system_update_1000 in core/modules/system/system.install

Enable entity module.

system_update_1009 in core/modules/system/system.install

Enable Admin Menu module.

system_update_1025 in core/modules/system/system.install

Convert block positioning and configuration to the default layout.

system_update_1032 in core/modules/system/system.install

Enable config module.

update_fix_requirements in core/includes/update.inc

Perform Drupal 7.x to Backdrop 1.x updates that are required for update.php to function properly.

update_prepare_language in core/includes/update.inc

Prepare Backdrop language changes for the bootstrap if needed.

update_upgrade_enable_dependencies in core/includes/update.inc

Enables needed dependencies.