Is is possible to view all the activities for all related records on an account?

Yes! In the account detail view, scroll down to the All Activities area. You will notice a Roll Up button. If the button displays Roll Up On, then roll up is enabled and you will see all related activities for related Contacts, Leads, Opportunities, etc. To disable roll up, simply click the button.

If the button displays Roll Up Off, this means that roll up is not enabled and you will only see activity records that are directly associated with the account. To enable roll up, simply click the button to read Roll Up On.

The roll up option is also available for use within contacts, leads, and opportunities.