Johnny, a Living Environment student, has a homework assignment where he must come up with an real-world analogy for the cell wall. Johnny decides that he will compare the cell wall to a doorman because a doorman only allows certain people into a building, just like a cell wall only lets certain materials into the cell. What error did Johnny make in his analogy?

A.
Instead of cell wall, he should have said cell membrane because it is selectively permeable.
B.
Instead of cell wall, he should have said the nucleus because the nucleus decides what enters and exits the cell.
C.
His analogy between the doorman and the cell wall was correct, but the cell wall doesn't allow any materials pass through into the cell.
D.
Johnny did not make an error.

Four types of motile cells in human body?

Sally and sue were investigating the topic of friction in science. they used a small car and a ramp as seen in the picture to test what they were learning. they knew that they slipped easily on waxed floors but not on carpet, so they decided to change the material on the surface of the ramp to see what happened. they planned to use glass, carpet, aluminum foil, and sandpaper and run the car down the ramp over each surface. what would be the best research question to guide the girls' experiment? a) does the amount of surface area affect the friction on the moving car? b) will the car travel fastest on the glass surface? c) how does the angle of the ramp affect the speed of the car? d)do rougher surfaces tend to create more friction than smooth surfaces?

In each transformation of energy , some energy what?