In Drosophila melanogaster, the cross between
(i) yellow body, white eyed one with its wild type, the percentage of recombination is less.
(ii) white eyed, miniature winged one with its wild type, the percentage of recombination is high.

A cross was made between pure breeding pea plant one with round and green seeds and the other with wrinkled and yellow seeds. (i) Write the phenotype of F_(1) progeny. Give reason for your answer. (ii) Write the different types of F_(2) progeny obtained along with their ratio when F_(1) progeny was selfed.

Which one is correct about Crossing over/Genetic recombination? (i) It occurs in tetrad stage. It occurs in pachytene of prophase I of meiosis I. (ii) It occurs between non-sister chromatids of homologous chromosomes. (iii) It is recombinase enzyme mediated process. (iv) It is also the reciprocal transfer of genes between the non homologous chromosomes.

Account for the following: (i) State the relation between hydrogen ion concentration of an aqueous solution and its pH. (ii) An aqueous solution has a pH value of 7.0 Is this solution acidic, basic or neutral. (iii) Which has a higher pH value, 1M HCl or 1M NaOH solutions? (iv) Tooth enamel is one of the hardest substances in our body. How does it undergo damange due to eating chocolates and sweets? What should we do to prevent it?