Hello there!
When one moves ahead in the field of biology, then Life Science is together studied in bits.
If you want to move ahead in the field of botany, then botany honors is best.
Then you can move ahead in the same field and go for Phd as well.
Although some universities offer graduation and post graduation in life science also. Look for the same when checking the course content of the college.
One needs to clear the NET JRF examination for further studies where you need to study all the course content of life science as a whole.
Choose accordingly.
Good Luck!