BIOLOGY 3 Marks Question

Fossils of the Neanderthal were excavated from the neander Valley in Germany in 1956 by C.Fuherott.
Characteristics :
1. Their origin and development occurred 40,000 to 1 lakh years ago.
2. They lived in huts built in the open fields.
3. Body length was about 1.8 m.
4. Cranial capacity was about 1600cc.
5. Absence of eyebrow ridges and flattened forehead.
6. Upright locomotion because Lumber curve had fully developed.
7. Well developed and elevated nose were present.
8. Face was orthognathous.
9. Evidences of making tools and uses of skin cloths, cave painting, burial ceremony of dead bodies confirmed their better advanced life then other Prehistoric man.

American scientist Stanley Miller under the guidance of teacher Harold C. Urey provided the first experimental evidence in the support of chemical evolution theory of Oparin. He filled a glass chamber of 5-litre with a gaseous mixture of methane, ammonia and hydrogen gases in the proportion of 2:1:2. A tube carrying water vapour was also connected to the chamber to provide a continuous supply of water vapour to the larger flask. To tungston electrodes connected to an electric were fitted to the larger flask to provide energy of electric discharge stimulating the effect of lightning of the primitive atmosphere that is why Millers apparatus is also called Spark discharge operator. On the other side, the large flask was connected to a small U-tube by means of a straight tube passing through a condenser. When the experiment had continue for about a week, the gases formed get condensed as dark red liquid in the U-tube. Chemical analysis of this mixture reported the presence of simple organic compound like amino acids such as glycine, alaline and simple organic acids like ribose sugar, purines, pyrimidines etc.

self

(i) In Australia.
(ii) Adaptive radiation (to study in detail read the topic adaptive radiation from point no. 6.3 in the Text.)
(iii) Placental wolf and tasmanian wolf exist sharing the same habitat in different continents former in Asia and the latter in Australia because these two show parallel evolution. They show independent development of similar characters in two animal groups living in similar habitats of different.

Differences between Darwinism and De Vries Theory :

Darwinism	De Vries Theory
1. According to Darwin, variations are small and directional.	According to De Vries, mutation are directionless and random.
2. Small and gradual variations cause evolution.	Sudden random and distinct variation called mutation causes evolution.
3. Evolution occured gradually	Evolution occurred all of sudden in single slip.

Homology : Bones of forelimbs of mammals like seal, horse, bat, whale and human show the great resemblance in arrangement and are drived from the same part of the body. The relationship between the structures having common basic plane and similar development origin is called homology or divergent evolution or adaptive radiation, although these structure might have diverse due to their specific functions. Homology also reveals common
ancestory and inter relationship.
Analogy : The wings of birds and butterfly are functionally similar but are different in basic structure and development origin these are called analogous organ and this relationship between structures of different groups of animals of separate lineage due to their similar function is called analogy or convergent or parallel evolution.

Differences between the theory of De Vries and Lamarck :

De Vries’s Theory	Lamarckism
1. De Vries proposed mutation theory of evolution	1. Lamarck proposed the theory of inheritance of acquired characters.
2. According to De vries, the origin of new species is not by inheritance of small variation but by inheritance of sudden large variations due to mutation.	2. According to Lamalck, the environment has a great influence on the growth and thaped shape of life due to which the structure of their organs gradually charges These acquired changes all inherited in ancestral traits from one generation to the next.
3. Example : Evening primrose plant.	3. Example : Giraffe’s neck is long

According to Darwin, struggle for existence of life can be of three types :
1. Intra specific struggle : It is the struggle between the individuals of the same species because their requirements like food, shelter, breedinging places etc are similar, i.e. if a loaf of bread is thrown between two dogs, they start fighting among themselves. The one who is more powerful among them takes the bread. Many human wars are the example of intra specific struggle. Cannibalism is another example of this type of struggle.
2. Inter-specific Struggle : It is the struggle between the members of different species. This struggle is normally for food and sheltereg. Usually seen as the cat see the rat, tries to hunt it while the rat tries to protect itself by escaping.
3. Environmental Struggle : It is the struggle between the organism and the environmental factor such as drought heavy rains extreme heat or cold earthquakes disease et cetera does climate and other natural factors also help in restricting the number of individuals of a particular species. 

In the classification, organisms with similar characteristics are placed in the same group. There are some animals which share the characteristics of two different groups. These animals are called connective links.
Examples of connective links are as follows :
1. Fossils of Aracheopteryx have been found in the Bavaria region of Germany. Some characteristics of this animal, such as—the shape of beak, wings and legs, are from the class Aves, while some characteristics like the presence of teeth, tail and scales on the body are from the classreptilia hence it is called the connecting link between birds and reptiles. This proves that birds have evolved from reptiles.
2. Similarly, the egg-laying mammals platypus and echidna are the connecting link between reptiles and mammals.
3. Peripatus is called the connecting link between phylum Annelida and phylum Arthropoda. Importance of Connecting Link in biological Evolution : Connective links are an important basis for proving biological evolution. Through them, knowledge of definite genealogy and ancestors of different castes and classes is available and the course and direction of biological evolution is also determined in them.

Artificial Selection : Genetic variation is used by humans to improve the quality of animals and plants. Humans select individuals with desirable traits from the population and separate them from those who do not have these traits. Now interbreeding is done between the selected individuals. This process itself is called artificial selection. If this process continues for several generations, eventually a new species with desirable characteristics is produced.
Through artificial selection by animal breeders, species of many domesticated animals with desirable characteristics have been developed from their common ancestors, such as dog, horse, pigeon, Chicken, cow, goat, sheep and pig etc. Similarly, plant breeders have also obtained the best variety of useful plants like wheat, rice, sugarcane, cotton, vegetables and fruits etc.
Artificial selection is similar to natural selection, only in this, instead of nature, useful traits are created by humans Selected traits that are useful to humans are developed. 

This phenomena was studied by Bernard Kettelwell. The study of this experiment made it clear that the stems of plants before industrial development in England were brown in color because they had a layer of brown lichen on them. At that time the number of brown colored moths was very high there and the black colored moths Carbonaria were less and rare in number. The probable reason for this was that the brown color of the stems was providing protection to the brown moth from carnivorous birds as the moths could not be identified due to the similar background on the stems. Due to industrial development, excessive use of coal started, due to which the amount of soot in the environment increased, as a result, due to accumulation of soot on the stems, their color became black. At this time, brown moths became easily identified by birds, they preyed them and destroyed them. After some time it was observed that the number of brown colored moths had reduced but the number of black colored moths had increased drastically because at this time the black color of the stem was providing them safety. At present, electricity is being used in place of coal in the industries. It started being used due to which black and smoke in the atmosphere almost got eliminated and as a result, the stems of plants returned to their previous color i.e. became bad. This color change also affected the number of black colored slugs. Now due to identification of black moths by the birds, they started being eaten easily but due to the birds not being able to identify the brown moths, they were saved from being hunted. In this way, nature plays an important role in the selection of life.

According to Oparin, after the origin of the Earth, life forms were created by the combination of chemical substances in its water reserves. These were organisms made of single cells. From these, various types of life were born through the process of biological evolution. Literally the biological evolution means unrolling or unfolding to reveal modifications, i.e. gradual origin of complex life from simple life is called biological evolution. In other words, the origin of complex multicellular life by gradual changes from the simpler unicellular life over millions of years is called biological evolution. Decent with modification is the fundamental hypothesis of biological evolution.Living organisms are different from each other, but the structural organization of all of them is the same, that is, each body is made up of cells. The biological functions in all organisms are similar. All organisms begin their life fromsingle cell structure, zygote which reveals a common ancestor of these diverse organisms.

The following four fact regarding the evolution of organism were proved by the study of fossil:
(i) Fossils escapted from deeper and lower layer of rocks were simple while advanced and complex fossils were as caveted from upper and recent layer of rocks.
(ii) At the beginning of evolution single cell protozoans were formed from which multicellular organism were evolved.
(iii) Some fossils represent the transitional or connecting link between the two groups of organism.
(iv) Angiosperms among and mammals among animals are not developed and modern creature evolved during evolution.
(v) The fossils story or genealogy of any animals can be made sequentially by studying its Fossil History.