The levels of Ecology is organisms, populations, communities, Ecosystems, and Biosphere, but you can remember it by going over you notes every day and then you will slowly start to remember it and get the hang of it.
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Answer:
Frequency of individuals with recessive trait(dd)
%
Explanation:
Please see the attached.
In the image it is clear that there are total
mouse out of which
are dark colored.
Since dark color allele is dominant, these
dark colored mouse will have genotype either DD or Dd
The individuals with genotype "dd" will be of light color.
Number of light colored mouse 
Frequency of individuals with recessive trait(dd)

%
The Membrane surrounding the cytoplasm of the cell
Answer:
D) infectious proteins with no associated nucleic acid.
Explanation: