MCQs

Question 1

Genetic information is organised at different levels. Regarding organisation at the chromosome level in eukaryotes, which statement is false?

A) During interphase, chromosomes are organised in chromosome territories in the nucleus
B) In mitosis and meiosis, genetic information is organised in highly condensed, visible chromosomes
C) Genetic information is organised in circular chromosomes in a region called a nucleoid
D) Genetic information is organised as paired, linear chromosomes in the nucleus

Answer 1

C) Genetic information is NOT organised in circular chromosomes in nucleoids in eukaryotes - this only applies to prokaryotes

Question 2

The gene structure in prokaryotes differs from that in eukaryotes because prokaryotic genes…

A) Have both 5’UTR and 3’UTR
B) Have both positive and negative regulation
C) Can be organised into operons
D) Have splicing

Answer 2

C) Prokaryotic genes can be organised into operons, which eukaryotes cannot

*Splicing is only found in eukaryotes, and A and B are true of both

Question 4

Which regulation provides the most rapid decrease of protein levels?

A) Negative regulation of transcription
B) Gene silencing
C) Protein degradation
D) Protein phosphorylation

Answer 4

C) Protein degradation is the most RAPID form of regulation

A and B are relatively very slow, and protein phosphorylation can regulate activity quickly but doesn’t decrease protein level necessarily

Question 4

Identify the incorrect statement on histone proteins.

A) Four main types are present
B) They are negatively charged
C) They affect DNA accessibility to transcription factors
D) They are post-translationally modified

Answer 4

B) They are NOT negatively charged, they can’t be, because they interact with DNA, which is itself negatively charged

Question 4

The telomerase catalytic activity is directly required for…

A) Protecting chromosome ends
B) Extending telomeres to compensate for the DNA loss due to the end-replication problem
C) Preventing recombination between telomeres
D) Accurately segregating chromosomes in meiosis

Answer 4

B) Extending telomeres to compensate for the DNA loss due to the end-replication problem

A,C, and D are all incorrect because these processes are indirectly connected to telomerase, meaning they depend on telomere length which in turn depends on function of telomerase

Question 5

Smoking and drinking alcohol increase the probability of cancer because these…

A) Compromise BRCA1 function
B) Decrease DNA repair accuracy in general
C) Increase the frequency of DNA lesions
D) Perturb the regulation of gene expression

Answer 5

C) Increase the frequency of DNA lesions

Question 6

The genetic code is (almost) universal. What does this mean?

A) Almost all living organisms use the same four bases and their codons specify the same amino acids
B) Only eukaryotes use the same four bases and their codons specify the same amino acid
C) Only prokaryotes use the same four bases and their codons specify the same amino acid
D) Only prokaryotic genes can be expressed in prokaryotes

Answer 6

A) Almost all living organisms use the same four bases and their codons specify the same amino acids

Question 7

Which of these statements about karyotype is NOT correct?

A) Autosomes are arranged by size
B) It is the chromosomal appearance during interphase
C) It is organism-specific
D) It represents the complete set of chromosomes in an organism

Answer 7

B) It is the chromosomal appearance during interphase

This is not true, karyotypes show chromosomes in metaphase, when they are most condensed

Question 8

Homologous recombination is important for mitotic cells because…

A) It is involved in the repair of broken replication forks
B) It is involved in the repair of mismatches
C) It prevents DNA damage caused by ionising radiation
D) It protects cells from DNA damage caused by UV light

Answer 8

A) It is involved in the repair of broken replication forks

Broken replication forks result in one-ended dsDNA breaks which are repaired via homologous recombination

Question 9

What mode of inheritance does this pedigree suggest?
(affected mother, affected father, one affected son, one unaffected daughter)

A) Autosomal recessive
B) Autosomal dominant
C) X-linked recessive
D) X-linked dominant

Answer 9

B) Autosomal dominant

The disease affects all generations and males and females, suggseting the condition is autosomal dominant - affected parents must therefore be heterozygous (Aa) and one child is homozygous dominant (AA) and the other is homozygous recessive (aa)

Question 10

Which of these is an example of recessive epistasis?

A) Bombay blood group in humans
B) Corn snake skin pigmentation
C) DNA repair in haploid yeast
D) Fur colour in cats

Answer 10

A) Bombay blood group in humans

*Haploid cannot be recessive epistasis
*Fur colour is an example of allelic series/a modifier
*Corn snake pigmentation is an example of a 9:3:3:1 ratio, no epistasis

Question 11

Which statement about pleiotropy is incorrect?

A) It is a common genetic situation
B) Explains why a QTL might appear in multiple GWAS
C) Involves multiple genes affecting one single trait
D) Can represent a constrain to the evolvability of development

Answer 11

C) Involves multiple genes affecting one single trait

Pleiotropy involves one gene affecting multiply traits - so C is false

Question 12

Which of the following is NOT a fate of a duplicated DNA sequence?

A) Loss
B) Retention through gene dosage compensation
C) Retention through neofunctionalisation
D) Horizontal gene transfer

Answer 12

D) Horizontal gene transfer

This is a method by which DNA could be duplicated, not the fate of DNA duplication

Question 13

Which of these examples does NOT represent a change in cis-regulatory elements?

A) Ultrabithorax inhibition of limbs in abdomen of insects
B) Loss of pelvic spines in Stickleback fish
C) Spots on the wings of certain Drosophila species
D) Extent of wing pigmentation in species of Drosophila

Answer 13

A) Ultrabithoriax inhibition of limbs in abdomen of insects

All the other examples involve changes in the cis-regulation of target genes
But for Ultrabithorax (a transcription factor), we saw that the addition of an amino acid motif to the TF changes the trans-regulation of the target genes (controlling limb development)

Question 15

A genetic variant that is a 2 base pair deletion can also be a…

A) CNV
B) SNP
C) Structural variant
D) None of the above

Answer 15

A) CNV - copy-number variant

If the 2bp deletion removes one of the several repeats, then it is a deletion AND a copy number variant (e.g. GAGAGA–>GAGA)
A SNP is a single nucleotide polymorphism, and a structural variant is a change that can be over 1000 base pairs long

Question 16

A population of 10 individuals has relative genotypic fitnesses of w11=1, w12=1, and w22=0.95. What is the expected fate of allele 1 which starts at a frequency of 0.5?

A) Allele 1 goes to fixation
B) Allele 1 goes to loss
C) Frequency of allele 1 remains the same
D) Whether allele 1 goes to fixation or loss is mostly due to chance

Answer 16

D) Whether allele 1 goes to fixation or loss is mostly due to chance

Although there are fitness differences between the genotypes favouring allele 1, the population size is only 10, so is small enough that drift will be the driving force in allele frequency change in this population, so whether or not the allele goes to fixation or loss is mostly due to chance

Question 17

Which trait is most likely a product of sexual selection by female choice?

A) Stronger antlers on an elk that improve an individual’s chance in combat
B) Bright colouration on a fish that is indicative of genetic quality
C) Barbs on the penis that remove the sperm of rival mails and increase probability of fertlisation
D) Successful bedbugs with the ability to overcome the female’s resistance to mating

Answer 17

B) Bright colouration on a fish that is indicative of genetic quality

*Stronger antlers on an elk that improve an individual’s chance in combat is an example of intra-sexual selection or sexual conflict, NOT an example of mate choice

Question 18

A selection regime of enforced monogamy in females but where males are allowed to evolve is established. In control lines, both males and females were allowed to freely interact as normal. Females from the monogamous treatment were then mated to males from the baseline wild population. These females were found to have:

A) The same fitness as females from the control lines
B) Had lower fitness than females from the control line
C) Had higher fitness than females from the control line
D) The fitness for these females aren’t comparable

Answer 18

B) Had lower fitness than females from the control group

The experimental setup allowed males to advance in the arms race of sexual conflict, but not the females, so the males were better able to manipulate female reproduction to their benefit - thus lowering overall female fitness

Question 19

As organisms have access to a finite amount of resources, senescence results from a trade-off between allocation of resources to either reproduction or maintenance of the body. This best describes which of the following hypotheses?

A) Rate-of-living hypothesis
B) Mutation accumulation hypothesis
C) Antagonistic pleiotropy hypothesis
D) Disposable soma hypothesis

Answer 19

D) Disposable soma hypothesis

This specifies the trade-off between the investment in somatic vs reproduction

Question 20

You discover a new species of plant, which has leaves that are poisonous to kill a whale. This high level of poison is likely the result of…

A) A predator/prey interaction
B) Antagonistic co-evolution
C) Red Queen co-evolution
D) all of the above

Answer 20

D) all of the above

Extreme toxicity is usually the result of an arms race with a predator that is continually evolving resistance to higher and higher levels of poison
This very poisonous plant is therefore engaged in an arms race, which is Red Queen coevolution, antagonistic coevolution, and it is likely the prey in a predator-prey interaction

Question 21

What is an adaptation?

A) A trait currently favoured by natural selection and previously favoured for another purpose
B) Aggression
C) Providing a plausible story for the adaptive significance of a trait
D) A trait that allows an individual to leave more offspring than individuals without that trait

Answer 21

D) A trait that allows an individual to leave more offspring than individuals without that trait

Providing a plausible story is the adaptationist program, or possibly just storytelling, A describes exaptation

Question 22

Which of the following statements about the UPGMA algorithm is false?

A) UPGMA requires a matrix of pairwise differences as input
B) UPGMA does not require an out-group
C) UPGMA works from the root of the tree to the tips
D) UPGMA is a clustering algorithm

Answer 22

C) UPGMA works from the root of the tree to the tips

Question 23

Why might the actual number of lineages not increase exponentially with time? A) Because clades have reached an intrinsic carrying capacity B) Because the rate of extinction is non-zero C) Because biotic interactions lead to rapid species evolution D) Because of the pull of the present

Answer 23

A) Because clades have reached an intrinsic carrying capacity *B) A non-zero extinction rate still leads to an exponential increase in the number of species as long as the net diversification rate is positive C) Rapid speciation still implies an exponential increase in the number of species D) The pull of the present only affects the number of lineages surviving until the present (not the actual number of lineages)

Question 24

Which statement about BDMIs is false? A) A BDMI is an incompatibility between alleles at two (or more) loci that have fixed independently of one another B) A BDMI could evolve in a single species if mutations at two loci fix sequentially C) The evolution of BDMIs critically depends on divergent selection D) Loci involved in BDMIs can be identified using genetic mapping and lab crosses

Answer 24

C) The evolution of BDMIs does NOT critically depend on divergent selection The null model of speciation only requires that BDMIs evolve (new mutation) and reach fixation (either by genetic drift OR selection)

Question 25

What is incomplete lineage sorting? A) Reciprocal monophyly at gene trees for samples taken from different species B) The observation that polyphyly is incomplete in samples from closely related species or populations C) The observation that samples from closely related species or populations are not reciprocally monophyletic D) The fact that nesting of gene trees within species trees may be incomplete because of gene trees

Answer 25

C) The observation that samples from closely related species or populations are not reciprocally monophyletic Complete lineage sorting implies that all samples from the same species have a common ancestor at the exclusion of samples from other taxa Incomplete lineage sorting implies that samples from closely related species or populations are not reciprocally monophyletic

Question 26

Which of the following is NOT an indicator that human populations are still evolving? A) Modern medicine and diet has reduced but not removed selection pressures B) There is still sexual selection in the form of mate choice C) Some people have more children than others, leading to differences in allele frequencies from one generation to the next D) Incidences of cancer are on the rise

Answer 26

D) Incidences of cancer are on the rise Increased incidences of cancer is a result of changes in human behaviour and would only be an indicator of current human evolution if we knew it was affecting fitness In most cases, increases in cancer rates are not associated with average lifetime reproductive success

Question 27

When an exonuclease is added to circular gapped DNA, what DNA product will remain after the reaction? A) Double-stranded linear B) Double-stranded circular C) Single-stranded linear D) Single-stranded circular

Answer 27

D) Single-stranded circular

Question 28

What factor contributes the most to acquiring DNA lesions in living organisms? A) UV B) Environmental pollution C) Ionising radiation D) DNA replication

Answer 28

D) DNA replication

Question 29

The work of which of these historic figures/scientists can be associated with the field of epigenetics? A) Waddington B) Auerbach C) Darwin D) Edmonstone

Answer 29

A) Waddington

Question 30

Which statement is false? Eukaryotes differ from prokaryotes because they... A) Use positive and negative regulation of transcription B) Have splicing C) Use post-translational modification of proteins to regulate gene expression D) Do not have operons

Answer 30

A) Use positive and negative regulation of transcription - this is false, because eukaryotes AND prokaryotes do this B) True, eukaryotes splice whereas prokaryotes do not C) True, eukaryotes do PTMs, prokaryotes do not D )True, only prokaryotes have operons

Question 31

Which type of recombination is the most wide-spread among living organisms? A) Site-specific recombination B) None of the above C) Illegitimate recombination D) Homologous recombination

Answer 31

D) Homologous recombination *Illegitimate recombination and site-specific recombination are specific to only some cells and viruses

Question 32

How can narrow sense heritability be quantified? A) Calculating a mean and a measure of variance for that trait B) Performing a QTL mapping experiment C) Measuring selection and response differentials in an experiment D) Performing a study involving twins

Answer 32

C) Measuring selection and response differentials in an experiment *Performing a study involving twins would help quantify BROAD sense heritability, but not narrow sense *Mean and variance would only give us descriptive statistics, but nothing about heritability *Performing a QTL mapping experiment would identify SOME regions associated with variance, but we wouldn't capture all the additive genetic causes of that variance

Question 33

What are the most dangerous DNA lesions? A) Mismatches B) Thymidine dimers C) Oxidised guanidine D) DSBs and ICLs

Answer 33

D) DSBs and ICLs Mismatches are not lethal if unrepaired in small amount, neither are thymidine dimers or oxidised guanidine DSBs and ICLs are dangerous - a single lesion of this type can kill a cell if unrepaired

Question 34

What is the region of chromatin most rich in genes called? A) Heterochromatin B) Euchromatin C) Histone D) Nucleosome

Answer 34

B) Euchromatin Euchromatin appears lighter on a microscope and is less dense, however DNA is more accessible so euchromatin is more gene rich than heterochromatin

Question 35

Coupled transcription and translation means that... A) Transcription of an mRNA molecule starts before its translation is finished B) Translation of an mRNA molecule starts before its transcription is finished C) Prokaryotes have no nucleus D) RNA polymerase co-ordinates its action with ribosomes

Answer 35

B) Translation of an mRNA molecule starts before its transcription is finished

Question 36

A gene which codes for an enzyme that cleaves disaccharides is duplicated by unequal crossover. After many generations, mutations in the duplicated gene have changed it so that its product now phosphorylates monosaccharides. This is an example of... A) Pseudogenisation B) Subfunctionalisation C) Neofunctionalisation D) Gene dosage compensation

Answer 36

C) Neofunctionalisation This is when a duplicated gene obtains a new function

Question 37

How can we tell that a phenotype is sex-linked recessive and not autosomal recessive? A) The recessive phenotype can only be seen in females B) The recessive phenotype is mostly seen in males C) The recessive phenotype is not seen at all D) The recessive phenotype can be seen in both males and females

Answer 37

B) The recessive phenotype is mostly seen in males

Question 38

Which of these statements correctly describes an aspect of binding co-operativity. A) It is enabled by physical interactions between cis-regulatory elements B) It creates shallow gradients of gene expression C) It is properly displayed by some maternal effect genes D) It involves a single cis-regulatory element

Answer 38

C) It is properly displayed by some maternal effect genes We saw the example of Bicoid regulating the Hunchback gap gene

Question 40

A mutation altering the expression of another gene is best described with what term? A) Recessive B) Modifier C) Epistatic D) Suppressor

Answer 40

B) Modifier Epistatic would be a mutation that MASKS the effect of another Suppressor would REVERSE the effect of another A modifier could be dominant or recessive, not enough information is given here to determine which that is

Question 41

A DNA sequence has been mutated at a single base and this is transcribed to the mRNA. This results in a change in one amino acid. What is the name of the point mutation? A) Suppressor B) Missense C) Sense D) Nonsense

Answer 41

B) Missense Results in a change of base that changes the codon, which is now recognised by a different amino acyl-tRNA

Question 42

What is the function of the syneptonemal complex? A) Segregation of chromosomes B) Organise chromatin C) Associate homologous chromosomes D) Associate sister chromatids

Answer 42

C) Associate homologous chromosomes *A) Segregation of chromosomes is not caused by this *B) Condensin is responsible for organising chromatin *D) Cohesin keeps sister chromatids together

Question 43

A mutation near the start of an exon that creates a new genetic variant is expected to be the most deleterious if it is... A) An insertion of 2bp B) A deletion of 3bp C) An SNP from A to T D) An SNP from T to C

Answer 43

A) An insertion of 2bp Would cause a frameshift, which will most likely result in a non-functional protein

Question 44

In one population of humans, the number of individuals with AA, AB, and BB genotypes at one locus are 12, 20, and 18 respectively. What are the expected genotype frequencies for AA, AB, and BB at Hardy-Weinberg equilibrium? A) AA = 0.24, AB = 0.4, BB = 0.36 B) AA = 9.68, AB = 24.64, BB = 15.68 C) AA = 0.25, AB = 0.50, BB = 0.25 D) AA = 0.1936, AB = 0.4928, BB = 0.3136

Answer 44

D) AA = 0.1936, AB = 0.4928, BB = 0.3136 Working: 1) Calculate the frequencies of the A and B alleles p = (2x12+20)/(2x50) = 0.44 q = (2x18+20)/(2x50) = 0.56 2) Calculate expected frequencies: AA: p^2 = 0.1935 AB : 2pq = 0.4928 BB: q^2 = 0.3136

Question 45

How do assortative mating and inbreeding differ? A) Assortative mating leads to greater homozygosity and inbreeding does not B) Inbreeding leads to greater homozygosity and assortative mating does not C) They both lead to greater homozygosity but with inbreeding, only loci affecting specific phenotypes become more homozygous D) They both lead to greater homozygosity but with assortative mating, only loci affecting specific phenotypes become more homozygous

Answer 45

D) They both lead to greater homozygosity but with assortative mating, only loci affecting specific phenotypes become more homozygous

Question 46

You encounter a species of animal in which all individuals in the population are very similar in every feature (e.g. size, shape, colouration) with no externally discernible males or females. Which of the following is the most likely explanation for your observation. A) Sexual selection is operating entirely by pre-copulatory mechanisms B) Sexual selection is operating entirely by post-copulatory mechanisms C) Parental investment is reproduction in the organism you observed is likely to be equal D) Parental investment in reproduction in the organism you observed is likely to be unequal

Answer 46

C) Parental investment in reproduction is likely to be equal As the sexes are indistinguishable, sexual selection is unlikely to be involved - and parental investment is more likely to be equal

Question 47

Male seed beetles have an intromittent organ covered in barbs that damage the female reproductive tract during copulation, which ultimately results in lower female lifetime reproductive output. Which of the following is the most likely explanation of how a trait that lowers overall fitness persists? A) Females choose males based on the features of the intromittent organ, with more barbs being preferred B) The damage to the female's reproductive tract leads to the female investing more in the male's offspring, maximising his fitness C) The barb feature of the intromittent organ is influenced by a gene that also controls other positive traits D) Females permit the damage from mating to be able to reproduce for the benefit of the species

Answer 47

B) The damage to the female's reproductive tract leads to the female investing more in the male's offspring, maximising his fitness This is an example of sexual conflict that increases the males reproductive success, but damaging the female's reproductive tract so that she is not able to re-mate and invests more in his offspring in the current reproductive event

Question 48

In which situation would you expect the interacting parties NOT to co-operate? A) The individuals are closely related B) The individuals have a history of repeated social interactions C) An individual that provides assistance in the present will in turn be assisted in the future D) Individuals are unlikely to encounter each other again in the future

Answer 48

D) Individuals are unlikely to encounter each other again in the future Co-operation requires individuals to either be close kin or exist in groups or societies that permit regular and repeated contact amongst the individuals

Question 49

Which of the following do not contribute to the trade-off when organisms start reproducing for the first time? A) Offspring number and investment per offspring are in conflict B) There is a negative relationship between time and survival C) Smaller individuals can invest more in reproduction D) Offspring size increases the survival probability of those offspring

Answer 49

C) Smaller individuals can invest more in reproduction Whilst there is a relationship between size and fecundity, it is larger individuals that are able to invest more in reproduction

Question 50

The rapid diversification of flowering plant species is the result of... A) Mutualistic coevolution B) Escalation C) Parallel evolution D) Genetic drift

Answer 50

A) Mutualistic co-evolution Mutualistic coevolution of plants and pollinators/dispersers leads to rapid diversification through specificity of pollinators/dispersers with their respective plants

Question 51

Which of the following will NOT help in determining whether a trait is adaptive or not? A) Looking for associations between genetic and phenotypic variation B) Apply stabilising selection to the trait and measure the response C) Comparing the number of offspring in individuals with their trait values D) Considering alternative explanations to adaptation

Answer 51

B) Apply stabilising selection to the trait and measure the response There may be no response to stabilising selection even if there is heritable variation because average trait value of the population is often near its optimum

Question 51

When might a phylogeny reconstructed using UPGMA be incorrect? A) The principle of maximum parsimony is violated B) We have specified the wrong root C) We have assumed the wrong substitution model D) Rates of evolution vary drastically between taxa

Answer 51

D) Rates of evolution vary drastically between taxa Clustering approaches such as UPGMA can yield topologically incorrect phylogenies when the amount of evolutionary change differs between branches

Question 51

What is the 'pull of the present'? A) A speed-up in the recent past in the rate of lineage diversification inferred from a dated phylogeny B) The expected increase in the (log) number of lineages for a clade with non-zero extinction rate C) The artefactual upturn in the (log) number of lineages in the recent past if we include both extinct and extant taxa D) The effect of niche filing on the change of the (log) number of lineages in the recent past

Answer 51

B) The expected increase in the (log) number of lineages for a clade with non-zero extinction rate If a lineage through time plot were based on all the taxa that ever lived (including extinct taxa), the log number of lineages would be expected to increase exactly linearly (given a constant rate of net diversification) The 'pull of the present' is an expected feature of a lineage through time plot that is based on an observed phylogeny reconstructed only from surviving taxa If the extinction rate is non-zero, the number of taxa in an observed LTT will appear to increase, because a fraction of the number of taxa present at the time of sampling has not had time to go extinct

Question 52

What determines the steepness of a lineage through time plot, which measures the (log) number of species against time? A) The ratio of the speciation and extinction rate S/E B) The carrying capacity for the clade C) The difference between the rate of speciation and the rate of extinction (S-E) D) The amount of incomplete lineage sorting for the clade

Answer 52

C) The difference between the rate of speciation and the rate of extinction (gradient = S-E)

Question 52

How have most hybrid zones in Europe arisen? A) As a result of reinforcement between taxa that have evolved partial post-zygotic isolation B) Via secondary contact between taxa that have evolved partial barriers during periods of allopatry C) As a by-product of allopolyploid speciation D) As a consequence of strong divergent selection during interglacial periods

Answer 52

B) Via secondary contact between taxa that have evolved partial barriers during periods of allopatry Most hybrid zones in Europe formed when populations that were isolated in different ice age refugia during glacial maxima have gotten into secondary contact during interglacial periods

Question 52

Which of the following is an example of adaptive introgression? A) The alleles controlling insecticide resistance in the 'eat your stuff' beetle B) The haplotypes present in many non-African populations of modern humans for Toll like receptor genes C) The oncogene repressor in sword-tailed fish D) The large effect locus associated with diapause duration in Rhagoletis fruit flies

Answer 52

B) The haplotypes present in many non-African populations of modern humans for Toll like receptor genes Haplotypes for ToL like receptor genes that were introgressed from Neanderthals and Denisovans into some modern human populations in Europe and Asia are one of the very few clear examples of adaptive introgression into humans

Question 53

How do we know that humans lived at the same time as Neandertals? A) Humans look very similar to Neandertals except that our skulls are bigger B) We emerged out of Africa around the same time C) We are both descendants of Homo erectus D) There was introgression between our two species

Answer 53

D) There was introgression between our two species The amount and distribution of shared genetic material between humans and Neandertals suggests that there was interbreeding (introgression) occurring between the two species