A man who is achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was six feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X- linked recessive. What proportion of their sons would be color-blind and of normal height ?

1. All 

2. None

3. Half

4. One out of four 

 

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On the basis of information given in the pedigree, if II 3 marries a hemophilic man, what is the probability that her first child will be normal ?

1. 1/4

2. 1/2

3. 3/4

4. 0

 

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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

 

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An individual with c d genes was crossed with the wild type ++. On test crossing F1,  the progeny were +c 105, +d 115, c d 880 and ++900. Distance between c d genes is :

1. 11 map units

2. 5.5 map units

3. 44 map units

4. 22 map untis

 

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A dihybrid test cross shows a frequency of recombination of 50 %. The best explanation will be :

1. The two genes are likely to be located on different chromosomes

2. All of the offspring have combinations of traits that match one of the two parents

3. The genes are located on sex chromosomes

4. Abnormal meiosis has occured 

 

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A woman receives her X chromosomes from :

1. her mother only

2. her father only

3. both her mother and her father

4. extranuclear DNA in her mother's egg

 

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A mechanism that can cause a gene to move from one linkage group to another is :

1. Translocation

2. Inversion

3. Crossing over

4. Duplication

 

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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 

 

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The recombination frequency between genes A and B is 9 percent ; between A and C is 17 percent ; and between B and C is 26 percent. What is the sequence of genes on the chromosome ?

1. ABC

2. ACB

3. BAC

4. Can't be determined from the given information 

 

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Abnormal chromosomes are frequent in malignant tumors. Errors such as translocations may place in gene in close proximity to different control regions. Which of the following might then occur to make the cancer worse ?

1. An increase in non-disjunction

2. Expression of inappropriate gene products 

3. A decrease in mitotic frequency 

4. Death of the cancer cells in the tumor 

 

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