Class 9 Science: Patterns in Life: Diversity and Classification — Chapter Question Set

(a) biodiversity

(b) endemic species

(b) Nilgiri tahr

(a) biodiversity hotspots

(c) the Thar desert

(a) pitcher plant

(c) every organism plays a role in keeping nature stable and functioning

(d) small differences accumulated over many generations

(c) habitat — land, water and air

(d) Plantae and Animalia

(d) Carolus Linnaeus

(a) unicellular organisms like Amoeba did not fit clearly into either kingdom

(a) unicellular microscopic organisms

(d) lack a true (membrane-bound) nucleus

(d) Robert H. Whittaker

(c) Monera, Protista, Fungi, Plantae, Animalia

(b) bacteria and cyanobacteria

(d) unicellular prokaryotes

(d) Protista

(a) are unicellular eukaryotes with a true nucleus

(b) chitin

(d) absorbing them from dead and decaying matter

(c) saprophytes

(c) yeast

(c) Aspergillus and Penicillium

(a) multicellular autotrophs with cellulose cell walls

(a) Thallophyta (algae)

(c) thallophyte

(a) need water for reproduction even on land

(a) rhizoids

(b) xylem and phloem

(d) Pteridophyta

(b) have seeds exposed on cones

(c) naked seed

(a) angiosperms (flowering plants)

(c) enclosed within fruits

(a) presence or absence of a notochord

(b) Porifera

(c) cellular (no true tissues)

(c) tentacles

(a) bilateral symmetry with distinct head-tail regions

(a) hooks and suckers

(c) two openings — mouth and anus

(b) Annelida

(b) jointed appendages and an external skeleton

(a) Mollusca

(a) calcium carbonate

(b) at least once during their life

(c) supports the body and protects the brain and spinal cord

(c) fish, amphibians, reptiles, birds, mammals

(b) Kingdom → Phylum → Class → Order → Family → Genus → Species

(d) Carolus Linnaeus

(c) genus

(b) Mangifera indica

(d) are acellular — they lack cellular organisation and show characteristics of life only inside a host

biodiversity

endemic

hotspots

classification

Monera

chitin

amphibians

pteridophytes (ferns)

cones

notochord

Arthropoda

mammary

genus

Panthera tigris

fungus

True

True

False

False (they are prokaryotes placed in Monera)

True

False (they are heterotrophic)

True

False (they form a simple thallus)

True

False (water is not essential for their fertilisation)

False (cellular level of organisation)

False (they have mouth and anus)

True

True

False (the genus starts with a capital, species with a small letter)

(a)

(a)

(d)

(a)

(a)

(d)

(d)

(a)

Biodiversity is the variety of living organisms — plants, animals and microorganisms — found on the Earth. It is essential because every organism plays a role in keeping nature stable and functioning; the loss of even one species can disturb the balance of the entire ecosystem.

Endemic species are those that are found naturally only in a particular region and nowhere else in the world. Two Indian examples are the Nilgiri tahr and the Neelakurinji plant; Nepenthes khasiana and the lion-tailed macaque are other examples.

Scientists classify organisms based on (i) cell structure, i.e., whether prokaryotic or eukaryotic; (ii) number of cells, i.e., unicellular or multicellular; (iii) mode of nutrition, i.e., autotrophic or heterotrophic; and (iv) ecological role. Reproduction methods and genetic similarity are also used as criteria.

Organisms sharing the same habitat can be very different from each other in structure and biology. For example, fish and frogs both live in water yet belong to different groups, so grouping by habitat misleads and is therefore an inadequate basis for classification.

Classification makes the study of vast numbers of organisms organised and systematic, and it helps in identifying and correctly placing newly discovered organisms. It also reveals relationships between organisms and supports biodiversity conservation efforts.

Unicellular organisms like Amoeba move and feed like animals but are single-celled like simple plants, so they did not fit clearly into either Plantae or Animalia. A separate kingdom, Protista, was therefore created to accommodate all unicellular eukaryotic organisms.

Bacteria are unicellular prokaryotes — their cells have no true nucleus or membrane-bound organelles. This makes them fundamentally different from the eukaryotic protists and from all other organisms, so they were placed in a separate kingdom, Monera.

Though fungi do not move like animals, they are heterotrophic — mostly saprophytes that grow on dead organic matter — and have cell walls made of chitin. Since they neither photosynthesise like plants nor behave like animals, they were given their own kingdom.

(i) Thallophytes have a simple thallus-like body that is not differentiated into true roots, stems or leaves. (ii) They mostly live in water or moist environments and lack specialised vascular tissues, making them structurally the simplest members of the plant kingdom.

Bryophytes live on moist land but need water for reproduction, just as amphibians live on land yet depend on water for breeding. Their male reproductive cells must swim through a film of water to reach the female cells for fertilisation.

Pteridophytes possess two vascular transport tissues: xylem and phloem. Xylem conducts water and dissolved minerals from the roots to all parts of the plant, while phloem transports the food made by photosynthesis throughout the plant body.

Gymnosperms have needle-like leaves that reduce water loss through transpiration, and they bear seeds that protect the embryo. Moreover, unlike bryophytes, they do not need water for fertilisation, all of which helps them thrive in cold, dry regions.

Angiosperms bear flowers that attract pollinators, making reproduction highly efficient and targeted. Their fruits protect the seeds and help spread them to new locations through animals and wind, allowing angiosperms to occupy many habitats and become the most diverse plant group.

Non-chordates, or invertebrates, lack a notochord at every stage of their life cycle. Chordates possess a notochord — a stiff rod-like supporting structure — at least at some stage of their development, along with a dorsal nerve cord.

The defining feature of arthropods is the presence of jointed appendages (jointed legs) along with a hard external skeleton. Examples include insects such as cockroaches and butterflies, as well as crabs and spiders — any two serve as examples.

The vertebral column provides a strong, flexible axis that supports a larger body size. It also encloses and protects the brain and spinal cord and allows complex movements, giving vertebrates a significant evolutionary advantage over animals without a backbone.

The correct order of the classification hierarchy, from the broadest to the most specific category, is: Kingdom → Phylum → Class → Order → Family → Genus → Species. Species is the smallest and most basic unit of this hierarchy.

Binomial nomenclature is the system of naming organisms with a two-part scientific name — the genus (written first, with a capital letter) followed by the species (written with a small letter), both in Latin. This system was introduced by Carolus Linnaeus.

A lichen is a symbiotic association between an alga and a fungus living together for mutual benefit. Lichens serve as natural bioindicators of air pollution because they are sensitive to pollutants and die out when the air becomes contaminated.

Viruses are not included in the five kingdom classification because they are acellular — they lack cellular organisation, cytoplasm and organelles. They also remain inactive outside a host cell and show no life processes until they infect a living cell, so they fit into none of the five kingdoms.

Introduction: Biodiversity depends on the linked spheres of the Earth's system working in balance.
Key Points:
1. Spheres interact — Geosphere, hydrosphere, atmosphere and biosphere continuously influence one another.
2. Disturbance spreads — A change in one sphere, like reduced snowfall, alters water availability and plant growth.
3. Habitat impact — Clearing forests or warming seas reduces habitats, threatening endemic species and ecosystems.
Conclusion: Conservation of biodiversity requires understanding and protecting these interconnected spheres.

Introduction: Biological classification is the systematic grouping of living organisms based on shared features.
Key Points:
1. Organised study — It makes the study of millions of species organised and systematic.
2. Relationships — It reveals similarities, differences and how organisms are related and interact.
3. Identification and conservation — It helps identify new organisms and protect species under threat.
Conclusion: Classification works like an address system for the entire living world.

Introduction: Scientists choose fundamental features rather than easily visible ones to group organisms.
Key Points:
1. Cellular features — Whether the cell is prokaryotic or eukaryotic; presence or absence of a cell wall.
2. Body organisation — Unicellular or multicellular; mode of nutrition (autotrophic or heterotrophic).
3. Evolutionary features — Ecological role (producer, consumer, decomposer) and genetic (DNA) similarity.
Conclusion: Shared fundamental features suggest organisms evolved from common ancestors.

Introduction: Robert Whittaker (1969) grouped all life into five kingdoms using cell type, body organisation and nutrition.
Key Points:
1. Monera — Unicellular prokaryotes like bacteria and cyanobacteria.
2. Protista — Unicellular eukaryotes like Amoeba, Paramecium and Euglena.
3. Fungi — Mostly multicellular eukaryotes with chitin cell walls that are heterotrophic and absorb nutrients.
4. Plantae and Animalia — Multicellular autotrophic plants and multicellular heterotrophic animals respectively.
Conclusion: The system separates life by increasingly fundamental differences of cell and body design.

Introduction: Monera contains the simplest, single-celled prokaryotic organisms of the Earth.
Key Points:
1. Members — Bacteria and cyanobacteria are found in soil, water, air, hot springs and even the human gut.
2. Prokaryotic cell — They lack a true nucleus but are essential and resilient in extreme environments.
3. Ecological role — Useful forms like Lactobacillus, Rhizobium and biogas bacteria cycle nutrients; cyanobacteria were early oxygen producers.
Conclusion: Though some bacteria cause disease, many sustain nutrient cycles and agriculture.

Introduction: Fungi are mostly multicellular eukaryotes with chitin cell walls that do not make their own food.
Key Points:
1. Nutrition — Saprophytes absorb nutrients from dead and decaying matter through filamentous hyphae.
2. Reproduction and habitat — They reproduce by spores and thrive in warm, moist conditions; yeast is unicellular.
3. Ecological role — As decomposers they recycle nutrients; some cause disease, some are symbiotic, and Penicillium gives antibiotics.
Conclusion: Without decomposers like fungi, soil fertility and ecological balance would collapse.

Introduction: Plantae is divided into five classes showing increasing structural complexity.
Key Points:
1. Thallophyta and Bryophyta — Algae have a simple thallus; mosses have rhizoids and need water to reproduce.
2. Pteridophyta — Ferns have true roots, stems, leaves and vascular tissue but still need water and lack seeds.
3. Gymnosperms and Angiosperms — Pines have naked seeds on cones and need no water; angiosperms enclose seeds in fruits and use flowers.
Conclusion: The series shows how plants gradually adapted from water to dry land.

Introduction: Animals are multicellular, heterotrophic eukaryotes capable of locomotion and rapid response.
Key Points:
1. Division by notochord — Animals are split into non-chordata (invertebrates) and chordata.
2. Invertebrate diversity — Porifera to Echinodermata show increasing body complexity from cellular to organ-system level.
3. Chordata and vertebrates — Protochordates have a notochord at some stage; vertebrates have a backbone and form five groups — fish, amphibians, reptiles, birds and mammals.
Conclusion: Animal classification traces a stepwise advance in body design from sponges to mammals.

Introduction: Arthropoda and Mollusca are two large invertebrate phyla with distinct body plans.
Key Points:
1. Arthropoda — Segmented bodies with jointed appendages and a hard external skeleton; examples include insects, crabs, spiders.
2. Mollusca — Soft bodies with a distinct head, muscular foot and hump, often protected by a shell; snails, squids, octopuses.
3. Adaptive value — The arthropod exoskeleton reduces water loss and supports muscles; molluscan shells protect soft bodies.
Conclusion: Both groups show how a basic body plan can be modified for varied environments.

Introduction: Classification follows a step-by-step order from broad groups to specific ones.
Key Points:
1. Hierarchy levels — Kingdom → Phylum → Class → Order → Family → Genus → Species.
2. Shared features increase downwards — Each lower group is part of the one above and shares more features.
3. Tiger example — Animalia → Chordata → Vertebrata → Mammalia → Carnivora → Felidae → Panthera → Panthera tigris.
Conclusion: Like an address, the hierarchy lets scientists locate, compare and study any organism exactly.

Introduction: Binomial nomenclature is the universal two-part scientific naming of organisms.
Key Points:
1. Two parts — The first word is the genus and the second the species, both written in Latin form.
2. Founder — Introduced by Carolus Linnaeus in the 18th century.
3. Examples — Tiger is Panthera tigris; mango is Mangifera indica; pea is Pisum sativum.
Conclusion: A common scientific name avoids the confusion caused by many local names.

Introduction: Vertebrates possess a vertebral column that supports larger size and complex organs.
Key Points:
1. Fins, gills and feathers — Fins and gills suit fish for water; hollow bones and feathers enable flight in birds.
2. Extreme-climate features — Fat storage in camels and thick fur in polar bears aid survival in extreme conditions.
3. Mammalian trait — Mammary glands feed the young, improving the survival of offspring.
Conclusion: Animal diversity reflects structural changes matched to diverse habitats.

Introduction: Protochordates mark the appearance of the notochord, bridging simpler and vertebrate animals.
Key Points:
1. Notochord presence — Protochordates like Amphioxus possess a notochord at least once during their life.
2. Internal support — The notochord provides internal support without restricting movement.
3. Link to vertebrates — They show how animals with a notochord may have arisen from simpler invertebrate forms.
Conclusion: Protochordates are a primitive but crucial stage in the evolution toward vertebrates.

Introduction: The Sangai, or dancing deer, is endemic to Manipur and listed in the IUCN Red Data list.
Key Points:
1. Habitat — It lives on floating grassland beds called phumdis in Loktak lake's Keibul Lamjao National Park.
2. Rediscovery — Declared extinct in 1951, it was rediscovered in 1953 by its unique hooves and elongated patterns.
3. Threat — Degenerating phumdis and habitat loss now threaten its small restricted population.
Conclusion: Conservation of phumdis is essential to save this endemic and endangered deer.

Introduction: Lichens are sensitive to air pollution and so reflect environmental health.
Key Points:
1. Symbiosis — A lichen is a mutual association of an autotrophic alga and a heterotrophic fungus.
2. Pollution response — They change colour with air pollutants, indicating pollutant concentration.
3. Indicator value — Their presence on tree trunks or stones signals a pollution-free environment.
Conclusion: Lichens thus serve as natural, low-cost bioindicators of air quality.

(a) The presence of jointed legs would confirm that the animal is an insect, as jointed appendages are the defining feature of arthropods.
(b) The earthworm belongs to the phylum Annelida, whose members have segmented, ring-like bodies.
(c) The beetle, being an arthropod, additionally has a hard external skeleton (exoskeleton) covering its segmented body.
(d) The exoskeleton protects the body from injury and predators, reduces water loss and supports powerful muscles, allowing the beetle to survive in dry, exposed environments.

(a) Tree size and fruit availability differ across the forest, so each hornbill species occupies the part that best provides its nesting cavities and food.
(b) Classification helps scientists identify, compare and understand the relationships and distribution of the species, making the study of such biodiversity systematic.
(c) The hornbills would lose both their nesting sites and their food supply, threatening their survival and causing their populations to decline.
(d) Scientists keep track through systematic identification and classification of organisms based on their shared features.

(a) P belongs to kingdom Monera, because it is a prokaryote with no true nucleus.
(b) Q belongs to kingdom Fungi, because it is multicellular with cell walls but no chlorophyll and grows on dead organic matter.
(c) R shows autotrophic nutrition (photosynthesis in light) as well as heterotrophic nutrition (absorbing food in darkness).
(d) Q is multicellular and heterotrophic, while R is unicellular — their different body organisation and nutrition place Q in Fungi and R in Protista.

(a) S most likely belongs to the amphibians, since it respires through gills in its aquatic larval stage (like a tadpole) and lives on land as an adult.
(b) Mode of nutrition alone is not enough because S is heterotrophic like many other groups; its backbone and life cycle are needed to place it correctly.
(c) T lacks cellular organisation, which is the fundamental basis of the five kingdom system, so it fits into none of them.
(d) It reveals that classification systems are evolving frameworks that cannot yet accommodate acellular life forms like viruses.

(a) It could belong to kingdom Protista, the group of unicellular eukaryotes.
(b) The supporting characters are its unicellular eukaryotic organisation and its ability to show locomotion, like flagellated protists such as Euglena.
(c) Euglena shows the same mixed mode — it is photosynthetic in light and heterotrophic when light is absent.
(d) It cannot go into Monera because it is not a prokaryote, and not into Plantae because it is not a multicellular plant body.

(a) Its cell wall is made of chitin, which is the defining fungal feature and justifies its placement in Fungi.
(b) This organism is yeast, a unicellular fungus.
(c) The flaw is that cell wall composition is a more fundamental criterion than the number of cells, so its chitin wall clearly outweighs its unicellularity.
(d) It tells us that fundamental biochemical and structural features should be given more weight than superficial ones like cell number when classifying organisms.

(a) These patches are lichens growing on the tree trunk.
(b) A lichen is not a single organism but a symbiotic association of an autotrophic alga and a heterotrophic fungus living together for mutual benefit.
(c) They change colour or disappear as levels of air pollutants like sulphur dioxide rise, so their presence and colour directly indicate pollutant concentration.
(d) Some lichens are poisonous, so correct identification is essential to ensure they are used safely as food, medicine or dye.

(a) Endemic means the Sangai deer is found naturally only in the Loktak lake region of Manipur and nowhere else in the world.
(b) Naturalists rediscovered it by identifying its unique characteristics — its distinctive hooves and elongated body patterns.
(c) Its population is small and restricted to the phumdis, so losing them would remove its food, shelter and breeding space, pushing it further towards extinction.
(d) Measures include regulating pollution and hydropower impacts on the lake, protecting Keibul Lamjao National Park, and involving local communities in conservation.

(a) A bacterium and an Amoeba would be wrongly grouped together in such a single kingdom.
(b) The bacterium is prokaryotic, with no true nucleus, whereas the Amoeba is eukaryotic and has a true nucleus.
(c) The bacterium belongs to kingdom Monera and the Amoeba to kingdom Protista.
(d) Cell wall composition and mode of nutrition separate them: chitin-walled heterotrophs are placed in Fungi, while wall-less or cellulose-walled forms remain in Protista.

(a) Like the ancient Indian approach, Aristotle also grouped animals mainly by habitat — terrestrial, aquatic or aerial — and by their ecological roles.
(b) Both relied only on easily observable external characters and missed the fundamental internal and cellular differences between organisms.
(c) Whittaker's five kingdom classification replaced it, being based on cell type, body organisation and mode of nutrition.
(d) Sacred groves preserve locally diverse habitats and endemic species untouched, acting as in-situ conservation reserves even today.

Introduction: Biodiversity is the immense variety of living organisms found in every habitat on the Earth.
Key Points:
1. Ecological stability — Every organism, from microscopic algae to eagles, plays a role in nature's functioning.
2. Ecosystem services — Algae release oxygen; fungi and bacteria decompose waste; insects, birds and bats pollinate flowers.
3. Human dependence — Humans rely on biodiversity for food, shelter, medicines and livelihoods.
4. Food security — Crop diversity with drought tolerance and pest resistance reduces the risk of crop failure.
5. Conservation need — Biodiversity hotspots like the Western Ghats need protection for ecosystem health.
Conclusion: Biodiversity sustains ecosystems and makes the Earth suitable for all life, including us.

Introduction: Classification systems have improved as knowledge and instruments like microscopes advanced.
Key Points:
1. Aristotle (4th century BCE) — Grouped animals by habitat — land, water and air — using external features.
2. Two kingdom system (18th century) — Linnaeus divided life into Plantae and Animalia.
3. Three and four kingdoms — Protista was added for microscopic life; Monera was separated for nucleus-less bacteria.
4. Five kingdoms (1969) — Whittaker added Fungi, recognising their unique heterotrophic absorption nutrition.
Conclusion: Each system refined the previous one by using more fundamental characteristics of organisms.

Introduction: Whittaker's system groups life into five kingdoms using cell type, body organisation, cell wall and nutrition.
Key Points:
1. Monera — Unicellular prokaryotes without a true nucleus, like bacteria and cyanobacteria.
2. Protista — Unicellular eukaryotes like Amoeba, Paramecium, Euglena and Chlamydomonas.
3. Fungi — Mostly multicellular eukaryotes with chitin cell walls, saprophytic, like mushrooms, yeast and Aspergillus.
4. Plantae — Multicellular autotrophs with cellulose cell walls, from mosses to flowering plants.
5. Animalia — Multicellular heterotrophs with organ systems, showing locomotion and rapid responses.
Conclusion: The five kingdoms separate life by increasingly fundamental differences of cellular design.

Introduction: Plantae is divided into five classes showing a sequence of adaptations to life on land.
Key Points:
1. Thallophyta — Simplest plants like Spirogyra with an undifferentiated thallus, mostly in water.
2. Bryophyta — Mosses and Marchantia with rhizoids; first land plants but still water-dependent.
3. Pteridophyta — Ferns with true roots, stems, leaves and vascular tissue; still water-dependent and seedless.
4. Gymnosperms — Pines with naked seeds on cones; fertilisation without water; needle leaves resist water loss.
5. Angiosperms — Flowering plants with seeds in fruits; the most diverse and widespread group.
Conclusion: Plant groups show how transport tissues, seeds and flowers gradually reduced dependence on water.

Introduction: Invertebrates range from simple sponges to complex animals without a notochord.
Key Points:
1. Porifera — Sponges with a cellular level of organisation; pores circulate water for food and oxygen.
2. Cnidaria and Platyhelminthes — Hydra shows tissue-level organisation; flatworms add bilateral symmetry.
3. Nematoda and Annelida — Roundworms gain two body openings; earthworms add segmentation and body cavity.
4. Arthropoda and Mollusca — Jointed appendages with exoskeletons; molluscs have soft bodies, often with shells.
5. Echinodermata — Starfish with a calcium carbonate internal skeleton but no notochord.
Conclusion: The invertebrate series traces a stepwise advance in feeding, movement and protection.

Introduction: Chordates possess a notochord at least once during their life, distinguishing them from invertebrates.
Key Points:
1. Protochordata — Primitive chordates like Amphioxus whose notochord provides internal support.
2. Vertebrata — Vertebrates have a vertebral column protecting the brain and spinal cord.
3. Five groups — Fish, amphibians, reptiles, birds and mammals differ in habitat, body covering and reproduction.
4. Adaptations — Fins and gills for water; feathers and hollow bones for flight; mammary glands for feeding young.
5. Advanced abilities — Larger body size, efficient movement and complex organ systems mark vertebrates.
Conclusion: The vertebral column enabled vertebrates to exploit diverse environments successfully.

Introduction: Classification follows a stepwise hierarchy from broad kingdoms to specific species.
Key Points:
1. Hierarchy levels — Kingdom → Phylum → Class → Order → Family → Genus → Species.
2. Tiger classification — Animalia → Chordata → Mammalia → Carnivora → Felidae → Panthera → Panthera tigris.
3. Pea classification — Plantae → Magnoliophyta → Magnoliopsida → Fabales → Fabaceae → Pisum → Pisum sativum.
4. Feature sharing — Each lower level groups organisms sharing more common features than the level above.
5. Address analogy — Just as an address locates a house, the hierarchy locates an organism in the living world.
Conclusion: The hierarchical system lets scientists identify, compare and study organisms precisely.

Introduction: Binomial nomenclature is the universal two-part scientific naming of organisms.
Key Points:
1. Origin — Carolus Linnaeus introduced it in the 18th century.
2. Two parts — The first word names the genus and the second the species, like Panthera tigris.
3. Latin form — Names are written in Latin or Latinised words to ensure global uniformity.
4. Related grouping — A genus like Panthera groups closely related species such as tiger and lion.
5. Advantage — 'Bagh' (Hindi), 'puli' (Tamil) and 'tiger' (English) all resolve to one universal name.
Conclusion: Binomial nomenclature removes linguistic confusion in global scientific communication.

Introduction: Adaptations are outcomes of structural changes that arose in animal bodies over long periods.
Key Points:
1. Aquatic life — Fins and gills let fish move and breathe in water efficiently.
2. Aerial life — Feathers and hollow bones make flight possible in birds.
3. Harsh climates — Fat storage in camels and thick fur in polar bears handle extreme conditions.
4. Feeding the young — Mammary glands in mammals improve survival of offspring.
5. Interconnected design — All these features reflect body forms shaped by different environmental demands.
Conclusion: Vertebrate diversity mirrors the range of structural solutions to survival challenges.

Introduction: Classification is not just naming — it underpins our ability to conserve life on the Earth.
Key Points:
1. Identifying threatened species — Classification identifies organisms under extinction threat, like the Sangai deer.
2. Recognising endemism — Endemic species like the Nilgiri tahr are located and protected in hotspots.
3. Understanding relationships — It reveals links like the alga–fungus partnership in lichens within ecosystems.
4. Ecological management — Grouping by ecological role (producer, consumer, decomposer) aids ecosystem management.
5. Global cooperation — A common system lets scientists worldwide share data for conservation planning.
Conclusion: Systematic classification converts the study of diversity into effective protection of it.