Introduction to biology |Chapter 1 (part 2)|biology |class 9


Comments

Post a Comment

Popular posts from this blog

Muscles in your body

Image
A complete guide to muscles in your body There are 650 muscles in your body ,muscles fall into different categories each with its unique function 1 .skeletal muscles : attached to bones power your voluntary movements like walking and jumping. 2 .smooth muscles: found in your internal organs control involuntary processes like digestion. 3. cardic muscles : keep your heart tirelessly beating ensuring the circulation of blood and oxygen
Read more

shapes of molecules Valence Shell Electron Pair Repulsion |VSEPR

Image
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)
Read more

chapter 3 | Biodiversity part1

Image
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 bio...
Read more