Answer: a. Identical twins who grew up together are essential for these studies so that we can see if environment is really an influence or not. Maybe it could be a different case for each one of them. So by comparing them we can know.
b. The results of inherited variation would be that the offsprings would get the same type of characteristics from their parents while environmental variation is variation causedby the environment like heat, temperature, etc.
Explanation:
Stem cells are undifferentiated cells that could develop to perform a variety of tasks. One type of stem cell is the embrionic stem cell. There are also adult stem cells. To use embrionic stem cell you need to have fertilized embrios. These can be donated to research. The use of the embrionic stem cells is controversial for this reason.
The correct answer is D.
Girls in general tend to spend more time with friends. This isn't to say that boys don't spend a lot of time with their friends but girls tend to engage more in their social relationships, whereas boys spend more time in competitive sports, more time in clubs and less time engaging in social relationships.
Answer: The answer is runoff.
Explanation: Runoff is water “running off” the land surface.
The most observable difference is the way in which cytokinesis occurs. In plants a new cell wall is fashioned between the new daughter cells, while in animal cells the cell membrane constricts to pinch the parent cell into daughter cells.