A membrane that only lets certain molecules in while keeping other molecules out is
1:flexible
2:bilipid layers
3:slectively permeable

Students in biology are studying the macromolecules of life. they used a calorimeter to determine the calories in various types of food. once the lab was completed, the students ate the left over food samples. monica commented that in just 6 or 7 "chews" of the saltine, it was gone; nothing but a sticky paste in her mouth. elaborate on what happened chemically while chewing the saltine. include the macromolecules present.

In the respiration-photosynthesis cycle shown above, what are the products of cellular respiration that belong in box 2?

Which test would show positive results for orange juice