Q. 25

<span lang="EN-US

Answer :


• When Streptococcus pneumoniae pneumococcus) bacteria are grown on a culture plate, some produce smooth shiny colonies S) while others produce rough colonies R)


• Mice infected with the S strain virulent) die from pneumonia infection, but mice infected with the R strain do not develop pneumonia.


• Griffith was able to kill bacteria by heating them.


• He observed that heat-killed S strain bacteria injected into mice did not kill them.


• When he injected a mixture of heat-killed S and live R bacteria the mice died.


• He recovered living S bacteria from the dead mice.


• He concluded that the R strain bacteria had somehow been transformed by the heat-killed S strain bacteria.


• Some ‘transforming principle’, transferred from the heat led S strain, had enabled the R strain to become virulent.



Live virulent S-cells + Live mice Mice died


Non-virulent R-cells + Live mice Mice survived


Griffith was able to kill bacteria by heating them.


Heat Killed R-cells + Live mice Mice survived


Heat killed S-cell + Live R-Cells + Live mice Mice died



b) Avery, MacLeod and McCarty purified bio chemicals such as proteins, DNA and RNA from the heat-killed S cells, and discovered that it was DNA alone from S bacteria that caused the R bacteria to become transformed.


OR


a)



b)


• In Galapagos Islands from the original seed-eating featured finches many other forms of finches, with altered beaks arose, enabling them to become insectivorous and vegetarian finches.


• This process of evolution of different species in a given geographical area, starting from a point and literally radiating to other areas of geography or habitats is called adaptive radiation.



Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses
RELATED QUESTIONS :

Two organisms occBiology - Exemplar

How do homologousBiology - Board Papers