The bonds that hold the tro stands of DNA together come from? A. the attraction of phosphate groups for each other

B. strong bonds between cogenous bases and deoxyribose.

C. wesk hydrogen bonds between the nitrogenous bases

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.

What happens when water’s salinity increases? mass decreases. freezing point decreases. buoyancy of objects decreases. the amount of dissolved minerals decreases.

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