Answer:
All the organisms of one kind in an ecosystem are called a population. For example, a pond ecosystem might have populations of frogs, waterlilies, insects, duckweed, and protists. Populations living and interacting with each other form a community.
Explanation:
It's actually A. Vertebrate have a hard out shell.
Answer:
B. Antibodies react specifically with an antigen.
Explanation:
Serological tests are blood tests that look for antibodies in your blood. They can involve a number of laboratory techniques. Flucculation tests are based on the precipitation that takes place when antibody and specially prepared antigens are mixed together
