| Date | May 2019 | Marks available | 1 | Reference code | 19M.3.SL.TZ1.2 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Suggest | Question number | 2 | Adapted from | N/A |
Question
When feed for animals is stored, moisture levels need to be kept low to prevent the growth of fungi. Feed was exposed to 15 % moisture and placed into a respirometer. O2 consumption was monitored using the respirometer over a period of six days.
[Source: © International Baccalaureate Organization 2019]
Outline how O2 consumption is measured using a respirometer.
Suggest one conclusion that can be drawn from the results shown in the graph.
Other than humidity, suggest a variable that would need to be controlled in this experiment.
Outline the role of fungi in nutrient cycling.
Markscheme
a. a CO2 absorber/KOH is added ✔
b. a bubble/starting water level is measured ✔
c. «the rate of» movement of the bubble/pressure reduction is a measure of O2 consumption ✔
a. as fungus grows, the rate of oxygen consumption increases ✔
b. around day 4/5 fungus begins to grow/no growth in days 1–3 ✔
c. the rate of fungus growth/rate of respiration is highest after 5 days ✔
temperature/amount or type of feed «in the respirometer»/amount of CO2 absorber
OR
other reasonable suggestion ✔
Do not accept light
a. act as saprotrophs/decomposers ✔
b. rot/feed on/break down organic matter/food/organisms
OR
return nutrients trapped in organic matter to the cycle/soil ✔
Do not accept detritivores
Examiners report
Very few candidates achieved a mark. Some confused a respirometer with a spirometer; others mentioned data logging probes. Credit was given for mention of a water column. Only the highest scoring candidates understood that a carbon dioxide absorber is required to allow pressure changes to be measured.
Many candidates described what was shown by the graph rather than making a conclusion related to the growth of fungi. Thus “oxygen consumption increased after day 4” or references to the feed respiring were common answers.
Often more than one answer was given but only the first was marked. Temperature and amount of feed were the most common answers.
Syllabus sections
- 19M.3.SL.TZ1.2a.iii: Other than humidity, suggest a variable that would need to be controlled in this experiment.
- 22M.2.HL.TZ2.6b: The processes of photosynthesis and respiration have some factors in common and others...
- 17M.2.SL.TZ2.1c.i: State the time when the point of fatigue occurred in the Epi–exercise group.
- 17M.3.SL.TZ2.1a: Suggest how the oxygen consumption rate is determined using this apparatus.
- 17M.2.SL.TZ2.1c.ii: Compare and contrast the results for the water–no exercise group and the Epi–no exercise group.
- 16N.1.SL.TZ0.12: Which pair of molecules are products of aerobic and anaerobic cell respiration in some...
- 22M.1.SL.TZ1.11: The graph shows the changes in lactate measured in an athlete’s blood during...
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21M.1.SL.TZ2.11:
The graph shows the results of an experimental investigation that compared the rates at which lactose, glucose and galactose are broken down in the process of anaerobic cellular respiration by the yeast Torulopsis cremoris.
[Source: Rogosa, M., 1948 Mechanism of the Fermentation of Lactose by Yeasts. Journal of Biological Chemistry, 175, p.418. (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/.]
What can be concluded from these results?
A. Cellular respiration of lactose involves the production of glucose and galactose.
B. The breakdown of glucose and galactose occurs more slowly in the presence of lactose.
C. The rate of cellular respiration is greater for glucose than for lactose and galactose.
D. The percentage of sugar remaining after 42 hours is greater for galactose than glucose.
- 17M.2.SL.TZ2.1b: Describe how increased capillary density could affect the aerobic capacity of muscle.
- 18N.1.HL.TZ0.10: What are final products of photosynthesis and of aerobic respiration?
-
19N.1.SL.TZ0.13:
The diagram shows a respirometer used to measure respiration rate in germinating seeds.
[Source: used with the kind permission of the Nuffield Foundation and the Royal Society of Biology]
What is the expected direction of movement of the fluid at X and the function of the fluid at Y?
-
21N.2.SL.TZ0.4b.ii:
Outline the use of ATP.
-
21N.2.SL.TZ0.4b.i:
State one process that produces ATP.
- 16N.3.SL.TZ0.1a: Suggest the purpose of the wire mesh.
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17N.1.HL.TZ0.09:
A cricket was placed in a respirometer at constant temperature for ten minutes. The soap bubble moved along the pipette.
[Source: © International Baccalaureate Organization 2017]
What was measured by the movement of the soap bubble?
A. Production of carbon dioxide
B. Volume of excretory products
C. Oxygen consumption
D. Release of heat
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19M.1.SL.TZ1.11:
Yeast cells, Saccharomyces cerevisiae, were incubated with and without glucose at three different temperatures for a period of four minutes, during which the rate of CO2 production was measured with a CO2 sensor.
[Source: © International Baccalaureate Organization 2019]
What conclusion can be drawn from the results of this experiment?
A. Yeast uses lipids rather than glucose in respiration at low temperatures.
B. Addition of glucose has a greater impact on rates of cell respiration at lower temperatures.
C. Rates of cell respiration increase with temperature.
D. More glucose is produced at higher temperatures.
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16N.3.SL.TZ0.1c:
Discuss whether the apparatus would be suitable for measuring the oxygen consumption of a small green plant during respiration.
- 17M.3.SL.TZ2.1c: Predict the effects of global warming on aerobic respiration in fish.
- 17M.2.SL.TZ2.1f: Mitochondria are essential for aerobic respiration. Suggest one possible role of the proteins...
- 17N.1.SL.TZ0.19: An experiment was set up so that each test tube contained water at a pH of 6.3 and a pH...
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16N.2.SL.TZ0.3b:
Identify the following processes as either anabolism or catabolism by placing a tick (√) in the correct box.
- 17M.1.SL.TZ2.27: The bacterium Neisseria gonorrhoeae causes infections related to the human reproductive...
-
16N.2.SL.TZ0.3c:
Describe cell respiration in terms of metabolism.
- 19N.1.SL.TZ0.12: Which compound is a waste product of anaerobic respiration in humans? A. Carbon dioxide B....
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19N.2.SL.TZ0.3d:
Using the following table, compare and contrast anaerobic cell respiration in yeasts and in humans. The first row has been completed as an example.
- 17M.1.SL.TZ1.21: Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is...
- 17N.1.SL.TZ0.12: Which process causes ADP to change to ATP? A. Hydrolysis B. Protein synthesis C. DNA...
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22M.2.HL.TZ2.6a:
Describe how plants transport organic compounds from where they are made to where they are stored.
- 16N.3.SL.TZ0.1b: Describe how the apparatus measures the oxygen consumption of the mouse
- 17M.2.SL.TZ2.1e: Analyse the effect of exercise on the presence of the mitochondrial proteins in the leg muscle.
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20N.1.SL.TZ0.11:
The diagram shows a respirometer.
[Source: Courtesy The Royal Society of Biology.]
What solution should be in the bottom of each tube and in which direction will the manometer fluid move?
- 17M.2.SL.TZ2.1d: Discuss the effect of exercise on the results of the experiment.
- 21M.1.SL.TZ1.11: What is a difference between aerobic respiration and anaerobic respiration in yeast? A....
- 17M.1.SL.TZ2.10: The graph shows the changes in lactate and pyruvate measured in an athlete’s blood during and...
- 17M.2.HL.TZ1.1f.ii: Suggest a reason for the greater expression of the gene for the urea transporter after an...
- 18M.1.HL.TZ2.9: What is a requirement for accurate measurements of the rate of respiration using a...
- 17M.2.SL.TZ1.1c: Estimate how much smaller drilled oysters raised in seawater at a high CO2 concentration were...
- 17M.3.SL.TZ2.1b: State the relationship between body mass and the oxygen consumption of fish.
- 17M.2.SL.TZ2.1g: The scientists concluded that Epi significantly increased aerobic capacity in leg...
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22M.2.SL.TZ2.3a:
Describe anaerobic respiration in humans and in yeast.
- 19M.3.SL.TZ1.2a.i: Outline how O2 consumption is measured using a respirometer.
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18N.2.HL.TZ0.6b:
Describe the role of oxygen in aerobic cell respiration.
- 21M.2.SL.TZ1.2c: The process X uses oxygen and produces ATP. Identify the process X.
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21N.1.SL.TZ0.12:
A respirometer is used to measure the oxygen consumption of germinating seeds. The distance that the oil drop moves is measured at 15-minute intervals.
[Source: © The Royal Society of Biology.]
What is the function of chemical X?
A. Absorbs carbon dioxide so the oxygen released by the seeds can be measured
B. Absorbs carbon dioxide so the oxygen absorbed by the seeds can be measured
C. Absorbs oxygen so the carbon dioxide released by the seeds can be measured
D. Absorbs oxygen so the carbon dioxide absorbed by the seeds can be measured
