You are studying genes in yeast and find that the genes can be placed into four groups that tend to be inherited together. from this you can conclude that yeast:

The answer would be: Have four chromosomes

The traits of the yeast are determined by their genes. The genes will be split and inherited by the child in cell reproduction. The genes should come from their chromosomes. If the yeast could have 4 groups of genetic variance, then it should have at least four chromosomes to code it. 

The return of the wolf to yellowstone national park will probably affect the bird population to some degree, not significantly. while wolves will hunt birds when necessary, they prefer to hunt larger prey. the bird population will most likely only be affected when hunting is scarce for the wolves. birds of prey will also probably not be affected as much as other birds who spend more time on the ground hunting for food as the tend to spend more time in the air or in trees since they do not need to stay on the ground for long due to the nature of the way they hunt.