The evolutionary story of moths in England during industrialisation reveals, that 'evolution is apparently reversible'. Clarify this statement. - Biology

Short Note

The evolutionary story of moths in England during industrialisation reveals, that 'evolution is apparently reversible'. Clarify this statement.



In a collection of moths made in the 1850s, i.e., before industrialisation set in, it was observed that there were more white-winged peppered moths (Biston betularia) on trees than dark-winged or melanised moths (Biston carbonaria). However, in the collection carried out from the same area, but after industrialisation, i.e., in 1920, there were more dark-winged moths in the same area, i.e., the proportion was reversed.

  • Before industrialisation set in, thick growth of almost white-coloured lichen covered the trees in that background the white-winged moth survived but the dark-coloured moth were picked out by predators.

Lichens can be used as industrial pollution indicators. They will not grow in areas that are polluted. During post-industrialisation period, the tree trunks became dark due to industrial smoke and soots.

  • Under this condition the white-winged moth did not survive due to predators, dark-winged or melanised moth survived. Hence, moths that were able to camouflage themselves, i.e., hide in the background, survived. This understanding is supported by the fact that in areas where industrialisation did not occur, e.g., in rural areas, the count of melanic moths was low. This showed that in a mixed population, those that can better adapt, survive and increase in population size.
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Chapter 7: Evolution - SHORT ANSWER [Page 49]


NCERT Exemplar Biology Class 12
Chapter 7 Evolution
SHORT ANSWER | Q 5. | Page 49

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Mammals : _________ : : Amphibia : Fishes

State the connecting links between Peripatus with Annelida and Arthopoda.

Give two examples of vestigial organs  in human beings and plants.

Which of the following pairs of two vegetables represent the correct homologous structures?

(A) Sweet potato and potato

(B) Sweet potato and tomato

(C) Carrot and potato

(D) Radish and carrot

Which of the following is a correct set of homologous organs?

(a) Forelimbs of frog, bird and lizard

(b) Spine of cactus and thorn of bougainvillea

(c) Wings of bat and wings of butterfly

(d) Wings of a bird and wings of a bat

 An example of homologous organs is

Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.

Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)

Enlist any four sequential evolutionary names of human ancestors.

Explain with an example for the given, how the following provides evidence in favor of evolution in organisms :

Analogous organs

Name the scientists who Discovered the fossil of Australopithecus

Explain the evolution of giraffe's neck according to Lamarck's theory of evolution.

Name any two temporary embryonic structures in vertebrates which provide evidence for evolution.

What are homologous organs?

How do homologous organs help in providing evidence for organic evolution?

The forelimbs of a frog, a bird and a man show the same basic design (or basic structure) of bones. What name is given to such organs?


Name two animals having homologous organs and two having analogous organs. Name these organs.


Out of bacteria, spider, fish and chimpanzee, which organism has a better body design in evolutionary terms? Give reason for your answer.

The organs P and Q of two animals have different structures but similar functions. On the other hand, the two organs R and S of two other animals have the same basic structure but different functions.
(a) What are the organs like P and Q known as?
(b) Name the organs like P and Q. Also name the animals which have such organs.
(c) What are the organs like R and S called?
(d) Name the organs like R and S. Also name the animals which have such organs.

Identify the following pairs as homologous and analogous organs:
(i) Sweet potato and potato
(ii) Eye of octopus and eye of mammals
(iii) Thorns of Bougainvillaea and tendrils of Cucurbits
(iv) Fore limbs of bat and whale

Select a set of homologous organs from the following: 
(A) Wings of a bat and wings of a butterfly
(B) Wings of a pigeon and wings of a bat
(C) Wings of a butterfly and wings of a pigeon
(D) Forelimbs of a duck, forelimbs of a cow and forelimbs of a lizard

Read the following statement and justify same in your own words with the help of suitable example.

There is evidences of fatal science among chordates.

Vestigial organ ______ present in human body is proof of evolution.

Answer the following question.

Explain with suitable examples the importance of anatomical evidence in evolution.

With the help of diagrams, describe emasculation and bagging. 

Draw a labelled diagram of T.S. of a leaf showing Kranz anatomy. 

What do you mean by vestigial structures? Name four vestigial organs found in man.

Choose the correct option of the following question:

Wings of Insect and Birds are examples of :

Explain any three molecular (genetic) evidences in favour of organic evolution.

Define fossils. 

Differentiate between connecting links and the missing links.

Define phylogeny.

Answer the following question:
What are homologous structures? Give an example. Is it necessary that homologous structures always have a common ancestor? Justify your answer.

Very short answer question.

What are homologous organs?

Very short answer question.

What is vestigeal organ?

Long answer question.

Would you consider wings of butterfly and bat as homologous or analogous and why?

_____________ is a vestigial organ in human beings.

Find an odd one out.

Find an odd one out.

Appendix : vestigial organ : : Peripatus : ____________

The decaying process of C-14 occurs continuously in dead organisms only.

Match the following.

Column A Column B
1) Morphological evidences a) Tail-bone or wisdom teeth
2) Paleontological evidences b) Leaf venation
  c) Fossils

Give scientific reason.

Peripatus is said to be the connecting link between Annelida and Arthropoda.

Give scientific reason.

Vertebrates have slowly originated from invertebrates.

Give scientific reason.

Duck-billed platypus shows relationship with mammals.

Enlist the evidences of evolution.

Define the evidence of evolution shown in the figure.

Which evidence of evolution is shown in the given picture? Explain the importance of this evidence.

Explain any five types of evidence that support the theory of evolution.

Write the answers to the questions by observing the figure below.

(a) (b) (c)
  1. Write the name of the animal ‘(a)’ in the figure.
  2. Write the name of the animal ‘(b)’ in the figure.
  3. Write the name of the animal ‘(c)’ in the figure.
  4. Which evolutionary evidence is illustrated by this figure?
  5. Write the definition of that evidence for evolution.

Biogenetic law states that ______.

The degenerated and non-functional organs found in an organism are called ______.

A human hand, a front leg of a cat, a front flipper of a whale and a bat’s wing look dissimilar and adapted for different functions. What is the name given to these organs?

How do you differentiate homologous organs from analogous organs?

Select vestigial organs from the following.

Homologous organs and vestigial organs are examples of ______ type of evidence in evolution.

Select the correct statement.

Select the CORRECT match.

Select the CORRECT set of homologous organs.

Define vestigial organs

Homologous organs are:

Cucurbits do not develop thick and woody stem as they are:

Tendons and ligaments are examples of ______.

Palaeontological evidence for evolution refers to the ______.

Basic principles of embryonic development were pronounced by:

Study of fossils is ______.

Evolutionary convergence is the development of:

The process of mating of individuals, which are more closing related than the average of the population to which they belong is called ______.

The presence of gill slits, in the embryos of all vertebrates, supports the theory of ______.

Which is not a vestigial organ in a man?

Flippers of Penguins and Dolphins are examples of: 

The study of fossil evidence of evolution is called ______

Organs having similar functions but different origin and development are known as:

Animal husbandry and plant breeding programmes are the examples of ______.

The bones of forelimbs of whale, bat, cheetah and man are similar in structure, because ______.

What are we referring to? When we say 'simple organisms' or 'complex organisms'.

How do we compute the age of a fossil?

While creation and presence of variation is directionless, natural selection is directional as it is in the context of adaptation. Comment.

Explain divergent evolution in detail. What is the driving force behind it?

Complete the following diagram:

What is the function of the appendix of our digestive system?

Find odd one out:

As shown in figure below some organisms that share a common ancestor have features that have different functions, but similar structures.

These are known as ______. Give example.

Write down the difference between homologous and analogous organs.

Find the odd one out:

Write a note on the significance of Palaeontology.

Define the term:

Homologous organs

Industrial melanism was highlighted by ______.

Industrial melanism in England after 1850 is an excellent example of Natural selection. Explain how?

Give examples of homologous organs and analogous organs in plants.


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