CBSE Class 12th Biology, NCERT Solutions, Sample & Previous Year Papers

Chapter 1 Reproduction in Organism Class 12 Notes Chapter 2 Sexual Reproduction in Flowering Plants Class 12 Notes Chapter 3 Human Reproduction Class 12 Notes Chapter 4 Reproductive Health Class 12 Notes Chapter 5 Principles of Inheritance and Variation Class 12 Notes Chapter 6 Molecular Basis of Inheritance Class 12 Notes Chapter 7 Evolution Class 12 Notes Chapter 8 Human Health and Disease […]

Pollution, Solid and Radioactive Wastes: 1. Pollution is an undesirable change’in the physical, chemical and biological characteristics of air, water, land and soil. (i) Pollutants are agents that cause undesirable change in the environment. (ii) The Government of India has passed the Environment Protection Act, 1986 to protect and improve the quality of our environment (air, […]

Biodiversity: 1. Biodiversity can be defined as the occurrence of different types of genes, gene pools, species, habitats and ecosystem in a given region. (i) The term biodiversity was given by a socio biologist Edward Wilson to describe the combined diversity at all the levels of biological organisation. (ii) There are more than 20,000 species of […]

Ecosystem—Structure and Function,- Productivity and Decomposition: 1. An ecosystem is a functional unit of nature, where living organisms interact among themselves and also with the surrounding physical environment. The word ‘Ecosystem’ was coined by Sir AG Tansley (1935). 2. The size of an ecosystem varies greatly from a small pond to a large forest or a sea. […]

Organisms and Its Environment: 1. Ecology is the branch of biology, which studies the interactions among organisms and their physical (abiotic) environment. 2. The subject ecology is basically concerned with four levels of biological organisation. These are given below: (i) Organism Living component of the environment at individual level and is basic unit of ecological hierarchy. (ii) […]

Biotechnological Applications in Agriculture and Medicine: 1. Biotechnology essentially deals with industrial scale production of biopharmaceuticals and biologicals. The applications of biotechnology include therapeutics, diagnostics, genetically modified crops for agriculture, processed food, bioremediation, waste treatment and energy production. 2. Biotechnology have the following three critical research areas: (i) To provide the best catalyst in the form of […]

Principles of Biotechnology and Tools of Recombination DNA Technology: 1. Biotechnology can be defined as the use of microorganisms, plants or animal cells or their components to produce products and processes useful to humans. According to the European Federation of Biotechnology (EFB), biotechnology is the integration of natural science and organisms, cells, parts thereof and molecular […]

Microbes in Household Products, Industrial Products and in Sewage Treatment: 1. Microbes are the major components of biological systems on the earth. They are present everywhere, i.e. in soil, water, air, inside our bodies and those of other animals and plants. They can also be found deep inside the geysers (thermal vents), deep in soil, under […]

Animal Husbandry: 1. Animal husbandry is the agricultural practice of breeding and raising livestock. It deals with the care and breeding of livestock like buffaloes, cows, pigs, horses, cattle, sheep, goat, etc. It also includes poultry farming and fisheries. More than 70% of the world’s livestock population is in India and China. Many new technologies have […]

Health, Common Diseases in Human and Immunity: 1. Health is defined as a state of complete physical, mental and social well-being. (i) The factors which affect human health are: (a) Genetic disorders (b) Infections (c) Lifestyle. (ii) Balanced diet, personal hygiene and regular exercise are very important to maintain good health. (Hi) Awareness about diseases and […]

The Origin of Life and Evidences of Evolution: 1. The study of history of life forms on earth is called evolutionary biology. 2. Evolution is a process that results in heritable changes in population spread over many generations leading to diversity of organisms on earth. 3. Origin of life is considered a unique event in the history of […]

The DNA and RNA World: 1. Over the years after Mendel, the nature of the genetic material was investigated, resulting in the realisation that DNA is the genetic material in majority of organisms. 2. Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA) are the two types of nucleic acid found in living systems. Nucleic acids are polymers of nucleotides. […]

Mendel’s Laws of Inheritance: 1. Genetics is the branch of biology, which deals with inheritance and variation of characters from parents to offspring. 2. Inheritance is the process by which characters or traits are transferred from one generation to the next. 3. Variation is the degree by which progeny differs from each other and with their parents. Humans […]

Reproductive Health Problems and Strategies: 1. Reproductive health simply refers to healthy reproductive organs with normal functions. According to the World Health Organisation (WHO), reproductive health means a total well-being in all aspects of reproduction, i.e. physical, emotional, behavioural and social. 2. The improved reproductive health of society requires following factors: (i) Better awareness about sex-related […]

1. Humans are sexually reproducing and viviparous organisms. There are remarkable differences between the reproductive events and systems in male and female. 2. Male reproductive system includes a pair of testes, accessory ducts, glands and the external genitalia. (i) Testes are located outside the abdominal cavity within a pouch called scrotum. Scrotum maintains the low temperature of […]

Sexual reproduction is the process of fusion of haploid gametes, resulting in the production of a diploid zygote, which ultimately develops into a new organism. All flowering plants show sexual reproduction. 1. Flowers are the site of sexual reproduction in flowering plants. (i) A flower has following parts arranged in four whorls, i.e. calyx (sepals), corolla […]

Reproduction: 1. The period between birth and natural death of an organism is called its lifespan. It can vary from less than a day to more than 400 yrs. Whatever be the lifespan, death of every individual organism is a certainty, i. e. no individual is immortal, except single-celled organisms. Lifespan of some organisms are […]