| Date | May 2017 | Marks available | 8 | Reference code | 17M.2.SL.TZ1.6 |
| Level | Standard level | Paper | Paper 2 | Time zone | Time zone 1 |
| Command term | Explain | Question number | 6 | Adapted from | N/A |
Question
James Beard, a famous chef, once said “Food is our common ground, a universal experience.”
Explain how the small intestine moves, digests and absorbs food.
Distinguish between the structures of the different types of fatty acids in food.
Outline how leptin controls appetite.
Markscheme
a. contraction of muscle «layers»/peristalsis helps move food
OR
circular muscle contraction prevents backward movement of food
OR
longitudinal muscle contraction moves food along gut
b. peristalsis/muscle contractions mix food with intestinal enzymes
c. enzymes digest macromolecules into monomers
Accept an example for mp c
d. pancreatic enzymes/amylase/lipase/endopeptidase «chemically» digest food in«lumen of» small intestine
e. «pancreatic» amylase digests starch
OR
lipases digest lipids/fats/triglycerides
OR
endopeptidases/dipeptidases digest proteins/polypeptides
f. bile/bicarbonate secreted into the small intestine creates favorable pH for enzymes
OR
bile emulsifies fat
g. some final digestion into monomers is associated with epithelial cells/epithelium «of small intestine»
h. mucosa layer/inside surface/lining of small intestine contains villi/finger-like projections
i. villi/microvilli increase surface area for better absorption
j. villi absorb products of digestion/monomers/mineral «ions»/vitamins
k. glucose/amino acids enter blood «capillaries»
OR
lipids enter lymph vessels/lacteals
l. absorption involves active transport/diffusion/facilitated diffusion
m. different nutrients are absorbed by different transport mechanisms
a. fatty acids can be saturated or unsaturated
b. unsaturated can be monounsaturated or polyunsaturated
c. saturated fats have no double bonds/have maximum number of hydrogen atoms
OR
unsaturated fatty acids have «at least one» double C=C bond
OR
polyunsaturated fatty acids have more than one double bond / OWTTE
d. cis-form has hydrogen atoms on same side of carbon double bond
OR
cis-form has bend at carbon double bond
e. trans-form has hydrogens on opposite sides of carbon double bond
OR
trans-form makes a straight carbon chain
f. length of hydrocarbon chain can vary
OR
position/number of carbon double bonds can vary
Accept labeled diagrams that illustrate these marking points
a. leptin suppresses/inhibits appetite
b. is secreted by adipose tissue/fat «storage» tissue
c. level is controlled by amount of adipose tissue/«ongoing» food intake
d. leptin targets cells in hypothalamus/appetite control centre in brain
e. causes hypothalamus/control centre in brain to inhibit appetite
f. if amount of adipose tissue increases, blood leptin concentration rises
Examiners report
Syllabus sections
- 18M.2.SL.TZ2.1a.i: Identify which organism has the highest percentage of edible mass.
- 22M.1.SL.TZ2.24: The graph shows the amounts of two substances present in food ingested by a healthy person as...
-
21N.1.SL.TZ0.24:
The diagram shows some of the organs associated with the digestion of starch. Which organ produces amylase?
[Source: Cancer Research UK. Diagram showing the parts of the digestive system. 30 July 2014. Available at: https://
commons.wikimedia.org/wiki/File:Diagram_showing_the_parts_of_the_digestive_system_CRUK_324.svg.
This file is licensed under the Creative Commons Attribution-Share Alike 4.0 International license.
https://creativecommons.org/licenses/by-sa/4.0/deed.en [Accessed 2 December 2021]. Adapted.] - 17M.1.HL.TZ1.21: Glucose is absorbed through protein channels in the plasma membrane of epithelium cells in...
-
21M.2.SL.TZ1.3c:
Wheat, barley and rye all contain gluten. Outline how a protein such as gluten is digested.
- 18M.2.SL.TZ2.1c: Outline the differences between the environmental impact of using mealworms and traditional...
-
17N.2.SL.TZ0.05b:
Discuss the roles of the enzymes secreted by the pancreas during digestion.
-
18M.1.SL.TZ1.24:
The photomicrograph drawing shows a longitudinal section of the small intestine.
[Source: Henry Gray (1918) Anatomy of the Human Body]
What is the function of the tissue layers labelled X and Y?
A. Secretion of digestive enzymes
B. Absorption of digested food
C. Transport of absorbed foods
D. Movement of food in the intestine
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21N.1.HL.TZ1.23:
The diagram shows a cross section through the small intestine of a mammal. Which label points to the mucosa?
[Source: JOSE LUIS CALVO MARTIN & JOSE ENRIQUE GARCIA-MAURIÑO MUZQUIZ / www.istockphoto.com.]
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18M.1.HL.TZ2.31:
The diagram shows the human digestive system. Where are lipids digested?
[Source: BruceBlaus/Wikimedia. File licensed under CC BY 3.0 (https://creativecommons.org/licenses/by/3.0/)]
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22M.1.HL.TZ1.20:
Where in the digestive system are lipids broken down?
[Source: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health. The Digestive System
[online] Available at: https://www.niddk.nih.gov/news/media-library/11172. Source adapted.] -
19N.1.SL.TZ0.24:
The micrograph is of a longitudinal section through the small intestine. Which letter represents the circular muscle layer?
[Source: Henry Gray (1918) Anatomy of the Human Body]
- 17M.1.SL.TZ2.24: Which is a process occurring in the small intestine?
- 18M.1.HL.TZ1.20: Bacteria from chicken feces can cause a loss of intestinal villi in small children who happen...
-
21N.2.SL.TZ0.5c:
Explain the adaptations of the small intestine to its function.
-
18M.1.HL.TZ2.2:
The micrograph shows part of a cell.
[Source: Louisa Howard/Katherine Connollly https://commons.wikimedia.org/wiki/File:Microvilli.jpg]
Which principal function is this cell likely to have, as judged by its cell structure and organelles?
A. High rate of protein processing
B. High rate of absorption
C. High rate of photosynthesis
D. High rate of movement
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18M.1.SL.TZ2.24:
The diagram shows the human digestive system. Which organ is responsible for the majority of the absorption of digested food?
[Source: BruceBlaus/Wikimedia. File licensed under CC BY 3.0 (https://creativecommons.org/licenses/by/3.0/)]
- 18M.2.HL.TZ2.4b.ii: Amylase is used in human digestion. State the function of amylase.
- 19M.1.SL.TZ1.24: Where in the human body is lipase produced? A. Stomach B. Pancreas C. Gall bladder D. Liver
- 19M.2.SL.TZ1.8b: Outline the role of amylase in digestion in humans.
-
20N.1.SL.TZ0.24:
The photomicrograph shows a section through a human small intestine.
[Source: Chiodini RJ, Dowd SE, Chamberlin WM, Galandiuk S, Davis B,
Glassing A (2015) Microbial Population Differentials between Mucosal and Submucosal Intestinal Tissues in
Advanced Crohn’s Disease of the Ileum. PLoS ONE 10(7): e0134382. https://doi.org/10.1371/journal.pone.0134382.]Which statement corresponds to the labelled structures?
A. X moves food along the intestine.
B. Y is the mucosa.
C. Y contains lacteals.
D. Z causes peristalsis
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21N.2.SL.TZ0.5a:
Outline the significance of surface area to volume ratio in the limitation of cell size.
- 17M.1.HL.TZ1.23: Which organ in the human body secretes lipase, amylase and protease? A. Pancreas B....
- 17M.1.HL.TZ2.32: Where is absorption of digested food carried out? I. Villi II. Pancreas III. Small...
- 18M.2.SL.TZ2.1a.ii: Calculate how much more feed is required by cattle than chickens to produce 1 kg of live mass.
- 18M.2.SL.TZ2.1a.iii: Identify which organism requires the least feed to produce 1 kg of edible mass.
- 18M.2.HL.TZ2.4b.i: Amylase is used in human digestion. State two sites of production of amylase.
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16N.2.HL.TZ0.2a:
The image is an electron micrograph of the lining of the small intestine.
(i) Label the microvilli using the letter M and a nucleus using the letter N.
(ii) State the function of the goblet cell.
(iii) Deduce, with a reason, whether or not the goblet cell is likely to divide.
- 17M.1.SL.TZ2.27: The bacterium Neisseria gonorrhoeae causes infections related to the human reproductive...
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18M.2.SL.TZ2.1b.ii:
Predict, with a reason, whether the amino acid composition of yellow mealworms or cattle is more suitable for a human diet.
- 16N.1.SL.TZ0.24: What is the main method of transport of monosaccharides such as fructose across the...
- 19N.1.SL.TZ0.25: Which part of the body secretes amylase, lipase and endopeptidase for use in the digestion of...
-
18M.2.SL.TZ2.1b.i:
Distinguish between the amino acid contents of yellow mealworms and cattle.
- 18N.1.SL.TZ0.23: Which products are formed by the action of the enzymes protease and amylase?
- 17M.1.SL.TZ1.21: Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is...
- 21M.1.SL.TZ2.24: What is the name of the enzyme in the diagram? A. Amylase B. Maltase C....
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21M.2.SL.TZ2.5b:
Explain how amino acids in casein could reach the liver, starting from the moment when the person takes a bite of pastry cream pie.
- 22M.1.SL.TZ1.24: Which process describes starch metabolism in humans? A. Starch is digested by amylase in the...
-
22M.2.HL.TZ2.6c:
Humans rely on carbohydrates for much of their energy. Outline the process of digestion and absorption of starch in the human digestive system.
-
20N.2.HL.TZ0.6b:
Outline how proteins are digested and the products of protein digestion absorbed in humans.
-
21M.1.SL.TZ1.26:
A fluid sample is taken from the digestive tract of a mammal. The sample is basic (alkaline) and able to digest starch and proteins. From which part of the digestive tract was the fluid taken?
A. Mouth
B. Stomach
C. Small intestine
D. Gall bladder
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19M.1.SL.TZ1.25:
What are these structures?
[Source: Burgstedt | Dreamstime.com]
A. Fatty acids in the small intestine
B. Bacteria in the large intestine
C. Villi in the small intestine
D. Feces egested from the large intestine
- 17M.2.HL.TZ1.1f.ii: Suggest a reason for the greater expression of the gene for the urea transporter after an...
-
21M.2.SL.TZ1.3a:
Outline the functions of the villi in the small intestine.
-
21M.1.HL.TZ1.18:
A fluid sample is taken from the digestive tract of a mammal. The sample is basic (alkaline) and able to digest starch and proteins. From which part of the digestive tract was the fluid taken?
A. Mouth
B. Stomach
C. Small intestine
D. Gall bladder
-
21M.2.SL.TZ1.3b:
Explain the consequences of celiac disease for absorption of digested nutrients.
-
21M.2.SL.TZ2.5c:
Congenital lactase deficiency is a type of lactose intolerance that occurs in infants. It is inherited in an autosomal recessive pattern. Calculate the chance of congenital lactose intolerance in a child whose parents are both carriers for the disorder, showing fully how you reached your answer.
- 17M.2.SL.TZ1.1c: Estimate how much smaller drilled oysters raised in seawater at a high CO2 concentration were...
- 18M.2.SL.TZ1.2b: Draw an annotated diagram to show how a peptide bond is formed.
- 18M.2.SL.TZ2.1e: Using all the relevant data in this question, discuss the use of insects as a major food...
-
18M.2.SL.TZ2.5b:
Describe the processes involved in absorbing different nutrients across the cell membrane of villus epithelium cells lining the small intestine.
- 17M.1.HL.TZ2.31: Where does the digestion of polypeptides start in humans? A. Mouth B. Esophagus C....
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18M.2.SL.TZ2.1d:
Birds and mammals maintain constant body temperature despite considerable losses of body heat to the environment. In insects such as mealworms, body temperature is variable and is often the same as the temperature of the environment or only slightly above it. Analyse the data in the bar charts, using this information.
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19M.2.SL.TZ2.5c:
Explain the action of enzymes in digestion and the different roles of at least two named enzymes that are produced in the pancreas.
![https://commons.wikimedia.org/wiki/File:Microvilli.jpg]](https://commons.wikimedia.org/wiki/File:Microvilli.jpg%5D){kind=link}