| Date | May 2021 | Marks available | 1 | Reference code | 21M.1.SL.TZ2.20 |
| Level | Standard level | Paper | Paper 1 | Time zone | Time zone 2 |
| Command term | Question number | 20 | Adapted from | N/A |
Question
Which is an example of speciation?
A. Selective breeding to produce new varieties of the wheat Triticum aestivum with higher crop yield
B. Evolution of different courtship behaviours in separate populations of the cricket Gryllus rubens
C. Natural selection leading to an increase in the frequency of darker individuals of Biston betularia
D. Selective feeding by koalas (Phascolarctos cinereus) on Eucalyptus species
Markscheme
B
Examiners report
Some G2 forms pointed out that speciation is not part of the SL material and only occurs in HL. Although there may be some justification in the comments, it was assumed that candidates would deduce what was required from their study of Topic 5.1 (Evidence for evolution) — populations of a species can gradually diverge into separate species by evolution. The question performed well according to difficulty and discrimination statistics.
Syllabus sections
- 19M.1.SL.TZ1.20: Which are examples of homologous structures? A. The wings of bats and butterflies B. The...
- 19M.1.SL.TZ1.21: Which is an example of natural selection? A. A giraffe stretching its neck to reach higher...
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18M.1.SL.TZ2.20:
The diagrams show various wings.
[Source: for pterodactyl, bird and bat wings:
John W. Merck, University of Maryland, College Park, Department of Geology;
for insect wing: Halvard Hatlen https://upload.wikimedia.org/wikipedia/commons/0/0f/Dip-trichoceridae-wing.png]Which statement describes the relationship between the structures of the wings?
A. The bat wing and the insect wing are homologous because they have the same function.
B. The limbs of the bird and bat wings are homologous due to convergent evolution.
C. The wings of the pterodactyl and the bat are analogous due to divergent evolution.
D. The bones of the wings of the pterodactyl, bird and bat are homologous as they have a common ancestor.
- 17M.2.HL.TZ1.7c: Describe, using one example, how homologous structures provide evidence for evolution.
- 21M.1.HL.TZ1.15: What are the evolutionary origins and functions of homologous structures?
- 20N.1.SL.TZ0.20: What process best explains the formation of different pentadactyl limbs? A. Adaptive...
- 19M.1.SL.TZ2.20: What is required for natural selection to occur? I. Acquired characteristics II....
- 17M.1.HL.TZ2.25: The graph shows the song duration of birds from the genus Phylloscopus sampled from west to...
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17N.1.SL.TZ0.20:
Which of these structures is not homologous?
[Source: https://en.wikipedia.org/wiki/Comparative_anatomy#/media/File:Homology_vertebrates-en.svg and
https://commons.wikimedia.org/wiki/File:Insect_leg_scheme.svg] - 17M.1.SL.TZ2.27: The bacterium Neisseria gonorrhoeae causes infections related to the human reproductive...
- 16N.1.SL.TZ0.20: Which evidence for evolution do the common features in the bone structure of vertebrate limbs...
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22M.1.SL.TZ2.20:
Humans have been improving crop species for thousands of years by cross-breeding plants with desirable characteristics. The photograph shows the changes in dry cobs of corn (Zea mays) over 10 000 years.
[Source: Evolution of Maize Cobs © Robert S. Peabody Institute of Archaeology,
Phillips Academy, Andover, Massachusetts. All Rights Reserved.]What is the name of the process that was used to produce modern corn?
A. Selective breeding
B. Adaptive radiation
C. Discontinuous variation
D. Natural selection
- 17M.1.SL.TZ1.21: Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is...
- 18N.2.HL.TZ0.7c: Explain how evolution occurs and which factors can cause the process to be rapid.
- 22M.1.HL.TZ1.17: What could be used as evidence for evolution? I. Selective breeding of domesticated...
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19N.1.SL.TZ0.21:
Which pentadactyl limb is adapted for flight?
[Source: adapted from Volkov Vladislav Petrovich, https://en.wikipedia.org/wiki/Homology_(biology)#/media/File:Homology_
vertebrates-en.svg and Zebra.element, https://en.wikipedia.org/wiki/File:Bat_mouse_forelimbs.png] - 17M.2.HL.TZ1.1f.ii: Suggest a reason for the greater expression of the gene for the urea transporter after an...
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17N.2.HL.TZ0.06c:
Cell biologists play an important role in research into disease, fertility, evolution and many
other areas of science.Outline the evidence for evolution provided by selective breeding.
- 17M.2.SL.TZ1.1c: Estimate how much smaller drilled oysters raised in seawater at a high CO2 concentration were...
- 18N.2.SL.TZ0.6b: The human hand is an example of adaptive radiation. Outline adaptive radiation.
- 22M.1.SL.TZ1.20: Mammals, birds and reptiles have an embryonic tail that may disappear during...
- 18N.2.HL.TZ0.7b: Outline the causes of variation in one example of continuous variation in humans.
- 21N.1.SL.TZ0.20: The pentadactyl limbs of mammals, birds, reptiles and amphibians are examples of which kind...
![https://upload.wikimedia.org/wikipedia/commons/0/0f/Dip-trichoceridae-wing.png]](https://upload.wikimedia.org/wikipedia/commons/0/0f/Dip-trichoceridae-wing.png%5D){kind=link}
![https://commons.wikimedia.org/wiki/File:Insect_leg_scheme.svg]](https://commons.wikimedia.org/wiki/File:Insect_leg_scheme.svg%5D){kind=link}