When would a cell be expected to use an active transport mechanism to move a substance from the outside environment into the cytoplasm? A: when a concentration gradient exists and more of the substance is on the inside of the cell

B: when a concentration gradient exists, and the same amount of substance is found inside and outside the cell

C: when no concentration gradient for the substance exists across the cell membrane

D: when a concentration gradient exists and more of the substance is on the outside of the cell

Someone me with this: a mineral' is determined by its actomic structure.

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.

The is an estimate of the fewest number of organisms a population needs to avoid extinction. this measurement will most if the number of offspring each female in the population produces increases. if the population's this measurement will most likely increase. 1 population density, minimum viable population, carrying capacity 2 decrease, be unaffected, increase 3 death rate increase, dead rate decrease