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A. Linkage prevents segregation of genes...

A. Linkage prevents segregation of genes present on the same chromosomes.
B. XY sex chromosomes were discovered by Nettie Stevens
C. Complete linkage has been reported in male Drosophila.
D. Term linkage was given by Correns. (a) All are correct

A

All are correct

B

All are incorrect

C

All are correct except D

D

Only D is correct

Text Solution

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The correct Answer is:
C
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Assertion (A): Inheritance of genes in which genes present on a particular chromosome show a tendency to get inherited together is termed as Linkage. Reason (R): Very low recombination frequency or strong linkage is shown by the genes grouped on the same chromosome.

The person A has only B chromosomes in all its gametes. On the other hand, another person C has chromosome D in half of gametes and chromosome E in the other half of gametes. When chromosomes B and D combine during fertilisation, a female zygote results. On the other hand, combination of B and E chromosomes produces a male zygote. (a) What are chromosomes (i) B (ii) D, and (iii) E ? (b) Out of B, D and E, which two chromosomes are of the same type ? (c) Which chromosome is smaller in size ? (d) What is the general name of chromosomes such as B and E ? (e) Out of the two persons A and C, which one is (i) male, and (ii) female ?

Knowledge Check

  • Maize has 10 pairs of chromosomes. How many linkage groups will be present if all the genes are mapped?

    A
    15
    B
    10
    C
    20
    D
    40

  • A scientist performed the gene mapping experiments in maize. He mapped the gene on chromosomes on the basis of % crossing over between different genes. One map unit corresponds to one % crossing over or recombination. Te genes showing more than 50% recombination were not supposed to be linked on same chromosome. In crossing over studies on maize, scientist observed the following % crossing over between A B, C, d- between. A and D 10% between A and C 3% between genes C and D 7% between genes A and B 5% , and between genes C and B 8% on the basis of above observation find out the correct sequence of tenes Alt B, C, and D on chromosomes :-

    A
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    B
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    C
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    D
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  • Go through the following statements : I. The fact that all seven of the garden pea traits studied by Mendel obeyed the principle of independent assortment means that the seven pairs of alleles determining these traits behave as if they are on different chromosomes. Il. A Barr body (sec chromatin) is normally found in the nucleus of somatic cells of a female only III. The particular position of a gene on a chromosome is known as a locus. IV. The frequency of crossing over between any two linked genes is proportional to the distance between them. V. A man who carries an X-linked allele will pass it on to all of his daughters. Vl Thomas Hunt Morgan is nest remembered for his discovery and explanation of crossing over and recombination. VII. There is good evidence for linkage when two different loci do not segregate independently during meiosis. Which statements are correct?

    A
    All are correct
    B
    I, III, V and VII are correct
    C
    II, IV and VI are correct
    D
    None are correct

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