MASTER THE GENETIC CODE (CLASS XII)
Meritnation|Mar 15th, 2012 12:21pm
Genetics is one of the most difficult but interesting subjects in biology. A good understanding of genetics requires knowledge about the structure and function of cell, cell division and reproduction. Here are a few tips on how to master this subject.
- The unit, Genetics and Evolution amounts to 18 marks in the biology paper.
- This unit consists of three chapters namely; Principles of Inheritance and Variation (Chapter 5), Molecular Basis of Inheritance (Chapter 6) and Evolution (Chapter 7).
- Figure out the critical aspects of genetics and try to perfect them.
- An analysis of previous years question papers shows that many questions are asked as it is from the NCERT textbooks.
- The table given below shows the exact question numbers of the questions in the question papers and the page numbers in the textbook where the answers to these questions are available.
|Marks||Chapter 5||Chapter 6||Chapter 7|
|Q. No.||Pg. No||Q.No||Pg. No||Q.No||Pg.No||2009 Set 1|
|1||1||130||2009 Set 2|
|1||3||111||2||130||2009 Set 3|
|1||4||112||6||127||2010 Set 3|
|1||7||112||2011 Set 1|
|1||7||112||2011 Set 3|
- We have compiled the questions that have come in the previous years examinations from this unit. Click here t:-
Important questions from the unit genetics and evolution 2009
Important questions from the unit genetics and evolution 2010
Important questions from the unit genetics and evolution 2011
- Smart people don’t just learn better. They learn differently. Instead of memorizing the theory, try to connect the points.
- The science of genetics is based on chance and probability.
- The crosses relating to Mendelian genetics need to be practised well. Try to practice these crosses thoroughly instead of memorising them.
- Here is a table representing the genotypic and phenotypic ratios of the crosses involved in Mendelian genetics
|Cross||Phenotypic Ratio||Genotypic Ratio|
- Constructing a Punnett square is an essential part of solving problems based on Mendelian genetics.
- In order to understand Punnett square, let us consider the given example.
Questions on Pedigree Analysis:
- Pedigree analysis questions are usually asked on the inheritance of diseases such as sickle cell anaemia, haemophilia and colour blindness.
- The inheritance pattern of such diseases involves the understanding of these traits as to whether they are sex-linked or autosomal.
- The inheritance of sex-linked disorders differ in males and females while in case of autosomal disorders, there is no distinction in males and females.
- The inheritance of autosomal disorders depends on whether the trait is dominant or recessive. Here are some examples of sex-linked and autosomal disorders.
- The given table enlists some common genetic diseases.
- Here is an example of a question on pedigree analysis.
- For questions on processes, try to give your answers in points or flow charts and then elaborate on them if the question asks for it.
- Try to support your answers with suitable diagrams.
- Now let us take a look at the chapter-wise important topics in this unit.
|Chapter / Marks
||1||2||3 and 5|
|Principles of Inheritance
|Laws of Mendel||Codominance|
|Test cross||Incomplete dominance|
|Sex Determination, Male and female Heterogamety|
|Mendelian and chromosomal disorders|
|Molecular Basis of Inheritance||Genetic code – start and stop codons||
Hershey and Chase Experiment
Messelson and Stahl
|histone proteins and
Modifications (capping, Tailing)
|Mutation||Features of the genetic code|
|Structure of tRNA|
|Goals and features of HGP|
|Evolution||Origin of life||Convergent and
|Natural selection and
|Natural selection and
|Human evolution||Hardy-Weinberg Principle|
Follow these simple tips to achieve great marks in the exam.
All the Best!