Some solutes move freely across cell membranes, while other solutes require assistance from special gates. Passive transport and active transport are methods of
moving solutes across cell membranes.
Which of the following accurately describes the difference between passive transport
and active transport?
A Passive transport can move molecules both in and out of a cell, but active transport
cannot.
B Passive transport works against a concentration gradient, but active transport does
not.
C Passive transport does not require energy, but active transport does.
D Passive transport requires carrier proteins, but active transport does not.

Two students are working together on an experiment that measures the effect of different liquid fertilizers on the thickness of plants’ stems. which is most likely to result in the greatest amount of error in their scientific experiment? a.one student measures the plant stem widths by using calipers. the other student measures the widths of the same plant stems again by using a different pair of calipers. b.one student measures the plant stem widths by using calipers. the other student types the measurements as they are taken into a computer spreadsheet. c.one student weighs liquids for the experiment by using a calibrated scale. the other student weighs liquids for the experiment by using a different calibrated scale.