Evolution Test - 15

Homologous organs are structures or organs of different animals that evolved from a common ancestor (similar developmental origin) but differ in their functions. On the other hand, analogous organs are structures that evolved independently (different developmental origin) in two different species of organisms to serve a similar function. The wings of a butterfly and a bird have a similar function of flying but they are anatomically different in origin.

If a starfish possess 6 arms instead of 5, it is an example of variation [variation  is  any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences (genotypic variation) or by the effect of environmental factors on the expression of the genetic potentials (phenotypic variation)]. Variation may be shown in physical appearance, metabolism, fertility, mode of reproduction, behaviour, learning and mental ability and other obvious or measurable characters. Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal 's body structure through cell growth and differentiation. Biogenesis is the production of new living organisms or organelles and evolution is change in heritable traits of biological populations over successive generations.

The organs which have different embryonic origin but perform same function are called as analogous organs, e.g., wings of bat and insects. The organs which have same embryonic origin but adapted to perform different functions are known as homologous organs, e.g., wing of bat and forelimb of humans.

The first theory of evolution was proposed by Jean Baptiste de Lamarck Lamarckism proposed, Some internal forces are present in all organisms. Due to  the presence of these forces, the organism has the tendency to increase the size of their organs or the entire body.
Environment influences all type of organisms. Changing environment give rise to new needs. New needs or desires produce new structure and change habits of the organism.
If an organ is constantly used, it would be better developed whereas disuse of organ results in its degeneration.
So, the correct option is 'Lamarck '.

Fossilization occurs after an organism dies and only affects hard body parts, such as bones and shells. Soft flesh, scales, and feathers will not become fossils, although, imprints of these parts are sometimes made. In order for fossilization n to occur three things must happen. First, an organism dies.

Fossil 'X 'can be considered to have evolved earlier than fossil 'Y 'if fossil 'X 'is found in lower stratum of undisturbed sedimentary rock than 'Y '. Fossils are preserved forms of living organisms that really existed on earth. Presence of 'X 'in lower stratum indicates that it existed of 'X 'in lower stratum indicates that it existed much before than 'Y '. 

The Mesozoic era is called the age of reptiles(golden)  because this is when dinosaurs dominated the Earth. When a mass extinction occurred, it killed off all of the dinosaurs and was one of the largest in the history of the Earth.

Answer:

Fossils are dated by:

• Amount of radioactive carbon compound: Fossils can be dated using a method called radiocarbon dating, which measures the amount of radioactive carbon compound (carbon-14) present in the fossil. This method is used to determine the age of organic materials up to approximately 50,000 years old.



 
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Other options:

• Amount of calcium residue: The amount of calcium residue in a fossil is not used to determine its age.


• Association with other mammals: While the association with other mammals can provide information about the environment and ecosystem in which the fossil was found, it does not directly date the fossil.


• Structure of bones: The structure of bones can provide information about the anatomy and characteristics of the organism, but it does not directly date the fossil.



 
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Therefore, the correct answer is b. Amount of radioactive carbon compound .

Life was not possible in Azoic era because it was the first era on earth and the temperature and climate was not favorable of living creatures.

Evolution leads to changes in the characteristics of a living organism according to the changing environmental conditions with time. This change creates variations which are inherited from one generation to the other. The modification leads to shifting of simpler structures into complex structures due to evolutionary changes and helps to adapt in harsh conditions. For example two-chambered heart of fishes turned to three chambered in amphibians and three to four chamber in reptiles which ends on completely modified four-chambered heart in man.

So, the correct answer is option C.