Antibiotics are routinely introduced into the food of cattle, chickens and other livestock, which causes the animals to grow faster. since the cost of antibiotics is low, the use of antibiotics is an easy way to achieve faster weight gain in animals. explain how this practice could affect the probability of developing populations of antibiotic-resistant bacteria that cause human disease.

Antibiotics are routinely introduced into the food of cattle, chickens and other livestock, which causes the animals to grow faster but the negative effect of using antibiotics is the development of antibiotic- resistant bacteria.

When we use antibiotics at large scale some bacteria that live in these cattle become resistance to these antibiotics and then these resistant bacteria are shed in the soil through poop of animals.  

Bacteria have the capability to transfer antibiotic-resistant genes to other bacteria by horizontal gene transfer mechanism so it can give rise to more antibiotic-resistant bacteria which can infect humans.

So when these resistant bacteria infect humans then if we take the antibiotics which the bacteria are resistant for then the antibiotic will not able to protect the patient.  

Therefore, this practice could affect the probability of developing populations of antibiotic-resistant bacteria that cause human disease.

the endomembrane system i think