If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, what would happen in environments that lack antibiotics?

#Question id: 5290

#XL - S Microbiology

The following table shows mapping data from three interrupted mating experiments using three different Hfr strains and an F- strain: The order of genes is

#Question id: 5295

#XL - S Microbiology

A cross is made between an Hfr that is met+ thi+ pur+ and an F-that is met- thi- pur-. Interrupted mating studies show that met+ enters the recipient last, so met+ recombinants are selected on a medium containing supplements that satisfy only the pur and thi requirements.  These recombinants are tested for the presence of the thi+ and pur+ alleles. The following numbers of individuals are found for each genotype:

What is the following correct combination?

#Question id: 5298

#XL - S Microbiology

Four E. coli strains of genotype a+ b− are labeled 1, 2, 3, and 4. Four strains of genotype a− b+ are labeled 5, 6, 7, and 8. The two genotypes are mixed in all possible combinations and (after incubation) are plated to determine the frequency of a+ b+ recombinants. The following results are obtained, where M = many recombinants, L = low numbers of recombinants, and 0 = no recombinants. On the basis of these results, assign a sex type (either Hfr, F+, or F−) to each strain

#Question id: 5323

#XL - T Zoology

An X-linked recessive gene produces red-green color blindness in humans. A woman with normal color vision whose father was color-blind marries a color-blind man. What is the probability that their son will be color-blind?

#Question id: 5324

#XL - T Zoology

In eusocial insects, males develop from unfertilized eggs while females develop from fertilized eggs. The ultimate consequence of this difference is that

#Question id: 5325

#XL - T Zoology

Cystic fibrosis is caused by a recessive lethal gene and can be detected by an excess concentration of chloride in sweat. A normal man whose sister has cystic fibrosis, his normal wife whose brother has cystic fibrosis. What is chance of cystic fibrosis in their child?