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3.1 Linkage & Crossing Over — Test 1
Q1. The procedure for mapping chromosomes (using recombination frequency) was invented by:✓ A. H. Sturtevant
Q2. The first chromosomal linkage map (five genes on the Drosophila X chromosome) was constructed by:✓ A. H. Sturtevant
Q3. The additive nature of a genetic map (Sturtevant–Morgan) holds best when there is:✓ No interference in crossovers
Q4. The cytological demonstration of crossing over was done by:✓ Curt Stern (and Creighton & McClintock)
Q5. The tendency of two or more genes to remain together during inheritance is called:✓ Linkage
Q6. A linkage group corresponds to a:✓ Chromosome
Q7. The number of linkage groups in an organism is always equal to the:✓ Haploid (n) number of chromosomes
Q8. Which statement about linkage is TRUE?✓ Linked genes are located close together on the same chromosome
Q9. Crossing over takes place during which stage of meiosis I?✓ Pachytene
Q10. Chiasmata are first clearly seen during:✓ Diplotene
Q11. The unit of a chromosome (genetic) map is the:✓ Centimorgan
Q12. The distance between genes on a chromosome is expressed in:✓ Centimorgan
Q13. The percentage of crossing over between two linked genes will be greater if the genes are:✓ Located far apart
Q14. The recombination frequency between two genes is such that:✓ More distant genes have higher recombination
Q15. The maximum frequency of recombination that can occur between two loci is:✓ 50%
Q16. However great the distance between two loci, the recombination fraction never exceeds:✓ 0.5
Q17. Linked genes (showing measurable linkage) always exhibit:✓ Recombination frequencies of less than 50%
Q18. One percent recombination between two genes is equal to:✓ One centimorgan
Q19. If a crossover in one region of a chromosome affects the likelihood of another crossover in an adjacent region, the phenomenon is called:✓ Interference
Q20. Match each event/term with its meiotic stage or definition and select the correct option.✓ A-ii, B-i, C-iv, D-iii