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Digestion Task
This digestion task should be completed for homework. You should
complete steps 1-7 during the class leaving only 2 questions for
homework. This will then allow you to complete the conclusion &
evaluation for the transpiration experiment which is due next lesson.
1) Go to the following site to familiarise yourself /revise aspects of
the digestive system
http://www.biologycorner.com/bio3/anatomy/notesdigestion.html
Time: 15-20 mins
2) Produce a large diagram of the human digestive system. The
diagram I have included can be used as a guide but you need to
be able to draw your own. Make sure the diagram clearly shows
the interconnections between the various organs. You are
allowed to use color in the diagram but make sure not include
too much detail eg no shading. Note to the artists in the class
this shouldn't take the majority of the lesson. I expect this
to take no longer than 20 mins.
Additional resources – Campbell: Mammalian digestive system (pg 855
7th ED or look up index for other editions)
http://kidshealth.org/teen/your_body/body_basics/digestive_system.h
tml – info on digestion designed for teens
3) Label the mouth, oesophagus, stomach, small intestine, large
intestine, anus, liver, pancreas and gall bladder.
4) Below your diagram outline the function of each of your labels
15 mins.
5) Explain the need for enzymes in digestion 10 mins
6) Label the source and site of production of the following enzymes:
a. Salivary Amylase
b. Pepsin
c. Phospholipase
For each enzyme state the substrate, products and optimum pH
15 mins.
7) Distinguish (give the differences) between absorption &
assimilation. Add villus to your diagram and explain how its
structure helps in the process of absorption 10 mins
Questions
1. Describe (give a detailed account) the two ways that the
products of digestion can be transported across the intestine
wall.
2. Compare (similarities & differences – referring to both
throughout) the functions of the stomach, the small intestines
and the large intestines.
http://www.enchantedlearning.com/subjects/anatomy/digestive/ info & diagram (same as
below)
Read the definitions below, then label the digestive system anatomy diagram.
anus - the opening at the end of the digestive system from which feces exit the body.
appendix - a small sac located near the start of the large intestine.
esophagus - the long tube between the mouth and the stomach. It uses rhythmic muscle
movements (called peristalsis) to force food from the throat into the stomach.
gall bladder - a small, sac-like organ located by the duodenum. It stores and releases bile
(a digestive chemical which is produced in the liver) into the small intestine.
large intestine - the long, wide tube that food goes through after it goes theough the
small intestine.
liver - a large organ located above and in front of the stomach. It filters toxins from the
blood, and makes bile (which breaks down fats) and some blood proteins.
mouth - the first part of the digestive system, where food enters the body. Chewing and
salivary enzymes in the mouth are the beginning of the digestive process (breaking down
the food).
pancreas - an enzyme-producing gland located below the stomach and above the
intestines. Enzymes from the pancreas help in the digestion of carbohydrates, fats and
proteins in the small intestine.
rectum - the lower part of the large intestine, where feces are stored before they are
excreted from the body.
small intestine - the long, thin winding tube that food goes through after it leaves the
stomach.
stomach - a sack-like, muscular organ that is attached to the esophagus. When food
enters the stomach, it is churned in an acid bath.
http://kidshealth.org/teen/your_body/body_basics/digestive_system.html – info on
digestion designed for teens
IB Biology
Digestion Question. - Model Answer.
a) List three major groups of macromolecules and the products formed upon complete
digestion. (3 marks)
Note: List = don't write too much, Complete digestion = no intermediate products
needed.
Three macromolecules: Carbohydrates, Proteins and Lipids.
The Products formed for each one:
Carbohydrate --> simple sugars (e.g. glucose finally).
Protein
--> amino acids
Lipids
---> fatty acids + glycerol.
b) Describe where and how the macromolecules listed in a) are digested. (8 marks)
Note: The key words on this question are Where , How and Digested.
Also - as the first question asks for the products of complete digestion there
are probably no marks for the products in part b)
This is a plan. You have to write in whole sentences the information included in the
table.
Carbohydrates:
Where
How Digested
In the mouth
mixed with salivary amylase which turns starch into maltose
in the duodenum of the small intestine
pancreatic amylase and maltase break down starch into maltose them maltose into
glucose.
Protein:
in the stomach
pepsin breaks the proteins into polypeptides
n the duodenum of the small intestine
endopeptidase enzyme breaks the polypeptides into amino acids.
Lipids
in the stomach
some digestion of the fats in milk (rennin is involved)
in the duodenum of the small intestine
Bile emulsifies the lipid,
Lipase enzymes break down the lipid into fatty acid and glycerol.
IB Questions to Revise Digestion (SL and HL)
1. What are the products of digestion of:
Proteins
Carbohydrates
Lipids?
2. What are the products of digestion using these enzymes:
Amylase
Lipase
Pepsin
Protease?
3. Where in the digestive system are these products absorbed:
Amino acids,
Glucose
Fatty acids
Glycerol?
4. Which products are absorbed by simple diffusion?
5. Which are absorbed by active transport?
6. Which part of the intestines is joined to the pancreas?
7. Which types of enzymes are produced by the pancreas?
8. Which types of enzymes are produced by the stomach?
9. Which parts of the digestive system contain villi?
10.
What are the two functions of acid in the stomach.
11.
What is the function of bile, and where is it produced and where is
it stored?
Longer Questions:
3. Describe the two ways that the products of digestion can be transported across the
intestine wall.
4. Draw a diagram of a villus in vertical section.
5. Compare the functions of the stomach, the small intestines and the large
intestines.
Digestion IB SL Essay Question
a) Draw a diagram of the human digestive system. [4]
Mark Scheme; one mark for each correctly drawn & labelled part; (max 4)
 mouth,
 esophagus
 stomach
 small intestine
 large intestine
 liver & gall bladder
 pancreas
b) Describe the role of enzymes in the process of digestion of proteins, carbohydrates &
lipids in humans. [6]
Mark scheme:
marks awarded for
 the-enzyme name, of one amylase, protease & lipase.
 correct substrate & products
 correct place where enzymes are produced & act.
 a general comment about role of enzymes in chemical digestion.
eg "Proteins are digested by protease enzymes (eg pepsin), in acid conditions in the stomach. They
become polypeptides / amino acids." Scores 3 marks.
c) Explain how blood glucose concentration is controlled in humans. [8]
Mark Scheme









explanation of homeostasis;
the role of negative feedback
involvement of the endocrine system (ie hormones)
insulin hormone - lowers blood glucose
glucagon - raises blood glucose
pancreas islets/ ß-cells/alpha-cells produce these hormones
liver & muscles convert glucose (with insulin);
to glycogen
and vice versa (with glucagon)