Beaumont described one of his investigation as follows juice was extracted from the stomach and placed in a small vial. a solid piece of boiled recently salted beef weighting three drachma was added. The vial was corked and kept under controlled conditions. A similar piece of beef was suspended on a string into the man's stomach."

i Suggest one condition around the vial that Beaumont would have kept constant.
ii What control experiment should Beaumont have performed?
iii Why did Beaumont use boiled, salted beef?

c After two hours, Beaumont recorded the following results: 'Beef in vial- the cellular texture seemed to be entirely destroyed, leaving the muscular fibres loose and unconnected, floating about in fine, small shreds, very tender and soft. Beef in stomach - I drew out the string, but the meat was all completely digested and gone." Use your knowledge of digestion to explain the difference between the changes in the vial and those in the stomach.

2 The liver produces a liquid which is added directly to the partly digested food in the small intestine. a Name the liquid. b Describe how it helps digestion.

3 Describe, in the correct sequence, how the protein and starch in a ham sandwich are broken down ready for absorption.

4 Digestive juices contain enzymes, water and some other substances. Name two of these other substances. State which digestive juice contains them, and state what function they perform.​