Principles of inheritance and variation: Previous Year Questions Part 1


2010 MARCH
1.     To find out the unknown genotype of violet flowered pea plant, a researcher done the following cross. Observe the diagram and answer the following questions.

a.   What would be the above cross is called? (½ )
b.   Can you determine the unknown genotype of violet flowered parent by drawing Punnet square? (2)
2.     Polypeptide chains of two hemoglobin molecules are shown below. One of the chains shows an abnormality. Observe the diagram and answer the following questions.
a.   Which of the polypeptide chain of the hemoglobin is abnormal leading to a disease? (½)
b.   What is the reason for this abnormality? (1)
c.    What will be the effect of this change in polypeptide chain? (1)
2010 SAY
1.     Some genetic abnormalities, their genotypes and features are distributed in columns A, B and C respectively. Match them correctly. (1½)
Down’s syndrome
44 A + XO
Rudimentary ovary and sterility
Turner’s syndrome
44 A + XXY
Furrowed tongue and partially opened mouth
Klinfelter’s syndrome
45 A + XX/XY
Gynaecomastia and sterility
2.     The flowcharts A & B given below represent the inheritance of normal haemoglobin and sickle cell haemoglobin 
a.   Observe the flowchart A and complete flowchart B (1)
b.   Note down the genotype of a sickle cell anaemia patient and mention the symptoms of disease. (1½)
c.    Mention the peculiarity of HbAHbS phenotype. (1)
2011 MARCH
1.     The frequency of occurrence of Royal disease or haemophilia is high in the pedigree of royal families of Queen Victoria. Which of the following cannot be generally inferred from this? (1)
a.   Queen Victoria was not homozygous for the disease.
b.   Many heterozygous females were there in the Royal families.
c.    Non-Royal families were not affected with haemophilia.
d.   There is less possibility to become a female diseased.
e.   Generally a diseased female cannot survive after the first menstruation.
f.    Pedigree analysis is the study of inheritance of patterns of traits in human females.
2.     After analyzing the karyotype of a short statured round headed person with mental retardation, a general physician noticed an addition of autosomal chromosome.
Answer the following questions.
a.   Addition or deletion of chromosome generally results in…………………. (½)
b.   What may be the possible syndrome or disorder the above person should suspected to be? (½)
c.    Suggest two more morphological peculiarities to confirm the chromosome disorder in that person. (1)
3.     A couple has 2 daughters. The blood group of husband and wife is ‘O’.
a.   What are the possible blood groups the children should have? (1)
b.   Whether any change in blood group will occur if they have two sons instead of daughters? Substantiate your answer. (1)
2011 SAY
1.     Symbols used in human pedigree analysis and their meanings are provided in the table. Fill the blanks with suitable symbols or meanings.     (1)
2.     Certain facts related to a human disorder are given.
                    i.    It is an inborn error in metabolism.
                    ii.   It is inherited as an autosomal recessive trait.
                   iii.    The affected person is mentally retarded.
a.   Name the disorder. (½)
b.   What are the physiological processes behind this mental retardation? (1½)
3.     A genetic cross is represented below.
a.   Identify the given cross. (1)
b.   Elaborate upon the significance of such a cross. (1)
2012 MARCH
1.     Complete the table using suitable terms. (2 Scores)
Turner’s syndrome
Sterile female
(b) …………
(c) …………
(d) …………
Trisomy 21
Mental retardation
2.     In pea plant the gene for yellow seed colour is dominant over green and round seed shape is dominant over wrinkled. Write the four types of gametes formed in a heterozygous pea plant with yellow and round seeds (YyRr). (1)
3.     The first child of a couple is affected with phenylketonuria. During the second pregnancy they visited a genetic counsellor and he prepared a pedigree chart of their family.
a.   What is pedigree analysis?  (½)
b.   Draw the symbols for
                    i.    Affected female
                    ii.   Sex unspecified
                   iii.    Consanguineous mating (½ x 3= 1½)
2012 SAY
1.     Diagrammatic representation of chromosome map of Drosophila is given below.
a.   Which genes are more linked? (½)
b.   Who mapped the chromosome firstly? (½)
c.    Tightly linked genes show low recombination. Why? (1)
2.     Work of a student is given below.
a.   From the above give an example for genotype & phenotype. (1)
b.   Complete the work using Punnett square and find out the phenotypic ratio in the F2 generation. (2)
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