Answer;
both positive and negative
Explanation;
-The elephant are keystone species, playing an important role in maintaining the biodiversity of the ecosystems in which they live. They may have both negative and positive interactions to the environment. For example, during the dry season, elephants use their tusks to dig for water, which has a positive impact to the surrounding.
-They clear large amounts of vegetation, which removes habitats for some organisms but makes the area inviting for other organisms. This has both positive and negative impact to the ecosystem.
A group of tissues working together is an organ.
ANSWER:
A. an organ
<span>Her data suggested that DNA is a helical structure that has two strands attached in the middle by the phosphate bases. That was the necessary information, needed to complete an accurate model of the structure of DNA. She also was the first one to announce that the phosphate units are located in the external part of the DNA and that the amount of water found in the molecule is in accordance with other parts of it.</span>
The answers are:
Zinc ,Iron , Copper , silver , lead , mercury .
