Notes Class 11 Chapter 1 Biology Maharashtra Board

Living World

Introduction

The living world is characterized by immense diversity in organisms, from microscopic bacteria to massive whales. This chapter explores the differences between living and non-living entities, the characteristics of life, and the tools used to study biodiversity. The planet Earth comprises abiotic (non-living) and biotic (living) components, and understanding their interactions is crucial for ecological balance, agriculture, and industries.

1.1 Basic Principles of Life

Living organisms share certain fundamental characteristics that distinguish them from non-living entities. These principles are essential for their survival, growth, and perpetuation.

A. Metabolism

• Definition: Metabolism is the sum of all chemical reactions in an organism, including catabolism (breaking down molecules to release energy) and anabolism (building new molecules using energy).
• Purpose: Provides energy and essential molecules for survival.
• Example: Digestion of food (catabolism) and synthesis of proteins (anabolism).

B. Growth and Development

• Definition: Growth is an increase in size or mass, while development is a well-orchestrated process of differentiation and maturation.
• Key Point: Growth in living organisms is internal (from within, e.g., cell division), unlike external growth in non-living entities (e.g., sand mounds or boulders).
• Example: A seed growing into a plant.

C. Ageing

• Definition: The process where molecules, organs, and systems lose efficiency over time, leading to old age.
• Key Point: Ageing is a natural part of life with a limited time span.

D. Reproduction

• Definition: The process by which organisms produce offspring to ensure the continuity of their species.
• Types:
  • Asexual reproduction (e.g., budding in yeast).
  • Sexual reproduction (e.g., flowering plants).
• Key Point: Reproduction is not an inclusive characteristic of life, as some organisms (e.g., mules, sterile worker bees) are living but do not reproduce.

E. Mortality

• Definition: The inability to sustain metabolism leads to the death of an organism.
• Key Point: No living organism is immortal; death is an inevitable outcome of life.

F. Responsiveness (Irritability)

• Definition: The ability to respond to environmental stimuli (thermal, chemical, or Hannah, biological, or physical).
• Key Point: This is a unique property of living beings, distinguishing them from non-living entities.
• Example: Plants bending toward sunlight (phototropism).

1.2 Differences Between Living and Non-Living

1.3 Are All Organisms Similar?

• Answer: No, all organisms are not similar.
• Justification: Organisms exhibit immense diversity in structure, function, habitat, and behavior. For example:
  • Morphological Diversity: Bacteria vs. humans.
  • Physiological Diversity: Autotrophs (e.g., plants) produce their own food, while heterotrophs (e.g., animals) depend on others.
  • Ecological Diversity: Organisms occupy varied habitats (e.g., deserts, oceans).
• This diversity is studied systematically to understand interrelations and maintain ecological harmony.

1.4 Taxonomical Aids

To study the vast diversity of organisms, taxonomical aids are used for identification, classification, and documentation.

A. Herbarium

• Definition: A collection of dried, pressed, and preserved plant specimens mounted on standard sheets.
• Features:
  • Includes details like date, place of collection, classification, ecological notes, local names, and collector’s name on a label.
  • Used for taxonomic studies and preservation.
• History: Initiated by Luca Ghini (1490-1556); the term coined by Pitton de Tournefort.
• Example: Kew Botanical Garden, England, houses over 7 million herbaria.

B. Botanical Gardens

• Definition: Places where living plants from different regions are grown scientifically and systematically (in vivo).
• Features:
  • Plants are labeled with scientific and common names.
  • Greenhouses provide controlled environments for exotic species.
  • Support conservation, research, and education.
• History: First established by Luca Ghini in 1543 at Pisa, Italy.
• Example: Kolkata Botanical Garden with a 255-year-old Banyan tree.

C. Museums

• Definition: Repositories of preserved plant and animal specimens.
• Features:
  • Specimens preserved in formalin (10-40% formaldehyde) or as dried exhibits.
  • Larger animals (e.g., birds, mammals) preserved via taxidermy (stuffing).
  • Include collections like shells, skeletons, and insect boxes.
  • Serve as reference hubs for biodiversity studies.
• Example: Biological museums in educational institutes.

D. Zoological Parks (Zoos)

• Definition: Facilities where wild animals are kept in captivity with conditions mimicking their natural habitats (ex situ).
• Features:
  • Used to study animal behavior and food habits.
  • Support conservation and public education.
• Example: Jijamata Udyan, Mumbai, with acclimatized Humboldt penguins.

E. Biodiversity Parks

• Definition: Ecological assemblages of species forming self-sustaining communities on degraded landscapes.
• Features:
  • Restore ecosystems and conserve natural heritage.
  • Example: Uttamrao Patil Biodiversity Park, Gureghar, Mahabaleshwar.

F. Other Tools

• Flora: Records plant life in a specific area at a given time.
• Monograph: Detailed study of a selected biological group.
• Manual: Provides keys and information for species identification.
• Key: Taxonomical aid using dichotomous (contrasting) characters for classification.
  • Lead: A statement in the key; one character is accepted, and the other rejected.

1.5 Conservation of Biodiversity

• Definition: Biodiversity is the variety of life forms in an ecosystem, essential for ecological stability.
• Importance:
  • Maintains ecosystem health and stability.
  • Ethical responsibility to protect coexisting species.
• Threats:
  • Population explosion and overexploitation of resources.
  • Habitat destruction due to ambitious projects (e.g., road construction, river linking).
• Conservation Strategies:
  • In situ Conservation: Protecting species in their natural habitats (e.g., sacred groves, national parks).
  • Ex situ Conservation: Conserving species outside their habitats (e.g., zoos, botanical gardens).
• Example Issue: Bauxite mining in Western Ghats threatens species like black panthers, Ceropegia spp., and Eriocaulon spp.