Inter-relationships of classification, Biology

Assignment Help:

Inter-relationships of Classification

The aim of classification is to put together organisms on the basis of their similarities. But the question is what type of similarities? You know that fish and whales live in water; birds and butterflies live in air. Should we place fish and whales, in one group and birds and butterflies in another? Perhaps you are tempted to do so because fish and whales have organs to swim; birds and butterflies possess wings to fly. One of the early biologists, Pliny, in fact, classified animals on the basis of such analogous organs, that is organs that serve the same function and have similar appearance but have different evolutionary origins However, with the advancement in knowledge about the structure of animals it was revealed that the fish and whales or birds and butterflies have more differences than similarities between their body characters.

For example, fish respire using gills while the whales have lungs for this function. Similarly, birds have an internal skeleton whereas insects like butterflies lack it; instead they have an exoskeleton. Karl Linnaeus recognised these basic differences and based his system-of classification on the principle of homology. Homologous organs are those with the same evolutionary origin but which may not necessarily have the same appearance or serve the same function. For example, if you examine the fore-limbs of a man, the wing of a bat and the flipper of the whale (all mammals) you will see that in each case, though the function and the appearance of each of the fore-limbs are different, their basic skeletal plan is the same and they are homologous.

Furthermore, fossil records show that they all have a common evolutionary origin from the forelimbs of ancient amphibians. Thus, we conclude that all animals with pentadactyl forelimbs are related. Thus classification based upon homology reveals an inherent relationship among groups. In other words, it tells us that all creatures sharing basic structural features are related to each other and have evolved from a common ancestor.


Related Discussions:- Inter-relationships of classification

Disability evaluations after injuries, Disability evaluations after injurie...

Disability evaluations after injuries: (a) Explain the following terms: "duration of disability" and "degree of disability". (b) Explain how degrees of disability after injur

Calculate the volume of a 25% urethane, Assume that the blood volume of a r...

Assume that the blood volume of a rabbit is 0.5 liters. If the effective dose of the anesthetic urethane is 10 µgrams/ml of blood, calculate the volume of a 25% urethane solution t

Phylum, morphological characterstics of e histolytica

morphological characterstics of e histolytica

Composition-atmosphere, Composition The present day composition of atmo...

Composition The present day composition of atmosphere is the product of a lengthy evolutionary process that began more than four billion years ago. It is composed of a mixture

What are the symptoms associated with campylobacteriosis, What are the symp...

What are the symptoms and foods associated with campylobacteriosis?  Campylobacteriosis incubation period: 2-5 days after ingestion of contaminated food.  Symptoms: Diarrhoe

Explain the effect of deficiency of thiamin, Explain the Effect of Deficien...

Explain the Effect of Deficiency of Thiamin? Thiamin deficiency causes the disease beriberi in human beings, which has been classically considered to exist in dry (paralytic) a

Potassium ions maintain the resting potential of neuron, Q. How do the pota...

Q. How do the potassium and sodium ions maintain the resting potential of the neuron? The plasma membrane of the neuron when at rest maintains an electric potential difference

Ethylene - plant hormones, Ethylene - Plant Hormones Amongst hormones ...

Ethylene - Plant Hormones Amongst hormones in both plant and animal kingdoms, ethylene, a gaseous hydrocarbon, is unique. Despite its chemical simplicity, it is a potent growt

Explain skeletal muscle, Explain Skeletal muscle Skeletal muscle has...

Explain Skeletal muscle Skeletal muscle has low activity of glucose-6-phosphate dehydogenase. Yet, like most other  tissues  it can synthesize ribose-5-phosphate.  This  is.

An experiment to test the hypothesis, How would you design, in principle, a...

How would you design, in principle, an experiment to test the hypothesis that a certain variety of lettuce seed needed daylight in order to germinate?  You would need as large

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