Identify the processes that occur during the electron transport chain.
(Select all that apply.)
A. Carbon dioxide is released.
B. Protons are moved across a membrane against their concentration gradient.
C. Oxygen is produced as a waste product.
D. Electrons are removed from the carrier molecules NADH and FADH2.

With the word calcite wich completes the analogy mineral, erosion, marble, or aragonite

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.

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.