Manipulative experiments alter levels of a predictor variable (or factor), and then measures how one or more variables respond to these alterations. ... Natural experiments-An observational study in which we take advantage of natural variation that is present in the variable of interest.
A very strong relationship. I'll take the easiest example :the bees. They are so important for our planet. Without them, we and all living creatures on earth would be on track to dispariton. Let me explain why. At first, the bees need the nectar from flowers to make honey ( source of food ). As they pollen from flower to flower, they transport pollen on their tiny little legs and in this way, they help the plants to reproduce themselves. If, for some reason, there will be no more bees. Plants and flowers will not thrive, plants will be eaten without having contribued to the productivity of the species and they will go out. No plants, no more veggies or fruits for herbivorous and humans, no more herbivorous no more food for carnivorous, etc. Also, without plants, there will be less oxygen on our planet. Slowly the fauna and flora will die on earth and then it will be our turn. That is why relationships with plants and insects are so important. Plants produce oxygen for all of us and they are a natural and healthy source of food and insects help plants to survive and thus save the species.
Answer:
Membrane proteins perform a variety of functions vital to the survival of organisms: Membrane receptor proteins relay signals between the cell's internal and external environments. Transport proteins move molecules and ions across the membrane.
Explanation:
they help transport some substances through the membrane.
The first animal fossils would be most like the main body bones. I hope that helped
