Answer:
A. They must compete for essential resources.
Explanation:
Cancer, other antigens, diseases, blood type
About 88 percent of geologic time is represented by the time span called the precambrian <span>era.</span>
Answer:
A.Earth's early atmosphere lacked oxygen, which multicellular organisms need to break apart food
Explanation:
One important feature that led to the development of multicellular organisms was the rise of oxygen-producing photosynthetic bacteria. Prior to this development, the unicellular organisms (anaerobes) then present on Earth obtained energy from inorganic fuels.
However, with the presence of oxygen in the atmosphere, a shift was observed as organisms that could obtain energy from the reduction of energy became predominant. This unicellular aerobes later paved way for the evolution of multicellular aerobes.
<span>•Central nervous system- the part of the nervous system that is made of two structures, the brain and the spinal cord. hope this helps!!
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