D it allows all substances to enter & exit the cell.
The first statement describes the environmental factor that affected the skipper butterflies.
When the birds became involved in the skipper butterflies ecosystem, they became a biotic environmental factor. The other answer choices are not environmental factors, but they are adaptations and examples of survival of the fittest.
Hope this helps! Good luck! :)
the skin has cells like that
The two membranes pull apart a little and create a small pocket or sack of air. As the developing bird grows, it breathes in oxygen from the air sack and exhales carbon dioxide. Several thousand microscopic pores all over the surface of the egg allow the CO2 to escape and fresh air to get in.
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