Chapter – 3 : Classification of Diversity of Life : Taxonomy | Chapter Solution Class 9

(a) Nomenclature

Explanation:

• Nomenclature refers to the system of naming organisms scientifically.
• Taxonomy is the science of classification, while classification is the broader process of categorizing organisms based on similarities.
• Identification is the process of determining the identity of an organism.

(c) Genus and species

Explanation:

• The binomial nomenclature system, introduced by Carolus Linnaeus, consists of two words: the genus (capitalized) and the species (lowercase).
• Example: Homo sapiens (Human).
• Order and family, family and genus, family and species do not follow the binomial system.

(c) Binomial nomenclature

Explanation:

• Linnaeus developed the binomial nomenclature system, where each organism is given a two-part Latin name.
• Polynomial nomenclature involves multiple names.
• Mononomial nomenclature uses a single word, and tetranominal nomenclature would imply four names, which is incorrect.

(d) R. H. Whittaker

Explanation:

R. H. Whittaker proposed the five-kingdom classification in 1969. The five kingdoms: Monera, Protista, Fungi, Plantae, and Animalia. Haeckel proposed three kingdoms, and Woese later revised classification with domains.

(d) Woese

Explanation:

Carl Woese revised Whittaker’s system and introduced the three-domain system (Archaea, Bacteria, Eukarya). He distinguished prokaryotes into two groups: Bacteria and Archaea.

(b) 1969

Explanation:

R. H. Whittaker proposed his five-kingdom system in 1969, classifying organisms based on cell structure, mode of nutrition, and complexity.

(b) Haeckel

Explanation:

Ernst Haeckel (1866) proposed Protoctista, which included single-celled eukaryotic organisms that did not fit into Plantae or Animalia.

(b) Taxonomy

Explanation:

Taxonomy is the study of classification, including principles, rules, and naming organisms. Biology is the study of life, Bio-geography deals with distribution, and “None of these” is incorrect.

(b) Species

Explanation:

Species is the most fundamental unit in classification, consisting of organisms that can interbreed and produce fertile offspring.

(c) Nucleoid

Explanation:

Prokaryotes lack a nucleus, and their DNA is located in a nucleoid region.

Plasmids are extra-chromosomal DNA, but they are not the main genetic material.

(a) Monerans

Explanation:

• Monerans (Bacteria, including Cyanobacteria) can fix atmospheric nitrogen through symbiotic and free-living methods.
• Protists, fungi, and plants do not have nitrogen-fixing capabilities.

(d) Both (a) and (b) (Chitin and Glycogen)

Explanation:

• Fungi have chitin in their cell walls (like arthropods) and store food as glycogen (like animals).
• Mycelium is a fungal structure, but it is not exclusive to animals.

(c) Algae

Explanation:

• Algae are autotrophic (photosynthetic), contain chlorophyll, and belong to Thallophyta.
• Lichens are symbiotic, Fungi are heterotrophic, and Pteridophytes are vascular plants.

(c) Pteridophyta

Explanation:

• Pteridophytes (Ferns) are the first vascular plants (with xylem and phloem) but do not produce seeds (cryptogams).
• Bryophytes and Thallophytes lack vascular tissue, and Angiosperms are not cryptogams.

(d) Gymnosperms

Explanation:

Carya (Hickory) is a Gymnosperm and corals belong to marine ecosystems, but the closest classification for Carya is Gymnosperms.

Two (2)

Explanation:

Carolus Linnaeus, in 1735, classified living organisms into two kingdoms:

• Plantae (Plants)
• Animalia (Animals)

This system was later modified into a five-kingdom system by Whittaker in 1969.

Carolus Linnaeus

Explanation:

Carolus Linnaeus proposed the binomial nomenclature system in 1753 for plants (Species Plantarum) and in 1758 for animals (Systema Naturae).

This system assigns each organism a two-part scientific name:

• Genus name (Capitalized)
• Species name (Lowercase)
• Example: Homo sapiens (Humans), Mangifera indica (Mango).

Pteridophytes

Explanation:

• Pteridophytes are the first vascular plants, meaning they contain xylem and phloem but do not produce flowers, seeds, or fruits.
• They reproduce through spores instead of seeds.
• Examples: Ferns (Dryopteris), Club Moss (Lycopodium), and Horsetails (Equisetum).

Gymnosperms

Explanation:

• Gymnosperms are plants that bear naked seeds (i.e., seeds are not enclosed within a fruit).
• They reproduce through cones instead of flowers.
• The word “Gymnosperm” means “naked seed” in Greek.
• Examples: Pine (Pinus), Cycas, Ginkgo, and Deodar (Cedrus).

Angiosperms

Explanation:

• Angiosperms are plants that produce enclosed seeds inside fruits.
• They bear flowers and are the most diverse group of plants.
• The term “Angiosperm” means “covered seed” in Greek.
• Examples: Mango (Mangifera indica), Wheat (Triticum aestivum), Rose (Rosa indica).

Five (5)

Explanation:

R. H. Whittaker, in 1969, proposed the Five-Kingdom Classification, which includes:

1. Monera (Bacteria, Cyanobacteria) – Prokaryotic organisms
2. Protista (Amoeba, Paramecium) – Single-celled eukaryotic organisms
3. Fungi (Mushrooms, Yeasts) – Absorptive heterotrophs
4. Plantae (Mango, Rose) – Multicellular autotrophs
5. Animalia (Humans, Dogs) – Multicellular heterotrophs

True

Explanation:

• The Monera Kingdom (bacteria and cyanobacteria) consists of prokaryotic organisms.
• Prokaryotes lack a true nucleus and membrane-bound organelles.
• Examples: E. coli, Streptococcus, and Blue-Green Algae (Cyanobacteria).

False

Explanation:

• Aristotle (384–322 BC) classified organisms into two kingdoms: Plantae and Animalia based on movement and habitat.
• The five-kingdom classification was proposed by R. H. Whittaker in 1969.
• The five kingdoms: Monera, Protista, Fungi, Plantae, and Animalia.

True

Explanation:

• Taxonomy is the science of classifying organisms, and a taxon (plural: taxa) is a category or level in the classification system.
• Example: Species, Genus, Family, Order, Class, Phylum, Kingdom are all taxa.

False

Explanation:

Reticulate venation (net-like veins) is found in dicot plants.

Parallel venation (veins run parallel) is found in monocots.

Example:

• Dicots (Reticulate venation) → Mango (Mangifera indica), Peepal (Ficus religiosa).
• Monocots (Parallel venation) → Wheat (Triticum aestivum), Grass (Poaceae family).

False

Explanation:

• Chlorophyll is present in all algae, including red and brown algae.
• Red algae (Rhodophyta) → Contain Chlorophyll a, d, and phycoerythrin (which gives the red color).
• Brown algae (Phaeophyta) → Contain Chlorophyll a, c, and fucoxanthin (which gives the brown color).
• Green algae (Chlorophyta) → Contain Chlorophyll a and b.

True

Explanation:

Bryophytes (e.g., mosses, liverworts) are called amphibians of the plant kingdom because:

• They live on land but need water for reproduction.
• Their sperm require a moist environment to swim to the egg.

Examples: Riccia, Marchantia, Funaria (Mosses), Sphagnum.

True

Explanation:

• A. P. de Candolle (1813) first used the term taxonomy to describe the science of classification and naming of organisms.
• He contributed significantly to plant taxonomy.

Kingdom Monera

R. H. Whittaker

70S ribosome

Amoeba

Carolus Linnaeus

Theophrastus’ Classification

Carolus Linnaeus

Pteridophyta

Parallel venation

Oryza sativa

Kingdom Protista

Mangifera indica

Homo sapiens

Species

Algae and Fungi

Gymnosperms have naked seeds, while Angiosperms have seeds enclosed within fruits.

Smallest grouping: Species

Largest grouping: Kingdom

The Plant Kingdom (Plantae) is divided into the following five divisions:

1. Thallophyta (e.g., Algae – Spirogyra, Chlorella)
2. Bryophyta (e.g., Mosses – Funaria, Riccia)
3. Pteridophyta (e.g., Ferns – Marsilea, Selaginella)
4. Gymnosperms (e.g., Pinus, Cycas)
5. Angiosperms (e.g., Mango, Rose)

Thallophyta (Algae) and Bryophyta possess the simplest plant organisms.

Kingdom Monera (Bacteria & Cyanobacteria)

1. Prokaryotic Cells: They lack a true nucleus and membrane-bound organelles.
2. Unicellular Organisms: Includes bacteria, cyanobacteria (blue-green algae), and mycoplasma.
3. Cell Wall Composition: Some have peptidoglycan in their cell walls (e.g., bacteria), while some (e.g., Mycoplasma) lack a cell wall.
4. Mode of Nutrition: Can be autotrophic (photosynthetic or chemosynthetic) or heterotrophic (saprophytic or parasitic).
5. Reproduction: Primarily asexual reproduction by binary fission or budding.
6. Motility: Some bacteria move using flagella, while others are non-motile.

Kingdom Protista (Amoeba, Paramecium, Euglena, etc.)

1. Eukaryotic Cells: They have a true nucleus and membrane-bound organelles.
2. Unicellular Organisms: Mostly single-celled, but some form colonies.
3. Locomotion: Uses cilia (Paramecium), flagella (Euglena), or pseudopodia (Amoeba) for movement.
4. Mode of Nutrition: Some are autotrophic (algae-like), while others are heterotrophic (protozoa-like).
5. Reproduction: Mostly asexual reproduction (binary fission), but some also reproduce sexually.

The need classification of living organisms are

1. Classification helps in arranging millions of organisms into groups for easy study.
2. Organisms with similar features are grouped together, showing their evolutionary connections.
3. Scientific classification provides a universal way to name and identify organisms.
4. If an organism belongs to a group, we can predict its characteristics based on that group.
5. Helps biologists study organisms’ structures, behaviors, and genetic makeup efficiently.

Theophrastus (370–285 BC) – Classified plants as herbs, shrubs, and trees.

Aristotle (384–322 BC) – Classified animals based on habitat (land, water, air).

John Ray (1627–1705) – Introduced the concept of species as a classification unit.

Carolus Linnaeus (1707–1778) – Developed the binomial nomenclature system and introduced a hierarchical classification with seven ranks:

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

Post-Linnaean developments – Later scientists refined taxonomy, leading to modern classification systems, including the Five-Kingdom System (Whittaker, 1969).

The merits of Linnaeus’s hierarchy are:

• Universal System – The classification is accepted worldwide, making species identification easier.
• Binomial Nomenclature – The two-word naming system avoids confusion from local names.
• Hierarchical Classification – Organisms are arranged from broad (kingdom) to specific (species) categories.
• Predictability – Based on the group an organism belongs to, we can predict its characteristics.
• Foundation for Modern Taxonomy – Linnaeus’s system paved the way for later advancements in taxonomy.

Features of Kingdom Monera:

1. Prokaryotic organisms – Lack a true nucleus and membrane-bound organelles.
2. Mostly unicellular – Includes bacteria and cyanobacteria.
3. Reproduction by binary fission – Asexual reproduction through simple cell division.

Features of Kingdom Protista:

1. Eukaryotic organisms – Have a true nucleus and organelles.
2. Mostly unicellular but complex – Some form colonies or multicellular structures.
3. Varied locomotion – Move using cilia (Paramecium), flagella (Euglena), or pseudopodia (Amoeba).

Kingdom Plantae (Plants):

1. Autotrophic – Photosynthetic organisms produce their own food.
2. Cell Wall – Made of cellulose.
3. Non-motile – Plants do not move from one place to another.
4. Reproduction – Both sexual and asexual reproduction occur.
5. Classification – Includes Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, and Angiosperms.

Kingdom Animalia (Animals):

1. Heterotrophic – Depend on other organisms for food.
2. No Cell Wall – Cells lack a rigid cell wall.
3. Highly Motile – Most animals can move actively.
4. Complex Organ Systems – Have specialized nervous, digestive, and reproductive systems.
5. Reproduction – Mostly sexual reproduction.