Human Evolution

Solutions for Biology, Class 10, ICSE

Assertion Reason Type

3 questions

Question 11

Assertion. Lamarck's theory of inheritance of acquired characters is mainly based on "survival of the fittest".

Reason. Lamarck has explained his principle of 'use and disuse' with the example of Giraffe's neck.

  1. Both A and R are True.
  2. Both A and R are False.
  3. A is True and R is False.
  4. A is False and R is True.
Assertion Reason Type

Answer:

A is False and R is True.

Explanation
"Survival of the fittest" is a concept associated with Darwin's theory of natural selection, not Lamarck's theory. Lamarck's theory is based on the idea that characteristics acquired during an organism's lifetime can be passed on to its offspring.
Lamarck used the example of the giraffe's neck to illustrate his principle of 'use and disuse,' suggesting that giraffes stretched their necks to reach higher leaves, and this trait was then passed on to their offspring.

Question 12

Assertion. The analogous organ to the vermiform appendix in herbivorous mammals is quite helpful in digesting cellulose. But it is considered a vestigial organ in humans.

Reason. Vermiform appendix is a wide worm-like tubular structure, projecting from the blind part of the colon (a part of large intestine). Its function is the same as that of the colon, i.e., absorption of water and some remnants of digested food.

  1. Both A and R are True.
  2. Both A and R are False.
  3. A is True and R is False.
  4. A is False and R is True.
Assertion Reason Type

Answer:

A is True and R is False.

Explanation
Vermiform appendix is a small and narrow worm-like tubular structure, projecting from the blind part of the colon. It is a vestigial organ in humans having no function.

Question 13

Assertion. The theory of natural selection, proposed by Charles Darwin, is a fundamental mechanism driving human evolution.

Reason. Natural selection operates through the preservation of favourable variations that enhance an organism's ability to survive and reproduce, leading to the gradual adaptation of populations to their environments over time.

  1. Both A and R are True.
  2. Both A and R are False.
  3. A is True and R is False.
  4. A is False and R is True.
Assertion Reason Type

Answer:

Both A and R are True.

Explanation
Natural selection is the differential survival and reproduction of individuals due to differences in their phenotypes (observable traits). It is a crucial mechanism of evolution, leading to changes in inheritable traits within populations over generations.

Descriptive Type

3 questions

Question 1

Define the following terms:

(a) Evolution

(b) Vestigial organs

(c) Speciation

(d) Bipedalism

(e) Natural selection

Descriptive Type

Answer:

(a) Evolution — Evolution is a slow and continuous process whereby complex forms of life have emerged from simpler forms through millions of years.

(b) Vestigial organs — Vestigial organs are remnants of once-functional structures in the organism's ancestors that have lost their original purpose through evolution in the present-day species.

(c) Speciation — Origin of new species by gradual modification is called 'speciation'.

(d) Bipedalism — Walking straight on hind limbs and freeing of forelimbs from ground is called bipedalism.

(e) Natural selection — Natural selection is the process by which certain heritable traits become more or less common in a population over generations based on their impact on an organism's survival and reproduction in a specific environment.

Question 2

Distinguish between:

(a) Australopithecus and Cro-magnon (Chin)

(b) Australopithecus and Modern man (Body hair)

(c) Homo habilis and Homo sapiens sapiens (Posture)

Descriptive Type

Answer:

(a) Difference between Australopithecus and Cro-magnon (Chin) —

AustralopithecusCro-magnon
Lack of chinWell-developed chin

(b) Difference between Australopithecus and Modern man (Body hair) —

AustralopithecusModern man
Body covered with hairHighly reduced body hair

(c) Difference between Homo habilis and Homo sapiens (Posture) —

Homo habilisHomo sapiens
Bent kneed postureFully erect posture

Question 3

Differentiate between Lamarck's Theory and Darwin's Theory.

Descriptive Type

Answer:

Main differences between the theories of Lamarck and Darwin —

Lamarck's TheoryDarwin's Theory
Known as the theory of inheritance of acquired charactersKnown as the theory of natural selection
Believes in the use and disuse of an organ. Parts used or changes acquired get transmitted to the next generation.Believes that since variations exist in individuals, only the fittest survive in the struggle for existence.
New species evolve after a long period of time after many generations by acquiring new characters.New species evolve due to accumulation of favourable variations over a long period of time.

Multiple Choice Type

10 questions

Question 1

Which of the following is not a vestigial organ ?

  1. Vermiform appendix
  2. Caecum
  3. Wisdom teeth
  4. Ear pinna
Multiple Choice Type

Answer:

Caecum

Reason — Caecum is not a vestigial organ as it absorbs fluid and salt from the digested food.

Question 2

The selective agent that was responsible for causing the change in peppered moth was :

  1. Lichens
  2. Humans
  3. Birds
  4. Smoke
Multiple Choice Type

Answer:

Smoke

Reason — Earlier the light colour winged moths outnumbered dark winged moths as they could escape the predators but after industrialisation the dark winged moths were able to escape the predators while light colour winged moths were preyed upon. Therefore, the smoke acted as selective agent.

Question 3

The first scientist who proposed his theory for evolution was ;

  1. Darwin
  2. Lamarck
  3. Mendel
  4. Wallace
Multiple Choice Type

Answer:

Lamarck

Reason — Lamarck was the first scientist to propose his theory of evolution.

Question 4

The theory proposed by Lamarck is :

  1. Autogenesis theory
  2. Germplasm theory
  3. Theory of inheritance of acquired characters
  4. Theory of abiogenesis
Multiple Choice Type

Answer:

Theory of inheritance of acquired characters

Reason — According to the theory of inheritance of acquired characters organisms can pass on traits acquired during their lifetime to their offspring.

Question 5

Charles Darwin explained the origin of species through:

  1. Mutation
  2. Natural selection
  3. Acquired characters
  4. Hybridization
Multiple Choice Type

Answer:

Natural selection

Reason — Charles Darwin explained the origin of species using the idea of natural selection.

Question 6

Which one of the following was not explained by Darwinism?

  1. Natural selection
  2. Struggle for existence
  3. Use and disuse
  4. Survival of the fittest
Multiple Choice Type

Answer:

Use and disuse

Reason — Use and disuse was discussed by Lamarck.

Question 7

Which of the following human ancestral stages came just before the modern man ?

  1. Cro-magnon
  2. Ramapithecus
  3. Homo habilis
  4. Neanderthal man
Multiple Choice Type

Answer:

Cro-magnon

Reason — Cro-magnon came just before the modern man.

Question 8

The scientist who is regarded as the "Father of Evolution" is :

  1. Mendel
  2. Walther Flemming
  3. Darwin
  4. Lamarck
Multiple Choice Type

Answer:

Darwin

Reason — Darwin is known as father of evolution because his theory of evolution by natural selection became the foundation of modern evolution studies.

Question 9

Industrial melanism was highlighted by :

  1. Polar bear
  2. Butterfly
  3. Peppered moth
  4. Bear
Multiple Choice Type

Answer:

Peppered moth

Reason — Peppered moth showed natural selection of dark winged moths after industrial revolution.

Question 10

The famous book “The Origin of Species” was written by :

  1. Carl Linnaeus
  2. Darwin
  3. Lamarck
  4. Mendel
Multiple Choice Type

Answer:

Darwin

Reason — "The Origin of Species" was written by Charles Darwin.

Short Answer Type

6 questions

Question 1

Mention four postulates of Darwin's theory.

Short Answer Type

Answer:

Four postulates of Darwin's theory were:

  1. Overproduction : more offsprings are produced than can survive
  2. Struggle for existence
  3. Variation : Individuals within a species show variation
  4. Survival of the fittest

Question 2

The range of cranial capacities in the following ancestral forms were

(a) Australopithecus

(b) Homo habilis

(c) Homo erectus

(d) Cro-magnon

(e) Homo sapiens sapiens

Short Answer Type

Answer:

(a) Australopithecus → 450 to 600 cm3

(b) Homo habilis → 680 to 735 cm3

(c) Homo erectus → 800 to 1125 cm3

(d) Cro-magnon → 1450 to 1600 cm3

(e) Homo sapiens sapiens → 1450 to 1600 cm3

Question 3

Mention the two principles through which Lamarck explained his ideas.

Short Answer Type

Answer:

Lamarck was the first scientist to propose his theory of use and disuse and inheritance of acquired characters to explain evolutionary process.

  1. Use and disuse — Parts of the body which are used extensively become larger and stronger, while those which are not used deteriorate.
  2. Inheritance of acquired characters — An organism could pass its modifications to its offspring.

Question 4

Name any three vestigial organs found in humans.

Short Answer Type

Answer:

Three vestigial organs found in humans are:

  1. Wisdom teeth
  2. Vermiform appendix
  3. Pinna

Question 5

Give the scientific name of the organism which is cited as the classical example of 'Natural Selection'.

Short Answer Type

Answer:

Biston betularia is a classical example of 'Natural Selection'.

Question 6

Tick mark (√) the correct option in the following statements.

(a) The fossil history of humans is complete/fragmentary.

(b) The first remarkable human fossil was that of H. habilis/H.africanus.

(c) Evolution is an ever continuing/promptly ending process.

Short Answer Type

Answer:

(a) The fossil history of humans is fragmentary.

(b) The first remarkable human fossil was that of Homo habilis.

(c) Evolution is an ever continuing process.

Structured Application Skill Type

3 questions

Question 1

Given below are two figures (A and B) representing the two stages of evolution of human beings.

Given alongside are two figures (A and B) representing the two stages of evolution of human beings. Mention any two contrasting characters between the two stages. Write all the stages of human evolution in their correct sequence. State any two characteristic features of stage B. Human Evolution, Concise Biology Solutions ICSE Class 10.

Answer the following:

(a) Mention any two contrasting characters between the two stages.

(b) Write all the stages of human evolution in their correct sequence.

(c) State any two characteristic features of stage B.

Structured Application Skill Type

Answer:

Stage A → Australopithecus

Stage B → Homo sapiens sapiens (modern man)

(a) Contrasting characters between Australopithecus and Homo sapiens sapiens :

CharactersAustralopithecusHomo sapiens sapiens
Cranial capacity450 to 600 cm31450 to 1600 cm3
Development of chinLack of chin, prognathous faceProminent chin, snout disappeared

(b) Stages of human evolution in their correct sequence:

Australopithecus → Homo habilis → Homo erectus → Neanderthal man → Cro-Magnon man → Homo sapiens sapiens (modern man)

(c) Characteristic features of stage B (Homo sapiens sapiens):

  1. Bipedal locomotion with four reversed curves in the spine.
  2. Thoracic region flattened into a broad chest by flattening of sternum.

Question 2

Given below are two figures (A and B) showing a phenomenon that was first observed in Manchester before and after the year 1850.

Given alongside are two figures (A and B) showing a phenomenon that was first observed in Manchester before and after the year 1850. What name has been given to this phenomenon? Give the common name and the scientific name of the insect involved in this phenomenon. Briefly mention why the changes shown in the two figures appeared. The following phenomenon provides a classical explanation of a scientific theory given by a certain scientist. Name and explain the said theory. Give the name of the scientist who gave this theory. Human Evolution, Concise Biology Solutions ICSE Class 10.

Answer the following.

(a) What name has been given to this phenomenon?

(b) Give the common name and the scientific name of the insect involved in this phenomenon.

(c) Briefly mention why the changes shown in the two figures appeared.

(d) The following phenomenon provides a classical explanation of a scientific theory given by a certain scientist.

(i) Name and explain the said theory.

(ii) Give the name of the scientist who gave this theory.

Structured Application Skill Type

Answer:

(a) Industrial Melanism

(b) Common name — Peppered moth

Scientific name — Biston betularia

(c) Biston betularia, this moth with its light coloured wings dotted with spots blended well with the lichens growing on the houses and tree trunks on which it rested. After the Industrial Revolution, pollution resulted in a decline in the growth of lichens. The tree bark got exposed due to the absence of lichens. As a result, dark-coloured moths now got an advantage of a dark background, were camouflaged and survived, while the light-coloured moths were easily picked by predators. This showed that in a mixed population, those moths which could adapt to the changing environment after the Industrial Revolution survived and increased in number, while the ones which could not adapt were slowly wiped out from the population.

(d) The theory explaining Industrial Melanism and the name of the scientist who gave it is given below:

  1. Natural selection — During the struggle for existence, only those individuals which have advantageous variations survive while the ones which lack these variations are wiped out. Nature selects only those variations which are suitable for existence. This process is called natural selection.
  2. Charles Darwin

Question 3

Observe the figure given below and answer the questions that follow:

What is the figure depicting? What is the name of the theory that is being depicted in the figure? Human Evolution, Concise Biology Solutions ICSE Class 10.

(a) What is the figure depicting ?

(b) What was the reason that the giraffe stretched their neck and forelimbs ?

(c) What is the name of the theory that is being depicted in the figure ?

(d) Who explained the theory ?

(e) What is the conclusion of this theory ?

Structured Application Skill Type

Answer:

(a) The figure depicts evolution in Giraffe due to extensive use of neck and forelimbs.

(b) The area where giraffe fed on grasses, fell short of its ground level vegetation and therefore they had to stretch their neck and forelimbs to reach leaves of trees.

(c) Lamarck's theory of inheritance of acquired characters

(d) Lamarck

(e) According to this theory, variations are seen in organisms due to less or overuse of organs. These variations are passed on to the offsprings. After many generation these variations become permanent feature of the organism.