A great example of a physical boundary is a mountain. For example, the Pyrenees Mountains, which serve to separate France and Spain, are a physical boundary. So are the Ural Mountains which separate Europe and Asia. Along with mountains, oceans, seas, even deserts are examples of physical boundaries.
An average size apple weighs 6.4 ounces, which is equal to 180  grams. One apple contains approximately 91 calories and 3 grams of  dietary fiber.
Cyanide is deadly at a dose of about 1 milligram per kilogram of body weight. On average, an apple seed contains 0.49 mg of cyanogenic compounds. The number of seeds per apple varies, but an apple with 8 seeds, therefore, contains about 3.92 milligrams of cyanide. A person weighing 70 kilograms would need to eat 143 seeds to reach the lethal dose or about 18 whole apples.