Answer:
Cytochrome c is an enzyme found in bacteria, fungi, plants and animals. Here it is given that the human amino acid sequence for cytochrome c differs at 12 locations from the sequence in horses and pigeons. This information might be useful for inferring in preliminary stages that horses and pigeons are closely related to each other since they both show similar amount of difference from humans.
However, this hypothesis is being made with respect to the the comparison between "humans and horses" and "humans and pigeons". To further test this hypothesis pigeons and horses should be directly compared to each other without the use of a third species like humans. Hence, the sequence for cytochrome c in horse and pigeon should be compared with each other rather than comparing to humans.
I would say immigration only.
emigration would theoretically reduce the genetic variation as unique individuals leave, but immigration would bring unique traits into circulation in an ecosystem.
I'm not super great at biogy tho so this might not be right... :)
Answer:
C
Animals have a mitochondria, a nucleus, and a cell membrane, bu they do not have chloroplasts. You can only find chloroplasts in human and plant cells, not a animal's cell. Hope it helps!
The integumentary system is the skin. Skin protects the inner organs from Bactria. Essentially the skin is a wall protecting against the outside world. It doesn't really release anything but is just there for protection.
Hope this helped!