After twins are conceived, their chance of survival until birth depends on the prenatal circumstances. An early sonogram might reveal two developing organisms, but later only one embryo continues to grow. This is referred to as the twin phenomenon.

In the african savanna,more wildebeests are born than the environment can support. which is most likely to happen over a period of years as a result

The endoplasmic reticulum (er) is an organelle in some cells. in these cells, it is continuous with the nuclear membrane and forms a large part of the cell\'s total membrane. sort the phrases below as describing rough er, smooth er, both, or neither. note: if you answer any part of this question incorrectly, a single red x will appear indicating that one or more of the phrases are sorted incorrectly.1) found in prokaryites and uekaryotys2) involved in protein synthesis3) involve in lipid synthesis4) contains molecular chaperones in lumen5) bound with ribosomes6) involved in toxin or drug metabolism7) large systemot internnected tubules,vesicles, and sacs8) "packages" enzymes in vesicles for secretion.

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?