estions 16 and 17 refer to the followings In Drosophila, females heterozygous fo
ID: 272222 • Letter: E
Question
estions 16 and 17 refer to the followings In Drosophila, females heterozygous for che recessive alleles m, g, and z were crossed to malee homozygous recessive for theBe three mutant genes. The phenotypes of the resulting progeny were: 315 305 142 138 mq+ 39 41 9z Total progeny 1000 16. The gene order is known to be mgz. How many map units separate genes g and z? a) 30 b) 28c) 15 d) 10e) 8 17· The gene order ?? known to be mqz . How many map units separate genes m and q? a) 30 b) 28 c) 15d) 10 e) 8 18. Given the wobble hypothesis, if CCu codes for proline, UUC codes for phenylalanine, and CGU codes for leucine, then it is most 1ikely that cCA codes for: a) serine b) threonine c) leucine d) phenylalanine e) proline 19. When n equals ABC, AAABBBCCC is: a) diploid b) trisomicc) monosomic d) triploid e) monoploid a) 4 b) 3 c) 2 d) 1 e) none alare present to add bases to RNA b) are present in bacteria 20. How many Barr bodies are present in a 48, XXXX female? 21. Spliceosomes : c) are the size of an enzyme d) contain RNA and protein 22. Considering al1 organisms, DNA repair mechaniems include: a) excision repair b) mismatch repair c) photoreactivation repair d) all of the abot eExplanation / Answer
Ans 20- B
3 barr bodies are present in genotype XXXX, because as according to the process of lyonization only one X chromosome is expressed in each cell while rest of them are inactivated in the form of heterochromatin barr bodies. Hence here among four X chromosomes one is expressed and rest 3 forms barr bodies.
Ans 21- D
Spliceosomes are composed of snRNA and SR proteins.hence option D is correct.
RNA polymerase add bases to RNA hence option A is incorrect.
Spliceosomes are found in eukaryotic nucleus hence option B is incorrect too.
Enzyme is a protein and its size is based on number of amino acids hence option C is also incorrect.
Ans 22- D
If DNA gets an error during synthesis or some chemical or physical agent causes damage in it then, base exicision repair, double stranded break repair, mismatch remair or photoreactivation repair mechanisms takes place to correct the errors in DNA.
hence all the options are correct so option D is the perfect choice.
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