If (births+immigrants) value is less than the (deaths+emigrants) value

Suppose you are estimating the size of a blue crab population. what is the population size if the number marked in the first catch is 40, the total number in the second catch is 200, and the number marked in the second catch is 50?

What does it mean for a cell membrane to be selectively permable

Abacteriophage typically attaches to the bacterium and then