Morphological and anatomical evidences of evolution, Biology

Assignment Help:

MORPHOLOGICAL AND ANATOMICAL EVIDENCES -

(i) HOMOLOGOUS ORGANS -

  • The organs apparently similar or dissimilar in structure and function, but of similar embryonic origin. Term homology used by Richard Owen 1804 - 1892.
  • A detailed and extensive study showes that all of them have following characteristics.
  • A fundamental similar plan
  • Contain approximately the same 'number of bones

1056_homologous organs.png

  • e.g. Fore limbs of whale, birds, bat, horse & man.
  • Mouth parts of insect is mode up of Maxilla, mandible, Labium, Labrum and hypopharynx but are adopted for different mode of feeding.
  • When function are different then it is called divergent evolution.

(ii) ANALOGOUS ORGANS -

  • The organs that have the same function and have superficial resemblance to one another but are dissimilar structure details and origin.
  • The phenomena among widely different groups is called convergent evolution.
  • e.g. Wings in insects, birds and bats are dissimilar in structure but similar in function i.e. flying.

(iii) VESTIGIAL ORGANS -

  • The organs that are present in reduced form and are useless to the possessor but correspond to the functional organs of related past animals.
  • e.g. Appendix, muscles of pinnae, nictitating membrane, coccyx, canine teeth and third molar in man, the rudimentary pelvic girdle in python.
  • In human beings total 180 vestigial organs are known.

382_vestigial rgans.png

(iv) ATAVISM (Reversal) -

  • It is the reappearance of certain ancestral characters that had either disappeared or reduced.
  • Example. Power of moving pinna in some person, greatly developed canine teeth, exceptionally long dense hairs (Lionboy of Russia), short tail in some babies, presence of additional mammae in some individuals.

Related Discussions:- Morphological and anatomical evidences of evolution

How white blood cells are collectively referred, The various types of white...

The various types of white blood cells are sometime together referred to as: a) Erythrocytes (pron: eh-rith-row-cites) b) Erythroblasts (pron: eh-rith-rah-blast) c) Leuko

Explain microbiology of vegetables, Q. Explain Microbiology of vegetables? ...

Q. Explain Microbiology of vegetables? Ans. All of us are well aware that vegetables are grown in soil, which, we already know, are a rnajor support system for the mi

Explain noncompetitive inhibitor, Explain noncompetitive inhibitor A no...

Explain noncompetitive inhibitor A noncompetitive inhibitor can combine with either the free enzyme or the enzyme- substrate  complex, interfering  both.  The  most  common  ty

What is hdls, HDLs have the opposite function to that of LDLs in which they...

HDLs have the opposite function to that of LDLs in which they deleted cholesterol from the tissues.  The HDLs are synthesized in the blood mainly from components derived from the d

Define isolated soybean proteins in seafood products, Define isolated soybe...

Define isolated soybean proteins in Seafood products? The most important application in this category is the use of ISP in fish sausage and surimi based restructured fish produ

Why is a leguminous crop rotation used in agriculture, Q. Why is a legumino...

Q. Why is a leguminous crop rotation used in agriculture? The Leguminous crop rotation and other crop rotations are used in agriculture for the reason that in these plants many

Define fluids required for underweight - nutritional care, Define Fluids re...

Define Fluids required for underweight - nutritional care? Take fluids only after a meal instead of with or before meals so that food intake is not reduced. High calorie nouris

What are the sources of dietary fibre in our diet, Q. What are the sources ...

Q. What are the sources of dietary fibre in our diet? The sources of dietary fibre include whole grain cereals, legumes, whole pulses, leafy vegetables, vegetables like peas,

Which areas of the globe is gymnosperm abundance noteworthy, Q. In which ar...

Q. In which areas of the globe is gymnosperm abundance noteworthy? These plants are the typical vegetation of cold regions like the boreal forest or taiga of the northern hemis

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd