April 10, 2026
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CHAPTER 12
Patterns in Life: Diversity and Classification
Verbatim Questions & Solutions | Exploration | Class 9 Science
Think It Over Page 248
Think It Over
What do you understand by biodiversity?
Solution
Biodiversity refers to the immense variety of living organisms on Earth, including microorganisms, plants, animals, and their habitats, ranging from microscopic organisms to giant trees and from snow-clad Himalayas to coral reefs.
Think It Over
How does the grouping of organisms help us understand diversity?
Solution
Grouping or classification helps us organize information systematically, understand relationships among organisms, study life in an organized manner, and identify newly discovered organisms.
Think It Over
On what basis, are plants and animals classified?
Solution
Plants and animals are classified based on cell type (prokaryotic/eukaryotic), cell structure (presence/absence of cell wall), level of organization (unicellular/multicellular), mode of nutrition (autotrophic/heterotrophic), and ecological role.
Think It Over
How does classification help address problems in farming?
Solution
Classification helps identify pest-resistant and drought-tolerant crop varieties, understand soil-microbe interactions, and develop sustainable farming practices by grouping organisms with useful characteristics.
Pause and Ponder Page 251
Pause and Ponder (Q1)
If many organisms share common features, could they also share a common ancestry?
Solution
Yes, similar features in organisms suggest that they have evolved from common ancestors. Shared characteristics indicate evolutionary relationships.
Activity 12.1 Pages 250-251
Activity 12.1
Fig. 12.2 shows the diversity of animals in an ecosystem. Observe the image carefully. Can you guess how the organisms are grouped in the image?
1. Ponder on the questions: (i) Which animals can you identify? (ii) Where are they seen? (iii) Which animals seem active during day, night, or both?
2. Record your observations in Table 12.1.
3. Try grouping the same organisms in more than one way. Each time change the criterion you are using for grouping (Table 12.2).
1. Ponder on the questions: (i) Which animals can you identify? (ii) Where are they seen? (iii) Which animals seem active during day, night, or both?
2. Record your observations in Table 12.1.
3. Try grouping the same organisms in more than one way. Each time change the criterion you are using for grouping (Table 12.2).
Solution
The same organism can fit into different groups depending on the criterion chosen (habitat, activity time, feeding habits, etc.). This shows that scientists use multiple characteristics to classify organisms systematically.
Activity 12.2 Page 252
Activity 12.2
Carefully read the given case study of Pakke Tiger Reserve. (i) How can scientists keep track of so many species? (ii) The four hornbills look similar in some ways. What features can help scientists distinguish them? (iii) What would happen if the large, old trees disappeared from the forest?
Solution
(i) Scientists use classification systems to organize and track species.
(ii) Features like coloration, beak shape, size, and nesting habits help distinguish hornbill species.
(iii) Hornbills would lose nesting sites, leading to population decline and ecosystem imbalance.
(ii) Features like coloration, beak shape, size, and nesting habits help distinguish hornbill species.
(iii) Hornbills would lose nesting sites, leading to population decline and ecosystem imbalance.
India's Scientific Contributions
Page 250
Some ancient Indian traditions, such as the Sangam Tinai classification of landscapes and the protection of sacred groves, demonstrate a sophisticated literary and cultural understanding of landscapes, and their biota. These customs effectively preserved locally diverse habitats, aligning with contemporary ecological principles, even if it is not articulated as a formal ecological theory.
Solution
Ancient Indian traditions like Sangam Tinai classification and sacred groves show a sophisticated understanding of ecosystems and biodiversity conservation, aligning with modern ecological principles.
Page 253
The Rigveda and the Brihat Samhita classify animals on the basis of their habitat (terrestrial, aquatic and aerial), behaviour patterns and ecological roles.
Solution
Ancient Indian texts like Rigveda and Brihat Samhita classified animals based on habitat (terrestrial, aquatic, aerial), behavior, and ecological roles, showing early understanding of biological classification.
Activity 12.3 Page 254
Activity 12.3
1. Study the concept map (Fig. 12.5). 2. List the criteria which form the basis of five kingdom classification. 3. Compare the criteria you have listed with the criteria given: cell type, cell structure, level of organisation, mode of nutrition.
Solution
Criteria for five kingdom classification: cell type (prokaryote/eukaryote), cell structure (presence/absence of cell wall), level of organization (unicellular/multicellular), mode of nutrition (autotrophic/heterotrophic), and ecological role.
Activity 12.4 Page 255
Activity 12.4
In the school laboratory, observe the available permanent slides of bacteria and cyanobacteria under the microscope. Compare them with Fig. 12.6. What do you observe? Bacteria and cyanobacteria are single-celled prokaryotes that are grouped under Monera.
Solution
Bacteria and cyanobacteria are unicellular prokaryotes without a well-defined nucleus or membrane-bound organelles. They are placed in Kingdom Monera.
Bridging Science and Society Page 255
Bridging Science and Society
Ram Bux Singh is popularly known as the 'Father of Modern Biogas'. He was a pioneering Indian scientist who contributed to the development of biogas technology. In 1957, he established India's first scientifically designed biogas plant at Ramnagar, Sitapur, Uttar Pradesh, which marked the beginning of systematic modern biogas research in the country.
Solution
Ram Bux Singh pioneered biogas technology in India, establishing the first scientifically designed biogas plant in 1957, promoting renewable energy and sustainable waste management.
Threads of Curiosity
Page 255
Cyanobacteria (blue-green algae) were among the first organisms to produce oxygen through photosynthesis. About 2.5 billion years ago, oxygen accumulated in the atmosphere, made the Earth suitable for other forms of life. Fossils of ancient cyanobacteria are found in structures called stromatolites. They were found in Rajasthan and Madhya Pradesh. They provide some of the earliest evidence of life on the Earth.
Solution
Cyanobacteria were among the first organisms to produce oxygen through photosynthesis, oxygenating Earth's atmosphere and enabling the evolution of other life forms. Stromatolite fossils in Rajasthan and MP provide early evidence of life.
Page 261
Research studies show that one kilogram of sponge can filter up to 24,000 litres of sea water per day.
Solution
Sponges (Porifera) are filter feeders that play a crucial role in maintaining water quality in aquatic ecosystems by filtering large volumes of water.
Page 267
When scientists discover a new organism, they compare it with the already known species. Sometimes, the species name reflects their place of discovery, or honours a scientist. The Purple Frog (Nasikabatrachus sahyadrensis) from Kerala has a species name after the Sahyadri Hills. The Purple Frog lives underground for most of the year and comes out only during the monsoon to breed. It belongs to an ancient family of frogs as understood from fossils. Its discovery in 2003 helped scientists understand ancient amphibian groups and highlighted the need for biodiversity conservation in the Western Ghats.
Solution
The Purple Frog (Nasikabatrachus sahyadrensis) is an ancient frog species endemic to the Western Ghats. Its discovery in 2003 highlighted the importance of biodiversity conservation and helped scientists understand amphibian evolution.
Activity 12.5 Pages 255-256
Activity 12.5
To make a hay infusion, follow the steps given. Do you notice moving organisms in the drop of water under the microscope? Can you identify them by comparing them with Fig. 12.7?
Solution
Hay infusion contains various protists like Amoeba, Paramecium, and Euglena. These are unicellular eukaryotes that move and feed on bacteria and organic matter.
Bridging Science and Society Page 256
Bridging Science and Society
Wild edible mushrooms are a valuable dietary food with high nutritional and medicinal values. They are important forest resources used and conserved by many communities, including tribal communities in India. These communities possess traditional knowledge about the edible and poisonous mushrooms based on folk taxonomy. Some wild mushrooms are used as sources of food and some as medicine for treating various ailments. Nowadays, mushroom cultivation is becoming a promising vocation for livelihood.
Solution
Mushrooms (Fungi) have high nutritional and medicinal value. Tribal communities have traditional knowledge of edible vs. poisonous mushrooms. Mushroom cultivation is now a promising livelihood option.
Pause and Ponder Page 256
Pause and Ponder (Q2)
How can a single-celled organism carry out all its life processes when billions of cells are required to perform similar functions in multicellular organisms like us?
Solution
A single-celled organism performs all life processes within one cell using specialized organelles (like nucleus, mitochondria, contractile vacuole), while multicellular organisms have division of labor across specialized cells.
Bridging Science and Society Page 257
Bridging Science and Society
Have you ever seen white-green patches on the tree trunk, damp walls or stones? In fact, the lichens change their colour with air pollutants. Based on their colour, researchers can find out the concentration of pollutants in the air. Therefore, they are natural bioindicators for the measurement of air quality. Villagers also collect these as forest produce for utilisation in their daily life. Some types of lichen, commonly called patthar ke phool are used as a spice, while some are used as medicines, and also for making dyes since ancient times to give maroon, violet, or burgundy colour to woollen and silk fabrics. Biologically, these are symbiotic (mutual associations of two organisms) — one partner is an autotrophic alga and the other one is a heterotrophic fungus.
Solution
Lichens are symbiotic associations of algae and fungi. They act as bioindicators of air pollution (changing color with pollutant concentration) and have traditional uses as spices, medicines, and natural dyes.
Activity 12.6 Page 258
Activity 12.6
Observe some bryophytes with the help of a hand lens. How do they differ from the leaves that you usually observe in plants in your surroundings?
Solution
Bryophytes have simple, leaf-like structures without true vascular tissue, unlike higher plants which have complex leaves with veins and specialized transport systems.
Pause and Ponder Page 258
Pause and Ponder (Q3)
Which plant features reduce their dependence on water but still require moist conditions?
Solution
Vascular tissues (xylem and phloem), cuticle, stomata, and seeds reduce dependence on water, but bryophytes still require moist conditions for reproduction as their male gametes need water to swim to the female gamete.
Pause and Ponder (Q4)
Why do taller plants need specialised transport tissues?
Solution
Taller plants need xylem to transport water and minerals from roots to leaves against gravity, and phloem to transport food from leaves to other parts, as diffusion alone is insufficient over long distances.
Pause and Ponder (Q5)
How do seeds and fruits affect where and how plants can survive?
Solution
Seeds protect the embryo and store food, enabling survival in unfavorable conditions. Fruits aid in seed dispersal by wind, water, or animals, allowing plants to colonize new areas.
Activity 12.7 Page 258
Activity 12.7
Recall the cross section of the sunflower stem you have studied in Chapter 3 (Fig. 3.7). Compare the cross section of the stem of a fern, a pteridophytic plant (Fig. 12.11) with a cross section of sunflower stem. What difference do you observe in the vascular tissue of the fern stem and of the stem of higher plants?
Solution
Ferns have less organized vascular tissue compared to sunflower (angiosperm). Sunflowers have well-developed xylem and phloem arranged in a ring, while ferns have scattered vascular bundles.
Activity 12.8 Page 259
Activity 12.8
Collect different leaves from your surroundings, and observe their shape and venation. Group them as monocots or dicots. Discuss how their structures help them adapt in different conditions to survive.
Solution
Monocots have parallel venation and fibrous roots; dicots have reticulate venation and taproots. These adaptations help in water absorption, support, and photosynthesis in different environments.
Bridging Science and Society Page 259
Bridging Science and Society
One of the earliest scientific books on Indian plants, Hortus Malabaricus, was compiled in the 17th century by Hendrik van Rheede with the help of Itty Achudan (an Indian Herbalist, Botanist and Physician) and other local experts. It describes hundreds of plant species and their medicinal uses, showing how traditional knowledge and science can work together.
Solution
Hortus Malabaricus is a 17th-century botanical text documenting hundreds of Indian plant species and their medicinal uses, demonstrating the integration of traditional knowledge with scientific documentation.
Activity 12.9 Pages 259-260
Activity 12.9
1. Carefully study the salient features of each plant group. 2. Analyse the salient features, and write the advantages for survival of the group and the exceptions or challenges faced in the given columns.
Solution
Thallophyta: simple body allows easy absorption but cannot live on land. Bryophyta: plant amphibians adapted to moist land but always need moisture. Pteridophyta: vascular tissues allow land living but still need water for reproduction. Gymnosperms: adapted to dry conditions, seeds not enclosed. Angiosperms: flowers and fruits enable efficient reproduction and dispersal.
Pause and Ponder Page 262
Pause and Ponder (Q6)
An earthworm (annelida) and a beetle (arthropoda), both have segmented bodies but the beetle has a hard external skeleton. How does the beetle's external skeleton help it survive?
Solution
The beetle's exoskeleton provides protection from predators, prevents water loss, and supports muscles, allowing it to survive in dry and exposed environments.
Bridging Science and Society
Page 261
Some infectious diseases are caused by parasitic worms. They enter our bodies through contaminated water and food. They live inside our body, especially in the alimentary canal. For this reason, it is suggested to wash your hands properly, maintain personal hygiene and good sanitary habits, consume properly cooked food and boiled or filtered drinking water.
Solution
Parasitic worms (Platyhelminthes, Nematoda) cause diseases. Prevention includes hand washing, hygiene, proper cooking, and drinking filtered/boiled water.
Page 264
Forests with rich biodiversity play a vital role to create physical, biological and chemical barriers to protect against challenges. Some of the examples are: (i) Mangrove forests helped during the super cyclone that hit Orissa in 1999. (ii) Rich biodiversity generally correlates with lower tick-borne disease risk in the Western Ghats against Monkey Fever (Kyasanur Forest Disease, KFD). (iii) Diverse microorganisms in forest soils absorb, transform, or break down pollutants.
Solution
Biodiverse forests act as barriers against natural disasters, reduce disease risk, and help in pollution control through microbial decomposition and transformation.
Page 268
Floating grasslands, locally known as phumdis are classified as one of the unique habitats in the world. It is located in the Loktak lake of the Keibul Lamjo National Park, in Manipur, India. The habitat supports an endangered variety of Sangai, the dancing deer, endemic to Manipur. The phumdis are degenerating and the Sangai deer is listed in the IUCN Red Data list. Provide your suggestions to save habitat and the Sangai deer.
Solution
Suggestions: Prevent pollution and encroachment of Loktak lake, regulate fishing and tourism, promote sustainable agriculture around the lake, and implement conservation programs for the Sangai deer and its phumdi habitat.
Ready to Go Beyond Page 266
Ready to Go Beyond
The five kingdom classification offered a more comprehensive way to group organisms compared to the previous systems, but it still could not fully explain the diversity of life. Latest advances in genetic research aided in modifying this classification. With advances in microscopes and genetic studies, scientists began to compare organisms at the DNA level. Based on the genetic data, Carl Woese (1977) proposed the three domain system — Bacteria, Archaea, and Eukarya. This system showed that microscopic life forms are far more diverse than previously believed.
Solution
Carl Woese's three-domain system (Bacteria, Archaea, Eukarya) is based on genetic (DNA) comparisons, revealing that microscopic life is much more diverse than previously understood.
Meet a Scientist Page 267
Meet a Scientist - Birbal Sahni
Birbal Sahni was an eminent scientist who studied fossil plants. He founded the Birbal Sahni Institute of Palaeosciences (BSIP) in Lucknow, which continues his work on ancient plants and past environments even to this day. His studies helped link present-day plants with their ancestors and showed that life on the Earth has a long, connected history.
Solution
Birbal Sahni founded BSIP in Lucknow and made significant contributions to paleobotany, linking present-day plants with their ancestors and revealing Earth's long evolutionary history.
Pause and Ponder Page 267
Pause and Ponder (Q7)
Does the term 'biodiversity' relate only to the variety of organisms, or does it encompass other elements?
Solution
Biodiversity encompasses not just the variety of organisms but also their genetic diversity, the ecosystems they form, and the ecological processes they sustain.
Pause and Ponder (Q8)
If you find a new organism in a pond, what features will you observe to classify it and why?
Solution
Observe: cell type (prokaryotic/eukaryotic), number of cells (unicellular/multicellular), presence of cell wall, mode of nutrition (autotrophic/heterotrophic), and motility. These help determine its kingdom placement.
Pause and Ponder (Q9)
Why do genetic studies provide deep information about living beings?
Solution
Genetic studies reveal evolutionary relationships, help identify species, and show how organisms are related at the molecular level, providing deeper insights than morphological features alone.
Pause and Ponder (Q10)
How can changes in climate affect the biodiversity?
Solution
Climate change can cause habitat loss, species extinction, altered migration patterns, disrupted food chains, and reduced genetic diversity, threatening biodiversity.
END-OF-CHAPTER EXERCISES Pages 269-271
1.
Meena and Hari observed an animal in their garden. Hari called it an insect while Meena said it was an earthworm. Choose the correct option which confirms that it is an insect.
(i) Bilateral symmetrical body
(ii) Body with jointed legs
(iii) Cylindrical body
(iv) Body with little segmentation
(i) Bilateral symmetrical body
(ii) Body with jointed legs
(iii) Cylindrical body
(iv) Body with little segmentation
Solution
Option (ii) is correct. Insects (Arthropoda) have jointed legs, while earthworms (Annelida) do not.
2.
Sponges represent one of the simplest animal body plans. Their bodies lack true tissues and organs. Which feature of sponge cells supports its classification under the animal kingdom?
(i) Absence of mitochondria
(ii) Ability to photosynthesise
(iii) Presence of a cell membrane
(iv) Presence of a cell wall
(i) Absence of mitochondria
(ii) Ability to photosynthesise
(iii) Presence of a cell membrane
(iv) Presence of a cell wall
Solution
Option (iii) is correct. Sponges have cell membranes (animal cells) and lack cell walls (plant cells), placing them in the animal kingdom.
3.
Observe two different animals in your immediate environment. What features help you distinguish between them? How do these features help place them into different groups?
Solution
Features like body symmetry, presence of legs/wings, body covering (fur/feathers/scales), and number of body segments help classify animals into different groups (e.g., insects, birds, mammals).
4.
How would a scientist justify choosing cellular organisation as a more fundamental characteristic for the basis of classification rather than the presence of xylem and phloem?
Solution
Cellular organization (prokaryotic/eukaryotic, unicellular/multicellular) is more fundamental because it reflects the basic structural level of life, while xylem/phloem appear only in certain plant groups.
5.
You find an unlabelled slide of a single-celled organism that has a well-defined nucleus and multiple cilia. Which group would it most likely belong to? Give reasons.
Solution
It belongs to Kingdom Protista (eukaryotic, unicellular, with cilia for movement).
6.
How does the diversity of organisms contribute to the balance and stability of an ecosystem?
Solution
Diversity ensures ecological balance through food webs, nutrient cycling, pollination, seed dispersal, and resilience against environmental changes.
7.
If all unicellular organisms were grouped into a single kingdom, what problems would arise?
Solution
Unicellular organisms include both prokaryotes (Monera) and eukaryotes (Protista). Grouping them together would ignore fundamental differences in cell structure and organization.
8.
Viruses were studied in earlier classes. Why are they not placed in any of the five kingdoms? Give reasons.
Solution
Viruses are acellular (lack cellular structure), cannot reproduce independently, and require a host cell. They do not fit into any kingdom because they are not considered living organisms.
9.
If you were asked to revise the five kingdom classification, would you create a separate category for viruses or keep them outside the system? Justify your answer and explain what this indicates about the evolving nature of scientific classification.
Solution
Viruses should remain outside the five kingdom system as they are acellular. Classification evolves with new scientific discoveries, showing that science is dynamic and self-correcting.
10.
Viruses contain genetic material like living organisms but lack cellular organisation. Which features prevent them from fitting into the five kingdom system? What does this tell us about the limitations of classification systems?
Solution
Viruses lack cellular structure, independent metabolism, and cannot reproduce on their own. Classification systems have limitations and cannot perfectly accommodate all entities, especially those that blur the line between living and non-living.
11.
Both pteridophytes and bryophytes lack flowers and seeds, yet they are placed in different groups. Explain this classification using their key features.
Solution
Bryophytes lack vascular tissues and have simple leaf-like structures; Pteridophytes have vascular tissues (xylem, phloem) and true roots, stems, and leaves. These differences justify separate groups.
12.
In the classification hierarchy, which group — class or genus — has fewer members but more features in common? Explain your answer.
Solution
Genus has fewer members and more common features than class, as lower taxonomic levels represent more closely related organisms.
13.
A scientist discovers a new organism with the characteristic features of locomotion and autotrophic nutrition. Which character(s) would help the scientist identify the organism belonging to Protista according to the five kingdom classification?
Solution
If the organism is unicellular, eukaryotic, and has both locomotion and autotrophic nutrition (like Euglena), it belongs to Protista.
14.
A researcher identified a unicellular eukaryotic organism as fungi. What identification key would you suggest according to the five kingdom classification to keep a unicellular organism in the Kingdom Fungi?
Solution
Yeast is a unicellular fungus with a cell wall made of chitin, heterotrophic nutrition (absorption), and reproduction by budding. These characteristics place it in Fungi, not Protista.
15.
A long-term ecological study examined organisms from three different environments. Based on the case study, answer the following:
(i) Identify one organism that clearly belongs to the Kingdom Fungi.
(ii) Which organism would be placed in the Kingdom Monera?
(iii) Organisms R and Q are both eukaryotic, yet they are placed in different kingdoms. Analyse the criteria that separate them.
(iv) Explain why organism S cannot be classified using the mode of nutrition alone.
(v) Organism T does not fit into any of the five kingdoms. Which fundamental characteristic used in classification does it lack?
(vi) If classification were based only on habitat, which organisms might be incorrectly grouped together?
(vii) Imagine scientists discover a new organism that is multicellular, eukaryotic, lacks chlorophyll and absorbs nutrients from a host externally. Should it be placed under fungi or animalia?
(i) Identify one organism that clearly belongs to the Kingdom Fungi.
(ii) Which organism would be placed in the Kingdom Monera?
(iii) Organisms R and Q are both eukaryotic, yet they are placed in different kingdoms. Analyse the criteria that separate them.
(iv) Explain why organism S cannot be classified using the mode of nutrition alone.
(v) Organism T does not fit into any of the five kingdoms. Which fundamental characteristic used in classification does it lack?
(vi) If classification were based only on habitat, which organisms might be incorrectly grouped together?
(vii) Imagine scientists discover a new organism that is multicellular, eukaryotic, lacks chlorophyll and absorbs nutrients from a host externally. Should it be placed under fungi or animalia?
Solution
(i) Q (multicellular, filamentous, cell wall present, no chlorophyll, grows on dead organic matter).
(ii) P (microscopic, no true nucleus, rigid cell covering).
(iii) R is unicellular (Protista), Q is multicellular (Fungi) — level of organization separates them.
(iv) S has a backbone (vertebrate), so it is classified by body structure, not just nutrition.
(v) T is acellular (virus), lacks cellular organisation.
(vi) Aquatic organisms from different kingdoms (fish, algae, aquatic plants) might be incorrectly grouped.
(vii) It should be placed under Fungi if it has a chitin cell wall and absorbs nutrients; under Animalia if it ingests food and lacks a cell wall.
(ii) P (microscopic, no true nucleus, rigid cell covering).
(iii) R is unicellular (Protista), Q is multicellular (Fungi) — level of organization separates them.
(iv) S has a backbone (vertebrate), so it is classified by body structure, not just nutrition.
(v) T is acellular (virus), lacks cellular organisation.
(vi) Aquatic organisms from different kingdoms (fish, algae, aquatic plants) might be incorrectly grouped.
(vii) It should be placed under Fungi if it has a chitin cell wall and absorbs nutrients; under Animalia if it ingests food and lacks a cell wall.
Chapter Summary
- Biodiversity is the immense variety of living organisms on Earth.
- Classification groups organisms based on cell type, cell structure, level of organization, mode of nutrition, and ecological role.
- Whittaker's five kingdom classification: Monera, Protista, Fungi, Plantae, Animalia.
- Kingdom Plantae: Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, Angiosperms.
- Kingdom Animalia: Non-chordata (invertebrates) and Chordata (vertebrates).
- Binomial nomenclature gives each organism a unique scientific name (genus and species).
- Classification helps understand relationships, trace evolutionary history, and conserve biodiversity.
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Chapter 12: Patterns in Life — Diversity and Classification — All Questions with Solutions
Chapter 12: Patterns in Life — Diversity and Classification — All Questions with Solutions
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