Basics of Biology

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.                         

How metabolism problems comes from parents ?? Watch this video for better understand

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.  polian vesicles,               7.  lateral canals and                8. tube feet. 1. Madreporite The water vascular system of star fish starts from the madreporite , which is rounded and hard due to calcareous plate on the aboral surfa

Gene may has more than 2 alleles   😕.... Is it !!!!!!!! As we have studied that some genes may exist in three or more allelic forms which we called as   multiple alleles . ⇦ Here are some examples of multiple allelism  ABO Blood group in Humans. Skin Colour in Humans. Eye colour in Drosophila. Coat colour in Rabbit. 1. ABO Blood group in Humans. A classical example of multiple alleles is found in the ABO blood group system of humans.  The RBC's of people with type A blood group contain A antigens, those with blood group B contain B antigens, those with type AB blood group have both A and B antigens and those with O blood group don't have any A or B antigens. The I A  and I B   alleles are responsible for production of A and B antigens. The alleles I A  for the A antigen is codominant with the allele I B   for the B antigens. Both I A   and  I B  are completely dominant to allele i, which fails to specify A or B antigens.  The plasma of type A bloo

Multiple Alleles As e ach gene may exist in alternative forms known as alleles , which code for different versions of a particular inherited character.  A part from that some genes may exist in three or more allelic which may be called as multiple alleles .  It is important to note that while multiple alleles occur and are maintained within a population, any individual possesses only two such alleles (at equivalent  loci  on  homologous  chromosomes). Characteristics of Multiple allelism A single gene has more than 2 alleles. Only 1 allele of a particular gene occupied by a gamete or a chromosome. Various alleles of the same gene express different alternative of same trait. Multiple alleles in a homologous chromosome occupy the similar locus. Examples of Multiple Allelism ABO Blood group in Humans. Skin Colour. Eye colour in Drosophila. Coat colour in Rabbit.