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Allele definition biology || NEET | AIIMS ||

  Alleles  Each gene may exist in alternative forms known as alleles, which code for different versions of a particular inherited character.  We may also define alleles as genes occupying corresponding positions on homologous chromosomes and controlling the same characteristic (e.g. height of plant) but producing different effects (tall or short).  The term homologous refers to chromosomes that carry the same set of  genes in the same sequence, although they may not necessarily carry    identical alleles of each gene.             Wild-type Alleles Normal or Prevalent alleles in a population are called wild-type alleles. These alleles typically encode proteins that are made in the right amount and function normally.  Mutant Alleles   Alleles that are present at less than 1% in the population and have been altered by mutation are called mutant alleles ....
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Larval forms of Echinoderms……..

Larval forms of Echinoderms…….. A. Dipleurula Larva: 1. The dipleurula form is reached during development and is characterised by its bilaterally symmetrical, egg-shaped body. 2. The ventral concave side bears the mouth and is encircled by a circumoral ciliated band. 3. The digestive canal is differentiated into oesophagus, stomach and intestine while anus is disposed ventrally. 4. The pre-oral lobe which is situated at the anterior to mouth, bears an apical sensory plate and a tuft of cilia. 5. The ciliation on the surface of the body becomes reduced to a ciliard band. >>> This Dipleurula form is regarded by many as the hypothetical ancestral form of Echinoderm, as this form is universally present. The Dipleurula concept was first propounded by Bather (1900). The major changes involved in other Echinoderm lar­vae are due to differential disposition of the ciliated bands.     ...
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Water Vascular or Ambulacral System of Star Fish ; Asterias

how start fishes moves without fins??????  let see how ⇊⇊⇊ Water Vascular or Ambulacral System Water Vascular System is a unique feature of  of all the echinoderms which helps mainly in locomotion .  This it is the modified part of the coelom and consists of a system canals which is filled with sea water, containing amoeboid corpuscle s .   It plays a vital role in the· locomotion of the animal and obtaining food is the major function of water Vascular system.  The water vascular system of starfish consists of                 1. madreporite,                2. stone canal ,               3. ring canal,               4. radial canal,               5. Tiedemann’s bodies,               6....
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