- Summary list for 6.1 Digestion and absorption
- Mindmaps
- Video tutorial
- Model answer
- Model answer
- 6.1 Digestion revision quiz 1/1
Learn and test your biological vocabulary for 6.1 digestion and absorption using these flashcards.
Summary list for 6.1 Digestion and absorption
- The outline structure of the digestive system (skill - annotated diagram).
- Food is mixed with enzymes and moved along by the contraction of circular and longitudinal muscle of the small intestine.
- Enzymes (amylase, lipase and an endopeptidase) are secreted by the pancreas into the small intestine where they digest macromolecules ( starch, glycogen, lipids and nucleic acids) in food into monomers.
- Tissue layers in the intestines include longitudinal and circular muscles, mucosa and epithelium.
- The presence of Villi in the small intestines increases the surface area of epithelium and helps absorb the monomers formed by digestion and mineral ions and vitamins.
- Different nutrients are absorbed into epithelial cells by different membrane transport mechanisms.
Skills
- Apply knowledge of the process or digestion and absorption in the small intestine to the digestion of starch and the transport of maltose and glucose to the liver.
- Describe your experience of the use of dialysis tubing as a model of the intestines.
- Draw an annotated diagram of the digestive system.
- Identify tissue layers in transverse sections of the small intestine.
Mindmaps
Video tutorial
Watch the 
Screencast of a teacher drawing the diagram below.
This shows how to draw a simple diagram of the digestive system that can be drawn quickly and used in IB exams.
This question tests an understanding of structure and function of the villi of the small intestine.
Answer the question below on a piece of paper, then check your answer with the model answer.
Outline the functions of the villi of the small intestine. (5 marks)
Examiner hint; outline the main points in short sentences.
Click the + to see a model answer.
This is a self marking quiz containing questions covering the topic outlined above.
Try the questions to check your understanding
START QUIZ!
1. Drag the labels to the gorrect place on the diagram below
mouth pancreas anus small intestine liver stomach large intestine esophagus
 A: B: C: D: E: F: G: H: |
Write a list of the ones you got wrong.
Try to sketch a diagram and place these organs into the digestive system.
Then try this question again.
2. Which row in the following list gives the correct functions of the enzymes named?
Amylase breaks down starch
Endopeptidase breaks the peptide bonds in polypeptides
Lipase breaks down triglycerides into fatty acids and glycerol
3. Which of the following best describes the process of peristalsis?
Circular muscles tighten and close the lumen of the intestines, then longitudinal muscles in the wall of the intestines contract pushing the partly digested food along the tube.
4. Which of the following best describes the role of the villi in the small intesines
Villi absorb nutrient molecules in a variety of ways including, diffusion, facillitated diffusion and active transport. The also increase the surface area of the epithelium of the small intestines. Goblet cells within this epithelium produce mucus, but it is not moved along by the villi.
Which of the following are involved in producing the process of peristalsis?
The contraction of circular and longitudinal muscle moves food along the digestive system
Peristalsis moves food, as it is being digested, along the intestines.
How does this movement help digestion?
As well as moving food along the digestive tract, peristalsis helps to mix the food with enzymes.
Which of the enzymes below are secreted by the pancreas?
The pancreas secretes digestive enzymes, including protease (trypsinogen), lipase, and amylase.
Interestingly - the pancreas also produces an enzyme, "phospholipase" which catalyses breakdown of phospholipids. (not required for IB)
The islets of the pancreas are involved in glucose control, but this is not a role in digestion.
What is the advantage of villi and microvilli increasing the surface area of epithelium in the small intestines?
The larger the surface area of epithelium the faster the rate of absorption is..
Which of the following statements best describes the molecules which are absorbed by villi, in the small intestines?
Large macromolecules cannot be absorbed by villi. Monomers are smaller molecules and are absorbed by the villi.
The term nutrients includes both monomers and macromolecues, so is less precise.
The diagram shows a representation of several layers in the wall of human intestines.
What is the name of the layer labelled X.
Villi are found in the layer called mucosa, and the layer beneath the mucosa is the submucosa.
What is the fate of cellulose in the human digestive system?
Humans don't make enzymes to digest cellulose. Bacteria can digest cellulose in the human intestines, but much of the cellulose eaten is undigested. It is sometimes called 'Fibre'.
Drag and drop activities
Test your ability to construct biological explanations using the drag and drop questions below.
The intestinal epithelia uses different methods of transport to move substances into the epithelial cells from the gut lumen.
Active co-transport is used to absorb hydrophilic organic molecules into the gut epithelium from the lumen.
Lacteals in the small intestine
Drag and drop the correct word or phrase into the gap to describe the absorbtion of glucose and amnio acids by the intestinal epithelium.
absorbed lipid area facilitated specific glucose transporter protein membrane channels sodium ions bind each active hydrophilic
Glucose is so cannot pass through the of the membrane. Glucose is absorbed by a combination of transport and diffusion by the sodium-glucose co-transporter protein. The sodium pump situated in the epithelia actively pumps Na+ into gut lumen. These with glucose and then to the in the membrane of the villus epithelium. Sodium ions coupled to glucose diffuse back into the cell through the protein . The glucose then moves through pores between the capillary cells to be very rapidly into the blood.
Amino acids are also absorbed in this way but by a variety of transporter proteins to amino acid.
Active transport moves sodium ions, once these combine with glucose or amino acids, they pass passively through channel proteins, hence co-transport. Transporter proteins are specific to particular amino acids or to glucose.
Click the '+' symbol to open the next explanation.
A little bit of fun to revise the digestion topic. Can you make it to the leader board?
If you can't see the content below, please click this link to Digestion card match game
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