42. which of the following is not true of a cell membrane?
cell membranes allow all substances to pass through easily
it is selectively permeable so only certain molecules can pass through it.
it is a bilayer composed mainly of phospholipids and proteins.
all of the above are true.

Use set buikder notation to represent the following set: {, -2, -1, 0}

Consider the proof. given: segment ab is parallel to line de. prove: what is the missing statement in step 5?

1. according to the internal revenue service, the mean tax refund for the year 2007 was $2,708. assume the standard deviation is $650 and that the amounts refunded follow a normal probability distribution. a. what percent of the refunds are more than $3,000? b. what percent of the refunds are more than $3,000 but less than $4,000? c. what percent of the refunds are less than $2,000?