Bright colors such as flowers or light green bushes/trees would result in an decrease in a blackbirds population because the blackbird wouldn't be able to blend into its environment due to the dark color it has, allowing many predators to spot it. So brighter colored environments would result in the decrease of the blackbird population.
Multicellular organisms require a lot of energy and resources to survive.
Unicellular organisms, on the other hand, require just the basic necessities. On top of that, unicellular organisms don't require a long time to reproduce as multicellular organisms do.
Thus, multicellular organisms are at a disadvantage because they require more energy, sources, and essentially time.
Hope this helps!
Genetic Engineering. They are changing the genes of something (In this case, Cabbage) to help is survive its environment better.
Probably a hinge joint or a tendon.
Have cones as reproductive structures.
Have vascular tissue.