1 Restricted-transducing particles are classes as P standing for ‘plaue-forming’ or D standing for ‘defective in lysogeny. Given the proceeding data, Delta-gal phage might be: a.D and recoversable if mixed infections were made using a P or a wild-type helper. b.D and recoversable if mixed infections were made using a D or a wild-type helper. c.P and recoversable if mixed infections were made using a P or a wild-type helper. d.P and recoversable if mixed infections were made using a D or a wild-type helper The following tetrads were observed in a yeast cross: + b c + b c + b c a b + a + + a + + + + c a + + ---------------------- ---------------------- 500 25 + b c + b + + b c a b c a + c a + + + + + a + + ---------------------- ----------------------- 300 100 + b c a b + + b + a b c + + + a + c + + + a + c ---------------------- ----------------------- 25 25 2-1. The chromosomal arrangement of these genese is a. a 10 + 20 + b. a 10 b 20 c c. b 10 a 20 c d. b 10 + 20 c --------------- -------------- ------------- ------------- + b c + + + + + + b + + 2-2. The coefficient of conincidence in ther above data is a. 1.0 b. 1.25 c.0.8 d.0.0 2-3. Is there any indication of either positive or negative chromatid interference in these data a. Yes, because there is a shortage of 2-strand double exchange. b. Yes, because there are fewer double-crossovers than expected. c. No, because there are as many 2-strand doubles as expected. d. No, because there are as many double-crossovers as expected. 这几题我不会，劳烦大大们教我...谢谢 -- ☆墨非☆ 越不可能出错的事～越是一定会出错 --

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