Locomotion In Earthworm

Locomotion in Earthworm: 

     Earthworms, being terrestrial, are adapted to locomotion in soil. Their movement is brought about by the contraction of two sets of muscles and their body fluid, serving as a hydrostatic skeleton. Contraction of longitudinal muscles shortens the body and contraction of circular muscles lengthens (elongation) the body. As a result of interaction of muscles contractions and compressed body fluid an earthworms crawls.   

          In addition bristles called setae extending from the body wall in each segment grasp the soil functioning as hold fast to take the grip of the soil.

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Gene Pool

Gene Pool:   

 All the genes / alleles found in a breeding population at a given time are collectively called the gene pool. It is the total genetic information encoded in the genes in a breeding population existing at a given time.

Explanation: 

     A population is any group of interbreeding organisms of the same species that exist in both time and space. 

Concept of 'Breeding Genetics'

    If we imagine population not as a group of individuals, but as a group of individually segregating and randomly assorting alleles, we can understand the concept of 'breanbag genetics'. The alleles are like beans in a bean bag. The entire bean bag full of beans is the gene pool of the population. In the bean bag approach we can imagine the entire gene pool comprising all the alleles for all the different traits at once, or we can just focus on some subset, such as all the alleles for a single trait.

      A sample population of 100 diploid plants, some of which bear red flowers, others bearing white flowers has a sum total of 200 of all the different alleles for flower colour trait as its gene pool.

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