1. Potassium channels open, allowing potassium ions to move out.
2. Some sodium channels open in the dendrite.
3. All ion channels close and the Na+/K+ exchange pump starts working.
4. Sodium ions diffuse toward a node of Ranvier.
5. Lights hit the retina.
6. The threshold level is reached.
7. Many sodium channels open in the axon membrane, allowing sodium ions to move in.
List, in order, the events in visual perception that must occur for a person to see an object:

Greenthe fossil record is the history of life recorded byhuman observationgod.climatologists.remains of the past.

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.

On a spring day, a middle-latitude city (about 40? north latitude) has a surface (sea-level) temperature of 10 ? c. if vertical soundings reveal a nearly constant environmental lapse rate of 6.5 ? c per kilometer and a temperature at the tropopause of –55 ? c, what is the height of the tropopause?