Study sheet: The Living World and Taxonomy

📋 Course Outline

1. Life and Biological Diversity
2. Taxonomy and Scientific Naming
3. Binomial Nomenclature Rules
4. Taxonomic Categories and Species
5. Species to Family
6. Order to Kingdom
7. Hierarchy and Classification Examples

📖 1. Life and Biological Diversity

🔑 Key Concepts & Definitions

• Biology : the science of life forms and living processes
• Biodiversity : the number and types of organisms present on Earth

★ Must-know

• The number of known and described species ranges between 1.7 and 1.8 million.

• All present-day living organisms are related to one another and to organisms that ever lived on Earth.

Further detail

• Living organisms occur in habitats including:
  • cold mountains
  • deciduous forests
  • oceans
  • fresh water lakes
  • deserts
  • hot springs

💡 Memory Hook

A living world spanning hot springs, deserts, oceans, forests, and mountains

📖 2. Taxonomy and Scientific Naming

🔑 Key Concepts & Definitions

• Identification : the process of correctly describing an organism so that its name can be determined
• Nomenclature : the process of standardising the naming of living organisms so that each organism is known by the same name worldwide
• Classification : the process of grouping organisms into convenient categories based on easily observable characters
• Taxonomy : the branch of knowledge dealing with the characterisation, identification, classification, and nomenclature of organisms
• Systematics : the study of organisms that includes identification, nomenclature, classification, and evolutionary relationships

💡 Memory Hook

Characterise → identify → classify → name

📖 3. Binomial Nomenclature Rules

🔑 Key Concepts & Definitions

• Binomial nomenclature : a naming system in which each biological name has a generic name and a specific epithet

★ Must-know

• The scientific name of mango is Mangifera indica, with Mangifera as the genus and indica as the specific epithet.

📌 The genus begins with a capital letter, while the specific epithet begins with a small letter.

Further detail

📌 Biological names are generally Latin or Latinised and are written in italics when printed.

• The author name may follow the specific epithet in abbreviated form, as in Mangifera indica Linn., indicating that Linnaeus first described the species.

💡 Memory Hook

Genus begins uppercase, specific epithet begins lowercase

📖 4. Taxonomic Categories and Species

🔑 Key Concepts & Definitions

• Taxon : a unit or category of classification representing a taxonomic rank
• Species : a group of individual organisms with fundamental similarities that can be distinguished from closely related species by distinct morphological differences

★ Must-know

• The taxonomic hierarchy consists of:
  • kingdom
  • phylum or division
  • class
  • order
  • family
  • genus
  • species

Further detail

• Species is the lowest category shared by organisms in both the plant and animal kingdoms.

💡 Memory Hook

Species → genus → family → order → class → phylum or division → kingdom

📖 5. Species to Family

🔑 Key Concepts & Definitions

• Genus : a group of related species that share more characters with one another than with species of other genera
• Family : a group of related genera with fewer similarities than the species and genera within those groups

📝 Essential Points

• Potato and brinjal are different species belonging to the genus Solanum.

• The genera placed in Solanaceae are:

  • Solanum
  • Petunia
  • Datura

💡 Memory Hook

Species share the most characters; families share fewer

📖 6. Order to Kingdom

🔑 Key Concepts & Definitions

• Order : an assemblage of families that exhibit a few similar characters
• Class : related orders
• Phylum : a higher animal category comprising related classes with common features such as a notochord and a dorsal hollow neural system
• Kingdom : the highest category in the classification hierarchy, with Kingdom Animalia containing animals from various phyla and Kingdom Plantae containing plants from various divisions

📝 Essential Points

• The animal order Carnivora includes the families Felidae and Canidae.

💡 Memory Hook

Order → class → phylum or division → kingdom

📖 7. Hierarchy and Classification Examples

★ Must-know

📌 As classification rises from species to kingdom, the number of common characteristics decreases.

📌 Lower taxa contain members that share more characteristics, while higher categories make relationships with other taxa at the same level more difficult to determine.

Further detail

• Modern taxonomic studies use:

  • external structure
  • internal structure
  • cell structure
  • developmental processes
  • ecological information

• Human beings are classified as Homo sapiens, with Homo as the genus and sapiens as the specific epithet.

• The housefly is classified as Musca domestica, the mango as Mangifera indica, and wheat as Triticum aestivum.

💡 Memory Hook

Higher rank → fewer shared characters → harder relationship determination