Chapter 7 — Diversity in Living Organisms
Welcome to HSLC Guru, your trusted destination for ASSEB Class 9 Science study material. This English-medium guide covers Chapter 7 — Diversity in Living Organisms in complete detail. You will find a clear summary, full textbook question answers (1-mark, 2–3 mark, and 5–6 mark), additional MCQs, fill in the blanks, true/false statements, and a glossary table. Whether you are revising for class tests or preparing for your HSLC exams, this resource is structured strictly as per the ASSEB Class 9 Science syllabus to help you score better and understand the wonderful variety of life on Earth.
Summary
Living organisms on Earth show enormous variety in shape, size, habitat, structure, and function. To study them efficiently, scientists group them based on similarities and differences — this process is called classification. Classification helps us identify organisms, understand their relationships, study their evolution, and use them in agriculture, medicine, and research. The need for classification arises because there are millions of species, and without grouping them it is impossible to study each one individually.
The biological hierarchy of classification arranges organisms in seven major levels — Kingdom → Phylum → Class → Order → Family → Genus → Species. As we move from Kingdom to Species, the number of organisms in each group decreases but the similarities between them increase. R.H. Whittaker (1969) proposed the Five Kingdom Classification — Monera (prokaryotes like bacteria), Protista (unicellular eukaryotes like Amoeba, Paramecium), Fungi (saprophytic decomposers like Mushroom, Yeast), Plantae (multicellular autotrophs), and Animalia (multicellular heterotrophs).
The Plant Kingdom is divided into five major groups — Thallophyta (algae like Spirogyra, Ulothrix), Bryophyta (amphibians of the plant kingdom — Moss, Marchantia), Pteridophyta (Fern, Marsilea — first plants with vascular tissue), Gymnosperms (naked-seeded plants like Pinus, Cycas), and Angiosperms (flowering plants with covered seeds). Angiosperms are further divided into Monocotyledons (one cotyledon, parallel venation — paddy, wheat, maize) and Dicotyledons (two cotyledons, reticulate venation — mango, gram, mustard).
The Animal Kingdom is classified into ten phyla — Porifera (sponges), Coelenterata (Hydra, Jellyfish), Platyhelminthes (flatworms like Planaria, Tapeworm), Nematoda (roundworms like Ascaris), Annelida (Earthworm, Leech), Arthropoda (largest phylum — insects, prawn, spider), Mollusca (Snail, Octopus), Echinodermata (Starfish, Sea urchin), Protochordata (Balanoglossus, Amphioxus), and Vertebrata (animals with a true backbone). Vertebrata is sub-divided into five classes — Pisces (fishes), Amphibia (Frog, Toad), Reptilia (Snake, Lizard), Aves (birds), and Mammalia (mammals including humans). Carolus Linnaeus introduced Binomial Nomenclature — the two-word naming system (Genus + species, e.g., Homo sapiens) which is universally used today.
Textbook Question Answers
1-Mark Questions
Q1. Who proposed the Five Kingdom Classification?
Answer: R.H. Whittaker proposed the Five Kingdom Classification in 1969.
Q2. What is the smallest unit of biological classification?
Answer: Species is the smallest and the most basic unit of biological classification.
Q3. Name the largest phylum of the animal kingdom.
Answer: Arthropoda is the largest phylum of the animal kingdom.
Q4. Who is known as the Father of Taxonomy?
Answer: Carolus Linnaeus is known as the Father of Taxonomy.
Q5. Give the scientific name of human beings.
Answer: The scientific name of human beings is Homo sapiens.
Q6. Which group of plants is called the “amphibians of the plant kingdom”?
Answer: Bryophyta (e.g., Moss, Marchantia) is called the amphibians of the plant kingdom because these plants need water for reproduction.
Q7. Name two organisms belonging to Kingdom Monera.
Answer: Bacteria and Cyanobacteria (Blue-green algae) belong to Kingdom Monera.
Q8. Which phylum do starfish belong to?
Answer: Starfish belongs to Phylum Echinodermata.
Q9. What are gymnosperms?
Answer: Gymnosperms are plants that bear naked seeds (seeds not enclosed inside a fruit), e.g., Pinus, Cycas.
Q10. Define species.
Answer: A species is a group of similar organisms that can interbreed among themselves and produce fertile offspring.
2–3 Mark Questions
Q1. Why do we need to classify living organisms?
Answer: Classification of living organisms is necessary because:
- It makes the study of millions of organisms easier and systematic.
- It helps in identifying new organisms.
- It shows the evolutionary relationships among different organisms.
- It is useful in agriculture, medicine, and biological research.
Q2. Differentiate between Monocotyledons and Dicotyledons.
| Feature | Monocotyledons | Dicotyledons |
|---|---|---|
| Cotyledon | One | Two |
| Venation | Parallel | Reticulate |
| Root | Fibrous | Tap root |
| Example | Paddy, Wheat, Maize | Mango, Gram, Mustard |
Q3. What is binomial nomenclature? Give an example.
Answer: Binomial nomenclature is a system of naming organisms using two Latin words — the first word denotes the Genus (capitalised) and the second word denotes the species (small letters). It was introduced by Carolus Linnaeus. Example: Mangifera indica (mango), Homo sapiens (human).
Q4. Write three differences between Plants and Animals.
| Plants | Animals |
|---|---|
| Autotrophic — prepare their own food | Heterotrophic — depend on others for food |
| Cell wall present | Cell wall absent |
| Generally cannot move from place to place | Most animals can move freely |
Q5. What are the main characteristics of phylum Arthropoda?
Answer: Main features of Arthropoda are:
- Body is segmented and has jointed appendages (legs).
- Body is covered with a hard chitinous exoskeleton.
- Body cavity (coelom) is filled with blood — open circulatory system.
- Examples: Cockroach, Prawn, Spider, Butterfly.
Q6. What are the distinguishing features of Mammalia?
Answer: The main features of Mammalia are:
- Body is covered with hair or fur.
- Mammary glands are present in females to feed young ones with milk.
- They are warm-blooded and have external ears (pinna).
- Most mammals give birth to young ones (viviparous), e.g., human, cow, dog, whale.
5–6 Mark Questions
Q1. Describe Whittaker’s Five Kingdom Classification with examples.
Answer: R.H. Whittaker (1969) classified all living organisms into five kingdoms based on cell structure, mode of nutrition, and body organisation.
- Monera: Prokaryotic, unicellular organisms without a true nucleus. Example — Bacteria, Cyanobacteria.
- Protista: Eukaryotic, unicellular organisms. Example — Amoeba, Paramecium, Euglena.
- Fungi: Eukaryotic, multicellular saprophytes that absorb food. Example — Mushroom, Yeast, Penicillium.
- Plantae: Eukaryotic, multicellular autotrophs that prepare food by photosynthesis. Example — Mango, Paddy, Fern.
- Animalia: Eukaryotic, multicellular heterotrophs that ingest food. Example — Frog, Fish, Human.
Q2. Classify the Plant Kingdom and write the main features of each group.
Answer: The plant kingdom is divided into five major groups:
- Thallophyta (Algae): Body not differentiated into root, stem and leaf. Mostly aquatic. Example — Spirogyra, Ulothrix, Chara.
- Bryophyta: Amphibians of the plant kingdom; require water for reproduction. Example — Moss, Marchantia.
- Pteridophyta: First plants to have vascular tissues (xylem and phloem). Example — Fern, Marsilea, Equisetum.
- Gymnosperms: Bear naked seeds; mostly evergreen. Example — Pinus, Cycas, Cedrus.
- Angiosperms: Flowering plants with seeds enclosed inside fruits. Divided into Monocots (Paddy, Wheat) and Dicots (Mango, Gram).
Q3. Write a short note on the major phyla of the Animal Kingdom.
Answer: The animal kingdom is divided into ten major phyla:
- Porifera: Pore-bearing animals; sponges. Example — Sycon, Spongilla.
- Coelenterata: Body has a cavity called coelenteron. Example — Hydra, Jellyfish.
- Platyhelminthes: Flatworms, mostly parasitic. Example — Planaria, Tapeworm.
- Nematoda: Cylindrical roundworms. Example — Ascaris, Wuchereria.
- Annelida: Body with true segments. Example — Earthworm, Leech.
- Arthropoda: Jointed legs; largest phylum. Example — Cockroach, Prawn, Spider.
- Mollusca: Soft-bodied; many have a shell. Example — Snail, Octopus, Pila.
- Echinodermata: Spiny-skinned marine animals. Example — Starfish, Sea urchin.
- Protochordata: Notochord present at some stage. Example — Balanoglossus, Amphioxus.
- Vertebrata: Animals with a true backbone — divided into Pisces, Amphibia, Reptilia, Aves, and Mammalia.
Q4. Differentiate between the five classes of Vertebrata.
| Class | Body Cover | Respiration | Reproduction | Example |
|---|---|---|---|---|
| Pisces | Scales | Gills | Eggs (water) | Rohu, Shark |
| Amphibia | Moist skin | Gills (larva), Lungs (adult) | Eggs (water) | Frog, Toad |
| Reptilia | Dry scales | Lungs | Eggs (land) | Snake, Lizard |
| Aves | Feathers | Lungs | Eggs (land) | Pigeon, Crow |
| Mammalia | Hair / Fur | Lungs | Viviparous | Cow, Human |
Q5. Explain the biological hierarchy of classification with an example.
Answer: The biological hierarchy is a system of arranging organisms in seven major levels — Kingdom → Phylum → Class → Order → Family → Genus → Species. As we move from Kingdom to Species, the number of organisms decreases but similarities increase. Example for human beings:
- Kingdom — Animalia
- Phylum — Chordata
- Class — Mammalia
- Order — Primata
- Family — Hominidae
- Genus — Homo
- Species — sapiens
Additional Multiple Choice Questions (MCQs)
Q1. The Five Kingdom Classification was proposed by —
(a) Linnaeus (b) Whittaker (c) Aristotle (d) Mendel
Answer: (b) Whittaker
Q2. The smallest unit of classification is —
(a) Genus (b) Family (c) Species (d) Order
Answer: (c) Species
Q3. Bacteria belongs to which kingdom?
(a) Protista (b) Fungi (c) Monera (d) Plantae
Answer: (c) Monera
Q4. Which of the following is a gymnosperm?
(a) Mango (b) Pinus (c) Fern (d) Moss
Answer: (b) Pinus
Q5. Earthworm belongs to phylum —
(a) Arthropoda (b) Mollusca (c) Annelida (d) Nematoda
Answer: (c) Annelida
Q6. The largest phylum of the animal kingdom is —
(a) Mollusca (b) Arthropoda (c) Chordata (d) Annelida
Answer: (b) Arthropoda
Q7. Frog belongs to class —
(a) Pisces (b) Reptilia (c) Amphibia (d) Aves
Answer: (c) Amphibia
Q8. Mammary glands are characteristic of —
(a) Aves (b) Reptilia (c) Mammalia (d) Pisces
Answer: (c) Mammalia
Q9. Which group is called the “amphibians of the plant kingdom”?
(a) Thallophyta (b) Bryophyta (c) Pteridophyta (d) Gymnosperms
Answer: (b) Bryophyta
Q10. Starfish belongs to phylum —
(a) Mollusca (b) Echinodermata (c) Coelenterata (d) Porifera
Answer: (b) Echinodermata
Fill in the Blanks
Q1. The Five Kingdom Classification was proposed by __________.
Answer: R.H. Whittaker
Q2. The basic unit of classification is __________.
Answer: Species
Q3. The naked-seeded plants are called __________.
Answer: Gymnosperms
Q4. The scientific name of human is __________.
Answer: Homo sapiens
Q5. Sponges belong to phylum __________.
Answer: Porifera
True or False
Q1. Whales are fishes.
Answer: False (Whales are mammals.)
Q2. Bacteria belong to Kingdom Monera.
Answer: True
Q3. Pteridophytes are non-vascular plants.
Answer: False (Pteridophytes are the first plants to have vascular tissue.)
Q4. Binomial nomenclature was introduced by Linnaeus.
Answer: True
Q5. Birds are warm-blooded animals.
Answer: True
Glossary
| Term | Meaning |
|---|---|
| Classification | Grouping of organisms based on similarities and differences. |
| Taxonomy | The branch of biology that deals with classification, identification, and naming of organisms. |
| Species | A group of similar organisms that interbreed and produce fertile offspring. |
| Kingdom | The highest level in the biological hierarchy. |
| Monera | Kingdom of prokaryotic, unicellular organisms (e.g., bacteria). |
| Protista | Kingdom of unicellular eukaryotes (e.g., Amoeba, Paramecium). |
| Fungi | Eukaryotic, saprophytic organisms (e.g., Mushroom, Yeast). |
| Thallophyta | Plants whose body is not differentiated into root, stem, and leaf (algae). |
| Bryophyta | Amphibians of the plant kingdom (e.g., Moss). |
| Pteridophyta | First plants to have vascular tissue (e.g., Fern). |
| Gymnosperms | Plants with naked seeds (e.g., Pinus). |
| Angiosperms | Flowering plants with covered seeds. |
| Monocotyledons | Plants having one cotyledon (e.g., Wheat). |
| Dicotyledons | Plants having two cotyledons (e.g., Mango). |
| Porifera | Phylum of pore-bearing animals (sponges). |
| Coelenterata | Animals with a body cavity called coelenteron (e.g., Hydra). |
| Arthropoda | Largest phylum with jointed legs (e.g., Cockroach). |
| Vertebrata | Animals with a true backbone (e.g., human, fish). |
| Binomial Nomenclature | Two-word naming system introduced by Linnaeus. |
| Carolus Linnaeus | Father of Taxonomy who introduced binomial nomenclature. |
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