In the 1880s, Louis Pasteur developed a method of weakening viruses. The weakened viruses could be injected into healthy individuals. How is this method effective in fighting viral diseases? * 1.The immune system develops antibodies in response to the weakened viruses.

2.The weakened viruses attach to unaffected viruses in the host and interrupt the viral reproductive cycle.

3.The rate of genetic mutation in the host is decreased due to the introduction of weakened viruses

4.Weakened viruses are unable to enter the host organism.

You are studying several alleles of an e. coli helicase gene. one allele, called rsr, confers resistance to rs2014, an antibiotic that works by inhibiting helicase activity. bacteria with the rss allele are sensitive to rs2014. another allele, called ts-, produces a temperature sensitive mutation of the helicase. in bacteria with the ts- allele, helicase is inactivated at 42 °c but functions normally at 37 °c. helicase functions normally at both temperatures in bacteria with the ts allele. you obtain the following data while testing four strains of e. coli at different temperatures and doses of rs2014. each number represents the percentage of maximal dna synthesis. based on this data, assign the appropriate genotype to strains a–d in the spaces provided