Definite volume refers to something which has a consistent, unchanging volume, which in practical terms may mean a static mass and density, or a predetermined shape, either of which will dictate volume. A cube with side length l has a definite volume because it can only be exactly one size.
One cup of raw plantains or one medium sized raw plantain contains: ~180-200 calories, 0.5 g total fat, 47-50 g carbohydrates, 3.5 g dietary fiber, 22 g sugar and 2 g protein. Because of it's high carbohydrate content, you need to monitor your portion, otherwise your blood sugars will spike.
Plantains can raise blood sugar levels. Any food that contains carbohydrates, such as plantains, can potentially raise your blood sugar. The effect of green plantains on your blood sugar will depend in part on how much you eat, how they are prepared and what other foods you eat at the same time.