Five Kingdom Classification

The Five Kingdom Classification system, proposed by biologist R.H. Whittaker in 1969, was a major breakthrough in organizing life’s diversity. It moved beyond the limitations of the earlier two-kingdom system by using more sophisticated criteria for grouping organisms. This system classifies all living things into five major kingdoms primarily based on their cell structure (prokaryotic or eukaryotic), body organization (unicellular or multicellular), mode of nutrition (autotrophic or heterotrophic), and phylogenetic relationships. The five kingdoms established are Monera, Protista, Fungi, Plantae, and Animalia, providing a much clearer and more scientific framework for understanding the vast biological world.

The first three kingdoms largely encompass simpler organisms. Kingdom Monera includes all prokaryotic organisms, meaning they lack a well-defined nucleus and membrane-bound organelles; this kingdom consists entirely of bacteria, which can be autotrophic or heterotrophic. Kingdom Protista is a group of eukaryotic, mostly unicellular organisms that do not fit into the other kingdoms, including diverse members like amoeba, paramecium, and unicellular algae; their mode of nutrition can be autotrophic (like algae) or heterotrophic (like protozoans). Kingdom Fungi comprises eukaryotic, mostly multicellular organisms with a unique heterotrophic mode of nutrition; they are saprophytes, absorbing nutrients from decaying organic matter, and have cell walls made of chitin, with examples like mushrooms, yeast, and moulds.

The final two kingdoms consist of complex, multicellular eukaryotes. Kingdom Plantae includes all autotrophic organisms that perform photosynthesis, thanks to the presence of chlorophyll. They are characterized by a rigid cell wall made of cellulose and are non-motile, encompassing all plants, from mosses and ferns to flowering plants. Finally, Kingdom Animalia is made up of multicellular, eukaryotic organisms that are heterotrophic, relying on other organisms for food. Their cells lack a cell wall, which allows for movement, and they digest their food internally. This kingdom includes all animals, from simple sponges and worms to insects, birds, and mammals. This five-kingdom model thus successfully groups organisms from the most primitive bacteria to the most advanced plants and animals based on fundamental biological distinctions.

• Multiple choice type

Question 1. 

The animals (Kingdom Animalia) are mainly grouped under two categories

1. bilaterally symmetrical and radially symmetrical
2. coelomate and acoelomate
3. aquatic and terrestrial
4. vertebrates and invertebrates

Question 2. 

Which one of the following examples do not come under the particular group?

1. Mushroom, Yeast, Fern – Fungi
2. Paramoecium, Euglena, Sponge – Protista 
3. Starfish, Cuttlefish, Dogfish – Pisces
4. Bat, Parrot, Oyster – Vertebrates

Question 3. 

Which one of the following is an example of a binomial scientific name?

1. Green alga
2. Snow leopard
3. Rana tigrina
4. China-rose

Question 4. 

Which one of the following is the correct statement about the respective animal(s)?

1. Donkey and horse should be considered one single species because they can successfully mate and produce offspring.
2. Donkey and horse are two different genuses.
3. Mules are a separate species.
4. Mule is neither a donkey nor a horse.

• Very short answer type

Question 1. 

Who had introduced the binomial system of naming living beings?

Ans:

Key Facts about the System

• When: Linnaeus standardized and popularized this system in the mid-18th century, most notably in his work Species Plantarum (1753) for plants and the 10th edition of Systema Naturae (1758) for animals.
• What it is: The system, called Binomial Nomenclature, gives every species a unique two-part scientific name:
  1. The Genus name (capitalized).
  2. The Species name (lowercase).
• Example: Humans are named Homo sapiens.
• Importance: This system provided a universal, standardized way for scientists worldwide to communicate about a specific organism, eliminating the confusion caused by varied common names in different languages and regions.

Question 2. 

Which two characters out of (a)-(e) given below are common to dogs, humans, squirrels, bats, camels and monkeys?

(a) scales on the skin

(b) wings

(c ) external ears

(d) give birth to young ones

(e) a functional tail

Ans:

The two characters common to all the animals listed (dogs, humans, squirrels, bats, camels, and monkeys) are: (c) external ears and (d) give birth to young ones .

Explanation

All the animals listed—dogs, humans, squirrels, bats, camels, and monkeys—belong to the Class Mammalia (Mammals).

1. (c) External Ears (Pinnae): All mammals possess external ears (pinnae) to collect sound, although the structure and size vary widely.
2. (d) Give Birth to Young Ones (Viviparity): Mammals are primarily viviparous, meaning they give birth to live young that develop inside the mother’s body.

Why the Others Are Not Universal:

• (a) Scales on the skin: This is characteristic of reptiles (like snakes), not mammals.
• (b) Wings: Only bats possess wings among the listed animals; the others do not.
• (e) A functional tail: Humans, gibbons, and some apes lack a functional tail, though other primates and mammals like dogs and squirrels do have one.

Question 3. 

Match the items in Column I with as many as possible and even repeatedly from column II.

Column I	Column II
1.Pine	(i) Fungi
2. Earthworm	(ii) Monera
3. Bread mould	(iii) Prokaryote
4. Amoeba	(iv) Gymnosperm
5. Moss	(v) Plantae
6.Bacteria	(vi) Animalia
	(vii) Protista
	(viii) Bryophyta

Ans:

Column I (Organism)	Column II (Classification)	Rationale
1. Pine	(iv) Gymnosperm (v) Plantae	Pine is a non-flowering, cone-bearing plant belonging to the division Gymnospermae, which is part of the Kingdom Plantae.
2. Earthworm	(vi) Animalia	The Earthworm is an invertebrate animal belonging to the Phylum Annelida, which is part of the Kingdom Animalia.
3. Bread mould	(i) Fungi	Bread mould (like Rhizopus) is a filamentous organism belonging to the Kingdom Fungi.
4. Amoeba	(vii) Protista	Amoeba is a single-celled eukaryotic organism classified under the Kingdom Protista.
5. Moss	(viii) Bryophyta (v) Plantae	Moss is a non-vascular plant belonging to the division Bryophyta, which is part of the Kingdom Plantae.
6. Bacteria	(ii) Monera (iii) Prokaryote	Bacteria are single-celled organisms that lack a true nucleus, classifying them as Prokaryotes and members of the Kingdom Monera.

• Short answer type

Question 1. 

Rearrange the following categories of classification in their proper sequence starting with the highest. species, family, genus, class, order, phylum

Ans:

The classification categories, or taxa, arranged in their proper hierarchical sequence starting with the highest (most inclusive) are:

Sequence of Taxonomic Categories

1. Phylum
2. Class
3. Order
4. Family
5. Genus
6. Species

Mnemonic Tip

A common mnemonic to remember the sequence is: King Philip Came Over For Good Spaghetti.

Category	Mnemonic Word	Level of Inclusiveness
Phylum	Philip	Most inclusive (Broadest)
Class	Came
Order	Over
Family	For
Genus	Good
Species	Spaghetti	Least inclusive (Specific)

Question 2. 

Give the scientific names of man, domestic cat, and peepal tree.

Ans:

Organism	Scientific Name
Man (Human)	Homo sapiens
Domestic Cat	Felis catus
Peepal Tree	Ficus religiosa

Question 3. 

Why are scientific names of living beings considered better than their common names?

Ans:

Scientific names are considered better than common names for several crucial reasons related to clarity, universality, and accuracy in communication among scientists worldwide.

Universal and Unambiguous

• Common Names are Ambiguous: A single common name can refer to multiple different species in different regions. For example, the name “robin” refers to Turdus migratorius in North America and Erithacus rubecula in Europe—two completely different species.
• Scientific Names are Unique: The binomial system ensures that every recognized species has one, and only one, valid scientific name globally (e.g., Homo sapiens for humans). This eliminates confusion regardless of language or geographic location.

Scientific Rigor and Consistency

• Reflect Relationships: Scientific names (binomial nomenclature) are hierarchical. The first part, the Genus (Felis in Felis catus), groups closely related species together, indicating evolutionary and morphological relationships. Common names lack this context.
• Language Independence: Scientific names are based on Latin (or Latinized forms of other languages), a dead language that doesn’t change over time. This provides stability and consistency across centuries and languages.
• Accuracy: Common names are often based on superficial characteristics or folklore and can be misleading (e.g., a “starfish” is not a fish). Scientific names follow strict rules and reflect the accurate classification of the organism.

Question 4. 

Mention any two drawbacks in classifying organisms under the old two kingdom classification.

Ans:

The old Two Kingdom Classification (Plantae and Animalia), proposed by Carolus Linnaeus, had significant drawbacks primarily because it failed to account for organisms that didn’t neatly fit into either category.

Here are two major drawbacks:

1. Fails to Distinguish Between Prokaryotes and Eukaryotes :
   • The system grouped all organisms without considering fundamental cellular differences. For example, bacteria (Prokaryotes, lacking a true nucleus) were grouped with complex plants (Eukaryotes, having a true nucleus). This ignored the most basic level of biological organization.
2. Ignored Fungi and Unicellular Organisms (Protists) :
   • Fungi (like molds and mushrooms) were incorrectly placed in the Kingdom Plantae simply because they had cell walls. This ignored the crucial fact that fungi are heterotrophic (they don’t photosynthesize) and have a different cell wall composition (chitin, not cellulose).
   • Unicellular organisms like Chlamydomonas (has a cell wall and chlorophyll, making it plant-like) and Euglena (lacks a cell wall and moves, making it animal-like) could not be consistently classified, creating a biological “dustbin” of contradictions.

Question 5. 

All humans on earth today may differ widely in their facial features, colour, height, etc. Yet, they belong to a single species, Homo sapiens. Give one reason why they are not considered belonging to different species.

Ans:

Humans are considered to belong to a single species, Homo sapiens, because they can successfully interbreed and produce fertile offspring.

Reason for Single Species Classification

The defining characteristic of a species is the ability of its members to reproduce naturally with one another to produce viable, fertile offspring.

• Despite differences in appearance (facial features, color, height, etc.), any human from any population on Earth can mate with another human and produce children who are themselves capable of having children (i.e., they are fertile).
• If humans were classified as different species, they would either be unable to reproduce at all, or their offspring would be sterile (unable to reproduce), like a mule (the infertile offspring of a horse and a donkey).

Question 6. 

Rewrite the following scientific names correctly.

ficus religiosa (peepal), zea Mays (maize) and Bombyx Mori (silk moth).

Ans:

Here are the correct ways to write the scientific names (binomial nomenclature) for the given organisms:

Common Name	Incorrect Name Given	Correct Scientific Name
Peepal Tree	ficus religiosa	Ficus religiosa
Maize	zea Mays	Zea mays
Silk Moth	Bombyx Mori	Bombyx mori

Rules of Binomial Nomenclature

The corrections follow the standard rules established by Linnaeus:

1. Genus Name (First Word): Must always begin with a capital letter (e.g., Ficus, Zea, Bombyx).
2. Species Name (Second Word): Must always begin with a small letter (e.g., religiosa, mays, mori).
3. Formatting: The entire name must be rendered in italics when typed (or underlined when handwritten).

Question 7. 

Name the five kingdoms according to the new classification.

Ans:

The five kingdoms used in the modern and widely accepted system of biological classification are:

1. Monera (Prokaryotes like bacteria) 
2. Protista (Single-celled Eukaryotes like Amoeba and Euglena) 
3. Fungi (Molds, yeasts, and mushrooms) 
4. Plantae (All plants) 
5. Animalia (All animals) 

This system, known as the Five Kingdom Classification, was proposed by R. H. Whittaker in 1969. It is based on key criteria such as cell structure (prokaryotic or eukaryotic), mode of nutrition (autotrophic or heterotrophic), and body organization (unicellular or multicellular).

Question 8. 

1.  What are the group names of the following categories of animals? Animals with a backbone _____________ 

2.What are the group names of the following categories of animals? Animals with hairy skin ___________ 

3. What are the group names of the following categories of animals? Animals with three pairs of legs ___________ 

4. What are the group names of the following categories of animals? Animals with feathers _________

Ans:

Here are the group names for the given categories of animals:

1. Animals with a backbone: Vertebrates (or Phylum Chordata)
2. Animals with hairy skin: Mammals (Class Mammalia)
3. Animals with three pairs of legs: Insects (Class Insecta)
4. Animals with feathers: Birds (Class Aves)

Question 9. 

Which ones of the following animals are invertebrates? Housefly, Silverfish, Trout, Jellyfish, Whale, Penguin, Lizard and Sponge

Ans:

The invertebrates in your list are the animals that lack a backbone (vertebral column).

The invertebrates are:

• Housefly (Insect)
• Silverfish (Insect)
• Jellyfish (Cnidarian)
• Sponge (Poriferan)

Breakdown of Categories

Animal	Category	Vertebrate or Invertebrate
Housefly	Arthropod/Insect	Invertebrate
Silverfish	Arthropod/Insect	Invertebrate
Trout	Fish	Vertebrate
Jellyfish	Cnidarian	Invertebrate
Whale	Mammal	Vertebrate
Penguin	Bird	Vertebrate
Lizard	Reptile	Vertebrate
Sponge	Poriferan	Invertebrate

Question 10. 

1. Give any one difference between protozoa and Metazoa.

2. Write one difference between the following pair: Invertebrates and Vertebrates  

3. Give any one difference between the following : Insecta and Arachnida 

4. Give any one difference between the following : Flatworm and Roundworm

Ans:

1. Protozoa and Metazoa

Feature	Protozoa	Metazoa
Cellularity	Unicellular (single-celled organisms).	Multicellular (composed of many cells).
Cell Function	All life functions are carried out by that single cell.	Cells are organized into tissues, organs, and systems.

2. Invertebrates and Vertebrates 

Feature	Invertebrates	Vertebrates
Backbone/Spine	Lack a backbone (vertebral column).	Possess a backbone (vertebral column).
Example	Insects, worms, mollusks, starfish.	Fish, amphibians, reptiles, birds, mammals.

3. Insecta and Arachnida 

Feature	Insecta (Insects)	Arachnida (Arachnids)
Legs	Have three pairs of legs (6 legs total).	Have four pairs of legs (8 legs total).
Body Divisions	Body is divided into three parts: head, thorax, and abdomen.	Body is typically divided into two parts: cephalothorax and abdomen.

4. Flatworm and Roundworm

Feature	Flatworm (Phylum Platyhelminthes)	Roundworm (Phylum Nematoda)
Body Shape	Body is dorsoventrally flattened (ribbon-like or leaf-like).	Body is cylindrical and tapered at both ends.
Body Cavity	Acoelomate (lacks a true body cavity).	Pseudocoelomate (has a false body cavity not fully lined by mesoderm).

Question 11. 

1. Given below is an animal followed by three terms or features. Underline the term which does not match with the animal. Amoeba – Nucleus, tentacle, food vacuole 

2. Given below is an animal followed by three terms or features. Underline the term which does not match with the animal. Hydra – Invertebrata, Cnidaria, Crustacea 

3. Given below is an animal followed by three terms or features. Underline the term which does not match with the animal. Fish – Gills, paired fins, ear drum 

4. Given below is an animal followed by three terms or features. Underline the term which does not match with the animal. Earthworm – Invertebrata, Annelida, Insecta 

5. Given below is an animal followed by three terms or features. Underline the term which does not match with the animal. Grasshopper-Wings, trachea, proboscis 

6. Given below is an animal followed by three terms or features. Underline the term which does not match with the animal. Butterfly- Insecta, Invertebrata, Mollusca 

7. Given below is an animal followed by three terms or features. Underline the term which does not match with the animal. Whale – Gills, mammary glands, fat under the skin 

8. Given below is an animal followed by three terms or features. Underline the term which does not match with the animal. Pigeon – Feathers, wings, hair 

9. Given below is an animal followed by three terms or features. Underline the term which does not match with the animal. Monkey – External ear, sweat glands, lateral line. 

10. Given below is an animal followed by three terms or features. Underline the term which does not match with the animal. Bat – Aves, Mammalia, Chordata

Ans:

Here are the underlined terms that do not match the given animal:

1. Amoeba – Nucleus, tentacle, food vacuole
   • (Amoeba uses pseudopodia for movement and feeding, not tentacles.)
2. Hydra – Invertebrata, Cnidaria, Crustacea
   • (Hydra belongs to Phylum Cnidaria, not Class Crustacea, which includes crabs and lobsters.)
3. Fish – Gills, paired fins, ear drum
   • (Fish do not have an external or middle ear with a tympanic membrane/ear drum; they detect sound via inner ears.)
4. Earthworm – Invertebrata, Annelida, Insecta
   • (Earthworms belong to Phylum Annelida (segmented worms), not Class Insecta.)
5. Grasshopper – Wings, trachea, proboscis
   • (Grasshoppers have biting/chewing mouthparts; a proboscis is a sucking mouthpart found in insects like butterflies or mosquitoes.)
6. Butterfly – Insecta, Invertebrata, Mollusca
   • (Butterflies belong to Phylum Arthropoda, Class Insecta, not Phylum Mollusca, which includes snails and clams.)
7. Whale – Gills, mammary glands, fat under the skin
   • (Whales are mammals and breathe using lungs, not gills.)
8. Pigeon – Feathers, wings, hair
   • (Pigeons are birds, and their body is covered in feathers, not hair.)
9. Monkey – External ear, sweat glands, lateral line
   • (The lateral line system is a sensory organ found in fish and some amphibians, not mammals like monkeys.)
10. Bat – Aves, Mammalia, Chordata
    • (Bats belong to Class Mammalia, not Class Aves (Birds), even though they fly.)

Question 12. 

Differentiate between warm-blooded and cold-blooded animals.

Ans:

Feature	Warm-Blooded Animals (Homeotherms/Endotherms)	Cold-Blooded Animals (Poikilotherms/Ectotherms)
Temperature Regulation	Internal Regulation (Endothermic): They can generate heat internally through metabolism to maintain a constant, high body temperature, regardless of the environment.	External Regulation (Ectothermic): They rely on external sources (like the sun or warm rocks) to regulate their body temperature, which fluctuates with the external environment.
Metabolic Rate	High metabolic rate, especially when maintaining temperature (e.g., shivering).	Low metabolic rate; rapid bursts of energy followed by periods of inactivity.
Tolerance to Temp Change	Less tolerant of wide internal temperature changes; maintaining constant temperature requires a high energy cost.	Highly tolerant of wide internal temperature changes (e.g., a lizard’s body temperature can vary by many degrees).
Activity Level	Generally active year-round in most climates.	Activity is highly dependent on ambient temperature (e.g., they become lethargic in cold weather, often entering dormancy like hibernation or estivation).
Insulation	Possess internal insulation like fat, fur, or feathers to retain internally generated heat.	Generally lack significant internal insulation; skin is often dry or scaly.
Examples	Mammals (e.g., humans, dogs, whales) and Birds (e.g., eagles, penguins).	Fish, Amphibians (e.g., frogs, salamanders), and Reptiles (e.g., snakes, turtles).

Question 13. 

Name three animals (belonging to different classes) which breathe by means of lungs but have no external ears (pinnae).

Ans:

Three animals belonging to different classes that breathe by means of lungs but lack external ears (pinnae) are:

• Lizard (Class Reptilia): Reptiles breathe using lungs but typically have only a small opening to the middle ear, not external pinnae.
• Frog (Class Amphibia): Adult amphibians breathe through lungs (as well as skin and buccopharyngeal lining) but only possess a visible eardrum (tympanum), not external ear flaps.
• Whale (Class Mammalia): Whales and other large cetaceans are mammals and breathe using lungs, but they lack external ears to reduce drag while swimming.

• Long answer type

Question 1. 

1. Mention any one major similarity and one major difference in the following pairs of an animal: Insects and Birds 

2. Mention any one major similarity and one major difference in the following pairs of an animal: Whales and Fishes 

3. Mention any one major similarity and one major difference in the following pairs of an animal: Snakes and Earthworms 

4. Mention any one major similarity and one major difference in the following pairs of an animal: Bat and Pigeon. 

5. Mention any one major similarity and one major difference in the following pairs of an animal: Cuttlefish and Dogfish 

6. Mention any one major similarity and one major difference in the following pairs of an animal:  Wall lizard and Frog

Ans:

1.  Insects and Birds 

Feature	Insects	Birds
Major Similarity	Both groups have the ability to fly (most species) using wings as their primary means of locomotion.
Major Difference	Insects are invertebrates (no backbone) with an exoskeleton; Birds are vertebrates (have a backbone) with an endoskeleton.

2. Whales and Fishes 

Feature	Whales	Fishes
Major Similarity	Both are aquatic and possess streamlined bodies and fins/flukes adapted for locomotion in water.
Major Difference	Whales are mammals (warm-blooded, breathe air with lungs, give birth to live young, suckle) ; Fishes are Pisces (cold-blooded, breathe water using gills, lay eggs).

3. Snakes and Earthworms 

Feature	Snakes	Earthworms
Major Similarity	Both have elongated bodies and move without true limbs (legs), using muscle contractions and body structure for locomotion.
Major Difference	Snakes are vertebrates (Phylum Chordata, Class Reptilia); Earthworms are invertebrates (Phylum Annelida).

4. Bat and Pigeon. 

Feature	Bat	Pigeon
Major Similarity	Both possess wings and are capable of true, sustained flight.
Major Difference	Bats are mammals (warm-blooded, hairy, suckle young); Pigeons are birds (warm-blooded, feathered, lay eggs).

5. Cuttlefish and Dogfish 

Feature	Cuttlefish	Dogfish
Major Similarity	Both are fully aquatic animals that use gills for respiration.
Major Difference	Cuttlefish is an invertebrate (Phylum Mollusca) with a soft body and no backbone; Dogfish is a vertebrate (Phylum Chordata, a type of fish/shark) with a cartilaginous backbone.

6.  Wall lizard and Frog

Feature	Wall Lizard	Frog
Major Similarity	Both are cold-blooded animals (Ectotherms) and belong to the higher group of Vertebrates.
Major Difference	Lizards are Reptiles (have dry, scaly skin, internal fertilization, lay amniotic eggs); Frogs are Amphibians (have moist, glandular skin, external fertilization, lay eggs in water, undergo metamorphosis).

Question 2. 

Match the names of animal groups in Column I with the names of animals in column II. 

Column I (Group)	Column II (Animals)
Annelida	Pigeon
Porifera	Snake
Mollusca	Earthworm
Amphibia	Octopus
Pisces	Trout
Mammal	Rabbit

Which names are left out that do not match and why?

Ans:

Column I (Group)	Column II (Animals)
Annelida	Earthworm
Porifera	Sponge (The only animal not listed but belongs here)
Mollusca	Octopus
Amphibia	Frog (The only animal not listed but belongs here)
Pisces	Trout
Mammal	Rabbit

• Structured/Application/Skill type

TYRANNOSAURUS

(One of the extinct animals which lived on the Earth about 100,000,000 years ago) Tyrannosaurus was about six meters long and it preyed upon other animals.

What do you think about its classification-was it an amphibian, a reptile or a mammal?

Can you call it a relative of Kangaroo? Yes/No. Give reason

Ans:

Classification of Tyrannosaurus

Tyrannosaurus was a Reptile.

It belonged to the group known as the Dinosauria, specifically the theropod dinosaurs. It possessed key reptilian characteristics, such as breathing with lungs, laying hard-shelled eggs, and having scaly skin. It does not share the defining features of amphibians (like moist skin) or mammals (like hair or mammary glands).

Relative of the Kangaroo?

No, you cannot call the Tyrannosaurus a relative of the Kangaroo in the context of close evolutionary kinship.

Reason

• Tyrannosaurus belongs to the Class Reptilia (Dinosaurs).
• Kangaroo belongs to the Class Mammalia (Mammals).

These two classes are separated by vast evolutionary time and represent fundamentally different branches of vertebrate life. While both are vertebrates (Phylum Chordata), they are not considered close relatives. The closest living relatives of Tyrannosaurus are widely considered to be birds (Class Aves).