Deck 34: Mechanisms of Evolution

Question 1

Which of the following is NOT consistent with the theory of natural selection?

A) Genetic variations can be inherited.
B) Successful competitors have more offspring.
C) The number of descendants inheriting an adaptation is a matter of chance.
D) Organisms with a trait that improves survival soon outnumber those that do not have this trait.
E) The reproductive capacity of organisms is greater than the number of offspring that survive.

Answer 1

The number of descendants inheriting an adaptation is a matter of chance.

Question 2

In adaptive evolution, selection

A) always leads to greater complexity.
B) increases the variation in populations.
C) causes the inheritance of acquired characters.
D) changes the frequencies of alleles in populations.
E) depends on the environment.

Answer 2

changes the frequencies of alleles in populations.

Question 3

Which of the following traits would be inherited by the organism's offspring?

A) A kangaroo is born with more acute hearing than others in its cohort.
B) A fish embryo exposed to a harmful drug early in development grows into an adult with stunted fins.
C) A tree has a twisted growth habit in a high-wind area.
D) An adult horse exposed to radiation has a mutation causing a pigmentation spot on its flank.
E) A flower growing in rich soil produces many brightly coloured flowers.

Answer 3

A kangaroo is born with more acute hearing than others in its cohort.

Question 4

Jean-Baptiste Lamarck published the first modern theory of evolution. He theorised that

A) natural selection allowed the inheritance of adaptive characteristics.
B) traits acquired during the lifetime of an organism are inherited by subsequent generations.
C) mutation provides the variation that allows evolution.
D) divergence of inherited characteristics occurs after the isolation of populations.
E) natural selection was due to environmental changes.

Question 5

The ultimate source of all genetic variation is

A) natural selection.
B) the environment.
C) mutation.
D) sexual recombination.
E) All of these answers contribute equally to genetic variation.

Question 6

Most genetic variation in populations results from

A) mutation.
B) polyploidy.
C) natural selection.
D) environmental pressure.
E) recombination of existing alleles.

Question 7

Mutations that have no effect on fitness

A) are advantageous.
B) will vary in frequency due to genetic drift.
C) usually become established in the population.
D) are always in the third position of a codon.
E) are selected for by environmental conditions.

Question 8

A population in Hardy-Weinberg equilibrium has the possible genotypes AA, Aa and aa. If the frequency of the A allele is 50 per cent in one generation, then the frequency of aa homozygotes in the next generation will be

A) 0.25.
B) 0.33
C) 0.5.
D) 0.75.
E) 1.

Question 9

The MN blood group in humans is controlled by two codominant alleles, LM and LN. Individuals with blood types M and N are homozygous, while heterozygous individuals are blood type MN. If, in an isolated population, the probability of carrying the LM allele is 0.3, what is the probability of carrying the LN allele?

A) 0.1
B) 0.3
C) 0.5
D) 0.7
E) 0.9

Question 10

In a population in Hardy-Weinberg equilibrium, one in a hundred people have the inherited ability to curl their tongue downwards in a particular fashion. If this trait is the recessive phenotype, what percentage of the population in the next generation is likely to be carriers of this allele, although unable to curl their tongues downwards?

A) 2 per cent
B) 10 per cent
C) 18 per cent
D) 90 per cent
E) 98 per cent

Question 11

A small population of wallabies lives on an island that was once connected to the mainland. Over many generations, several alleles have completely disappeared from the island population, although they are still present on the mainland. These alleles have probably disappeared due to

A) genetic drift.
B) a high rate of mutation.
C) non-random mating.
D) environmental conditions.
E) gene flow.

Question 12

A small population of wallabies lives on an island that was once connected to the mainland. Over many generations, several alleles have completely disappeared from the island population, although they are still present on the mainland. If the gene locus we were investigating contributed to the wallabies' efficient use of a particular food resource, the alleles may have disappeared from the island population due to

A) migration.
B) selection.
C) mutation.
D) inbreeding.
E) assortative mating.

Question 13

Most marine turtles in a small population have six large scales down the centre of their carapace; however, in each generation, a few have seven. Every year, females of a population of marine turtles come ashore to lay their eggs on a small coral atoll. Some turtles bury their eggs in 'nests' that they dig in the sand, just above the high-tide mark, while others dig their nests further inland. The females return to the sea immediately after burying their eggs and the eggs incubate in the sand for about 8 weeks. In one season, heavy seas accompanying a cyclone destroy 85 per cent of all turtle nests on the island. Some years later it is observed that very few turtles lay their eggs just above the high-tide mark; most lay their eggs well inland. It is also observed that the majority of the nesting females have seven central carapace scales.
The change in carapace morphology of the population is most likely the result of

A) natural selection.
B) neutral selection.
C) genetic drift.
D) environmental adaptation.
E) Based on this information, it is impossible to say.

Question 14

A seabird living on a small island is born with a mutation that gives it a coloured patch on the top of its head. The mutation is dominant and appears to be neutral. Over the next twenty generations, the frequency of the 'head patch' allele should

A) increase.
B) decrease.
C) remain the same.
D) disappear.
E) Based on this information, it is impossible to predict.

Question 15

Persistent use of a drug against disease-causing bacteria can result in populations that are resistant to the drug. Which of the following is the best explanation for the appearance of these drug-resistant bacterial strains?

A) The bacteria learn to excrete the drug so that they are not affected by it.
B) The drug increases the rate of cell division until the bacteria are reproducing faster than they are being killed.
C) The drug causes a mutation that confers resistance.
D) The bacteria produce membrane proteins which prevent the drug from entering the cell.
E) Drug-resistant bacteria already exist within the population. Application of the drug kills the non-resistant bacteria, so that only resistant bacteria survive to contribute to the gene pool of subsequent generations.

Question 16

Using 'Insecticide A' to control insect pests can lead to selection for alleles that convey resistance. Agricultural scientists have discovered that the development of resistance, in a population of insect pests, can be hindered by rotating the use of 'Insecticide A' with other pesticides. A reasonable explanation for the effectiveness of this strategy is that

A) alleles for resistance to 'Insecticide A' are disadvantageous in the absence of 'Insecticide A'.
B) the other pesticides induce the resistant allele to mutate into a non-resistant form'.
C) resistance is an acquired adaptation, not transmitted to offspring.
D) it prevents an increase in the frequency of the resistant allele due to genetic drift.
E) resistance acquired to one insecticide may not provide resistance to a different insecticide.

Question 17

In a chorus of male frogs of one species, which would be considered by evolutionary biologists to be the fittest?

A) The frog that attracts the most females.
B) The biggest frog.
C) The frog that has the most descendants.
D) The frog with the largest territory.
E) The loudest frog.

Question 18

Which of the following species concepts cannot distinguish among species of lizards that reproduce solely by parthenogenesis?

A) The cohesion species concept.
B) The morphological species concept.
C) The evolutionary species concept.
D) The biological species concept.
E) The taxonomic species concept.

Question 19

Two species of yabbies inhabit the same mountain creek. They are morphologically indistinguishable but can be split into two groups according to presence or absence of a number of genetic markers in their mitochondrial DNA. When yabbies from the two groups interbreed, they produce healthy but infertile offspring. These two groups are classified as distinct species according to

A) the taxonomic species concept.
B) the evolutionary species concept.
C) the recognition species concept.
D) the biological species concept.
E) All of the species concepts are correct.

Question 20

Which of the following reproductive isolating mechanisms acts after fertilisation?

A) Mechanical.
B) Hybrid breakdown.
C) Temporal.
D) Ethological.
E) Ecological.

Question 21

Two closely related orchid species inhabit the same region of rainforest and have mature pollen at the same time. Both orchids are pollinated by wasps, and in the same manner. The flower of the orchid mimics the shape of a female wasp and releases a chemical scent that imitates the pheromone of a female wasp. Male wasps are attracted by the pheromone and, while attempting to mate with the flower, are doused with pollen that they will deposit on another orchid flower the next time they are similarly deceived. However, one orchid species imitates, and is pollinated by, one species of wasp and the other orchid species imitates, and is pollinated by, a different species of wasp. The male wasps are very particular in their preferences and are never attracted to the 'wrong' orchid.
Which of the following types of reproductive barrier separates the two orchid species?

A) Ethological isolation
B) Gametic isolation
C) Temporal isolation
D) Mechanical isolation
E) Ecological isolation

Question 22

Postzygotic reproductive isolating mechanisms act

A) before fertilisation.
B) before mating.
C) after mating but before fertilisation.
D) to produce non-viable zygotes.
E) after fertilisation.

Question 23

A river takes a new path and divides a species of skinks into two isolated populations. Climate changes gradually cause the river to dry up, bringing the two populations together again, but when individuals of the two populations mate, the resulting hybrids are sterile. This is an example of

A) sympatric speciation.
B) allopolyploid speciation.
C) allopatric speciation.
D) parapatric speciation.
E) reproductive speciation.

Question 24

X and Y are two species of grasses, each with a diploid number of 20. A new sexually reproducing species, Z, arises as a polyploid following hybridisation between X and Y. The diploid number of Z would be

A) 20.
B) 30.
C) 40.
D) 60.
E) 80.

Question 25

A particular species of frog has a broad geographic distribution across southern Australia. In the breeding season, males congregate at marshy areas and call to attract females. Young frogs do not disperse widely from their natal marsh. Through time, the mating call of male frogs in the north-western region of the distribution gradually diverges from the 'normal' call, until females from the rest of the species range no longer recognise and respond to the call. Similarly, females from the north-western region no longer recognise male frogs from other parts of the species distribution as potential mates. This would be considered an example of

A) allopatric speciation.
B) sympatric speciation.
C) parapatric speciation.
D) either sympatric or parapatric speciation.
E) both allopatric speciation and parapatric speciation.

Question 26

Sympatric speciation

A) is defined as the formation of polyploids.
B) involves geographic barriers to migration and gene flow.
C) occurs without geographic separation of populations.
D) results from secondary contact between populations.
E) describes the interaction between populations which exist in adjacent areas.

Question 27

Gene duplications

A) arise due to the duplication of the chromosome set.
B) result in orthologous genes.
C) allow mutations to accumulate in one copy of the gene.
D) are detrimental.
E) result in the loss of viable offspring.

Question 28

Evolutionary trees constructed from gene sequences

A) may allow us to determine the evolutionary history of species.
B) reveal information about the history of the gene itself.
C) can be used in conjunction with trees constructed from morphological characters.
D) demonstrate the relatedness of species.
E) All of the answers are correct.

Question 29

Adaptation

A) results from mutation in individual organisms.
B) is the increased production of offspring in each generation.
C) occurs when a trait increases the fitness of an organism in a particular environment.
D) results from genetic variation in the population.
E) All of the answers are correct.

Question 30

Sickle cell anaemia is a debilitating disease caused by a mutation in a haemoglobin gene. Homozygotes for this allele have decreased fitness and suffer haemolytic anaemia. However, the allele occurs at high frequencies in some populations because

A) heterozygotes for the mutant allele have the same fitness as homozygotes for the normal allele.
B) homozygotes for this allele have a high reproductive capacity.
C) selection does not act to reduce this allele as haemolytic anaemia is not a problem in some populations.
D) heterozygotes for this allele have increased resistance to malaria than homozygotes with the normal allele.
E) there is very little difference in fitness between people with the mutant allele and those with the normal allele.

Question 31

The Hardy-Weinberg principle states that

A) the phenotypic properties of an ideal population tend to change with natural selection.
B) the phenotypic properties of an ideal population tend to remain in equilibrium proportions.
C) an ideal population is one in which there is no mutation in their DNA.
D) equilibrium in the phenotypic properties of a population will occur after many generations.
E) the probability of a specific allele occurring in offspring is dependent on the whole population.

Question 32

Mutation

A) is consistent with the Hardy-Weinberg's ideal population.
B) occurs at high frequency in genomic DNA.
C) significantly shifts the Hardy-Weinberg population from equilibrium.
D) is the basis of the Hardy-Weinberg principle.
E) is essential for the generation of genetic variation.

Question 33

Cryptic species are

A) species in which mating produces sterile offspring.
B) morphologically similar but cannot interbreed.
C) species where males from one species may fertilise females from the other species, but the reverse cannot occur.
D) organisms in which differences in phenotype are inheritable.
E) species which occur in a hybrid zone.

Question 34

The biological species concept defines species as potentially interbreeding populations. One complication of such a definition is that

A) it cannot determine if the offspring may be sterile.
B) it does not account for the reproductive differences between species.
C) different species always look different.
D) it cannot be applied to organisms that reproduce asexually.
E) it does not account for the relatedness of species which are able to mate.

Question 35

Speciation involves all of the following, EXCEPT

A) physical isolation.
B) ecological isolation.
C) temporal isolation.
D) geographical isolation.
E) polyploidy.

Question 36

Most random mutations

A) are slightly advantageous.
B) are benign.
C) are very advantageous.
D) are passed on to progeny.
E) reduce the fitness of an individual.

Question 37

A individual has a spontaneous single nucleotide polymorphism within an intron region of a transcriptional regulator. Such a mutation is likely to

A) be advantageous.
B) be deleterious.
C) result in an altered transcript.
D) be neither advantageous not deleterious.
E) be inherited and increase or decrease in populations in a predictable fashion.

Question 38

Two genes are shown to be close together on the same chromosome. In regard to recombination, these two genes would be

A) independently assorted.
B) readily amenable to crossing over.
C) shuffled.
D) linked.
E) localised loci.

Question 39

Whether alleles increase, decrease or remain constant in a population is dependent on

A) the level of expression of those alleles.
B) the biology of organisms and their interaction with their environment.
C) the extent to which an environment changes.
D) the species of the organism.
E) allelic copy number and/or degree of replication.

Question 40

A geneticist is studying the prevalence of two alleles in a small, isolated population. He finds that many individuals are heterozygous and that across several generations there is little change in allelic frequency. The most likely reason for this result is

A) there is a high degree of genetic drift.
B) the population has been isolated for an extended period of time.
C) the population is 'fixed' for one allele.
D) the population is not actually isolated and is outcrossing with one or more larger populations of the same species.
E) assortative mating is occurring.

Question 41

In sexual selection, why do males often compete for female reproductive resources?

A) Because males often have extravagant displays such as dancing and plumage
B) Because males are more physically capable of acts of physical contest
C) Because female reproductive structures are invaginated
D) Because spermatozoa are motile
E) Because oocytes tend to be fewer in number than spermatocytes

Question 42

According to the biological species concept, the study of speciation is equivalent to

A) the study of gene flow between non-diverging lineages.
B) the study of the evolution of reproductive isolating barriers.
C) the study of heritable phenotypic traits by exchanging alleles.
D) the study of characteristic differences in heritable genotypes.
E) the study of preferential sexual selection in a non-randomly mating population.

Question 43

A tropical palm tree population is identified on an isolated atoll that appears to be Areca triandra. However, they are much shorter than other members of this species and have a broader stem. Scientists speculate that this morphology is due to sea spray stunting the trees growth. If controlled experiments reveal this is NOT the case, what does this suggest?

A) That the population is isolated
B) All the options listed here are correct
C) No outcrossing is occurring
D) That the morphological differences have a genetic basis
E) The morphological difference are not plastic

Question 44

Which of the following is NOT a barrier that can prevent gene flow between populations?

A) Temporal isolation
B) Spatial isolation
C) Physical isolation
D) Fractional isolation
E) Ecological isolation