NCERT Solutions for Class 12 Biology Chapter 7

Evolution Class 12

Chapter 7 Evolution Exercise Solutions

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Exercise : Solutions of Questions on Page Number : 142

Q1 :  

Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.


Answer :

Darwinian selection theory states that individuals with favourable variations are better adapted than individuals with less favourable variation. It means that nature selects the individuals with useful variation as these individuals are better evolved to survive in the existing environment. An example of such selection is antibiotic resistance in bacteria. When bacterial population was grown on an agar plate containing antibiotic penicillin, the colonies that were sensitive to penicillin died, whereas one or few bacterial colonies that were resistant to penicillin survived. This is because these bacteria had undergone chance mutation, which resulted in the evolution of a gene that made them resistant to penicillin drug. Hence, the resistant bacteria multiplied quickly as compared to non-resistant (sensitive) bacteria, thereby increasing their number. Hence, the advantage of an individual over other helps in the struggle for existence.

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Q2 :  

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


Answer :

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.Confuciusornis is one such genus of primitive birds that were crow sized and lived during the Creataceous period in China.

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Q3 :  

Attempt giving a clear definition of the term species


Answer :

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Q4 :  

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


Answer :

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Q5 :  

Find out through internet and popular science articles whether animals other than man have self-consciousness.


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Q6 :  

List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.


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Q7 :  

Practise drawing various animals and plants.


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Q8 :  

Describe one example of adaptive radiation.


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Q9 :  

Can we call human evolution as adaptive radiation?


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Q10 :  

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.


Answer :

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Biology : CBSE NCERT Exercise Solutions for Class 12th for Evolution will be available online in PDF book form soon. The solutions are absolutely Free. Soon you will be able to download the solutions.

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