Endocytosis and exocytosis are forms of active transport. What is active transport? (1 point)
the movement of molecules up a concentration gradient from low to
high, using no energy
the movement of molecules down a concentration gradient from
high to low, using energy
the movement of molecules down a concentration gradient from
high to low, using no energy
the movement of molecules up a concentration gradient from low to
high, using energy

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 8 options: the cold balloon expands and rises. the warm balloon shrinks and sinks. the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the warm balloon expands and rises. the cold balloon shrinks and sinks.