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Definition: The term “biodiversity” has been derived from ‘bio’ and ‘diversity ’. “Diversity” means variety within a species and among species.  Biodiversity is a measure of the variety of organisms present in  different ecosystems. The diversity of plants’ (flora) and animals’ (fauna) in a region depends on climate, altitude, soils and the presence of other species. Biodiversity is not distributed evenly on Earth. Importance of biodiversity Biodiversity provides food for humans.  Drugs are derived, directly or indirectly, from biological sources.   Industrial materials e.g. building materials, fibres, dyes, resins, gums, adhesives, rubber and oil are derived directly from plants. Biodiversity plays important role in making and maintaining ecosystems.  It plays a part in regulating the chemistry of our atmosphere and water supply. Biodiversity is directly involved in recycling nutrients and providing fertile soils. Classification - Aims And Principles biologists classify the organism

“A species is a group of organisms which can interbreed freely among them and produce fertile offspring, but are reproductively isolated from all other such groups in nature.”  In the definition of species we must emphasize “in nature” because two organisms related to two different but closely related species can cross-breed under artificial conditions. Carolus Linnaeus divided nature into three kingdom s: mineral, vegetable and animal .  Linnaeus used five ranks in classification: class, order, genus, species, and variety .  Linnaeus is best known for his introduction of the method still used to formulate the scientific name of every species i.e. binominal nomenclature . Oldest system  classifies all organisms into two kingdoms i.e. Plantae ( organisms that can prepare food from simple inorganic materials and thus can store energy, are autotroph) and Animalia( organisms that cannot synthesize their food and depend on autotrophs or others are heterotrophs  )  and is known as two

The Shapes of Molecules (VSEPR Theory)  The shapes of molecules are  predicted and rationalize by  Va l ence  Sh ell Electron Pair Repulsion (VSEPR) theory .  The theory is based on minimizing the electrostatic repulsion between electron pairs, as first proposed by Sidgwick and Powell in 1940,   then generalized by Gillespie and Nyholm in 1957. Determine the number of lone pairs on the central atom in the molecule, and add the number of bonded atoms (a.k.a. bonding domains) the  steric number  defines the electronic shape of the molecule by minimizing repulsion. For example a steric number of three gives a trigonal planar electronic shape. The angles between electron domains are determined primarily by the electronic geometry (e.g., 109.5° for a steric number of 4, which implies that the electronic shape is a tetrahedron) These angles are adjusted by the hierarchy of repulsions: (lone pair - lone pair) > (lone pair - bond) > (bond - bond)

Here you go students an easy way to memories parts of your brain ,its basic structure . The  CNS   ( central nervous system ) is comprises of the brain and the spinal cord. The  PNS   ( peripheral nervous system ) comprises of  the spinal nerves that branch from the spinal cord and cranial nerves that branch from the brain. The brain have three parts  cerebrum :  composed of right and left hemispheres. It performs functions like interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement. cerebellum :  function is to coordinate muscle movements, maintain posture, &balance. brainstem  : connecting the cerebrum and cerebellum to the spinal cord. It performs many automatic functions such as breathing, heart rate, body temperature, wake and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing. The cerebrum is divided into four lobes:  frontal ,  parietal ,  occipital  temporal The surface of the cerebrum is ca