As you move up to the food chain, the energy will decrease. This explains that the more the consumers, the lesser the energy that the last consumer will get from the sunlight. This is because each energy will decrease as it passes by the consumers because each consumers takes a portion of the full energy from the sun.
I think it's the simple columnar epithelium.
A semipermeable membrane is a membrane that allows certain substances to pass through it. The most accurate definition is the third choice, "It is a barrier with tiny openings that let some, but not all, materials pass through." hope this helps:)
