I had no problems in expanding the partition 2 to the space left on the SD.
I had no problems installing the Raspbian Jessie image to a USd 1TB harddrive. The problem I ran into was that what worked for the Wheezy version of Raspi to expand partition 2 by taking note of the start position of partition 2, delete partition 2 and create a new partition 2 starting from the same start position as the original wheezy image made no problems either. Doing the same with Jessie led to my Raspi rebooting after having written the changes of the partition ending in a dark screen and a blinking cursor, underline, . on the upper left corner. The LED on the USB HD was also blinking as was the WiFi module, from EDIMAX. My Raspi is a B+, so I decided to leave the raspi running over night but nothing changed. On the Internet I found no information about expanding a partition on an external USB mass storage device for Jessie, but a couple of times the instructions I am familiar with from the Wheezy version of Raspbian. Further investigations and searches in recently released books about Linux and Raspi, books that are considered to be the "bibles" for Linux and for Raspi in german languages showed that depending of the type of partition table, MBR or GUID, different instructions have to be used.
What I could not find so far is if:
a. The type of partition table is under the "rule" of Raspian, in this case Jessie,
b. or of the USB HD.
So I have chosen the option to publish my problem here with the hope to get some tips!