The salivary gland chromosomes in the dipteran larva, are useful in gene mapping because:

1. They have endoreduplication chromosomes
2. These are fused
3. These are easy to stain
4. These are much longer in size
Subtopic:  Recombination & Gene Mapping |
AIPMT - 2005

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A dihybrid test cross leads to a frequency of recombinants of 50% in progeny. The most obvious conclusion will be:

1. The two genes likely are located on different chromosomes.
2. All of the offspring have combinations of traits that match one of the two parents.
3. Abnormal meiosis has occurred.
4. Independent assortment is hindered.
Subtopic:  Linkage | Recombination & Gene Mapping |
 65%

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If a chiasma forms between the loci of genes A and B in 20 % of the tetrads of an individual of genotype AB/ab, the percentage of gametes expected to be Ab is:

1. 40 2. 20
3. 10 4. 5

Subtopic:  Understanding Linkage | Linkage Types | Recombination & Gene Mapping |

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What map unit (Centimorgan) is adopted in the construction of genetic maps?

1. A unit of distance between genes on chromosomes, representing 50% cross-over.
2. A unit of distance between two expressed genes, representing 10% cross-over.
3. A unit of distance between two expressed genes, representing 100% cross-over.
4. A unit of distance between genes on chromosomes. representing 1% cross-over.
Subtopic:  Recombination & Gene Mapping |
 58%
NEET - 2019

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The frequency of crossing over between any two linked genes will be:

1. Higher if they are recessive
2. Dependent on how many alleles there are
3. Determined by their relative dominance
4. Proportional to the distance between 
Subtopic:  Understanding Linkage | Linkage Types | Recombination & Gene Mapping |
 79%
From NCERT

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Consider crossing over does not take place between chromosomes shown as:
(i) Chromosome 1: ABC/abc
(ii) Chromosome 2:Qr, qr.
Which of the following gametes will not be formed by this organism?

1. ABCqr 2. abcqr
3. ABcqr 4. abcQr
Subtopic:  Recombination & Gene Mapping |
 73%

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The recombination frequencies for four different linked genes of Drosophila are shown in the figure:

 

The order of the four genes will be:

1.rb-cn-vg-b2.vg-b-rb-cn
3.cn-rb-b-vg4.b-rb-cn-vg

Subtopic:  Recombination & Gene Mapping |
 56%

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