Characteristics of Living Organisms

Segregation of Living and Non-Living

Living organisms grow due to cell division:
- Multicellular organisms: Growth results in an increase in mass.
- Unicellular organisms (e.g., amoeba): Cell division leads to formation of new organisms.
Plants: Grow through cell division throughout their lifespan.
Animals: Grow up to a certain age; thereafter, cell division is only for replacing lost cells.
Growth in living organisms is internal; non-living things may grow externally (e.g., rocks).

Important characteristic but not definitive:
- Unicellular organisms: Growth and reproduction are synonymous.
- Multicellular organisms: Reproduce either sexually or asexually.
- Sexual reproduction: Seen in higher organisms like humans.
- Asexual reproduction: Seen in lower organisms (e.g., yeast through budding).
Some organisms (e.g., sterile worker bees) cannot reproduce but are still considered living.

All living organisms undergo metabolic reactions involving chemicals.
Metabolism is the sum of all chemical reactions and is a definitive feature of living organisms.
Laboratory reactions (in vitro) are not classified as living.

Living organisms exhibit cellular organization, a definitive feature not found in non-living things.

Living organisms send and respond to stimuli (e.g., sunlight, temperature).
Example: Sunflowers turn towards the sun; humans adapt clothing based on temperature.
Non-living objects do not respond to stimuli.

Earth hosts millions of organisms; diversity increases with area exploration.
Species: A group of similar individuals that interbreed and produce fertile offspring.
Current estimates identify about 1.8 million species, with ongoing discoveries.

Standardization of living organism names is crucial to avoid confusion.
Nomenclature: Process of naming organisms; requires correct description and identification.
Scientific names are standardized under:
- ICBN: International Code for Botanical Nomenclature (plants).
- ICZN: International Code for Zoological Nomenclature (animals).
Binomial Nomenclature: Two-component naming system (e.g., Ficus religiosa).
- First word: Genus (capitalized)
- Second word: Specific epithet (lowercase)

Taxonomy: Classifying organisms into categories based on observable characteristics.
Taxonomic categories include: Kingdom, Phylum, Class, Order, Family, Genus, Species.
Understanding taxonomy aids in identifying similarities and differences among organisms.

Species: Basic taxonomic unit; individuals with fundamental similarities.
Genus: Group of related species; more similarities than species from different genera.
Family: Group of related genera.
Order: Collection of related families.
Class: Collection of related orders.
Phylum: Grouping based on shared features (e.g., Chordata).
Kingdom: Highest category (e.g., Animalia, Plantae).

Herbarium: A collection of dried plant specimens.
Botanical Gardens: Cultivation of various plants for research and education.
Museums: Collections of preserved plants and animals for study.
Zoos: Protect habitats and allow study of wild animals.
Taxonomic Keys: A series of questions that help in identifying organisms.
Flora Manuals: Documents containing information about plants of a particular region.
Monographs: Descriptions of single taxa with detailed information.

Taxonomy is crucial for studying and conserving biodiversity.
Continuous discovery of new species emphasizes the importance of classification and nomenclature.