3. Mode of nutrition: R is autotrophic in light and heterotrophic in dark, like Euglena. Q is only heterotrophic (saprophytic).
So R is placed in Protista, and Q is placed in Fungi.
Step 1: mode of nutrition alone would show only that S is heterotrophic. This is true for all animals and also for fungi and many others.
Step 2: so it cannot decide the place of S.
Step 3: S needs the features of body organisation: well-differentiated tissues and a backbone. They place it among the vertebrates (an animal, like a frog or a fish).
Lacking characteristic: cellular organisation. T is acellular (a virus).
Reveals: the five kingdom system is based on cell features, so it has no place for acellular entities.
So no classification system is perfect. It depends on the chosen criteria and must change with new knowledge.
Wrongly grouped:
1. In water: fish, frogs, whales (a mammal), protists like R and algae would be together.
2. In damp soil: fungi (Q), bacteria and earthworms would be together.
Consequences:
1. Very different organisms would be in one group, and close relatives would be separated.
2. The groups would not show the structure, the relationship or the evolution of organisms.
3. We could not predict the features of an organism from its group.
(Aristotle’s habitat system had the same limitation.)
Decision: Fungi.
Reasons:
1. Fungi are multicellular eukaryotes without chlorophyll, which is the same as the organism.
2. Fungi absorb their nutrients from outside (from dead matter or from a host as parasites). Animals eat and digest the food inside the body.
3. The organism absorbs nutrients from a host externally, so this is the absorptive nutrition of fungi.
Check: to be sure, we would look for a chitin cell wall and a filamentous body (mycelium) that forms spores. If it has no cell wall, and has tissues and movement, it would be an animal.
Steps:
1. Visit the park or pond. Note the organisms in the water, on the land and in the air.
2. Identify each one using a book or an app, and write its features.
3. Classify it by cell type, level of organisation and nutrition.
Sample record (replace with your own observations):
| Organism | Main feature | Kingdom |
|---|---|---|
| Algae (Spirogyra) | Green, filamentous, autotrophic | Plantae (Thallophyta) |
| Moss | Green mat on damp wall | Plantae (Bryophyta) |
| Fern | True roots, stem, leaves | Plantae (Pteridophyta) |
| Banyan or mango tree | Flowers and fruits | Plantae (Angiosperm) |
| Mushroom | No chlorophyll, absorbs food | Fungi |
| Yeast (on bread or fruit) | Single-celled, chitin wall | Fungi |
| Frog | Backbone, moist skin | Animalia (Vertebrate) |
| Crow | Feathers, wings, backbone | Animalia (Vertebrate) |
| Earthworm | Segmented, no backbone | Animalia (Annelida) |
| Amoeba or Paramecium (pond water, microscope) | Single-celled, true nucleus | Protista |
Bacteria (Monera) are too small to see, but they are present in the soil and water.
Questions to ask: How do you recognise a plant or animal? Which features do you look at? Do you use local names?
| Point | Traditional method | Scientific method |
|---|---|---|
| Features used | Leaf, flower, smell, taste, sound, season, habitat | Cell structure, body organisation, reproduction, DNA |
| Name | Local names that change from place to place | Universal binomial name (e.g. Panthera tigris) |
| Record | Handed down by speaking, from experience | Written, in books and databases, with keys |
| Tools | Eyes, hands, experience | Microscope, keys, DNA studies |
Conclusion: traditional knowledge is rich and practical (like the knowledge of edible mushrooms). The scientific method is systematic and the same everywhere. They can work together.
Step 1: give each species its common name and its scientific (binomial) name.
Step 2: arrange the species by classification, from class Aves to order, family, genus and species.
Step 3: make a table with columns for habitat, food, nesting place, active time, and whether it is resident or a migrant.
Step 4: group the species by different criteria: forest or water birds, fruit or insect or fish eaters, and so on.
Step 5: record the count of each species, and mark the endangered and endemic species.
Example: in Pakke, the four hornbill species would be put together in one family, with notes on the tree sizes and fruits for each.
Steps:
1. Take a community resource person or a forest guide with you. Go in the season of rain.
2. Photograph the mushrooms and note the colour, shape, smell, place of growth and local name.
3. Ask which are edible and which are poisonous and how they know.
4. Record the data in a table (local name, features, edible or poisonous, use).
5. Compare it with the books or an expert.
Safety: never eat or taste a wild mushroom yourself. Some are poisonous, and the two types can look alike. Wash your hands after touching.
Learning: mushrooms are fungi. Communities have folk knowledge of them, and correct identification is important for safe use.
Steps:
1. Collect stamps showing plants and animals, and note the year and country.
2. Make criteria, and sort the stamps into groups.
| Criterion | Groups |
|---|---|
| Kingdom | Plants, animals, fungi |
| Plant group | Algae, mosses, ferns, conifers, flowering plants |
| Animal group | Mammals, birds, reptiles, amphibians, fish, insects |
| Habitat | Forest, desert, water, mountains |
| Status | Endemic or endangered species |
3. Mount the stamps group-wise, and write the name (common and scientific) of each organism.
4. Display them in the school with charts that explain your criteria.
Example: the Indian cheetah, which was declared extinct in India in 1952.
Cause: hunting and loss of grassland habitat.
Impact on others:
1. The top predator of the grassland was lost, so the numbers of its prey (like blackbuck and chinkara) were no longer controlled by it.
2. Scavengers lost a source of food.
3. The grassland itself was cleared, which affected many other species.
Effect on balance: food webs were disturbed, and the ecosystem became less stable.
(Any other extinct species, like the dodo, can be used in the same way.)
Farm animals used in different practices and regions:
| Practice / region | Animals | Use |
|---|---|---|
| Dairy farming (Gujarat, Punjab, Haryana) | Gir, Sahiwal cows, Murrah buffalo | Milk |
| Ploughing and transport (plains) | Bullocks, buffalo | Draught power |
| Arid regions (Rajasthan) | Camel, goat, sheep | Transport, milk, wool, meat |
| Hills and cold regions (Ladakh, Arunachal Pradesh) | Yak, sheep, mithun (north-east) | Milk, wool, meat, transport |
| Poultry farming (all over India) | Hens, ducks | Eggs, meat |
| Coastal and inland fish farming | Fish such as rohu and catla | Food |
Conclusion: the animals differ in different regions, as they are adapted to the climate and food available there. Local breeds are important for biodiversity.
New knowledge:
1. More DNA and genome studies will show the exact relationship among organisms.
2. Discovery of new species, including those in the deep sea, soil and microbes.
3. Better tools (electron microscopes, AI, environmental DNA) to study tiny organisms and viruses.
Effect on classification:
1. Some groups may be merged, split or moved (like the three domain system).
2. There may be a place for viruses and other borderline forms.
3. Scientific names and groups may change. Classification will be based more on evolutionary relationships.
Conclusion: classification will keep changing, as science grows with evidence.
Earth's biodiversity — from a single bacterium to a tiger — is organised, not chaotic: the five kingdom system groups life by cell type, structure, nutrition and ecological role, the hierarchical ladder from Kingdom down to Species narrows every group to its closest relatives, and this entire framework keeps evolving, as fossils, genetics, and even boundary cases like viruses continue to reshape how we understand and protect the diversity of life.
Seven extra questions in the style of the textbook, for independent practice. Attempt each one on paper first, then tap to check.
Features: multicellular, chitin cell wall, no chlorophyll, absorbs nutrients from decaying wood.
Kingdom: Fungi.
Reasons:
1. Chitin cell wall is the feature of fungi.
2. No chlorophyll means it is heterotrophic.
3. It absorbs food from dead matter, so it is a saprophyte (decomposer).
Order from the broadest to the narrowest:
1. Kingdom
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species
Check: at each lower level, the organisms are fewer and share more features.
Rules: the genus name starts with a capital letter, and the species name is in small letters. The name is written in italics (or underlined if handwritten).
Error 1: the genus name panthera starts with a small letter. It should be Panthera.
Error 2: the species name Tigris starts with a capital letter. It should be tigris.
Correct name: Panthera tigris. (In handwriting: Panthera tigris.)
Gymnosperms (pine): the seeds are naked. They are not covered in fruits and are exposed on cones.
Angiosperms (mango): they have flowers, and the seeds are enclosed within fruits.
Key feature: seeds enclosed in fruits (formed from flowers) or not.
Pair 1: two organisms in the same genus.
Pair 2: two organisms in the same kingdom but different genera.
Step 1: genus is much lower than the kingdom in the hierarchy.
Step 2: a lower group has fewer members and they share more features.
Step 3: organisms of the same genus also share the family, order, class, phylum and kingdom. Pair 2 shares only the kingdom, and some higher levels.
Example: a tiger and a lion (same genus Panthera) are more alike than a tiger and a bat (same kingdom).
Why viruses do not fit:
1. They are acellular, with no cell membrane or cytoplasm.
2. They cannot do life processes without a host cell, and are inactive outside it.
3. The five kingdoms are based on the features of cells, which viruses do not have.
What it shows:
1. Classification is made by humans on the basis of the knowledge and the criteria of the time.
2. When new organisms or information do not fit, the system is revised (two kingdoms → five kingdoms → three domains).
3. So scientific classification is always developing.
Read the graph at 20 m²: it is 18.
At 30 m² the species are 22, and at 50 m² they are 25.
At 10 m² the species are 12, and at 50 m² they are 25.
Species lost = 25 − 12 = 13
Step 1: the plants lose their habitat, so many species disappear. A smaller area holds fewer species, as the graph shows.
Step 2: animals, birds, insects and fish that depend on these plants for food and shelter also decline.
Step 3: food webs are broken, and the pollination and nutrient recycling reduce.
Step 4: the wetland stores water, recharges groundwater, reduces floods and cleans water. People lose these services, and the fishing or local livelihoods.
Step 5: the genetic diversity of the species is lost forever.
Browse the full list of Class 9 Science (Exploration) NCERT Solutions chapters, visit the Class 9 Science hub, or revise with the Class 9 Science Notes, or test yourself with the free Class 9 Science Sample Paper and Marking Scheme.
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