Es orcas, or killer whales, are natural predators of sea otters. it has been observed that in regions where the sea otters are not
present, sea urchins grow rapidly and destroy much of the natural kelp vegetation
which of these statements is correct in this context?
kelp is the keystone species because their survival is key to the survival of
the entire ecosystem.
sea otters cannot be considered the keystone species because they are not
the top predators in the ecosystem.
sea urchins are the keystone species because they multiply rapidly in the
absence of their natural predators,
sea otters are a keystone species as they prevent a herbivorous species
from completely destroying a plant species.
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interdependence of organisms

from my research i have to the conclusion that decomposers, such as fungi, bacteria and invertebrates, play a critical role in nutrient cycling and without them the earth's ecosystem may not support life as we know it. elements such as carbon, nitrogen and phosphorus exist in limited amounts on earth, although huge amounts of carbon are being released into the atmosphere from underground sources now by humans. it is still extremely important that other nutrients be retained by the process of re-use. decomposers are organisms that are able to chemically break down dead material and make these elements available for use by other organisms. without this breakdown of dead material, dead bodies would pile up. so decomposers also play a role in clean up also. without them, life might not continue as we know it and dead material would overwhelm the earth.    

what is shown in the image?

eukaryote

chloroplast

mitochondrion

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