Answer:
D it has a nucleus 
Explanation:
It has a nucleus because it is an eukaryotic organism.
 
        
             
        
        
        
Long eyelashes is the dominant trait because, in the last sentence, donna mentioned how nearly everyone in the family had long eyelashes, while barbara and her had short ones. this proves that long eyelashes are much more common in the family than short eyelashes, which means long eyelashes would be dominant, while short eyelashes would be recessive.
        
             
        
        
        
<h2>a) is the correct option </h2>
Explanation:
The extracellular domain of the transmembrane receptor protein acts as binding site for primary messenger molecule whereas the transmembrane domain holds the receptor within membrane and the cytosolic domain has intrinsic tyrosine kinase activity, all these helps in proper cell signaling 
If because of any mutation there is change in shape of the extracellular domain then that molecule that normally binds to the receptor protein will no longer attach hence cellular response will be deactivated 
 
        
        
        
Answer:
 External respiration: CO2 diffuses into the blood
Explanation:
External respiration is also called the pulmonary gas exchange. It refers to the diffusion of O2 from the air in the alveoli of the lungs to blood in pulmonary capillaries and diffusion of CO2 in the opposite direction from the capillary blood into the alveolar air. External respiration in the lungs is responsible for oxygenation of deoxygenated blood coming from the right side of the heart. The oxygenated blood is then returned to the left side of the heart.