Answer:
all of them apply
Explanation:
In my opinion all of them apply (except the 4th one). Ecosystems can be small, big, have living and non-living parts and they are made of biomes. Not only can ecosystems vary in size, but they can also differ in just about every imaginable biotic or abiotic feature.
1. outer covering - none of the other answers can occur due to the absorbed solutions inability to reach the centre of the organism, smaller cells in greater numbers are more efficient as they can group together yet all absorb the right amounts of nutrients for its need. multi cellular organisms, such as humans can have the other answers in them as cells group together to make skin, muscles and organs. it also gives the organism to grow larger.
2. bacteria are single celled. bacteria reproduce through mitosis (cell division). bacteria break down decaying matter to obtain energy. every organism requires energy to live. Bacteria can move in order to reach their nutrient source.
I think the answer is the individuals born per unit time.
Because skin falls off, or are you talking bout why don't people stick together?
