Place shrimp and scallops in a large resealable plastic bag. In a microwave-safe bowl, combine the oil, lemon juice, soy sauce, garlic powder and paprika. Microwave at 50% power for 1-1/2 minute. Stir to blend; set aside 1/3 cup for basting. Pour remaining marinade over shrimp and scallops. Seal bag and turn to coat; refrigerate for 1 hour, turning occasionally.