Class 10th Science Chapter 8 – Heredity | Evolution and Classification

🧬 Heredity | Evolution and Classification

Class 10 Science | Chapter – Heredity & Evolution | CBSE + Foundation + Competitive

🧬 Heredity | Evolution and Classification

1. Introduction | परिचय

Classification (वर्गीकरण) is the systematic arrangement of organisms into groups based on similarities and differences.

Evolution (विकास/उद्विकास) is the change in inherited characteristics of populations over generations.

Classification → Organising Biodiversity
Evolution → Explaining Biological Relationships

Classification is not merely a method of naming organisms. Modern classification also reflects evolutionary relationships among organisms.

2. Why Do We Need Classification? | वर्गीकरण की आवश्यकता

There are millions of organisms on Earth. Studying each organism individually is difficult. Classification helps us to:

• Organise biodiversity.
• Identify organisms.
• Study similarities and differences.
• Understand evolutionary relationships.
• Communicate about organisms using standard names.
• Predict characteristics based on relationships.

3. Basis of Classification | वर्गीकरण का आधार

Organisms can be classified using characteristics such as:

• Cell type – prokaryotic or eukaryotic
• Number of cells – unicellular or multicellular
• Mode of nutrition
• Body organisation
• Presence or absence of cell wall
• Reproductive characteristics
• Morphology and anatomy
• DNA and molecular similarities

Evolutionary classification: The more characteristics two organisms share, especially inherited/molecular characteristics, the more evidence there may be for a closer evolutionary relationship.

4. Classification Hierarchy | वर्गीकरण की श्रेणियाँ

Hierarchy: Kingdom → Phylum/Division → Class → Order → Family → Genus → Species

Memory: “King Philip Came Over For Good Soup” K → P → C → O → F → G → S

5. Species – Basic Unit of Classification | प्रजाति

A species is generally a group of organisms that are sufficiently similar and can reproduce with one another to produce fertile offspring. The concept of species can be more complex in some organisms, especially organisms that reproduce asexually or through other mechanisms.

6. Scientific Naming | वैज्ञानिक नामकरण

The binomial system gives an organism a two-part scientific name:

Genus + Specific Epithet

Example: Homo sapiens

• Homo → Genus
• sapiens → Specific epithet

In scientific writing, the genus name begins with a capital letter and the specific epithet begins with a small letter. The complete scientific name is conventionally italicised.

7. Classification as a Reflection of Evolution | वर्गीकरण एवं विकास

Modern biological classification attempts to reflect evolutionary relationships. If two organisms share many inherited characteristics, they may have a relatively recent common ancestor. If organisms have fewer shared derived characteristics, their evolutionary relationship may be more distant.

Common Ancestor

→

Divergence

→

Accumulated Differences

→

Different Groups

8. Common Ancestry | सामान्य पूर्वज

Different organisms may have evolved from common ancestral populations. Evolution can be represented as a branching pattern rather than a simple straight line.

Branching pattern → Divergence from common ancestors

9. Five Kingdom Classification | पाँच जगत वर्गीकरण

Robert Whittaker proposed the five-kingdom classification:

Kingdom	Main Characteristics
Monera	Prokaryotic, generally unicellular organisms.
Protista	Mostly unicellular eukaryotic organisms.
Fungi	Eukaryotic, heterotrophic organisms; generally absorptive nutrition.
Plantae	Multicellular eukaryotic organisms, generally photosynthetic.
Animalia	Multicellular eukaryotic organisms with ingestive heterotrophic nutrition.

For Class 10, remember the major differences between prokaryotic/eukaryotic organisation, unicellular/multicellular organisation and modes of nutrition.

10. Monera | मोनेरा

Typical features:

• Prokaryotic cells
• No true nucleus
• Usually unicellular
• Examples include bacteria and cyanobacteria

11. Protista | प्रोटिस्टा

Typical features:

• Eukaryotic cells
• Mostly unicellular
• Examples include Amoeba, Paramecium and Euglena

12. Fungi | कवक

Typical features:

• Eukaryotic
• Mostly multicellular, with some unicellular forms such as yeast
• Heterotrophic
• Cell wall generally contains chitin
• Nutrition commonly occurs through absorption

13. Plantae | पादप जगत

Plants are generally multicellular eukaryotic organisms capable of photosynthesis. Their cells generally possess:

• Cell wall
• Chloroplasts in photosynthetic tissues
• Large vacuoles

14. Animalia | जन्तु जगत

Animals are multicellular eukaryotic organisms. Typical characteristics include:

• No cell wall
• Heterotrophic nutrition
• Usually ingestive nutrition
• Specialised tissues and organs in many groups

15. Homologous Organs and Classification | समजात अंग

Homologous organs have similar basic structural plans but may perform different functions. Examples:

• Human arm
• Whale flipper
• Bat forelimb

Their structural similarities provide evidence of common ancestry.

16. Analogous Organs | समरूप/सादृश्य अंग

Analogous organs have similar functions but different basic structural origins. Example: Bird wing and insect wing Both help in flight, but their structures and evolutionary origins are different.

17. Fossils and Classification | जीवाश्म

Fossils provide information about organisms that lived in the past. They help scientists:

• Study extinct organisms.
• Understand changes over geological time.
• Reconstruct evolutionary history.
• Identify relationships between ancient and modern organisms.

18. Molecular Evidence | आणविक प्रमाण

DNA and protein comparisons are powerful tools for studying evolutionary relationships. When organisms have highly similar DNA sequences, it generally provides evidence of a closer evolutionary relationship.

19. Evolutionary Tree / Phylogenetic Tree | विकासीय वृक्ष

A phylogenetic tree is a diagram that represents hypothesised evolutionary relationships among organisms or groups. The branching points represent common ancestors or inferred divergence points.

Common Ancestor

↘

Lineage A

Common Ancestor

↘

Lineage B

The closer two branches are in a well-supported phylogenetic tree, the more recent their inferred common ancestry may be.

20. Classification Changes with New Evidence | नए प्रमाण और वर्गीकरण

Classification is not completely fixed. As scientists obtain new evidence from:

• DNA sequencing
• Protein analysis
• Cell biology
• Embryology
• Fossils
• Comparative anatomy

relationships among organisms may be revised.

21. Evolution Produces Biodiversity | विकास एवं जैव विविधता

Evolution over long periods can produce diversity of life. A common ancestral population can give rise to different lineages when populations experience different environments, selection pressures, mutations, genetic drift and reproductive isolation.

Common Ancestor → Variation → Divergence → Adaptation → Biodiversity

22. Adaptive Radiation | अनुकूली विकिरण

Adaptive radiation is the diversification of an ancestral group into multiple forms adapted to different ecological conditions. Darwin's finches are a classic example. Different populations developed different beak characteristics associated with different food resources.

23. Speciation and Classification | प्रजाति निर्माण

Speciation is the formation of new species. Factors that may contribute include:

• Geographical isolation
• Mutation
• Genetic recombination
• Natural selection
• Genetic drift
• Reproductive isolation

Isolation → Genetic Divergence → Reproductive Isolation → Speciation

24. How Classification Reflects Common Ancestry

Observation	Possible Evolutionary Meaning
Similar DNA sequences	May indicate closer evolutionary relationship
Homologous structures	Evidence consistent with common ancestry
Fossil similarities	Can reveal historical relationships
Similar developmental patterns	May support evolutionary relationships
Different structures with same function	May indicate analogous adaptation rather than close ancestry

25. 30 MCQs | बहुविकल्पीय प्रश्न

Q1. Classification means:

A. Systematic arrangement of organisms into groups

B. Destruction of organisms

C. Digestion of organisms

D. Reproduction only

Answer: A

Classification systematically groups organisms based on similarities and differences.

Q2. Modern classification can reflect:

A. Evolutionary relationships

B. Only body weight

C. Only habitat

D. Only colour

Answer: A

Modern classification uses inherited and molecular characteristics to infer evolutionary relationships.

Q3. The basic unit of classification is:

A. Kingdom

B. Species

C. Family

D. Order

Answer: B

Species is generally treated as the basic unit of biological classification.

Q4. Which is the correct sequence?

A. Kingdom → Phylum → Class → Order → Family → Genus → Species

B. Species → Kingdom → Family → Class

C. Genus → Kingdom → Species → Family

D. Family → Species → Kingdom → Class

Answer: A

This is the standard descending taxonomic hierarchy.

Q5. Homo in Homo sapiens represents:

A. Species

B. Genus

C. Family

D. Kingdom

Answer: B

Homo is the genus name.

Q6. The five-kingdom classification was proposed by:

A. Darwin

B. Mendel

C. Robert Whittaker

D. Lamarck

Answer: C

Robert H. Whittaker proposed the five-kingdom classification.

Q7. Monera contains mainly:

A. Prokaryotic organisms

B. Multicellular animals

C. Flowering plants

D. Fungi only

Answer: A

Monera consists mainly of prokaryotic organisms.

Q8. Protista mainly contains:

A. Unicellular eukaryotic organisms

B. Only bacteria

C. Only plants

D. Only animals

Answer: A

Protists are generally unicellular eukaryotes.

Q9. Fungi generally obtain nutrition by:

A. Absorption

B. Photosynthesis

C. Ingestion like animals

D. Chemosynthesis only

Answer: A

Fungi commonly secrete enzymes and absorb dissolved nutrients.

Q10. Which kingdom contains multicellular organisms that are generally photosynthetic?

A. Plantae

B. Monera

C. Protista

D. Animalia

Answer: A

Plants are generally multicellular eukaryotic photosynthetic organisms.

Q11. Animals are generally:

A. Multicellular eukaryotes

B. Prokaryotes

C. Unicellular bacteria

D. Photosynthetic prokaryotes

Answer: A

Animals are multicellular eukaryotic organisms.

Q12. Homologous organs have:

A. Similar basic structure

B. Always identical function

C. Completely unrelated origins

D. No evolutionary importance

Answer: A

Homologous organs share a basic structural plan.

Q13. Bird wings and insect wings are:

A. Analogous

B. Homologous

C. Vestigial

D. Identical

Answer: A

They perform similar functions but have different structural origins.

Q14. Fossils provide evidence about:

A. Ancient life

B. Future organisms

C. Digestion

D. Respiration only

Answer: A

Fossils preserve remains, impressions or traces of ancient organisms.

Q15. Which provides molecular evidence for evolution?

A. DNA sequence comparison

B. Body temperature only

C. Height only

D. Weight only

Answer: A

DNA comparison can reveal evolutionary relationships.

Q16. A phylogenetic tree represents:

A. Evolutionary relationships

B. Food digestion

C. Blood circulation

D. Respiration

Answer: A

Phylogenetic trees represent inferred evolutionary relationships.

Q17. A common ancestor is:

A. An ancestral population from which different lineages descended

B. A modern species only

C. A fossil mineral

D. A type of tissue

Answer: A

Different evolutionary lineages can descend from common ancestral populations.

Q18. Adaptive radiation refers to:

A. Diversification from a common ancestral group

B. Extinction of every species

C. Formation of fossils only

D. Digestion of food

Answer: A

Adaptive radiation involves diversification into different ecological niches.

Q19. Darwin's finches are an example of:

A. Adaptive radiation

B. Binary fission

C. Budding

D. Regeneration

Answer: A

Different finch populations diversified from common ancestral stock.

Q20. Which can contribute to speciation?

A. Geographical isolation

B. Digestion

C. Sweating

D. Respiration

Answer: A

Geographical isolation can reduce gene flow and allow divergence.

Q21. The scientific name of humans is:

A. Homo sapiens

B. Homo humanus

C. Human sapiens

D. Homo erectus

Answer: A

The accepted scientific name for modern humans is Homo sapiens.

Q22. Which characteristic is especially useful for modern evolutionary classification?

A. DNA sequence

B. Body colour alone

C. Height alone

D. Weight alone

Answer: A

Molecular data can provide strong evidence about evolutionary relationships.

Q23. If two species have many homologous structures, this may suggest:

A. Common ancestry

B. No relationship

C. Identical habitats only

D. Identical species

Answer: A

Homologous structures are consistent with descent from common ancestors.

Q24. Analogous organs usually indicate:

A. Similar function with different structural origin

B. Identical ancestry

C. Same DNA sequence

D. Same species

Answer: A

Analogous structures may arise when unrelated organisms adapt to similar functions.

Q25. Which is NOT normally a basis for biological classification?

A. Cell organisation

B. Mode of nutrition

C. Reproductive characteristics

D. Favourite food of the observer

Answer: D

Classification uses biological characteristics, not personal preferences.

Q26. Evolution generally occurs:

A. In populations over generations

B. In one minute

C. Only in individual muscles

D. Only during digestion

Answer: A

Evolution is a population-level change across generations.

Q27. Which kingdom includes bacteria in the five-kingdom system?

A. Monera

B. Plantae

C. Animalia

D. Fungi

Answer: A

Bacteria are included in Monera in the traditional five-kingdom classification.

Q28. Which is a eukaryotic kingdom?

A. Protista

B. Monera

C. None

D. Only viruses

Answer: A

Protista consists of eukaryotic organisms.

Q29. Classification helps scientists understand:

A. Biodiversity and relationships

B. Only weather

C. Only nutrition

D. Only temperature

Answer: A

Classification organises biodiversity and helps reveal relationships among organisms.

Q30. Which sequence best represents evolutionary diversification?

A. Common ancestor → variation → divergence → different lineages

B. Digestion → respiration → excretion

C. Growth → digestion → circulation

D. Water → salt → minerals

Answer: A

Evolutionary lineages can diverge from common ancestral populations as differences accumulate.

26. 30 Subjective Questions with Answers | वर्णनात्मक प्रश्न

2 Marks Q1. What is biological classification?

Biological classification is the systematic arrangement of organisms into groups based on similarities and differences.

2 Marks Q2. What is evolution?

Evolution is the change in inherited characteristics of populations over generations.

2 Marks Q3. Name the basic unit of classification.

Species is generally considered the basic unit of biological classification.

2 Marks Q4. What is a homologous organ?

A homologous organ has a similar basic structural plan to another organ but may perform a different function.

2 Marks Q5. What is an analogous organ?

An analogous organ performs a similar function but has a different basic structural origin.

3 Marks Q6. Why is classification important?

Classification organises biodiversity, makes identification easier and helps scientists understand similarities, differences and evolutionary relationships.

3 Marks Q7. Write the taxonomic hierarchy.

Kingdom → Phylum/Division → Class → Order → Family → Genus → Species.

3 Marks Q8. What is the importance of DNA comparison in classification?

DNA comparisons provide molecular evidence. Similar DNA sequences generally support closer evolutionary relationships.

3 Marks Q9. What are fossils?

Fossils are preserved remains, impressions or traces of organisms that lived in the past.

3 Marks Q10. Give three examples of evidence for evolution.

Fossils, homologous organs and molecular evidence such as DNA sequence comparisons are important examples.

4 Marks Q11. Explain how classification can reflect evolution.

Classification groups organisms according to similarities and differences. When inherited and molecular similarities are considered, groups can be arranged to reflect evolutionary relationships and common ancestry.

4 Marks Q12. Differentiate between homologous and analogous organs.

Homologous organs have similar basic structures but may have different functions. Analogous organs have similar functions but different basic structural origins.

4 Marks Q13. Explain the importance of fossils in evolution.

Fossils provide evidence of ancient organisms, show extinct forms and help scientists reconstruct biological changes through geological time.

4 Marks Q14. Write the main characteristics of Monera.

Monerans are generally prokaryotic and unicellular. They lack a true nucleus and include bacteria and cyanobacteria.

4 Marks Q15. Explain the role of molecular evidence in classification.

DNA and protein sequences can be compared among organisms. Greater molecular similarity generally indicates closer evolutionary relationships and can help revise or support classifications.

5 Marks Q16. Explain the relationship between heredity, variation and evolution.

Heredity transmits genetic information from parents to offspring. Variation creates differences among individuals. Heritable variations can influence survival and reproduction. Over generations, selection and other evolutionary processes can change the population, producing evolution.

5 Marks Q17. Explain adaptive radiation with an example.

Adaptive radiation is diversification from a common ancestral group into different forms adapted to different environments or resources. Darwin's finches are a classic example.

5 Marks Q18. Explain how geographical isolation may result in speciation.

Geographical isolation separates populations and reduces gene flow. Genetic differences can accumulate through mutation, recombination, natural selection and genetic drift. If reproductive isolation develops, a new species may arise.

5 Marks Q19. Explain why modern classification is different from simple grouping based only on appearance.

Modern classification uses evolutionary relationships, comparative anatomy, fossils and molecular evidence. Two organisms that look similar may not be closely related, while organisms with different appearances may share common ancestry.

5 Marks Q20. Explain the significance of homologous organs.

Homologous organs have similar basic structural plans despite differences in function. Their similarities provide evidence that the organisms inherited the basic structure from common ancestors and later adapted it for different functions.

6 Marks Q21. Explain how biological classification helps us understand evolutionary relationships.

Classification organises organisms according to similarities and differences. When inherited characteristics, fossils, comparative anatomy and molecular data are considered, organisms can be grouped according to common ancestry and evolutionary relationships. Thus classification provides an organised framework for understanding biodiversity and evolution.

6 Marks Q22. Describe the five kingdoms of Whittaker.

The five kingdoms are:

• Monera: prokaryotic organisms.
• Protista: mostly unicellular eukaryotes.
• Fungi: eukaryotic heterotrophs, generally absorptive.
• Plantae: multicellular eukaryotic organisms, generally photosynthetic.
• Animalia: multicellular eukaryotic heterotrophs with ingestive nutrition.

6 Marks Q23. Explain the evidence for common ancestry.

Evidence includes homologous organs, fossils, similarities in embryological development and molecular similarities in DNA and proteins. These independent lines of evidence can support relationships among organisms and common ancestry.

6 Marks Q24. Explain the role of DNA in evolutionary classification.

DNA contains inherited genetic information. Comparing DNA sequences among organisms allows scientists to estimate genetic similarities. Organisms with greater molecular similarity often have a closer evolutionary relationship. DNA evidence can therefore support or revise classifications based on morphology alone.

6 Marks Q25. Explain homologous organs with examples and evolutionary significance.

Human arms, whale flippers and bat forelimbs have the same basic tetrapod structural plan but perform different functions. Such similarities are evidence consistent with common ancestry followed by modification and adaptation in different lineages.

6 Marks Q26. Explain analogous organs with examples.

Analogous organs perform similar functions but have different structural origins. Bird wings and insect wings both enable flight but are built differently. Their similarity results from adaptation to a similar function rather than close structural ancestry.

6 Marks Q27. Explain the formation of different species from a common ancestor.

A population may become separated. Different mutations, genetic recombination, genetic drift and selection pressures can cause genetic differences to accumulate. If reproductive isolation develops, gene flow stops and separate populations may become distinct species.

6 Marks Q28. Explain the importance of fossils, homologous organs and DNA in studying evolution.

Fossils provide historical evidence of past organisms. Homologous structures provide anatomical evidence of common ancestry. DNA comparisons provide molecular evidence. Together these different types of evidence help scientists reconstruct evolutionary relationships.

6 Marks Q29. Explain why classification may change when new scientific evidence becomes available.

Earlier classifications often depended heavily on visible characteristics. Modern methods provide additional information from DNA, proteins, cell biology, fossils and development. New evidence can reveal previously unknown relationships and therefore classifications can be revised.

6 Marks Q30. Explain how evolution contributes to biodiversity.

Variation creates differences among individuals. Over generations, natural selection, genetic drift, mutation, recombination and reproductive isolation can cause populations to diverge. This divergence can produce different adaptations and eventually new species, contributing to biodiversity.

27. Assertion–Reason | कथन–कारण

Q1. Assertion: Classification can help us understand evolutionary relationships.
Reason: Modern classification can use inherited and molecular characteristics.

Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.

Q2. Assertion: Homologous organs can provide evidence of common ancestry.
Reason: They have similar basic structural plans.

Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.

Q3. Assertion: Analogous organs necessarily indicate close common ancestry.
Reason: Analogous organs have similar functions but different structural origins.

Answer: Assertion is false, but Reason is true.

Q4. Assertion: DNA comparison can help in evolutionary classification.
Reason: DNA contains inherited genetic information.

Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.

Q5. Assertion: Evolution occurs only in individual organisms during their lifetime.
Reason: Evolution involves changes in populations across generations.

Answer: Assertion is false, but Reason is true.

28. HOTS / Competency-Based Questions

HOTS 1. Two organisms look different but have highly similar DNA sequences. What can this suggest?

It may suggest that they have a relatively close evolutionary relationship, although evolutionary conclusions should be based on appropriate comparative evidence rather than appearance alone.

HOTS 2. Why are homologous organs more useful than analogous organs for studying common ancestry?

Homologous organs share a basic structural plan inherited from common ancestors, whereas analogous organs mainly share function and have different structural origins.

HOTS 3. A mountain separates two populations of the same species. How can this eventually contribute to speciation?

The mountain reduces gene flow. Over generations, mutations, recombination, genetic drift and natural selection can cause the populations to diverge. Reproductive isolation may eventually develop.

HOTS 4. Why can classification based only on external appearance sometimes be misleading?

Different organisms can independently evolve similar appearances due to similar environmental pressures. Conversely, closely related organisms may become structurally different. Molecular and anatomical evidence therefore provides additional information.

HOTS 5. Why is classification considered dynamic?

New evidence from DNA sequencing, fossils, comparative anatomy and developmental biology can change our understanding of evolutionary relationships. Therefore classifications may be revised as scientific knowledge improves.

29. Important Diagram Labelling | महत्वपूर्ण आरेख

Important labels to remember:

Diagram	Important Labels
Taxonomic Hierarchy	Kingdom, Phylum/Division, Class, Order, Family, Genus, Species
Evolutionary Tree	Common ancestor, branch, lineage, divergence
Homologous Limb	Humerus, radius, ulna, wrist, digits
DNA	Base sequence, genetic information
Fossil Sequence	Older layer, younger layer, fossil remains

30. CBSE Golden Points ⭐

• Classification is the systematic arrangement of organisms.
• Modern classification can reflect evolutionary relationships.
• Species is generally the basic unit of classification.
• Taxonomic hierarchy: Kingdom → Phylum/Division → Class → Order → Family → Genus → Species.
• Monera contains mainly prokaryotic organisms in the traditional five-kingdom system.
• Protista contains mostly unicellular eukaryotic organisms.
• Fungi are heterotrophic and commonly obtain nutrients by absorption.
• Plants are generally multicellular, eukaryotic and photosynthetic.
• Animals are multicellular eukaryotic heterotrophs.
• Homologous organs have similar basic structures.
• Analogous organs have similar functions but different structural origins.
• Fossils provide evidence about ancient life.
• DNA and protein comparisons provide molecular evidence for evolutionary relationships.
• Phylogenetic trees represent inferred evolutionary relationships.
• Geographical isolation can contribute to speciation.
• Adaptive radiation involves diversification from a common ancestral group.
• Evolution occurs in populations over generations.
• Classification can be revised when new scientific evidence becomes available.

31. Memory Tricks 🧠

Taxonomic Hierarchy:

King → Phylum → Class → Order → Family → Genus → Species

“King Philip Came Over For Good Soup”

---

Homologous = Same Basic Structure
Analogous = Same Function

---

Evolution Evidence = F-D-H-M
F = Fossils
D = Developmental evidence
H = Homologous organs
M = Molecular evidence

---

Evolution Flow:
Variation → Selection → Divergence → Adaptation → Biodiversity

32. One-Line Quick Revision | त्वरित पुनरावृत्ति

Classification: Systematic grouping of organisms.

Species: Basic unit of classification.

Evolution: Change in inherited characteristics of populations over generations.

Homologous: Similar basic structure, functions may differ.

Analogous: Similar function, different structural origin.

Fossils: Evidence of ancient life.

DNA: Molecular evidence for evolutionary relationships.

Phylogenetic tree: Diagram representing inferred evolutionary relationships.

Speciation: Formation of new species.

Adaptive radiation: Diversification from a common ancestral group.

Classification + Evolution: Modern classification attempts to organise organisms in a way that reflects their evolutionary relationships.

33. Final Summary | अंतिम सारांश

Classification helps organise the enormous diversity of living organisms. Modern classification goes beyond simple appearance and considers cell organisation, body structure, nutrition, reproduction, fossils, comparative anatomy and molecular information. Evolution explains how populations change over generations. Organisms sharing common ancestry may retain homologous structures and molecular similarities, while different lineages can accumulate differences and adapt to different environments.

Common Ancestry → Variation → Divergence → Adaptation → Speciation → Biodiversity

Most Important Exam Statement:

“Modern biological classification is closely related to evolution because similarities and differences among organisms can provide evidence about their common ancestry and evolutionary relationships.”

🧬 Heredity | Evolution and Classification
Class 10 Science | CBSE + Foundation + Competitive Preparation