Following statements are related to slow block to polyspermy in mammals.

A. A First slow block to polyspermy comes When the cortical granules fuse with the egg cell membrane, they release protein-digesting enzymes which is called as ovastacin that modify the zona pellucida proteins.

B. A second slow block to polyspermy comes from the so-called zinc spark, the release of billions of zinc ions that is induced by the entry of the first sperm, these released zinc ions are seen to bind to the egg cell membrane form a “zinc shield” that prevents further sperm entry.

C. A third slow block to polyspermy occurs at the level of the egg cell membrane and involves Juno.

Which of the following is incorrect?

#Question id: 5348

#Unit 8. Inheritance Biology

Miniature wings (Xm) in Drosophila result from an X-linked allele that is recessive to the allele for long wings (XL). Following different cross with resulting progeny were possible

Which of the following above offspring is not possible to carry miniature wings?

#Question id: 5239

#Unit 8. Inheritance Biology

Which of the following statements is not true for Hfr strains of E. coli ?

#Question id: 5240

#Unit 8. Inheritance Biology

If bacteria grow in the presence of a large amount of DNase, which of the following recombination process completely inhibited?

#Question id: 5241

#Unit 8. Inheritance Biology

Genes a, b, and c are widely spaced in the bacterial genome. Transducing phage from an a+ b+ c+ bacterium were used to infect a culture of a- b- c- cells, and b+ transductants were selected. Which of the following best describes the predicted genotypes of these transductants?

#Question id: 5242

#Unit 8. Inheritance Biology

Auxotrohic bacteria plating on different medium, it is observed that colonies grow on minimal plus threonine only, no colony on minimal plus leucine and no colonies grow on minimal medium cystein only. What are the actual genotypes of auxotroph?

#Question id: 5243

#Unit 8. Inheritance Biology

Auxotroph culture (His- and Lac-) culture of E. coli was mutagenised. On what media would one spread the mutagenised cells to select prototroph for both His+  and Lac+ cells?