Answer:
The answer is ectoderm. The mesoderm is the middle layer of lining. The endoderm is the innermost layer. You can remember it by:
Endo/ sounds like inner
Meso/ M for middle
Ecto/ sounds like exo, bugs have exoskeletons that are on the outside.
Explanation:
Answer:
That statement described a tissue.
I disagree because although recycling is good, Earth firstly is not a closed system and new matter enters the environment all the time, such as comets.
It is definitely not a primary source: this would be a book itself.
Now, is it a tertiary source? I don't think so: the author of the review should have read the book and should only be referring to this book in the review.
I think it's a secondary source.
