Describe the most common molecular mechanism for recessively inherited human genetic diseases such as cystic fibrosis.

Explanation:

cystic fibrosis is an autosomal recessive disorder. When the child receives the defective gene from both of his parents, he suffers from cystic fibrosis. Because his parents are carriers. In recessive genetic disorder, the genes will be expressed when both recessive genes are present in one person. The person suffering from this disease have a lung infection and pancreatic dysfunction.  

In this cystic fibrosis, genes are located in chromosome 7. The effective gene is the CFTR gene. The CFTR gene is present in the DNA and by transcription, this forms CFTR protein. This is a channel protein and transports chloride ion.

This CFTR protein transports chloride ions and it makes a balance in the cell membrane. These genes are commonly present in the epithelial cells. Outside the epithelial mucus is present to keep the cells moist.

The epithelium gets a lack of water and chloride due to the defect. Therefore cells need CFTR proteins also. This causes lung infection and pancreatic disorder.

the correct answer is option b

behavioral response need communication and thus co-ordination at several levels such as interaction among cells, organ system and the entire organism.

behavioral response produces both internal and environmental stimulus.