False there may be two or more dependent variables in a well designed experiment
Answer:
C
Explanation:
A. Since
B. Because
C. Although
D. For example
<em>Zebra mussels have been known to have a lifespan of six or seven years in the past but recent discoveries have shown that their average lifespan now ranges between one to two years. Hence, the correct word to fill in the gap would be 'Although'. </em>
<em>The correct option is C</em>
Answer;
Cycilc AMP
Explanation;
-Second messengers are molecules that relay signals received at receptors on the cell surface; such as the arrival of protein hormones, growth factors, etc., to target molecules in the cytosol and/or nucleus.
-Many of the chemical messengers such as hormones, that transmit messages from one cell to another never enter the target cell, these molecules are known as first messengers which work by binding to a specific receptor on the cell surface. The receptor then stimulates or inhibits the production of a so-called second messenger within the cell.
-The second messenger are small molecules such as Cyclic AMP, which activate an effector within a cell.
The immune system.
The immune system acts as a defense system of the body. It fights against bacteria, viruses and any other disease causing pathogens. Some chemicals can weaken the immune system and make them vulnerable.
