Biology

   Population Interactions For any species, the minimal requirement is one more species on which it can feed. Even a plant species, which makes its own food, cannot survive alone; it needs soil microbes to break down the organic matter in soil and return the inorganic nutrients for absorption. In nature, animals, plants and microbes interact in various ways to form a biological community. Interspecific interactions arise from the interaction of populations of two different species. They could be beneficial, detrimental or neutral (neither harm nor benefit) to one of the species or both. Assigning a ‘+’ sign for beneficial interaction, ‘-’ sign for detrimental and 0 for neutral interaction, look at all the possible outcomes of interspecific interactions. Species A Species B Name of Interaction + + Mutualism - - Competition + - Predation + - Parasitism + 0 Commensalism - 0 Amensalism Both the species benefit in mutualism and both lose in competition in their interactions with ea...

  Evolutionary Biology is the biology in which we study about history of life forms on earth. Various theory has been proposed about origin of life forms. Theories about origin of life forms Various theories has been given in support how first life appear on earth. They are as below - Some scientists believe that it came from outside. Early Greek thinkers thought units of life called spores were transferred to different planets including earth. ‘Panspermia’ is still a favourite idea for some astronomers. For a long time it was also believed that life came out of decaying and rotting matter like straw, mud, etc. This was the theory of spontaneous generation . Louis Pasteur by careful experimentation demonstrated that life comes only from pre-existing life. He showed that in pre-sterilised flasks, life did not come from killed yeast while in another flask open to air, new living organisms arose from ‘killed yeast’. Oparin of Russia and Haldane of England pro...