Answer:
a. antigen
Explanation:
The Immune system is composed of immune cells that defend the body against foreign substances such as bacteria or virus. Lymphocytes (B and T cells) are one of the main immune cells
Lymphocytes have the ability to recognize and bind to antigens, wich are substances foreign to the body ( i.e bacterial or virus elements) that evokes an immune response.
If it's two different kinds of birds it's called competition.
Answer:
This is so simple. Read your lesson. If you cheat like this you'll never get through the rest of the course.
Explanation:
C. The Bering Land Bridge once connected what would be Russia and North America but the the movement of these continents separated the land bridge
