Notes

Air Pollution and Its Control * An undesirable change in the physical, chemical or biological characteristics of air, water, land or soil that may have detrimental effects on living organisms is called pollution. * Substances that bring about such undesirable changes are called pollutants. * Common air pollutants are automobile exhausts, chemicals and toxic gases ... Read more

Garbage In Garbage Out * A landfill is a large, low-lying area used for garbage disposal. * The useful components of garbage are fruits, vegetable waste, food remains, tea leaves, coffee grounds and paper. * The non - useful components of garbage are polythene bags, plastic and aluminium wrappers. * The government or the municipality ... Read more

Air Pollution: Gaseous Pollutants * Pollution is the harmful effect on the environment that can prove fatal to all living organisms. * Pollutant can be solid, liquid or gaseous, and originate from human actions and natural sources. * Air pollution takes place in two different layers of the earth’s atmosphere- the troposphere and the stratosphere. ... Read more

Heredity and Evolution - Evolutionary Relationships II * Homologous and analogous characteristics help identify an evolutionary relationship between different species. * Fossils are an important evidence of evolution. * Evolution of eye in different species is an example of biological convergence. * Reptiles and birds have evolved from a common ancestor through adaptation. * Different ... Read more

Population Change * Population change refers to the change in the number of people due to birth, death or migration during a specific period of time. * The rapid growth in population is referred to as population explosion. * Birth rate is the number of live babies born in a year for every 1000 people ... Read more

How Do Organisms Reproduce? - Reproduction in Unicellular and Multi-cellular Organisms * Organisms like Hydra reproduce by building. They use the regenerative cells for reproduction in the process of budding. A bud develops as an outgrowth due to repeated cell division at a specific site on the hydra. Each of these buds develops into a ... Read more

Human Endocrine System * Endocrinology is a branch of medicine dealing with the study of the endocrine glands and the actions of their hormones. * The hypothalamus, pituitary, thyroid, parathyroid, thymus, pancreas, adrenal and gonads are the endocrine glands on our body. * Endocrine glands are also called ductless glands due to the absence of ... Read more