The Living World: Class 11 Biology Notes

To be classified as 'living', an organism must exhibit certain characteristics:

• Growth: Increase in mass and number of cells. (However, non-living things like mountains also 'grow' by accumulating sand, so growth is not a defining feature).
• Reproduction: Producing progeny. (But mules and worker bees cannot reproduce, yet they are living. So, reproduction is not a defining feature).
• Metabolism: The sum total of all chemical reactions occurring in the body. (This IS a defining feature of life).
• Cellular Organization & Consciousness: The ability to sense the environment and respond to stimuli. (This IS a defining feature).

Since a local bird is called 'Goraiya' in Hindi and 'House Sparrow' in English, scientists needed a universal naming system. Carolus Linnaeus introduced 'Binomial Nomenclature', where every organism gets a two-word scientific name.

• Example: Human is Homo sapiens.
• Rules: The first word (Homo) is the Genus (starts with a capital letter). The second word (sapiens) is the Specific epithet (starts with a small letter). Both must be printed in italics or underlined separately.

Classification involves grouping organisms into a step-by-step hierarchy. From the broadest category to the most specific, the order is: Kingdom → Phylum → Class → Order → Family → Genus → Species (Trick to remember: Keep Pots Clean Or Family Gets Sick).