What limiting factor keeps birds from arriving too early in the taiga?

Pls me i need this ! each cell has genes activated depending on it's job and what kind of cell it is. it is the presence of that causes the repressor protein to fall off and unblock the gene on the lac operon. if a gene is turned on then it is being an additional circular chromosome found in some bacteria that is used in genetic engineering.

If one were to horizontally divide the earth in half at the equator each half would be a

Question 1 of 205 pontsthe graph shows the size of two populations of the same species over time.area aarea b.