| Date | May 2017 | Marks available | 1 | Reference code | 17M.1.HL.TZ2.20 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 2 |
| Command term | Question number | 20 | Adapted from | N/A |
Question
The graph shows variations in beak size for the bird Geospiza fortis on an island in the Galápagos archipelago.
What evidence from the graph indicates that disruptive selection is occurring?
A. An intermediate beak size is less common.
B. Median beak size is the most common.
C. Smaller beaks are favoured.
D. Larger beaks are favoured.
Markscheme
A
Examiners report
Syllabus sections
- 17M.2.HL.TZ2.7a: Outline how reproductive isolation can occur in an animal population.
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18M.1.HL.TZ1.36:
What could account for this distribution of height in a population?
[Source: Graph adapted from Six Minutes http://sixminutes.dlugan.com/good-public-speaker-average/]
A. Gene linkage
B. Dominant alleles
C. Independent assortment
D. Multiple genes
- 17N.1.HL.TZ0.35: How do the concepts of gradualism and punctuated equilibrium differ? A. The timing of...
- 17M.1.HL.TZ1.36: What can lead to reproductive isolation after just one generation? A. Polyploidy B....
- 16N.2.HL.TZ0.4a: List two causes of variation within a gene pool.
- 18M.1.HL.TZ2.21: Which example shows disruptive selection? A. Giraffe necks have become longer over time. B....
- 19M.1.HL.TZ1.35: Natural selection can operate in different ways. What is the effect of disruptive...
- 19N.1.HL.TZ0.36: A hunter tends to kill the bigger individuals of a population for their meat or for large...
-
19M.1.HL.TZ2.19:
The cheetah (Acinonyx jubatus) is a large cat found in Africa. It has been discovered that organs could be transferred between any two individuals without rejection of the organ.
What is the probable reason for this?
A. Cheetahs have poor reproductive success.
B. Cheetahs have high heterozygosity.
C. Cheetahs have a large gene pool.
D. Cheetahs have a small gene pool.
- 17M.1.SL.TZ1.1: Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C....
- 22M.1.HL.TZ1.35: What is polyploidy? A. Having an extra set of chromosomes B. Having an extra sex...
- 16N.2.HL.TZ0.4c: Outline what is required for speciation to occur.
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21N.1.HL.TZ1.36:
The graph shows the relationship between mass at birth and the percentage that die shortly after birth for Scottish Blackface lambs.
[Source: Dwyer, C.M., Conington, J., Corbiere, F., Holmoy, I.H., Muri, K., Nowak, R., Rooke, J., Vipond, J. and Gautier,
J.-M., 2016. Invited review: Improving neonatal survival in small ruminants: science into practice. Animal, 10(3),
pp. 449–459.]What type of selection for the lambs is shown in the graph?
A. Disruptive selection, as there is a drop in mortality at intermediate birth masses
B. Stabilizing selection, as lambs with low or high birth mass are less likely to survive
C. Directional selection, as lambs with a high birth mass have high mortality
D. There is no evidence in the graph of selection, as survival frequency is not shown
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22M.2.HL.TZ2.7c:
Explain how speciation occurs, including the different processes of isolation and selection.
- 16N.1.HL.TZ0.36: Fossil records show that black bears increased in size during the Ice Age and decreased in...
- 18N.2.HL.TZ0.8c: Research suggests that many living plant species are polyploid. Explain how polyploidy occurs...
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20N.2.HL.TZ0.8b:
Describe the changes that occur in gene pools during speciation.
- 17M.1.HL.TZ2.19: The genetic determination of dogs’ coats can be quite complex, with many different genes...
- 17M.2.HL.TZ1.7b: Outline the process of speciation.
-
22M.1.HL.TZ2.36:
Three-spined stickleback fish (Gasterosteus aculeatus) vary in the number of armour plates. The graph shows the frequency of individuals with low, partial or complete plating in a three-spined stickleback population living in Kennedy Lake, Vancouver Island, Canada.
[Source: Reprinted from Current Biology, 24, Marchinko, K.B., Matthews, B., Arnegard, M.E., Rogers, S.M. and Schluter, D., Maintenance of a Genetic Polymorphism with Disruptive Natural Selection in Stickleback.
2014. pp.1289–1292 with permission from Elsevier.]Which type of natural selection could result in this pattern of variation in the population?
A. Disruptive
B. Directional
C. Stabilizing
D. Convergent
- 17M.2.HL.TZ1.7a: Discuss the role of genes and chromosomes in determining individual and shared character...
- 19M.2.HL.TZ1.7b: Explain how natural selection can lead to speciation.
- 17M.3.HL.TZ2.1c: Explain the concept of directional selection with respect to this example.
- 21M.1.HL.TZ2.36: Which cell is a polyploid zygote produced by fusion of one haploid and one diploid gamete?
