Why is the energy transfer between trophic levels not even close to 100% efficent?

Hey me with this one❤☺❤ how do you say that a cell also has a life span and death like an organism? give one example.

The fruit of a certain plant is sweet and fleshy. the seeds of this plant have a seed coat that is fairly tough. the seeds germinate better if they are exposed to acid, or scarification. what is the most likely type of dispersal for this seed? water animal wind

The activity of the modern sample is 1.10 bq . how long does that measurement take?