Secondary since plants/animals already lived there, but got killed/driven out of the area they lived/thrived in/on.
Answer:
secrete a cytokine that triggers apoptosis
Explanation:
Cytotoxic T cells secrete granzymes and perforins when targeting cells. Additionally they secrete cytokines such as IFN-, TNF-α and TNF-β that act to activate macrophages and help kill infected cells.
Answer:
they all have a membrane
Explanation:
although some cells may have similar structure and chemical features, the only thing they all share is a membrane^^
Answer:
B probably I think but I'm not sure
Answer:
They occur when the Sun reaches its highest or lowest point in the sky.