Define autopolyploidy. briefly describe the methods of production of autodolyploids and their importance and limitations in crop improve- ment.

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What are the common aneuploid analyses for locating genes on a particular chromosome? Give abrief description of these techniques using suitable diagrams where necessary.

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Define heteroploidy. List the various types of changes ni chromosome number. Briefly describe the modes of origin of aneuploids and their applications in crop improvement.

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Discuss the physiological bases of heterosis.

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Write short notes on the following: (i) sickle cell anaemia, (ii) pab locus in Neurospora, (ili) ma gene in maize, (iv) Adh alleles in maize, (v) inbreeding depression, and (vi) hybrid vigour.

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Explain the dominance and overdominance hypotheses of heterosis giving their muin features, objections and answers to the objections. Which of the above two hypotheses is more widely accepted and why ?

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Define heterosis. List its characteristic features, applications and achievements in crop improvement.

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What are the man features of inbreeding depressipn? Briefly describe the degrees of inhreeding depression encountered in crop species.

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Diffetentiate between the following ; (i) homozygous and homogeneous lines, (it) homozygous and heterozygous balance, (iji) genetic coad and gene pool, (iv) heterosis and luxuriance, (v) heterosis and hybrid vigour, (vi) dominance and overdominance.

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Define inbreeding depression and hybrid vigour. How do these phenomena atfect the self. and cross-pollinated species? Explain with the help of suitable examples.

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