In a monohybrid cross, ¼ of the random fertilisations lead to:
I: Homozygous dominant progeny
II: Homozygous recessive progeny
III: Heterozygous progeny
 
1. Only I and II are correct
2. Only I and III are correct
3. Only II and III are correct
4. I, II and III are correct

Subtopic:  Monohybrid Cross: Further Understanding |
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Consider the given two statements:
Assertion (A):  Mendel self-pollinated the F2 plants and found that dwarf Fplants continued to generate dwarf plants in F3 and F4 generations.
Reason (R):  The genotype of the dwarfs was homozygous.
 
1.  Both (A) and (R) are True but (R) does not correctly explain (A).
2.  Both (A) and (R) are True and (R) correctly explains Assertion.
3.  Both (A) and (R) are False.
4.  (A) is True but (R) is False.
Subtopic:  Monohybrid Cross: Further Understanding |
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In Antirrhinum majus, how many of the given cross will produce all progeny exhibiting similar phenotypes [symbols carry usual meanings]?
I: \(Rr \times Rr\) II: \(Rr \times rr\)
III: \(RR \times rr\) IV: \(Rr \times RR\)
 
1. 1
2. 2
3. 3
4. 4
Subtopic:  Monohybrid Cross: Further Understanding |
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Mendel published his work on inheritance of characters in 1865 but for several reasons, it remained unrecognised till 1900. These reasons included all the following except:
1. Communication was not easy in those days.
2. His concept of genes (or factors, in Mendel’s words) as stable and discrete units that controlled the expression of traits and, of the pair of alleles which did not ‘blend’ with each other, was not accepted by his contemporaries as an explanation for the apparently continuous variation seen in nature.
3. Mendel’s approach of using mathematics to explain biological phenomena was totally new and unacceptable to many of the biologists of his time.
4. Although Mendel’s provided correct physical proof for the existence of unit factors as discrete entities, his explanations could mot convince others.
Subtopic:  Chromosomal Basis of Inheritance: Introduction |
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Identify the incorrectly matched pair:
1. de Vries, Correns and von Tschermak Independently rediscovered Mendel’s laws
2. Walter Sutton and Theodore Boveri Gave chromosomal theory of inheritance
3. Sturtevant Discovered the mechanism of sex determination in fruit flies
4. T. H. Morgan Demonstrated that genes are carried on chromosomes
Subtopic:  Chromosomal Basis of Inheritance: Introduction |
 83%
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Consider the given two statements:
Statement I: The two alleles of a gene pair are located on homologous sites on homologous chromosomes.
Statement II: The pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried.
 
1. Statement I is correct; Statement II is correct
2. Statement I is correct; Statement II is incorrect
3. Statement I is incorrect; Statement II is incorrect
4. Statement I is incorrect; Statement II is correct
Subtopic:  Chromosomal Basis of Inheritance: Introduction |
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Consider the given two statements:
Assertion (A): X-linked recessive disorders are always expressed in males.
Reason (R): Males have only one X chromosome.
 
1. Both (A) and (R) are True but the (R) does not correctly explain the (A).
2. Both (A) and (R) are True and the (R) correctly explains the (A).
3. (A) is False but (R) is True.
4. (A) is True but (R) is False.
Subtopic:  Pedigree Analysis: Problem Solving |
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Both parents are carriers for an autosomal recessive trait. What proportion of their progeny are expected to be affected by this disorder?
1. 0
2. ¼
3. ½
4. ¾
Subtopic:  Pedigree Analysis: More Examples |
 68%
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Consider the given two statements:
Assertion (A): Human skin colour trait is spread over a gradient rather than having distinct alternate forms.
Reason (R): Human skin colour is a polygenic trait.
 
1. Both (A) and (R) are True but the (R) does not correctly explain the (A).
2. Both (A) and (R) are True and the (R) correctly explains the (A).
3. (A) is False but (R) is True.
4. (A) is True but (R) is False.
Subtopic:  Polygenic Inheritance & Pleiotropy |
 67%
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The genotype of a husband is IAIB and that of a wife is IAi. How many different genotypes and phenotypes are possible in their progeny?
1. 2 genotypes; 3 phenotypes
2. 3 genotypes; 4 phenotypes
3. 4 genotypes; 4 phenotypes
4. 4 genotypes; 3 phenotypes
Subtopic:  Polygenic Inheritance & Pleiotropy |
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