Answer:
Some bacteria are used as indicators because if they are present in the product, we can say that it is a product with the presence of pathogens that will cause diseases. Some of them are: total coliforms, fecal coliforms and enterococci.
To be a good indicator they must have a correlation with the pathogens and be more abundant than them. Its presence in a food indicates the possible presence simultaneous pathogen microorganisms. For example, E. coli has been used as Index of possible presence of pathogens of enteric origin in water and food
The control is the group of no fertilizers.
A control in an experiment is usually the group without the variable to be tested. In this case, the farmer wanted to test the effects of fertilizers, therofre the group without it is the control group.
Answer: C. Black snakes will not prey on cane toads in areas where cane toads have been present for 40–60 years.
Explanation:
Cane toad secret a toxin called bufotoxin which is a defense mechanism against predators. These defense mechanism is capable of killing black snakes if they eat cane toads. Within a period of 40 to 60 years, the black snakes in these area will be aware of the presence of a toxin capable of killing them in cane toads and will not prey on them. This phenomenon is termed learned behavioral adaptation.
I'm guessing its so they can be able to diagnose a patient and see whether they need treatment or not
