CBSE Class 9 Science Chapter 12: Patterns in Life: Diversity and Classification — Assertion & Reason
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The following Assertion and Reason questions are based on Chapter 12: Patterns in Life: Diversity and Classification from the NCERT Class 9 Science textbook. Each question has four options - read both the Assertion (A) and Reason (R) carefully before selecting your answer.
How to attempt Assertion & Reason questions:
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is NOT the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is NOT the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Assertion & Reason Questions
1
Assertion (A): Biodiversity contributes to the stability and functioning of ecosystems.
Reason (R): Different organisms perform interconnected roles such as producing food, pollinating plants, decomposing matter, and recycling nutrients.
Reason (R): Different organisms perform interconnected roles such as producing food, pollinating plants, decomposing matter, and recycling nutrients.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. These complementary roles help ecosystems continue functioning when conditions change.
2
Assertion (A): An endemic species occurs naturally only within a particular geographical region.
Reason (R): A biodiversity hotspot contains many endemic species and has experienced substantial habitat loss.
Reason (R): A biodiversity hotspot contains many endemic species and has experienced substantial habitat loss.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. Both definitions are correct, but the hotspot definition does not explain why a particular species is endemic.
3
Assertion (A): Small heritable differences can accumulate over generations and contribute to biological diversity.
Reason (R): Every characteristic acquired during an organism's lifetime is necessarily inherited by its offspring.
Reason (R): Every characteristic acquired during an organism's lifetime is necessarily inherited by its offspring.
Answer: (c)
A is true, but R is false. Only heritable variation can be passed between generations; acquired changes are not automatically inherited.
4
Assertion (A): Endemic species are naturally distributed throughout all continents.
Reason (R): Regions rich in endemic species and facing major habitat loss are important priorities for conservation.
Reason (R): Regions rich in endemic species and facing major habitat loss are important priorities for conservation.
Answer: (d)
A is false, but R is true. Endemic species have restricted natural distributions rather than worldwide ranges.
5
Assertion (A): Scientific classification helps reveal relationships among organisms.
Reason (R): It groups organisms using shared characteristics and evolutionary relationships.
Reason (R): It groups organisms using shared characteristics and evolutionary relationships.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Systematic comparison of common features provides evidence of relatedness and makes diversity easier to study.
6
Assertion (A): External form and mode of nutrition can both be used as classification criteria.
Reason (R): Cell structure, including whether a cell is prokaryotic or eukaryotic, is another classification criterion.
Reason (R): Cell structure, including whether a cell is prokaryotic or eukaryotic, is another classification criterion.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. Both statements list valid criteria, but the cellular criterion does not explain why external form and nutrition are also used.
7
Assertion (A): In a classification hierarchy, groups become smaller and their members share more characteristics toward the species level.
Reason (R): A genus is broader and contains more diverse organisms than a kingdom.
Reason (R): A genus is broader and contains more diverse organisms than a kingdom.
Answer: (c)
A is true, but R is false. Kingdom is much broader than genus; genus has fewer and more closely related members.
8
Assertion (A): All unicellular organisms can be scientifically placed in one kingdom because cell number is the only fundamental criterion.
Reason (R): Unicellular organisms may be prokaryotic or eukaryotic and may differ greatly in nutrition and organisation.
Reason (R): Unicellular organisms may be prokaryotic or eukaryotic and may differ greatly in nutrition and organisation.
Answer: (d)
A is false, but R is true. These fundamental differences separate unicellular organisms into groups such as Monera and Protista.
9
Assertion (A): Whittaker's five-kingdom system uses features such as cell type, level of organisation, and mode of nutrition.
Reason (R): These criteria distinguish major groups including Monera, Protista, Fungi, Plantae, and Animalia.
Reason (R): These criteria distinguish major groups including Monera, Protista, Fungi, Plantae, and Animalia.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. The selected cellular and nutritional differences provide the basis for separating the five kingdoms.
10
Assertion (A): Protists are generally unicellular eukaryotes.
Reason (R): Fungi are eukaryotic organisms that obtain nutrients heterotrophically.
Reason (R): Fungi are eukaryotic organisms that obtain nutrients heterotrophically.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. Both descriptions are correct, but the fungal description does not explain the defining placement of protists.
11
Assertion (A): Fungi commonly absorb nutrients from organic matter and possess cell walls.
Reason (R): Fungi contain chlorophyll and manufacture food by photosynthesis.
Reason (R): Fungi contain chlorophyll and manufacture food by photosynthesis.
Answer: (c)
A is true, but R is false. Fungi lack chlorophyll and obtain nutrients heterotrophically.
12
Assertion (A): Thallophytes have well-differentiated roots, stems, leaves, and vascular tissue.
Reason (R): Members of Kingdom Plantae are generally multicellular eukaryotes that perform photosynthesis.
Reason (R): Members of Kingdom Plantae are generally multicellular eukaryotes that perform photosynthesis.
Answer: (d)
A is false, but R is true. Thallophytes have a relatively simple body without true roots, stems, or leaves.
13
Assertion (A): Pteridophytes are distinguished from bryophytes by the presence of vascular tissues.
Reason (R): Vascular tissues transport water and food through a differentiated plant body.
Reason (R): Vascular tissues transport water and food through a differentiated plant body.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. The presence of conducting tissues is a key structural advance used to separate these plant groups.
14
Assertion (A): Animals are multicellular heterotrophic eukaryotes without cell walls.
Reason (R): Fungi are also heterotrophs, although they absorb nutrients and possess cell walls.
Reason (R): Fungi are also heterotrophs, although they absorb nutrients and possess cell walls.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. Both are true, but the fungal mode does not by itself explain all defining characteristics of Animalia.
15
Assertion (A): Bryophytes lack true vascular tissue.
Reason (R): Pteridophytes also lack vascular tissue and therefore cannot conduct water internally.
Reason (R): Pteridophytes also lack vascular tissue and therefore cannot conduct water internally.
Answer: (c)
A is true, but R is false. Pteridophytes possess vascular tissues even though they do not form seeds.
16
Assertion (A): Arthropods are animals that lack jointed appendages.
Reason (R): Jointed legs and a segmented body are characteristic features of arthropods.
Reason (R): Jointed legs and a segmented body are characteristic features of arthropods.
Answer: (d)
A is false, but R is true. The name and classification of arthropods are closely associated with jointed appendages.
17
Assertion (A): Binomial nomenclature assigns a two-part scientific name consisting of genus and species.
Reason (R): A standard naming system allows scientists in different regions to refer unambiguously to the same organism.
Reason (R): A standard naming system allows scientists in different regions to refer unambiguously to the same organism.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. The shared genus-species convention overcomes confusion caused by varying local names.
18
Assertion (A): Fossils in rock layers provide evidence that life has changed over long periods.
Reason (R): Birbal Sahni studied fossil plants and helped connect present-day plants with their ancestors.
Reason (R): Birbal Sahni studied fossil plants and helped connect present-day plants with their ancestors.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. Both statements are correct, but the scientist's contribution is an example rather than the reason fossils preserve historical evidence.
19
Assertion (A): Pollution, deforestation, overuse of resources, and climate change can reduce biodiversity.
Reason (R): The disappearance of any species can never affect organisms that depend on it.
Reason (R): The disappearance of any species can never affect organisms that depend on it.
Answer: (c)
A is true, but R is false. Species are interconnected, so the loss of one can cause declines in others and disrupt ecological balance.
20
Assertion (A): Viruses are placed in Kingdom Monera because they are very small.
Reason (R): Viruses are acellular and remain inactive outside host cells, so they do not fit the cellular basis of the five-kingdom system.
Reason (R): Viruses are acellular and remain inactive outside host cells, so they do not fit the cellular basis of the five-kingdom system.
Answer: (d)
A is false, but R is true. Their lack of cellular organisation keeps them outside Whittaker's five kingdoms.
❓ Frequently Asked Questions
What is covered in CBSE Class 9 Science Chapter 12 Patterns in Life: Diversity and Classification?
This chapter covers all key topics from Patterns in Life: Diversity and Classification as per CBSE 2026-27 syllabus.
Is this Assertion & Reason useful for CBSE board exams?
Yes, designed for CBSE Class 9 board exam preparation covering the complete syllabus.
Are these CBSE Class 9 Science Assertion & Reason updated for 2026-27?
Yes, all content at eBookPublisher is updated as per the latest 2026-27 CBSE syllabus.
How many chapters are in CBSE Class 9 Science?
All chapters of CBSE Class 9 Science are covered at eBookPublisher with free Assertion & Reason for each chapter.
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