MP Board Class 12th Biology Important Questions Chapter 7 Evolution

MP Board Class 12th Biology Important Questions Chapter 7 Evolution

Evolution Important Questions

Evolution Objective Type Questions

Question 1.
Choose the correct answers:

Question 1.
Atmosphere of earth just before the origin of life consisted of:
(a) Water vapour, CH4, NH3and O2
(b) CO2, NH3and CH4
(c) CH4, NH3, H2 and water vapour
(d) CH4 O3, O2 and water vapour.
(a) Water vapour, CH4, NH3and O2

Question 2.
Primitive atmosphere is made up of mixture of these gases :
(a) CH4
(b) NH3
(C) Water vapour
(d) None of these.
(d) None of these.

Question 3.
What is the meaning of Abiogenesis :
(a) Life is originated from non – living things
(b) Life is originated from living things
(c) Origin of virus and microorganisms
(d) None of these.
(a) Life is originated from non – living things

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Question 4.
Primitive atmosphere of earth did not posses :
(a) CH4
(b) NH3
(C) H2
(d) O2
(a) CH4

Question 5.
Which of the following was formed in Miller’s experiment:
(a) Microspheres
(b) Nucleic acid
(c) Amino acid
(d) UV – radiation.
(d) UV – radiation.

Question 6.
What is the unit of evolution :
(a) Community
(b) Genus
(c) Order
(d) Species.
(a) Community

Question 7.
Whith of the following has not life :
(a) Azoic era
(b) Mesozoic era
(c) Paleozoic era
(d) Cenozoic era.
(a) Azoic era

Question 8.
Which of the following are not an analogous organ :
(a) Wings of birds and butterfly
(b) Eye of octopus and mammals
(c) Thom of Baugainvilla and tendril of Cucurbita
(d) Tuberous roots of sweet potato and tuber of potato.
(d) Tuberous roots of sweet potato and tuber of potato.

Question 9.
The earliest era is :
(a) Cenozoic
(b) Mesozoic
(c) Paleozoic
(d) Precambrian.
(c) Paleozoic

Question 10.
Which of the following is analogous organ :
(a) Which has structural symmetry
(b) Which has functional and structural symmetry
(c) Similar in functional structure
(d) Mostly inactive.
(c) Similar in functional structure

Question 11.
Who gave the exact proof of evolution :
(a) Fossils
(b) Vestigeal organ
(c) Embryo
(d) Morphology.
(a) Fossils

Question 12.
Which era is called of mammals and angiosperm’s era :
(a) Mesozoic
(b) Cenozoic
(c) Paleozoic
(d) Archaeozoic.
(b) Cenozoic

Question 13.
Whose dental structure is similar to human :
(a) Homo erectus erectus
(b) Homo erectus pekinensis
(c) Homo habillis
(d) Homo sapiens neanderthalensis.
(c) Homo habillis

Question 14.
Which of these cells are immortal:
(a) Germ cells
(b) Liver cells
(c) Kidney cells
(d) Neurons.
(a) Germ cells

Question 2.
Fill in the blanks:

  1. Earth is a member of ……………….
  2. The great explosion that resulted into the formation of universe is ……………….
  3. ‘Philosophic Zoologique’ is written by ……………….
  4. ………………. is a link between reptiles and birds.
  5. ………………. is the ancient ancestor of modem horses.
  6. At present marsupiales (kangaroos) are found only in ……………….
  7. ………………. is the first photosynthetic organism that originate on the earth.
  8. ………………. is the process by which changes in the genetic composition of organism.
  9. ………………. constructed geological time scale.
  10. ………………. is the first prehistoric human.
  11. ………………. was among the first fossils to be recognized as belonging to Homo sapiens.
  12. ………………. is found since the 19th century in the Siwalik Hills of the Indian sub – continent.
  13. Discoveries related to the genetic code and its function in protein synthesis is given by ……………….
  14. ………………. was the father of the Paleontology.
  15. ………………. is the name of Darwin’s ship.


  1. Solar system
  2. Big bang
  3. Lamarck
  4. Archaeopteryx
  5. Eohippus
  6. Australia
  7. Cyanobacteria
  8. Organic evolution
  9. Geovani Abduna
  10. Homo habilis
  11. Cro – magnon
  12. Ramapithecus
  13. Dr. Hargovind khorana
  14. Leonardo da Vinci
  15. Beagle.

Question 3.
Match the followings :
MP Board Class 12th Biology Important Questions Chapter 7 Evolution

  1. (d)
  2. (e)
  3. (b)
  4. (c)
  5. (a)

MP Board Class 12th Biology Important Questions Chapter 7 Evolution 2

  1. (d)
  2. (a)
  3. (e)
  4. (c)
  5. (b)

Question 4.
Write the answer in one word/sentences:

  1. The matter which is a link between acellular and cellular system.
  2. The island at which Darwin studies the organisms for his theory of evolution.
  3. When the earth is originate?
  4. Which is known as the link between living and non – living?
  5. Where are originate the first animal on the earth?
  6. Name the scientist who disapproved Lamarkism.
  7. The whole process of the development at changes from embryo to adult organism.
  8. Other name of natural selection.
  9. Who proposed the Mutaion Theory of Evolution?
  10. The organs which are different in their origin but have similar function.
  11. Who proposed the theory of inheritance of acquired characters?
  12. Who proposed the theory of natural selection ?
  13. The remains of ancient organisms.


  1. Coacervates
  2. Galapagos
  3. 4.6 million years ago
  4. Virus
  5. In water
  6. Weismann
  7. Ontogeny
  8. Darwinism
  9. Hugo de Vries
  10. Homologous organ
  11. Lamarck
  12. Darwin
  13. Fossils.

Evolution Very Short Answer Type Questions

Question 1.
Who proposed the theory of natural selection?

Question 2.
Who proposed the Recapitulation theory or Biogenetic law?

Question 3.
Astronomical distance measured in?
Astronomical distance measured in Light years.

Question 4.
Name the theory by which earth is said to originate.
The big – bang theory.

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Question 5.
What is fossil?
Fossils are the remains or impressions of ancient organisms preserved in sedimentary rocks or other media.

Question 6.
What is mutation?
New species originate due to changes of hereditary characters are called mutation.

Question 7.
Name the scientist who tell the spontaneous theory is wrong.
Louis Pasteurs.

Question 8.
Which era is called golden period of Dinosaurs?
Mesozoic period is billed golden period of Dinosaurs.

Question 9.
In which ship Darwin studied the nature?

Question 10.
Name any two vertibrates body organ which are homologus organs of human forelimb.

  1. Flipper of whale
  2. Wing of birds.

Question 11.
What is the scientific name of modern man?
Homo sapiens.

Question 12.
Who is the early man of the modern human?
Cro – Magnon peoples are early human of modem human.

Question 13.
Who are the early human and sub – human.
Ramapithecus is early human and Australopithecus is early human.

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Question 14.
Which human form first started to walk on two legs?
Australopithecus form first started to walk on two legs.

Question 15.
Which type of human was ‘Cro – Magnon’ on the basis of food intake?
Cro – Magnon was carnivorous.

Question 16.
On the basis of evolution which human had brain size of 1400cc?

Question 17.
Give the name of ape-like ancestors of humans.
Ape – like ancestors of human’s are Dryopithecus.

Question 18.
Differenciate between Dryopithecus and Ramapithecus.
Dryopithecus were apelike but Ramapithecus were mostly human like.

Evolution Short Answer Type Questions

Question 1.
Explain antibiotic resistance observed in bacteria in light of Darwinism selection theory.
Darwinism theory of natural selection states that environment selects organisms with favourable variations and these organisms thus, survive and reproduce. It is observed when bacterial populations are exposed to certain antibiotic, the sensitive bacteria could not tolerate and hence, died due to the adverse environment. Whereas some bacteria that devel¬oped mutation became resistant to the particular antibiotic and survived.

As a result such resistant bacteria survive and multiply quickly as compared to other sensitive bacteria. So, the whole population is regained by multiplication of resistant variety and antibiotic resistant gene becomes widespread in the bacterial population.

Question 2.
Find out from newspapers and popular science articles any new fossil dis – coveries or controversies about evolution.
Fossils of dinosaurs have revealed the evolution of reptiles in Jurassic period. As a result of this evolution of other animals such as birds and mammals has also been discovered. However, two unusual fossils recently unearthed in China have ignited a controversy over the evolution of birds confuciusomis is one such genus of primitive birds that were crow sized and lived during the Cretaceous period in China.

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Question 3.
Attempt giving a clear definition of the term species.
A species generally includes similar organism. Members of this group can show interbreeding. Similar group of genes are found in the members of same species and this group has capacity to produce new species. Every species has some cause of isolation which intruped the interbreeding with nearest reactional species which is refer as reproduptively isolated.

Question 4.
What is virus? Why is it treated as a link between living and non – iiving ?
Viruses are simplest organism,of the earth, which consist of nucleic acid (DNA or RNA) surrounded by protein cover. It shows characteristics of living as well as non – living organisms.

(A) Living characters of virus:

  1. Virus shows structural differentiations.
  2. They contain hereditary material.
  3. They exhibit mutation.
  4. They spread plant and animal diseases.
  5. Growth and development present.
  6. They exhibit adaptaion.
  7. They possess sensitivity.

(B) Non – living characters of virus:

  1. Lack protoplasm and cell organelles.
  2. Can be crystallized.
  3. No metabolic activities seen.
  4. Cannot reproduce outside living cells.
  5. They lack enzymes.
  6. Due to above reason, viruses are considered as link between living and non-living organisms, thus, it is the first life
  7. originated in the earth.

Question 5.
What is oxygen revolution? Explain.
Oxygen revolution:
Evolution of O2 in photosynthesis during primitive environmental conditions is very important because, it is required in the evolution of organism and conversion of reducing environment into oxidizing environment hence, it is called oxygen revolution. Oxygen evolution should cause the following changes in the environment:

  1. Oxygen evolution should cause the conversion of reducing envronment into oxidizing environment.
  2. Ozone layer is formed 15 miles above from the earth which absorbs the ultraviolet light of the sunlight and thus, prevents
  3. the entry of uv light in the atmosphere.
  4. O2 present in the environment dissociates methane (CH4) into CO2 and O2. This CO2 is used in photosynthesis.
  5. NH3 of the primitive environment is dissociated into H2O and nitrogen.
    CH4 + 2O2 → CO2 + 2H2O
    4NH3 + 3O2 → 2N2 + 6H2O.

Question 6.
Explain the origin of the earth.
Origin of the earth:

  1. Earth was formed 4 – 5 billion years back.
  2. Initially, the surface was covered with water vapour, methane, CO2 and NH3.
  3. The UV rays of the sun broke water into hydrogen and oxygen.
  4. Hydrogen escaped and oxygen combined with NH3 and CH4 to form water, CO2 and other gases, also forming the ozone layer.
  5. Cooling of water vapour led to rain which filled the depressions on earth’s surface, forming water bodies.

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Question 7.
Mention the names of discoveries and principles given by the following scientists:

  1. Louis Pasteur
  2. A. I. Oparin
  3. Urey and Miller
  4. Francesco Redi
  5. Faux.


  1. Louis Pasteur – He proved that air contains spores of microorganism and Biogenesis theory was supported by him.
  2. A. I. Oparin – He presented the biochemical explanation of origin of life in his book “The Origin of Life on Earth”.
  3. Urey and Miller – They supported the evidence of Oparin – Haldane theory of Origin of life.
  4. Francesco Redi – He by conducting experiments proved that abiogenesis cannot exist but bioginesis theory can exist i.e., Life arises from pre – existing life.
  5. Faux – He has been experimentally supporting the organic substances as described by Oparin.

Question 8.
What are homologous organs?
What is homology?
Organs which are similar in structure and origin but different in appearance and functions are called homologous organs and the phenomenon is called homology.

Forelimbs of bat, wings of bat, hands of man, forelimbs of horse. These are the examples of homologous organs because, they are made up of similar bones, humerus, radius – ulna, carpals, metacarpals and fingers.

Question 9.
What do you mean by analogous?
Analogous organs:
Organs which are different in origin and structure but performing similar functions are known as analogous organs and the phenomenon is called as analogy. Analogous organs do not indicate phylogeny.

Wings of butterflies are made up of chitin, wings of birds made by produc¬tion of feathers on forelimbs and skin present between the fingers of bat are the examples of analogous orgAnswer:

Question 10.
What is the difference between homologous and analogous organs ? Give two examples of each of them.
Differences between Homologous and Analogous organs :

Homologous organ:

  • Organs which are similar in structure and origin but different in function are known as homologous organs.
  • These structures indicate that organisms bearing them are evolutionary related.
  • These organs are differ in outlook.
  • They exhibit similarity in internal structure.
    Example: Forelimbs of frog, hand of human, wings of bat and forelimb of horse.

Analogous organ:

  • Organs which are differing in structure and origin but similar in function are known as analogous organs.
  • These structures indicate that organisms bearing them are evolutionary different.
  • These organs are similar in outlook.
  • They do not exhibit similarity in internal structure.
    Example: Wings of butterflies, bats and birds.

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Question 11.
What do you mean by vestigial organs?
Write the two names of vestigial organs of man.
What are vestigial organs? Explain. Write four vestigial organs of the human body.
Vestigial organs:
Organs that are reduced and have become functionless in an organism but were functional in their ancestors are called as vestigial organs.

  1. Vermiform appendix.
  2. Coccygial vertebrae.
  3. Nictitating membrane in the eyes of human.
  4. Muscles of external ear (Pinna).

Question 12.
Write down the demerits of Darwinism.
Some of the demerits of Darwinism are:

  1. Darwinism stresses upon small fluctuating variations which has no role in evolution.
  2. Does not satisfactorily explain effect of use and disused and presence of vestigial organs.
  3. It did not differentiate somatic and germinal variations.
  4. It explains survival of the fittest but not arrival of the fittest.

Question 13.
Differentiate between lamarckism and darwinism.
Differences between Lamarckism and Darwinism:


  • It is based on the theory of inheritance of acquired characters.
  • According to this theory the length of neck of Giraffe increased only to facilitate it in eating leaves of higher trees.
  • Increase in length of neck of Giraffe resulted in evolution of Giraffe with long necks.
  • The theory is based on the use or misuse of the organs.


  • It is based on the theory of natural selection.
  • Ancestors of Giraffe were both with long and short necks.
  • Giraffe with long neck only could survive in struggle for existence.
  • This theory is based on the inheritance of the characters in next generation.

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Question 14.
Explain Lamarckism in short.
Explain Lamarckism of organic evolution in brief.
In 1809, Lamarck has proposed a theory to explain organic evolution, which is known, as the “Theory of inheritance of acquired characters.” According to Lamarck, organisms acquire certain characters during their lifetime due to changes in environment and these acquired characters are heritable. According to this theory, new species are originated as follows:

  1. New requirements and wills are produced in the organisms due to the effect of changed environment.
  2. New requirements and wills of organisms resulting in the production of new habits.
  3. Changes in the habit bringing about modifications of the organ.
  4. New habits resulting in the use or disuse of the organs.
  5. Use of organ resulting in the development of acquired characters.
  6. These acquired characters are heritable.
  7. Inheritance of acquired characters resulting in the development of new species.

Question 15.
Write two incidences which influenced Darwin to set out theory of evolution.
Two incidences which influenced Darwin are:

1. During the voyage of Beagle Darwin noticed distribution of a kind of bird called as finches and other organisms by looking at his observation of Galapagos island. He found variation in the beaks of finches adapted according to the environment.

2. Pegion keepers kills weak varieties of pegion generation after generation to obtain better variety of pegion.

3. Above two incidences influenced Darwin to set out theory of evolution (Natural selection).

Evolution Long Answer Type Questions

Question 1.
Draw a well – labelled diagram of Miller and Urey’s experiment.
MP Board Class 12th Biology Important Questions Chapter 7 Evolution 3
Experimental evidence of Chemical evolution or Miller’s experiment:

1. Experiment was performed by S.L. Miller and H.C. Urey in 1953.

2. Experimental set – up:
In a closed flask containing CH4, H2, NH3and water vapour at 800°C, electric discharge was created. The conditions were similar to those in primitive atmosphere.

3. Observations:
After a week, they observed presence of amino acids and complex molecules like sugars, nitrogen bases, pigments and fats in the flask.

4. Conclusions:

  • It provides experimental evidence for the theory of chemical origin.
  • It showed that the first non-cellular form of life was created about 3 billion years ago.
  • It showed that non-cellular biomolecules exist in the form of DNA, RNA, polysaccharides and protein.

Question 2.
Write an essay on modern concepts of origin of life.
Explain the role of non – living in origin of life.
Modern concept of origin of life:
The modem concept of origin of life was postulated by a Russian biochemist A.I. Oparin in 1936. According to this theory, after the formation of earth various chemicals played important role in the formation of atmosphere. Life originated and first organism came into existence from certain molecules when atmospheric conditions became suitable. According to Oparin, life originated in the following steps:

1. Formation of earth and its atmosphere:
Earth is believed to be originated some 4,500 million years ago by the condensation and cooling of the clouds of cosmic dust and gases called ylem. The heavier elements collected at the core and lighter elements around the core. Outermost layer contains H, C, O and N. Oxygen was found only in combination of other elements. These four elements reacted with each other forming H2, H2O, CH4, NH3, CO2 and HCN.

2. Formation of small organic molecules:
The mixture of methane, ammonia, water and hydrogen comes in contact of solar energy. Cosmic rays and electric discharge could produce some simple organic compounds. These simple organic compounds formed in such a way and accumulated in primitive atmosphere and oceans were responsible for synthesis of complex micro-molecules as follows :

1. CH4, H2O → Sugars
→ Fatty acids
→ Glycerine

2. CH4, H2O, NH3 → Amino acids

3. CH4, HCN, H2O, NH3 → Nitrogenous bases (Purines and Pyrimidines)

3. Formation of polymers:
It is clearly understood from the above description that a large number of micro molecules such as hydrocarbons, amino acids, fatty acids, purine and pyrimidines and simple sugars accumulated in the oceans. When atmospheric water condensed on further cooling, the inorganic precursors collided, reacted and aggregated to form new molecules of increasing size and complexity. Thus, by polymerization macromolecules were formed. The chemical reactions for the formation of macro – molecules can be summarized as follows:

  • Sugar + Sugar → Polysaccharides
  • Fatty acid + Glycerine → Lipids
  • Amino acid + Amino acid → Protein
  • Nitrogenous base (Adenine) + Sugar + Phosphate → Adenosine phosphate
  • Nitrogenous base + Sugar → Nucleoside
  • Nucleoside + Phosphate → Nucleotide
  • Nucleotide + Nucleotide → Nucleic acid.

4. Formation of molecular aggregates and primitive cells:
Over a vast of time, these molecules became associated with one temporary complex. Ultimately, it leads to the formation of a coacervate. A coacervate is a solution of high molecular weight of chemicals, i.e., proteins and carbohydrates, which become bounded by lipid membrane, which is selectively permeable.

The coacervate grows by absorbing molecules from their environment. The substances which got accumulated in the coacervates underwent reactions and resulted in the molecular reorganization of some proteins into enzymes. A coacervate having nucleoprotein surrounded by various nutritive organic substances and covered by surface membrane is considered to be the precell, which got later transformed into first living cell. The coacervate can reproduce by budding.

5. Evolution of complex biochemical reactions:
Primitive organism utilize chemical substances present in the environment as food hence, they are :

(a) Heterotrophic, chemosynthetic organisms appeared due to mutation and natural selection in heterotrophs.

(b) Blue – green algae evolved from chemosynthetic organisms by mutation and natural selection.

(c) The liberation of free oxygen into the atmosphere produced by the blue – green algae due to the process of photosynthesis. It finally changed the reducing atmosphere into an oxidizing one and therefore, all possibilities of further chemical evolution were finished.

Free living eukaryotes originated in the ocean from blue – green algae.

6. The origin of well – developed organisms:
From the simple eukaryotes which were like unicellular organisms of today various forms of life evolved during passage of time.

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Question 3.
Write the process of formation of organic molecules in sea water on earth with the help of Miller and Urey’s experiment.
The work of A.I. Oparin (1938 – 1965), H.Urey and Stanley Miller (1959) provided evidences in the favour of biochemical origin of life. They had prepared the atmosphere like that of primitive earth and as described by Oparin, they made the synthesis of organic compounds by the following methods:

1. Four elements H, C, O (not free O2) and N react with each other to form H2O, CH4, NH3, CO2 and HCN on primitive earth.

2. From these four elements following organic molecules were formed in sea water of earth:
MP Board Class 12th Biology Important Questions Chapter 7 Evolution 4

(ii) CH4, H2O, NH3 → Amino acids.

(iii) CH4, HCN, H2O, NH3 → Nitrogenous bases.

3. Macro – molecules of organic compounds were synthesized by these above prepared organic compounds.

  • Sugar + Sugar → Polysaccharides (Carbohydrate).
  • Fatty acids + Glycerol → Fats.
  • Amino acid + Amino acid → Protein.
  • Nitrogenous base + Sugar → Nucleoside.
  • Nucleoside + Phosphoric acid → Nucleotide.
  • Nucleotide + Nucleotide → Nucleic acid.
  • Nitrogenous base (Adenine) + Sugar + Phosphate → Adenosine phosphate.

4. The above organic compounds and salts together constituted the first living being.

Question 4.
Name connecting link of reptiles and birds. Also write their characters.
Archaeopteryx is the connecting link of birds and reptiles. Archaeopteryx was a bird. It is regarded as the connecting link between reptiles and birds, which suggests the path of evolution of the latter from the former. It is found as fossils. They are found during Jurassic period 140 million years. Archaeopteryx exhibits both reptiles and birds like characters.

1. Reptiles like characters:

  • Bones were similar to that of reptiles in which air sacs were absent.
  • Tail bearing vertebra.
  • It had teeth in jaws, scales were present on the body.
  • Metacarpals were free.
  • Pelvic girdle recombines with the pelvic girdle of reptiles.

2. Birds like characters:

  • Presence of feathers on body.
  • Forelimbs were modified in wings.
  • Skull large and monocondylar.
  • Jaws were modified into beak.
  • Hallux was backwarded and pointed.

Question 5.
Give a detailed account of theory of natural selection.
Describe the Darwin’s opinion about the origin of new species of organisms.
Charles Darwin (1809 – 1882) explained the theory of evolution in his book “Origin of species by natural selection.” Darwin undertook a long voyage for five years in the capacity of a naturalist on a British warship ‘Beagle’. He travelled to islands of Galapagos and collected evidences to explain evolution.

To explain origin of species he gave theory of natural selection as a mechanism for evolution.

The main points of Darwinism are given below:

1. Over production of offsprings:
Every living being has an inherent tendency to produce more offspring than that can survive.

2. Struggle for existence:
Though the offsprings are produced in large number yet their production remain almost constant. This is because of struggle for existence. There is struggle for food, space, breeding, etc. Moreover death of individuals due to diseases and predators, population are kept under control.

3. Survival of the fittest:
Darwin believed that any individual is successful in struggle for existence if it survives long enough to produces offsprings. Individuals who are fit in a particular environment can only survive.

4. Variation:
Due to constant struggle, the organisms change themselves in accordance with the new needs.

5. Natural selection:
In the struggle, for existence organisms having variations favourable to the environment would have more chance to survive and reproduce their own kind. Those which do not possess favourable variations would die or fail to reproduce.

6. Origin of species:
Any changes in environmental conditions cause natural selection to act upon the population and select the well adapted individuals. It results in changes of characters of the populations. By the inheritance of these changes in successive generations, new species are formed.

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Question 6.
Organic Evolution is a continuous process, explain it. And giving any three evidences.
Evolution is a complex phenomenon accounting for the present day diversity among organisms. But it has clearly maintained the basic unity among them since it occurred over a period of millions of years, no one would have seen/recorded evolution and hence scientists have provided various evidences to prove evolution. Some of the evidences of organic evolution are described below:
MP Board Class 12th Biology Important Questions Chapter 7 Evolution 5

I. Evidences from Embryology:
Important activities that occur various animals are:

  1. For the survival, all animals get energy and various substances from environment.
  2. In all organisms energy is produced from ATP.
  3. In all organisms, the duplication of DNA is similar.
  4. In all organisms, protein synthesis is same and it is produced from ribosomes.
  5. In all organisms respiration and steps of respiration is same.
  6. All organisms multiplicate and reproduce, due to which they have basic similarities.
  7. All organisms conduct hereditary characters on similar principles.

II. Evidence from Anatomy:
Anatomy of living organisms will be explained with different examples:

1. Homologous organs : Organs which are similar in structure and origin but different in function and appearance is known as homologous organs.

2. Analogous organs : Organs which are different in origin and structure but performing similar functions are known as analogous organs.

3. Vestigial organs : Organs that are reduced and have become functionless in an organism, but were functional in their ancestors are called vestigial organ.

III. Evidences from vestigial organs:
Organs of the body which are non – functional but they are functional in some other organisms are called vestigial organs: Morphological evidence of evolution is provided by the presence of vestigial organs of body which are often undesired, degenerated and non-functional. These might have been large and functional in some other animals or in ancestors of those which now possess it in rudimentary forms, example vermiform appendix in man, muscles of external ear (pinna) in man, nictitating membrane or plica, semilunaris in human eye, wisdom teeth (third pair of molars) tail bone (coccyx) in man, wings of ostrich, hindlimbs in snakes, etc.

Question 7.
What do you mean by organic evolution? How do fossils exhibit evidence to prove organic evolution?
Descent with modification in organism is known as organic evolution.

Evidences of organic evolution from fossils record:
Fossils are treated as significant evidence of organic evolution. Fossils are the remains or impressions of ancient organisms preserved in the layers of rock and soil. Fossils only do not prove the theory of organic evolution, yet it evidently prove that gradually complexity increased in body organization. The complexity in the body of organization can be noticed as we study the upper layers. Thus, it can be concluded from above observations :

  1. The crust of the earth and the organisms living on it underwent change in the course of time.
  2. The organisms with simple structural organization originated earlier than the complex ones.
  3. Some of the organisms lived on the earth for short time and became extinct. This was a result of drastic changes in the climate on the earth.

Hence, forth fossils produce bonafide record of such plants and animals which had shown their existence once upon a time and now are extinct or not present exactly in the same form, thus, producing strong evidence in favour of organic evolution.

Question 8.
Try to trace the various components of human evolution (Hint: Brain size and function, skeletal structure, dietary preference, etc.)
The various components of human evolution are as follows:

  1. Brain capacity.
  2. Posture.
  3. Food/Dietary preference and other important features.

Name, brain capacity, posture and food features:

1. Dryopithecus Africans:
Knuckle walker, walked similar to Gorillas and Chimpanzees (was more apelike), soft fruit and leaves; canines large, arm and legs are of equal size.

2. Ramapithecus:
Semi – erect (more manlike) ate seeds and nuts, canines were small while molars were large.

3. Australopithecus africanus:
Brain capacity 450 cm3, full erect prosture, height 1.05m, herbivorous (ate fruits), hunted with stone weapons, lived as trees, canines and incisors were small.

4. Homo habilus:
Brain capacity 735 cm3, fully erect posture, height, 1.5m, carnivorous, canines were small. They were first tool makers.

5. Homo erectus:
Brain capacity 800 – 1100 cm3, fully erect posture, height 1.5 – 1.8m, omnivorous. They used stone and bone tools for hunting games.

6. Homo neanderthalensis :
Brain capacity 1300 – 1600 cm3, fully erect posture, height 1.5 – 1.6m, omnivorous cave dwellers, used hiles to protect their bodies and buried their dead.

7. Homo sapiens fossils:
Brain capacity 1650 cm3, fully erect posture with height 1.8m, omnivorous. They had strong jaw with teeth close together. They were cave dwellers, made painting and carvings in the caves. They developed a culture and were called first modern man.

8. Homo sapiens sapiens:
Brain capacity 1200 – 1600 cm3, fully erect posture, height 1.5 – 1.8m, omnivorous. They are the living modem men with high intelligence. They developed art, culture, language, speech, etc. They cultivated crops and domesticated animals.

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Question 9.
Find out through internet and popular science articles whether animals other than man has self – consciousness.
There are many animals other than humans, which have self – consciousness. An example of an animal being self-conscious is dolphins. They are highly intelligent. They have a sense of self and, they also recognize others among themselves and others. They communicate with each other by whistles, tail – slapping, and other body movements. Not dolphins, there are certain other animals such as Crow, Parrot, Chimpanzee, Gorilla, Orangutan, etc., which exhibit self – consciousness.

Question 10.
List 10 modern day animals and using the internet resources link it to a corresponding ancient fossil. Name both.
Modern and Ancient corresponding animals:
MP Board Class 12th Biology Important Questions Chapter 7 Evolution 6

Question 11.
Practise drawing various animals and plants.
MP Board Class 12th Biology Important Questions Chapter 7 Evolution 7

Question 12.
Using various resources such as your school Library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal, say horse.
The evolution of horse started with Eohippus during Eocene period. It involved the following evolutionary stages:

  1. Gradual increase in body size.
  2. Elongation of head and neck region.
  3. Increase in the length of limbs and feet.
  4. Gradual reduction of lateral digits.
  5. Enlargement of third functional toe.
  6. Strengthening of the back.
  7. Development of brain and sensory organs.
  8. Increase in the complexity of teeth for feeding on grass.

MP Board Class 12th Biology Important Questions Chapter 7 Evolution 8

1. Eohippus:
It had a short head and neck. It had four functional toes and a splint of 1 and 5 on each hind limb and a splint of 1 and 3 in each forelimb. The molars were short crowned that were adapted for grinding the plant diet.

2. Mesohippus:
It was slightly taller than Eohippus. It had three toes in each foot.

3. Merychippus:
It had the size of approximately 100 cm. Although it still had three toes in each foot, but it could run on one toe. The side toe did not touch the ground. The molars were adapted for chewing the grass.

4. Pliohippus:
It resembled the modern horse and was around 108 cm tall. It had a single functional toe with splint of 2nd and 4th in each limb.

Pliohippus gave rise to Equus or the modern horse with one toe in each foot. They have incisors for cutting grass and molars for grinding food.

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Question 13.
How far inter relationship among? The living organisms is helpful to understand the process of evolution?
Organisms which are externally different shows some similarities. This is known as interrelationship. It proves that they might have evolved from the same ancestor. Inter relationship among the living organisms can be understood by following example:

  1. All living organisms obtain energy and various materials from the environment.
  2. All living organisms multiply and reproduce.
  3. All living organisms show transmission of genetic information according to same principle.
  4. All living organisms synthesize protein in the ribosome and steps of protein synthesis are same in all living organisms.
  5. All organisms respire and steps of respiration in them are same.
  6. In all organism method of DNA replication are same.
  7. In all living organisms flow of information occurs by the help of nucleic acids present in the nucleus.
  8. In all living organisms energy is obtained from ATP.

MP Board Class 12th Biology Important Questions

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