Which of the following comparisons between different degrees of dominance between alleles of same gene are correct?
Complete dominance Incomplete dominance Co-dominance
I F1 progeny Resemble one of the parents Do not resemble either of the parents Resemble both parents
II F2 phenotypic ratio 3 : 1 1: 2 : 1 1: 2 : 1
III F2 genotypic ratio 1: 2 : 1 1: 2 : 1 1: 2 : 1
IV Example Height in garden pea Flower colour in snapdragon ABO blood group
V Blending Does not occur Occurs Occurs

1.    I, II, III and IV only
2.    I and IV only
3.    II and III only
4.    I, II, III, IV and V
 

Subtopic:  Monohybrid Cross: 1 | Monohybrid Cross: Further Understanding |
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In a typical dihybrid cross AaBb X AaBb [assuming independent assortment], what would be the ratio of the progeny with the genotypes – AaBb, Aabb, aaBb and aabb respectively?
1.    1: 1: 1: 1
2.    4: 2: 2: 1
3.    3: 1: 1: 3
4.    9: 3: 3: 1
 
Subtopic:  Dihybrid Cross Analysis |
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Level 2: 60%+
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Consider the given two statements:
Statement I              If two genes are located on heterologous chromosomes they will assort independently and a dihybrid cross will yield a F2 phenotypic ratio of 9: 3: 3: 1.
Statement II If the two genes are linked the dihybrid F2 phenotypic ratio will vary significantly from 9: 3: 3: 1 with strength of linkage directly proportional to the distance between the genes.

1.    Statement I is correct; Statement II is incorrect 
2.    Statement I is incorrect; Statement II is incorrect
3.    Statement I is correct; Statement II is correct
4.    Statement I is incorrect; Statement II is correct
 
Subtopic:  Chromosomal Basis of Inheritance: Introduction | Chromosomal Basis of Inheritance: Further Considerations | Recombination & Gene Mapping |
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In polygenic inheritance:
1.    traits have distinct alternate forms.
2.    the expression of the genes is immune to the effects of the environment.
3.    the phenotype reflects the contribution of each allele.
4.    a single gene can exhibit multiple phenotypic expression.
 
Subtopic:  Polygenic Inheritance & Pleiotropy |
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Identify the incorrect statement regarding mechanism of sex determination in varied organisms:
1.    Male honeybees do not have a father and cannot have sons, but have a grandfather and can have grandsons.
2.    Male grasshoppers have odd number of chromosomes in their somatic cells while the female grasshoppers have even number.
3.    The females are heterogametic in birds.
4.    If a couple has a daughter, they will have a son in next pregnancy as there is 50 percent probability of either a male or a female child in each pregnancy.
 
Subtopic:  Sex Determination |
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Level 3: 35%-60%
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Which of the following are correct differences between sickle cell anaemia and thalassemia?
Sickle Cell Anaemia Thalassemia
I Mode of inheritance Autosomal recessive Sex linked recessive
II Cause Substitution of valine by glutamic acid due to a single base substitution at the sixth codon of the beta globin chain Mutation or deletion of genes located on chromosomes 11 or 16
III Effect on haemoglobin Qualitative – incorrectly functioning globin Quantitative – synthesis of too few haemoglobin molecules

1.    Only I and II
2.    Only I
3.    I, II and III
4.    Only III     
 
Subtopic:  Mendelian Disorders: Sickle Cell Anemia | Mendelian Disorders | Mendelian Disorders: Thalassemia |
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Failure of segregation of chromatids during cell division cycle results in anuploidy. Given below are some important aneuploidies seen in humans. Identify the ones which are correctly matched to their description:
I. Down’s syndrome Trisomy 21; Simian palmar crease, Furrowed tongue, Mental retardation
II. Klinefelter’s  syndrome 47,XXY; Genetically female, gynaecomastia and sterility
III. Turner’s syndrome 45, XO; genetically male, Rudimentary ovaries, lack of secondary sexual characters
1.    Only II and III
2.    Only I
3.    I, II and III
4.    Only II

 
Subtopic:  Non - Disjunction & Aneuploidy | Sex Aneuploidy - Turner & Klinefelter Syndrome |
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The phenomenon of pleiotropism refers to:
 
1. more than two genes affecting a single character.
2. presence of several alleles of a single gene controlling a single crossover.
3. presence of two alleles, each of the two genes controlling a single trait.
4. a single gene affecting multiple phenotypic expressions.
Subtopic:  Polygenic Inheritance & Pleiotropy |
 80%
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Frequency of recombination between gene pairs on same chromosome as a measure of the distance between genes to map their position on chromosome, was used for the first time by:
1.Henking 2.Thomas Hunt Morgan 
3.Sutton and Boveri 4.Alfred Sturtevant 
Subtopic:  Understanding Linkage | Linkage Types | Recombination & Gene Mapping |
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Which of the following statements are correct about Klinefelter's Syndrome?
A. This disorder was first described by Langdon Down (1866).
B. Such an individual has overall masculine development. However, the feminine development is also expressed. 
C. The affected individual is short statured.
D. Physical, psychomotor and mental development is retarded.
E. Such individuals are sterile. 
Choose the correct answer from the options given below:
1. A and E only  2. A and B only 
3. C and D only  4. B and E only
Subtopic:  Non - Disjunction & Aneuploidy | Sex Aneuploidy - Turner & Klinefelter Syndrome |
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Level 1: 80%+
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