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

Coronary revascularization, When underlying coronary artery disease is the ...

When underlying coronary artery disease is the cause of heart failure in the coronary revascularization may both improve symptoms and prevent  progression. Patients with angina and

What are the main proteins that constitute the sarcomere, What are the main...

What are the main proteins that constitute the sarcomere? What is the function of those molecules in the muscle cells? In the sarcomere there are organized myosin and actin blo

Define the parathyroid gland cells, Which of the following serves as a sens...

Which of the following serves as a sensor, or as part of a sensor, that functions in a negative feedback system? A. CaSRs (Calcium-Sensing Receptors) located in the plasma memb

Devonian, Devonian  is the period of geologic time from 410 - 360 million y...

Devonian  is the period of geologic time from 410 - 360 million years before the present. Life on land diversified, with amphibians appearing late in this period of time. Plants we

How is carbon dioxide made by producers and consumers, Q. How is carbon dio...

Q. How is carbon dioxide made by producers and consumers? The Carbon dioxide is made by consumers and producers through cellular respiration.

Explain starch - tests for presence of exoenzymatic activity, Explain Starc...

Explain Starch - Tests for the Presence of Exoenzymatic Activity? Starch is a polymer of glucose linked together by glycosidic bonds. Microorganisms produce hydrolytic enzyme a

Sterilization of apparatus for microbiology experiments, Sterilization of A...

Sterilization of Apparatus for Microbiology Experiments : Containers of dangerous biological materials and the doors leading to laboratories or rooms in which work with pathogenic

Explain sialography, Question 1 Explain Sialography? How will you perfo...

Question 1 Explain Sialography? How will you perform the same? Question 2 How will you set up your radiology department to take up the IVU studies? Question 3 D

Respiratory system in living organisms, Respiratory System in Living Organi...

Respiratory System in Living Organisms Respiration is a necessary physiological process in all living organisms by which they obtain energy for carrying out all the metabolic

Taxonomy, A In taxonomy, what is a "KEY" ? List the different types of key...

A In taxonomy, what is a "KEY" ? List the different types of keys. How are they prepared and what are they used for ?sk question #Minimum 100 words accepted#

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