The Keychain consolidates various passwords and passphrases in one place and makes them accessible through a master password or passphrase. When an application (including the Finder) needs to access a password stored in the Keychain, the application asks you to unlock the Keychain if it's not already open.
Nutritional Summary: There are 345 calories in a 100g serving of Tesco Plain Flour. Calorie Breakdown: 3% fat, 84% carbs, 12% prot.
I'd be better if you used Romaine lettuce or fresh spinach leaves instead of iceberg lettuce. It's healthier. Actually a flour tortilla has only 70 calories, so how does a whole-wheat one have 140 calories.