| Date | May 2021 | Marks available | 1 | Reference code | 21M.1.HL.TZ1.3 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 1 |
| Command term | Question number | 3 | Adapted from | N/A |
Question
The images show samples of red blood cells that were placed in different concentrations of salt solutions.
Which solution has the highest salt concentration?
A. The original solution
B. Solution 1
C. Solution 2
D. Solution 3
Markscheme
B
Examiners report
Three quarters of candidates answered this question correctly so it was not difficult, but the discrimination index was only moderate suggesting that some well-prepared candidates answered incorrectly. The most popular wrong answer showed a cell bursting in the way that would have happened in a hypotonic solution. Either candidates muddled up hypo- and hypertonic or they did not think carefully enough about the direction of water movement in osmosis. It is always worth double checking in one's mind to make sure that a chosen answer is not the opposite of what it should be.
Syllabus sections
- 17M.2.HL.TZ2.3b: Define osmolarity.
- 21M.1.SL.TZ2.4: Which graph best represents the relationship between the concentration of chloride ions in...
- 17N.1.SL.TZ0.24: Dialysis membrane was set up to model digestion and absorption in the small...
- 16N.3.HL.TZ0.3b: Suggest reasons for different amounts of sucrose in the leaf phloem sap of the potato plants.
- 18M.1.SL.TZ1.29: Neural pathways in living brains can now be mapped by tracking the movement of water...
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22M.1.SL.TZ2.7:
Which feature(s) allow(s) transport of glucose in blood plasma?
I. It is hydrophobic.
II. It is polar.
III. Its solubility is low at 37 °C.
A. I only
B. II only
C. I and II only
D. II and III only
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22M.1.HL.TZ2.2:
Red blood cells from a small mammal were immersed in NaCl (sodium chloride) solutions of different concentrations for 2 hours. The graph shows the percentage of hemolysed (ruptured) red blood cells at each concentration.
[Source: Zaidan, T. , de Matos, W. , Machado, É. , Junqueira, T. , Vicentini, S. , Presta, G. and Santos-Filho, S. (2010)
Cellular effects of an aqueous solution of Losartan® on the survival of Escherichia coli AB1157 in the presence
and absence of SnCl2, and on the physiological property (osmotic fragility) of the erytrocyte. Advances
in Bioscience and Biotechnology, 1, 300–304. doi: 10.4236/abb.2010.14039. Available at https://www.scirp.org/pdf/ABB20100400005_18844979.pdf Licensed under a Creative
Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).]What can be deduced from the graph?
A. At Y, the net movement of Na ions between red blood cells and the NaCl solutions is zero.
B. At X, Na and Cl ions disrupt the structure of cell membranes.
C. At Y, the hypertonic NaCl solutions diffuse into the red blood cells.
D. At X, water has moved by osmosis into the red blood cells.
- 18M.1.SL.TZ1.3: How does potassium move across the membrane of a neuron during repolarization? A. Simple...
- 19N.3.SL.TZ0.1c: From the evidence provided by the graph, evaluate the reliability of these data.
-
19M.1.SL.TZ1.4:
Which process(es) occur(s) by osmosis?
I. Uptake of water by cells in the wall of the intestine
II. Loss of water from a plant cell in a hypertonic environment
III. Evaporation of water from sweat on the skin surface
A. I only
B. I and II only
C. II and III only
D. I, II and III
-
19M.1.SL.TZ2.5:
The table shows concentrations of potassium ions and sodium ions inside and outside human cells.
[Source: © International Baccalaureate Organization 2019]
What explains these concentrations?
A. Potassium ions diffuse in and sodium ions diffuse out.
B. Sodium ions diffuse in and potassium ions diffuse out.
C. Active transport pumps sodium ions in and potassium ions out.
D. Active transport pumps sodium ions out and potassium ions in.
- 17M.1.SL.TZ2.27: The bacterium Neisseria gonorrhoeae causes infections related to the human reproductive...
- 18M.1.HL.TZ2.4: Which type of transportation happens in the sodium–potassium pump? A. Facilitated...
- 16N.1.HL.TZ0.4: The giant marine alga Halicystis ovalis is able to move sodium ions from vacuoles to the...
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20N.1.SL.TZ0.4:
The diagram shows a section through a membrane. What are the modes of transport in the diagram?
[Source: © International Baccalaureate Organization 2020.]
- 19N.1.SL.TZ0.2: By which process do potassium ions move through potassium channels in axons? A. Active...
- 19N.3.SL.TZ0.1d: Explain one reason for calculating the percentage change in mass.
- 19N.3.HL.TZ0.3b: If a zucchini is allowed to dry in the open air, predict how the osmolarity of the zucchini...
-
22M.1.SL.TZ2.3:
In an experiment on osmosis, red blood cells were immersed in a salt solution for two hours. The micrographs show the appearance of these cells before and after immersion in the salt solution.
[Source: Ed Uthman, Acanthocytes, from peripheral blood [image online] Available at:
https://en.wikipedia.org/wiki/Acanthocyte#/media/File:Acanthocytes,_Peripheral_Blood_(3884092551).jpg
This file is licensed under the Creative Commons Attribution 2.0 Generic (CC BY 2.0) https://creativecommons.org/licenses/by/2.0/ Source adapted.]What explains the observed changes?
A. The salt solution was hypertonic and entered the red blood cells.
B. The salt solution was hypotonic and disrupted the membranes of the red blood cells.
C. The salt solution was hypertonic and water moved into it from the red blood cells.
D. The salt solution was hypotonic and mineral salts were lost from the red blood cells.
- 21M.1.SL.TZ1.4: A human organ is being prepared for transplant. In what type of solution must it be...
- 17M.1.SL.TZ1.21: Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is...
- 21M.1.HL.TZ1.2: Which process explains the observations shown in the images? A. Active transport B....
-
18M.3.HL.TZ1.1a:
Data was collected on rabbit red blood cells that were exposed to sodium chloride (NaCl) and scorpion venom. Under some osmotic conditions red blood cells swell and burst, releasing hemoglobin (hemolysis). The graph shows the response of red blood cells to different concentrations of sodium chloride, with and without scorpion venom.
[Source: Adapted from Mirakabadi A Z, et al., (2006), J. Venom. Anim. Toxins incl. Trop. Dis., 12 (1), pages 67–77 (London: BioMed Central)]
Outline the effect of the venom on the hemolysis of red blood cells.
- 17M.2.HL.TZ2.3c: Deduce, with a reason, which red blood cell has been placed in a hypertonic solution.
- 22M.1.SL.TZ1.3: What is/are required for facilitated diffusion? I. A concentration gradient II. ATP III. A...
- 19N.3.HL.TZ0.3a: Estimate the solute concentration of the zucchini cells.
- 19N.3.HL.TZ0.3d: Predict what would happen to a red blood cell placed in distilled water.
- 17N.1.SL.TZ0.03: The salt concentration inside an animal cell is 1.8 %. The salt concentration in the...
- 17M.2.HL.TZ1.1f.ii: Suggest a reason for the greater expression of the gene for the urea transporter after an...
-
21N.2.SL.TZ0.5b:
Describe transport across cell membranes by osmosis.
-
19N.3.SL.TZ0.1a:
Using the graph, estimate isotonic sucrose solutions for potato tissue and carrot tissue.
Potato:
Carrot:
- 17M.2.SL.TZ1.1c: Estimate how much smaller drilled oysters raised in seawater at a high CO2 concentration were...
- 17N.1.HL.TZ0.02: The salt concentration inside the Paramecium is 1.8 %. The salt concentration in the...
-
18M.3.HL.TZ1.1b :
Describe how the variables would be controlled in an experiment to estimate the osmolarity of plant tissue.
- 18N.2.HL.TZ0.6a: Calcium is absorbed from food in the human gut by both active and passive processes. Outline...
-
17N.2.HL.TZ0.01d.ii:
Muscle fibres are stimulated to contract by the binding of acetylcholine to receptors in their membranes and the subsequent depolarization.
Suggest a reason for increasing the concentration of sodium–potassium pumps in the membranes of diaphragm muscle fibres.
- 19M.2.HL.TZ1.6c: Explain how blood solute concentrations are kept within narrow limits in the human body.
- 19M.2.SL.TZ2.5a: Outline four types of membrane transport, including their use of energy.
- 19M.2.HL.TZ2.6a: Outline four types of membrane transport, including their use of energy.
- 21N.1.SL.TZ0.3: How is facilitated diffusion in axons similar to active transport? A. They both require the...
-
21N.2.HL.TZ0.3a:
The image shows human red blood cells.
[Source: someoneice/123rf.com.]
Outline what will happen to human red blood cells if transferred to distilled water.
- 19N.3.SL.TZ0.1b: Suggest a reason for the difference in the isotonic points for the potato and the carrot...
- 19N.3.HL.TZ0.3c: Explain one reason for calculating the percentage changes in mass.
-
17N.2.HL.TZ0.01d.i:
Analyse the graph to obtain two conclusions about the concentration of sodium–potassium pumps.
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21M.1.SL.TZ2.1:
The diagrams represent cells with the same concentration of dissolved substances in their cytoplasm. If all the cells were placed in the same hypertonic sucrose solution, which cell would show the greatest rate of change in the concentration of its cytoplasm?
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