Name ________________________________________________________ Date ________________
Digestion Worksheet
1.	(a)	State the missing source, optimum pH requirement, substrate and product of the human enzymes in the table below.

Enzyme	Source	Optimum pH	Substrate	Products	
Amylase	Salivary gland	7			
Lipase			Lipids	Fatty acids and glycerol	
(2)
(b)	Explain the need for enzymes in digestion.
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(2)
(Total 4 marks)
2.	List three of the materials that are egested.
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 (Total 1 marks) 
3.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw and label a diagram of the digestive system.
(4)

(b)	Discuss factors that affect enzyme activity.
(9)
 (Total 15 marks)

 
4.	What does the digestion of starch by amylase produce?
A.	Lactose
B.	Sucrose
C.	Galactose
D.	Maltose
(Total 1 mark)
5.	 Outline the reason for one named substance found in food not being digested and absorbed by humans.
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(Total 2 marks)
6.	What is the main function of the large intestine?
A.	Absorption of water
B.	Digestion of fats and proteins
C.	Absorption of nutrients
D.	Recycling of digestive enzymes
(Total 1 mark)

7.	Helicobacter pylori is able to live inside the stomach wall of humans. This bacterium can cause inflammation of the stomach wall (gastritis). There may be a link between H. pylori and the development of stomach cancer.
	The graph below shows the blood levels of antibodies resulting from H. pylori infection for a control group without stomach cancer and a group with stomach cancer. The solid lines show the median concentrations for the control group and the group with stomach cancer.
Antibody concentrations above 10 μg ml–1 indicate that there has been infection with H. pylori.
		
	[Source: Forman, D. 1991. “Association between infection with Helicobacter pylori and risk of gastric cancer: evidence from a prospective investigation”. British Medical Journal. Vol 302. Pp 1302–1305.]
(a)	47 % of the control group had been infected with H. pylori. Calculate the percentage of the group with stomach cancer that had been infected. Show your working.
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(2)
(b)	Using all of the data, evaluate the hypothesis that H. pylori causes stomach cancer.
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(3)
(c)	A study in gerbils indicated that infection with H. pylori leads to a decrease in the secretion of hydrochloric acid. Discuss the consequences of this finding for the digestion of proteins in the stomach in humans.
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(2)
(Total 7 marks)
8.	The diagram below shows parts of the human digestive system.
		
	Which points are linked by the small intestine?
A.	I and III
B.	II and III
C.	II and IV
D.	III and IV
(Total 1 mark)
9.	Researchers extracted an enzyme from the human digestive system and tested its activity at different pH values on proteins extracted from the blood of cows. The results are shown in the graph below.
		
Deduce from where in the human digestive system this enzyme was extracted.
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(Total 1 marks)
10.	Up to two additional marks are available for the construction of your answers.
(2)
	Plants store carbohydrate in the form of starch. Explain the reasons for starch being digested by the human digestive system.
(4)
 (Total 6 marks)

11.	Discuss the roles of gastric acid and Helicobacter pylori in the development of stomachulcers and cancers.
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(Total 5 marks)
12.	The diagram below shows water in the human body.

	Where in the digestive system is the largest volume of water absorbed from?
A.	Colon
B.	Pancreas
C.	Small intestine
D.	Liver
(Total 1 mark)
13.	Which of the following parts of the digestive system secrete proteases?

	Stomach	Small Intestine	Large Intestine	
A.	Yes	Yes	Yes	
B.	Yes	No	Yes	
C.	Yes	No	No	
D.	No	No	No	
(Total 1 mark)