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Class 12 Biology notes

Written by Dr. Hira Salman (Biology)

Chapter notes with key points, definitions, short questions and model answers. Each chapter links to practice questions.

Chapter notes

Homeostasis

What homeostasis is, negative feedback, osmoregulation, excretion and the structure and working of the human kidney, and the control of body temperature. Chapter notes

Nervous coordination

The organisation of the human nervous system, the neurone, resting and action potentials, synapses and neurotransmitters, reflex arc, the brain and spinal cord, autonomic nervous system, the eye and ear, and common nervous disorders. Chapter notes

Endocrine coordination

Hormones and endocrine glands, the hypothalamus and pituitary, thyroid, parathyroid, adrenal and pancreatic hormones, sex hormones, feedback control, mechanisms of hormone action and disorders caused by too much or too little hormone. Chapter notes

Reproduction

Asexual and sexual reproduction, the male and female reproductive systems, gametogenesis, the menstrual cycle, fertilisation, pregnancy, birth, the placenta, lactation, birth control, and reproduction in flowering plants. Chapter notes

Inheritance

Mendel's experiments and laws, monohybrid and dihybrid crosses, test cross, incomplete dominance, codominance and multiple alleles, sex determination, sex linkage, linkage and crossing over, and mutations. Chapter notes

Evolution

Origin of life ideas, evidence for evolution, Lamarck's and Darwin's theories, natural selection, variation and adaptation, speciation, the Hardy Weinberg idea, and the evolution of humans. Chapter notes

Ecology

Levels of organisation in ecology, ecosystem components, food chains and energy flow, ecological pyramids, nutrient cycles, populations, succession, human impact such as pollution and climate change, and conservation. Chapter notes

Biotechnology

Traditional and modern biotechnology, genetic engineering tools, recombinant DNA, PCR and gel electrophoresis, cloning, transgenic organisms, gene therapy, applications in medicine and agriculture, and ethical issues. Chapter notes

Support and movement

The need for support and movement, the human skeleton, types of bone and cartilage, joints, muscles and the sliding filament mechanism, antagonistic muscles, skeletal disorders and support in plants. Chapter notes

Immunity and disease

Pathogens and the diseases they cause, how infections spread, body defences, the immune response with antibodies and lymphocytes, types of immunity, vaccination, allergy, HIV and AIDS, and control of disease.

Class 12 Biology practice questions