Antibiotics, such as penicillin, are drugs that kill or prevent the growth of bacteria. when antibiotics were first discovered, they seemed to represent a miracle cure for human diseases like pneumonia, typhoid, bubonic plague, and gonorrhea. today there are resistant strains of bacteria that cannot be killed by antibiotics. can you pick out the statements that accurately describe the development of antibiotic resistance? antibiotic resistance is not an example of natural selection. mutations may be a source of variation in any population of bacteria. when antibiotics are used at first, all the disease-causing bacteria are killed. there is always variation in a population and might include resistant bacteria. bacteria that are not initially killed by the antibiotic, reproduce passing the resistance on to offspring.

In a hypothetical breed of dogs, coat color is controlled by two genes. there are six different coat colors in this breed: black, brown, cream, gray, silver, and tan. consider the following crosses. cross 1: black females from a lineage of all black dogs are crossed with brown males from a lineage of all brown dogs. f1 males and females are all black. when f1 are intercrossed, f2 males and females are black or brown. cross 2: black females from a lineage of all black dogs are crossed with tan males from a lineage where all males are tan and all females are cream. f1 males are black, f1 females are gray. when f1 are intercrossed, f2 males and females are black, brown, gray, or tan. cross 3: silver females from a lineage where all females are silver and all males are gray are crossed with brown males from a lineage of all brown dogs. f1 males and females are all gray. when f1 are intercrossed, f2 males are black, brown, gray, or tan, f2 females are cream, gray, silver, or tan. select the correct statements regarding the mode of inheritance of the coat color genes. a) both genes are x-linked. b) both genes are autosomal. c) one of the genes modifies the expression of the other gene. d) each gene has an additive effect on the intensity of coat color. e) each gene independently specifies three colors. f) one of the genes is autosomal, and the other is x-linked.