| Date | May 2019 | Marks available | 4 | Reference code | 19M.2.SL.TZ1.8 |
| Level | Standard level | Paper | Paper 2 | Time zone | Time zone 1 |
| Command term | Outline | Question number | 8 | Adapted from | N/A |
Question
Describe how detritivores obtain nutrition and the effects they have in ecosystems.
Outline the role of amylase in digestion in humans.
Explain how plants capture and use light in photosynthesis.
Markscheme
a. «detritivores» obtain nutrition from detritus/waste/dead bodies ✔
b. are heterotrophic ✔
c. removes large waste/cleans up the ecosystem
OR
helps control spread of disease ✔
d. facilitates further decomposition ✔
e. contribute to the supply of «inorganic» nutrients for autotrophs/nutrient cycling
OR
improve soil conditions/aeration ✔
a. amylase is an enzyme ✔
b. secreted by salivary glands/pancreas ✔
c. active/released into the mouth/small intestine ✔
d. acts on starch/polysaccharides ✔
e. breaks «glycosidic» bond by hydrolysis/adding water ✔
f. converts insoluble/large molecule to soluble/small molecules ✔
g. product is maltose/disaccharide/sugar molecule ✔
a. plants convert light energy into chemical energy by photosynthesis ✔
b. photosynthesis takes place in chloroplasts ✔
c. chloroplasts «are organelles that» contain the pigment chlorophyll ✔
d. chloroplasts/chlorophyll «in plants» absorb sunlight ✔
e. «chlorophyll» absorbs red AND blue light most effectively ✔
f. light causes photolysis/splits water molecule ✔
g. carbon dioxide AND water are reactants «in photosynthesis» ✔
h. glucose AND oxygen are products «of photosynthesis» ✔
i. light intensity is a limiting factor for the rate of photosynthesis ✔
j. organic/carbon compounds/glucose provide food/stored energy «for plant itself, animals,food chains» ✔
k. up to one additional mark for an accurate detail from AHL ✔
Examiners report
Most candidates got max 2 for mp a (nutrition of detritivores) and mp e (recycling of nutrients). Candidates getting high marks were able to provide correct examples of detritivores and correctly link to their role in enriching the soil and remove dead material. The biggest problem was the notion that detritivores recycle energy.
The name, location and correct function of the enzyme was very common making 3 max the most common marks. Students who got fewer marks gave generic explanations of the process of digestion. Some students made incorrect references to amylase digesting proteins. A few candidates ignored amylase and discussed digestion in general.
Generally well done with some very knowledgeable answers from the Higher Level programme sometimes to the detriment of the more basic answers required by the standard level examination. Many candidates who attempted this response got more than 4 marks for mp b, d, g and h which were the most common. Students getting higher marks were able to focus on correct conversion of energy, efficiency of red and blue light absorption, and photolysis. Some egregious misconceptions exist among candidates such as plants are green because they absorb green light. The idea that during photosynthesis light energy is converted to chemical energy was frequently neglected.
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...
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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/)]
-
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...
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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
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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...
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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....
-
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...
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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...
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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....
- 17M.2.SL.TZ1.6a: Explain how the small intestine moves, digests and absorbs food.
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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}