Unit-4 Evolution

#. Answer the following Questions 

1). What is organic evolution?
Ans: The sequence of gradual changes which take place in primitive organisms over million of years in which new species are evolved called oragnic evolution.

2. List any two evidences of organic evolution?
Ans: They are over here:
1. Evidences from the study of fossils
2. Embryological Evidences

3. What are fossils? Where are they found?
Ans: Fossils are the relics of dead plants and animals preserved in rocksover along period of time.
The fossils are found in rocks as well as in underground of the soil.

4. What are bridge animals? Write with examples.
Ans: Organisms having characteristics of two different groups are called bridge animals.
For Exmaples:
1. Duck- billed platypus
2. Lungfish, etc

5. What are vestigial organs?
Ans: Vestigial organs are the organs present as reduced structure and functionless in the body.

6. What is struggle for existence?
Ans: The struggle for existence may be intraspecific i.e. among the memeber of same species and interspecific, i.e. among the members of different species sharing a common enviroment.

7. What are homologous organs? Write with example?
Ans: Homologus organs are organs having similar strucutre and origin but different in function.
Examples are: Wings of birds , Flipper of a Whale

8. What is natural selection?
Ans: The selection which has been made by the nature or by god is known as natural selection.

9. What is variation and heredity?
Ans: The structural difference that provides individually to each member of a species is called a variation.
The passing of physical or mental characteristics genetically from parents to their off spring or from one generation to another generation is called heridity.

10. Name any two biologists who propounded the theory of organic evolution.
Ans: Any two biologist who propounded the the theory of organic evolutions are over here:
1. Charles darwin
2. Lamarck’s (Jean Baptiste Lamarck)

11. Write any two features of mutation theory.
Ans: The any two features of mutation theory:
1. All mutations are inheritable
2. Mutations appear in all conceivable directions

12. What is neutral mutation?
Ans: The mutations that are neither benefical nor deterimental to the ability of any organism to survive or reprouduce are called netural mutations.

13. Define harmful mutation?
Ans: Any random change in gene’s DNA is likely to result in a protein that does not function normally or may not function at all such mutations are harmfull mutation.

14. Write any two differences between fossils and vestigial organs.
Ans: They are given below:

Fossils	Vestigial organs
Fossils are the petrified remains of ancient plants and animals or impressions left by them in rock.	Vestigial oragans are those organs in an organisms which are functionless
Fossils found in the sedimentry rocks.	Body hair, nictitating membrane etc. are some vestigial organs

16. Forelimbs of a human and forelimbs of a horse are called homologous organs. Why?
Ans: Forelimbs of a human and forelimbs of a horse are called homologous organs because they contain almost similar type and number of bones, blood vessels, nerves and muscles arranged in the same pattern.

17. Differentiate between variation and mutation.
Ans: They are given below:

Variation	Mutation
The structural differences that provide individually to each member of a species is called variation.	The structure of the genes, or chromosomes gets altered on rate occasions such change in gene or chromosome called mutation.
Occur due to mutations, genetic recombination, gene flow, genetic drift, random mating, random fertilization and enviromental factors.	Occur due to errors in DNA replication and exposure to UV or chemicals.

18. Duck-billed platypus is called a bridge animal. why?
Ans: Duck-billed platypus is called a bridge animal because they serves as connecting link between reptiles and mammals. It is oviparous and cold-blodded like reptiles and it has mammary glands, hairs and other mammalian characteristics.

19. Differentiate between embryology and paleontology.
Ans: They are given below:

Embryology	Paleontology
The branch of biology and medicine concerned with the study of embryos and their development .	The study of ancient life from dinosaurs to prehistoric plants, mammals, fish inscets, fungi and even microbes.
Concerns emmbryos and their devlopment.	Concerns fossils of animals and plants.
A branch of medicine.	A branch of science.

20. Archaeopteryx is considered as the animal development into bird from a reptile. Give reason.
Ans: Archaeopterxy is cosidered as the animal devlopment into bird from a reptile because they have characteristics of two different groups of oraganisms.

21. Lamarck’s theory is not accepted universally. Justify this statement.
Ans: Lamarck’s theory is not accepted universally beacuse the muscles of an athlte increase in strength and bulk with extensive use but they are never transmitted from father to child and the change in the strucutre of a body by use and disuse of organ is not manifested practically.

22. Differentiate between neutral mutation and benifical mutation.
Ans: They are given below:

Neutral Mutation	Beneficial Mutation
The mutations that are neither beneficial nor detrimental to the ability of an organism to survive or reproduce are called Neutral Mutation.	The mutations that have a positive effect on the organism in which they occur are called beneficial mutations
Neutral mutation do not affect living being.	Beneficial mutation can be found throughout the natural world

23. Write any two points in favour of mutation theory.
Ans: Any two points in favour of mutation theory are given below:
i) Mutations are actually the source of all variations and hence fountain head of evolution.
ii) Mutation theory can explain both progressive and retrogressive evolution.

24. Give any two example of beneficial mutation.
Ans: Any two example of beneficial mutation are given below:
i) Mutation have occured in bacteria that allow the bacteria to survive in the presence of antibiotic- resistance strains of bacteria.
ii) A unique mutation is found in people in limone, a samll town in Italy

25. How do evidences obtained from the study of embryos support the theory of oragnic evolution? Describe in breif.
Ans: Embryology provides evidence for evolution since the embroyonic forms of divergent groups are extremly charles drawin’s theory of evolution of life from a common ancestors. In fact early-stage human embryos have a tail and embryonic development help scientists classify organisms in toxonomy embroynic development is also used to study the evolution of organisms.

26. How do evidences obtained from the study of fossils supports the Darwin’s theory of organic evolution? Describe om berif.
Ans: Fossils provide evidence for the evolutionary theory beacuse they document the existence of new – extinct species that are related to the present day species. Fossils indicate the gradual evolution and prove that organisms from the past are not the same as those in the present day fossils of the simplest organisms are found in the oldest rocks and fossils of more complex organisms in the newest rocks, supporting the drawin’s theory of of evolution.

27. What is the struggle for existence? Describe on the basis on Drawinism.
Ans: The population of most species remains constant because of the various checks. According to drawinism struggle for exsistence may be intraspecific i.e. among the members of the same species and interspecis.

28. What is the effort of the Enviroment on organisms? Describe on the basis of lamarckism.
Ans: The effort of the enviroment on organisms are described below:
Due to changed mode of life certain physical needs originate in the animal which is responsible for the modification of organs. This can be illustrated by several examples, A land bird is drived by the necessity to seek its food in the water gradually assumed characters adopting it ti swimming, wanding or searching food in the water.

29. Write any six criticism of Hugu De Vries mutation theory.
Ans: Any six criticims are given below
1) Oenothera lamarckiana ( Evening primrose) of Hugo De vries was not a normal plant but a complex heterozygous form with chromosome aberrations.
2) Natural Mutations are not common as Hugo De Vries though them to occurs.
3) Most of the mutation are negative or retrogressive.
4) Mutations are generally recessive which traits taking part in evolution are usually dominent.
5) Hugo De Vries mutations theory doesn’t explain the role of nature.
6) Mutation theory cannot satisfactory explain the development of mimicry, mutual dependence of flower and pollination.

30. Write any three siginficance of variation?
Ans: Any three significance of varation are:
1) Variation increases the chance of survival of an organisms in a changing enviroment.
2) Variation helps in organic evolution.
3) Variation provides individuality to an organism of a species from other memeber of the species.

31. Write down the criticism of Drawin’s theory?
Ans: Criticism of Drawin’s theory are given below:
1) Drawin’s theory explains how variations arise.
2) Drawin’s theory explains the survial of the fittest but not about the arrival of the fittest.
3) According to Drawin’s theory, natural selection is only a factor to bring out evolution but not the only complete factor for evolution.

32. How are living beings selected naturally? Describe on the basis of Drawinism.
Ans: The living beings seleted naturally by the following method:
1) Balance of population growth
– Living orgainisms have an enormous potential to produce a large number of off-spring
but the size of population of any kind of organism remains more or less constent of
organisms remains more or less constent and they are not found in a large number.
2) Struggle for the existence
– The struggle for existence may be intraspecific. i.e. among the member of the same
Species and inter-specific, i.e among the member of different species sharing a common
enviroment , the struggle for existence removes many individuals.
3) Survival of the fittest or natural selection
– Drawin regarded that in the struggle for existence, the individuals which are provided
existence the individuals which are provided with favourable varation will lead a more
successful life and would survive and propagaye their off-spring and the other with
unfavourable vartions.

33. Describe the effect of Hugo De Vries mutation theory.
Ans: They are described below:
1. Neutral Mutation: The mutation that are neither beneficial nor detrimental to the ability of an organisms to survive or reproduce are called neutral mutations. In neutral mutation, natural selection does not affect the spread of the mutation in a species.
2. Beneficial Mutation: The mutations that have a positive effect in the organisms in which they occur are called Beneficial mutations. These mutations have a positive effect on organisms and increase an organisms chance of surviving or reproducing.
3. Harmful Mutation: Any random change in a gene’s DNA is likely to result in a protein that does not function normally or may not function at all such mutations are likely to be harmful.