Q1. Why are living organisms classified?

A1. Living organisms are classified for several reasons:

  1. To Organize Diversity: It is impossible to study all 1.7-1.8 million known species individually. Classification groups them into convenient categories based on shared characteristics.
  2. To Standardize Study: It provides a universal framework, allowing scientists worldwide to study and discuss organisms without confusion from local names.
  3. To Understand Relationships: Classification helps in revealing the interrelationships and evolutionary history (phylogeny) among different groups of organisms.

Q2. What is binomial nomenclature? Explain its universal rules with an example.

A2. Binomial nomenclature is the scientific system of naming organisms with a two-part name, developed by Carolus Linnaeus. The universal rules are:

  1. Language: Names are in Latin and written in italics.
  2. Components: The first word is the Genus (capitalized), and the second is the specific epithet (lowercase).
  3. Handwritten: When handwritten, both parts are underlined separately.
  4. Author Citation: The name of the scientist who first described the species is written after the name in abbreviated form.

Example: Mangifera indica Linn. Here, Mangifera is the genus, indica is the specific epithet, and Linn. indicates it was described by Linnaeus.

Q3. What do we learn from the identification of individuals and populations?

A3: Identification allows us to know what organism we are observing. This is the first step in any biological study. For populations, identification helps us to map the biodiversity of an area, understand its ecological relationships, and apply this knowledge in fields like agriculture, medicine, and conservation.

Q4. Identify the correctly written scientific name for Mango.

  • (a) Mangifera Indica
  • (b) Mangifera indica

A4: The correctly written name is (b) Mangifera indica. According to the universal rules of binomial nomenclature, the genus name (Mangifera) starts with a capital letter, but the specific epithet (indica) must start with a small letter.

Q5. Define a taxon. Give some examples of taxa at different hierarchical levels.

A5: A taxon (plural: taxa) is the scientific term for any unit of classification, regardless of its rank. It represents a distinct group of organisms. For example:

  • Kingdom: Animalia is a taxon.
  • Phylum: Chordata is a taxon.
  • Class: Mammalia is a taxon.
  • Family: Felidae is a taxon.
  • Species: sapiens is a taxon.

Q6. Can you identify the correct sequence of taxonomical categories?

  • (a) Species -> Order -> Phylum -> Kingdom
  • (b) Genus -> Species -> Order -> Kingdom
  • (c) Species -> Genus -> Order -> Phylum

A6: The correct sequence among the choices is (a) Species -> Order -> Phylum -> Kingdom. The complete correct ascending sequence is Species -> Genus -> Family -> Order -> Class -> Phylum -> Kingdom. Option (a) follows this ascending order, while (b) and (c) do not.

Q7. Define and understand the following terms:

(i) Phylum (ii) Class (iii) Family (iv) Order (v) Genus.

A7.

  • (i) Phylum: A principal taxonomic category that ranks above Class and below Kingdom. It consists of classes with a few similar characters. The term 'Division' is used in its place for plants. It is an assemblage of related classes. (e.g., Chordata).

  • (ii) Class: A category that ranks above Order and below Phylum. It is an assemblage of related orders (e.g., Mammalia).

  • (iii) Family: A category that ranks above Genus and below Order. It is an assemblage of related genera (e.g., Felidae).

  • (iv) Order: A category that ranks above Family and below Class. It is an assemblage of related families (e.g., Carnivora).

  • (v) Genus: A category that ranks above Species and below Family. It is an assemblage of related species (e.g., Panthera).

Q8. Illustrate the taxonomical hierarchy with suitable examples of a plant and an animal.

A8: The hierarchy can be illustrated using the examples of Mango (plant) and Man (animal) :

Taxon Man Mango
Kingdom Animalia Plantae
Phylum Chordata Angiospermae (Division)
Class Mammalia Dicotyledonae
Order Primata Sapindales
Family Hominidae Anacardiaceae
Genus Homo Mangifera
Species sapiens indica

Q9: What is the relationship between the number of common characteristics and the hierarchical level?

A9: The relationship is inverse. As we go higher in the taxonomic hierarchy (from species to kingdom), the categories become more general, and the number of common characteristics among the members decreases. Conversely, as we go down the hierarchy (from kingdom to species), the number of common characteristics increases, and the organisms become more similar to each other.

Q10. Define a taxon. Give some examples of taxa at different hierarchical levels.

A10: A 'taxon' is the scientific term for any unit of classification, regardless of its rank. It represents a distinct group of organisms. For example, 'Mammalia' is a taxon at the class level, 'Felidae' is a taxon at the family level, and Panthera is a taxon at the genus level.

Q11. Differentiate between Taxonomy and Systematics.

A11:

  • Taxonomy is the science of classification. Its main processes are characterisation, identification, classification, and nomenclature of organisms.
  • Systematics is a broader field. It includes all aspects of taxonomy but also incorporates and emphasizes the evolutionary relationships (phylogeny) between organisms.

Q12. What are the four processes that are fundamental to taxonomy?

A12: The four processes basic to taxonomy are:

  1. Characterisation: Understanding the morphological, anatomical, and other characters of the organism.

  2. Identification: Correctly describing the organism to determine its place in the established classification.

  3. Classification: Grouping the organism into convenient categories (taxa).

  4. Nomenclature: Providing a universal scientific name.

Q13. What are the defining characteristics of living organisms?

A13: The defining characteristics of living organisms—those without any exception—are:

  1. Metabolism: The sum total of all chemical reactions occurring in the body.

  2. Cellular Organization: All living things are composed of one or more cells.

  3. Consciousness: The ability to sense the environment and respond to stimuli.

(Growth and reproduction are also characteristics of life, but not defining, as non-living things can 'grow' (e.g., mountains) and some living organisms are sterile (e.g., mules) and cannot reproduce.)

Q14: Explain the difference between 'flora', 'manuals', and 'monographs'.

A14:

  • Flora: Contains the actual account of the habitat and distribution of plant species found in a particular area. It provides an index of the plants in that area.

  • Manuals: Are useful for providing information for the identification of names of species found in a specific area.

  • Monographs: Contain comprehensive information on any one specific taxon (e.g., a monograph on the family Solanaceae).

Q15. What is a taxonomic 'key'? What is a 'couplet' in this context?

A13: A key is a taxonomical aid used for the identification of plants and animals based on their similarities and dissimilarities. It is analytical in nature. A key is based on a pair of contrasting characters known as a couplet. Each statement in the couplet is called a lead. By accepting one statement and rejecting the other, one can proceed to identify the organism.

Q16: What is a herbarium? What information is included on a herbarium sheet label?

A16: A herbarium is a storehouse of collected plant specimens that are dried, pressed, and preserved on sheets. The herbarium sheet label provides information including the date and place of collection, the English, local, and botanical names, the family, and the collector's name.

Q17. What is the role of a botanical garden?**

A17: A botanical garden is a taxonomical aid that has collections of living plants for reference. These gardens are used for identification purposes and also play a crucial role in the ex-situ conservation of rare and endangered plant species.

Q18. How is a museum different from a zoological park as a taxonomical aid?

A18:

  • A Museum has collections of preserved plant and animal specimens for study and reference. Specimens are kept in containers with preservative solutions, or as dried specimens (like insects in boxes or skeletons).
  • A Zoological Park is a place where living wild animals are kept in protected environments under human care, which are as similar to their natural habitats as possible. It helps us study their behavior and is a site for ex-situ conservation.

Q19: What do the abbreviations ICBN and ICZN stand for?

A19:

  • ICBN stands for International Code for Botanical Nomenclature. It provides the set of rules and principles for the scientific naming of plants.
  • ICZN stands for International Code of Zoological Nomenclature. It provides the set of rules and principles for the scientific naming of animals.

Q20. What is the relationship between the number of common characteristics and the hierarchical level?

A20: The relationship is inverse. As we go higher in the taxonomic hierarchy (from species to kingdom), the categories become more general, and the number of common characteristics among the members decreases. Conversely, as we go down the hierarchy (from kingdom to species), the number of common characteristics increases, and the organisms become more similar to each other.