Why doesn't redmine see the bundler package on startup?

Question

Ruby on Rails

#ruby -v
ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-linux]

# gem --version
2.4.5

# rails -v
Rails 4.2.1

# gem install bundler
Successfully installed bundler-1.9.9
Parsing documentation for bundler-1.9.9
Done installing documentation for bundler after 4 seconds
1 gem installed

# gem install passenger
Building native extensions.  This could take a while...
Successfully installed passenger-5.0.8
Parsing documentation for passenger-5.0.8
Done installing documentation for passenger after 5 seconds
1 gem installed

When starting redmine

Answer 1

can be run via bundler exec ?