Yeah! After MBBS also you can pursue research in Basic sciences (Biology related fields). Top institutes such as TIFR, NISER's, IISER's, IISc etc offers MBBS graduates to be eligible for the entrance examination for the Integrated MSc-PhD courses. So if you wish you can obviously go for it. If you want you can also appear for the NET examination & on qualifying you can take admission to the PhD directly as well provided you need to have atleast 55% marks in MBBS.

For more information regarding CSIR NET you can consider the link provided below:

https://competition.careers360.com/articles/csir-ugc-net-exam-dates

I hope this helps. Wish you a great eve!