The small intestine is long ( about 6m in length ). How does this help in digestion and absorption

What's the waste product of electrons and pyruvate combining in fermentation?  

Which heredity condition causes a buildup of mucus in lungs and pancreas? a. cystic fibrosis b. heart disease c. huntington's disease d. sickle cell anemia

How have crops been modified? a.plants have been made more susceptible to pests b.plants have been made resistant to herbicides c.plants have been made more susceptible to herbicides d.plants have been modified to have reduced yield