According to the passage, many of disease's treatment are result of experiment on animals and without experimenting on animal it wouldn't be possible to reach this point in treatment and curing of diseases. on the other hand lecture says that, testing the effect of drugs without testing on animals is possible and making the drugs that didn't test on animals in history of medical science have been proving this.
There are a lot of drugs such as penicillin which at first was tested on animals but who knows such discoveries wouldn't possible without experimenting on animals. There are a lot of drugs such as Aspirin which was discovered without testing on animals.
The passage says that some animals have same genes with humans and testing the drugs on animals would help to cure disease. On the other hand, there are some drugs which have different effects on different animals and human.
In conclusion, however testing the drugs on animals is resulted in curing and treatment of diseases in human but maybe this result would be possible without testing on animals.