CBSE CLASS 11 BIOLOGY
CHAPTER 1 — THE LIVING WORLD
Quick Exam Notes
1. WHAT IS LIVING?
Living organisms show several characteristics:
Growth – Increase in size and/or number of cells.
Reproduction – Production of new individuals.
Metabolism – Sum of all chemical reactions in an organism.
Cellular organisation – Living organisms are made up of cells.
Response to stimuli – Ability to respond to environmental changes.
Consciousness – Ability to sense and respond to surroundings.
Note: Reproduction is not an absolute defining feature because some living organisms cannot
reproduce.
2. BIODIVERSITY
Biodiversity means the variety and variability of living organisms.
Classification is needed because of the enormous diversity of organisms.
3. TAXONOMY
Taxonomy is the study of:
Identification + Nomenclature + Classification
Identification: Recognising an organism.
Nomenclature: Giving a scientific name.
Classification: Grouping organisms based on similarities and differences.
Systematics
Systematics studies organismal diversity and their relationships, including evolutionary
relationships.
4. TAXONOMIC CATEGORIES
The major taxonomic categories are:
Species → Genus → Family → Order → Class → Phylum/Division → Kingdom
CHAPTER 1 — THE LIVING WORLD
Quick Exam Notes
1. WHAT IS LIVING?
Living organisms show several characteristics:
Growth – Increase in size and/or number of cells.
Reproduction – Production of new individuals.
Metabolism – Sum of all chemical reactions in an organism.
Cellular organisation – Living organisms are made up of cells.
Response to stimuli – Ability to respond to environmental changes.
Consciousness – Ability to sense and respond to surroundings.
Note: Reproduction is not an absolute defining feature because some living organisms cannot
reproduce.
2. BIODIVERSITY
Biodiversity means the variety and variability of living organisms.
Classification is needed because of the enormous diversity of organisms.
3. TAXONOMY
Taxonomy is the study of:
Identification + Nomenclature + Classification
Identification: Recognising an organism.
Nomenclature: Giving a scientific name.
Classification: Grouping organisms based on similarities and differences.
Systematics
Systematics studies organismal diversity and their relationships, including evolutionary
relationships.
4. TAXONOMIC CATEGORIES
The major taxonomic categories are:
Species → Genus → Family → Order → Class → Phylum/Division → Kingdom
