Biology G.C.E. (Advanced Level) Grade 12 In-depth Notes

General Information about Biology

  • Biology is the study of living organisms. It is divided into three main branches:
  • Zoology (study of animals)
  • Botany (study of plants)
  • Microbiology (study of microorganisms)

Importance of Biology

  • Understanding biological diversity formed over 3.8 billion years. There are estimated to be 10 to over 100 million species.
  • Biodiversity contributes to the balance of ecosystems and ecological roles.
  • Knowledge of biology leads to health improvements and sustainable use of resources.

Curriculum Changes in the G.C.E. (Advanced Level) Biology

  • A rationalized curriculum has been implemented since 2017 to reduce subject matter and improve teaching methodologies.
  • The new resource book was created to provide curriculum-aligned content for better learning experiences in the local language.

The Nature of Living Things

  • Life processes include:
  • Order and organization
  • Metabolism (the sum of all chemical activities)
  • Growth and development
  • Response to stimuli
  • Adaptation
  • Reproduction and heredity
  • Evolution

Properties of Water

  • Colorless, tasteless, and odorless.
  • Cohesive behavior (water molecules stick together)
  • Moderates temperature (high specific heat)
  • Ice is less dense than liquid water (expansion upon freezing)
  • Versatile solvent (dissolves many substances)

Organic Compounds in Living Matter

Carbohydrates
  • Classification: monosaccharides, disaccharides, polysaccharides
  • Functions include energy storage and structural support.
Lipids
  • Types: fats, phospholipids, steroids
  • Roles in energy storage, forming cell membranes, and hormones.
Proteins
  • Made of amino acids and have diverse functions like enzymes and immune responses.
  • Structure levels: primary, secondary, tertiary, quaternary.
Nucleic Acids
  • DNA and RNA structure and functions: genetic information storage and transfer.

Cell Basics

  • Cell theory: All organisms are composed of cells.
  • Differences between prokaryotic and eukaryotic cells: Prokaryotes lack nucleus and membrane-bound organelles; eukaryotes have complex structures.

Photosynthesis

  • Process by which plants convert sunlight into chemical energy.
  • Phases: Light-dependent reactions, Calvin cycle.

Cellular Respiration

  • Breaking down glucose to release energy.
  • Aerobic vs anaerobic respiration.

Plant and Animal Responses

  • Phototropism (light response), gravitropism (gravity response), and thigmotropism (touch response).
  • Hormones play an important role in regulating growth and response.

The Human Body

Digestive System
  • Composed of the alimentary canal and associated glands.
  • Primary functions include ingestion, digestion, absorption, and elimination.
Circulatory System
  • Comprises of heart, blood vessels, and blood.
  • Types: open circulatory system (insects) and closed circulatory system (humans).
  • The role of blood includes transportation of gases, nutrients, and waste.
Excretory System
  • Kidneys play a crucial role in osmoregulation and excretion.
  • Nephrons are the functional units of the kidney.
Immune System
  • Two types: innate (immediate response) and adaptive (specific response involving T and B lymphocytes).

Important Concepts in Evolution

  • Natural selection, genetic drift, mutations, and their roles in the adaptation and evolution of species.
  • Importance of biodiversity for ecosystem stability and resilience.

Environmental Concerns

  • Issues such as pollution, climate change, and conservation efforts to protect biodiversity.