Certain substances can't pass through the membrane but need to get in/out. What can cells use to allow specific substances in/out, "doors"
A. Protein tunnels
B. Protein ions
C. Protein channels
D. Protein stations

please don’t give me the link to get the answer .. it doesn’t work

2. cheryl hears a new song on the radio every day during the week on her commute to work. surprisingly, when the song comes on at a party on saturday night, she knows most of the words without trying. describe the three ways that we use cognition to learn without reinforcement. which type of cognitive learning without reinforcement best explains how cheryl knew the song lyrics? explain your answer.