Syllabus Edition
First teaching 2023
First exams 2025
Which is the correct definition for a species according to the biological species concept?
A group of organisms which look similar.
A group of organisms with similar characteristics.
A group of organisms which can interbreed to produce fertile offspring.
A group of living things.
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Which of the following statements about genomes is not correct?
Humans have around 20 000 genes
Species vary in the number of genes they have
The number of genes of an organism is not proportional to genome size
Humans have the most genes of any organism
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1 markThe image shows a karyogram.
Which of the statements about the karyogram is correct?
The source of DNA for the karyogram was a haploid cell.
All 23 pairs of chromosomes are arranged in descending order of size.
Chromosomes banding is visible.
The source of DNA for the karyogram was a human cell.
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1 markWhat is an appropriate unit for comparing the length of genomes?
Micrometers
Nanometers
Picometer
Million base pairs
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1 markWhat is the most efficient way to compare the genome sizes of different species?
Read scientific articles and extract relevant information.
Extract information from an online database.
Compare the chromosome number of the different species.
Compare the proteome size of the different species.
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Which of the following series of statements about genome sequencingis correct?
| A | Scientists now know the location and role of every human gene | The genomes of humans are the only genomes to be sequenced in their entirety | Advancing computer technology means that the rate at which a genome can be sequenced continues to increase |
| B | Scientists can now look for correlations between changes in a gene and particular human traits | The genomes of humans are the only genomes to be sequenced in their entirety | Genome sequencing technology is now so advanced that further developments are not expected |
| C | Scientists can now look for correlations between changes in a gene and particular human traits | The genomes of many species have now been sequenced | Advancing computer technology means that the rate at which a genome can be sequenced continues to increase |
| D | Scientists can now look for correlations between changes in a gene and particular human traits | The genomes of many species have now been sequenced | Genome sequencing technology is now so advanced that further developments are not expected |
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Dichotomous keys can be used to identify species from their observable features.
To which order of insects does the insect below belong? Note that the insect is shown at rest and not in flight.
| 1 |
Hard wing cases are present. . . . . . . . . . Hard wing cases are not present. . . . . . . . . . |
Coleoptera Go to 2 |
| 2 |
Wings are not membranous (not thin and translucent). . . . . Wings are membranous (thin and translucent). . . . . |
Go to 3 Go to 4 |
| 3 |
Wings are leathery. . . . . . Wings are scaly. . . . . . |
Orthoptera Lepidoptera |
| 4 |
Only one pair of wings used to fly (the second pair is very small). . Two equal-sized pairs of wings are used to fly. . . . . . |
Diptera Go to 5 |
| 5 |
Wings held out at right-angle to body when resting. . . . . Wings are folded over the body when resting. . . . . |
Odonata Hemiptera |
Lepidoptera
Odonata
Coleoptera
Hemiptera
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1 markWhich of the following presents a difficulty when applying the biological species concept?
Sexual reproduction
Horizontal gene transfer
Gamete incompatibility
Linnaean classification
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Back in evolutionary history, the ancestors of giraffes used to have much shorter necks. At this time they possessed a nerve called the laryngeal nerve that travels from an area just below the brain into the brain. At this time the nerve looped under a blood vessel that was quite close to the brain and this allowed the nerve to be short and send impulses very quickly.
Over time as the giraffe evolved to develop a longer neck, the laryngeal nerve also grew longer. Although it still started just below the brain and sent impulses to the brain, the restriction of looping under the blood vessel near the heart prevented the nerve from avoiding growing with the neck of the giraffe.
The image below shows the structure of the laryngeal nerve in the giraffe.
Which of the statements below correctly describes the evolution of the giraffe laryngeal nerve?
The evolution of the laryngeal nerve provides evidence for the concept of punctuated equilibrium.
The evolution of the laryngeal nerve is an example of stabilising selection.
The evolution of the laryngeal nerve provides evidence for the concept of gradualism.
The evolution of the laryngeal nerve provides evidence against natural selection because natural selection would never allow for such a flawed, inefficient structure to develop.
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1 markThe two karyotypes belong to a donkey (Q) and a horse (R).
Breeding these two individuals resulted in the production of a sterile mule (S).
Why would S be sterile?
The sex of the mule (S) will be undetermined at birth due to the unnatural combination of chromosomes
Different combinations of alleles formed as a result of crossbreeding Q and R which leads to disadvantageous characteristics in S
There are different numbers of chromosomes in the gametes of Q and R so S would not live long enough to breed
The process of meiosis will not be possible in S as homologous pairs cannot form
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