OBJECTIVE & FILL IN THE BLANKS OF LINKAGE AND CROSSING OVER

Multiple Choice Questions (MCQs)

I. The phenomenon in which genes are present on the same chromosomes is:

(a) Cross over (b) Segregation (c) Linkage(d) assortment

2. The linked gene does not follow:

(a) Cross over (b) Segregation (c) Linkage(d) assortment

3. The linkage groups in man are:(a) 46                  (b) 23               (c) 22                (d) 24
   4. The linkage group of sickle cell anemia, leukemia and albinism is present on chromosome:

   (a) 10                  (b) 11               (c) 12                (d) 13

   5. The gene linkage minimize the chances of: (a) Cross over (b) Segregation(c) recombination(d) assortment
   6. Gene A and B are linked gene. Which of following gametes show recombination?

   (a) AB               (b) ab               (c) Ab               (b) ab

   7. There is 30% recombination frequency between two genes. The distance between them in unit map is:

   (a) 15               (b) 30               (c) 60                (d) 80

   8. There are 80% parental and 20% recombinant in a cross. Its recombinant frequency is:

   (a) 10%            (b) 20%            (c) 40%            (d) 80%
   Answers:

   I. (c) 2. (d) 3. (b) 4. (b) 5. (c) 6. (a) 7. (b) 8. (b)

   Fill in blanks

   1. All the genes located on the same chromosome are linked to
      each other. This phenomenon of staying together of all the

   genes of a chromosome is called______________

   
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   2. A chromosome carries its linked genes en bloc in the form of a______________.
   3. The exchange of segments between non-sister chromatids of homologous chromosomes during meiosis is called___________.
   4. Linked genes can be separated by______________
   5. Two genes are strongly linked if they have closer gene__________.
   6. The proportion of recombinant types between two gene pairs as compared to the sum of all combinations is called cross over or_____________ frequency.
   7. The two linked genes A and B with a 20% recombinationfrequency must be____________ apart.
   8. Crossing over produces genetic___________ among offspring.
      3. Ans:

      1. Linkage   2. linkage group3. crossing over 4. crossing over

      5. loci              6. recombination7. 20               8. variation

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• SUBJECTIVE & SHORT QUESTIONS OF LINKAGE AND CROSSING OVER
• Construction of Linkage Maps
• Crossing over
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