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.

Accepted Answer

The theory of natural selection posits that traits conferring a survival or reproductive advantage are more likely to be passed on to subsequent generations, not by chance but due to their beneficial effects on the organism's fitness.

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.

Accepted Answer

D

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.

Accepted Answer

The trait in choice A is genetic and can be passed on to offspring, as it is a natural variation in hearing ability. Other choices involve environmental effects or acquired traits that are not inherited.

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.

Accepted Answer

Jean-Baptiste Lamarck is best known for his theory that traits acquired during the lifetime of an organism (such as muscles developed from regular use or characteristics adapted to a particular environment) could be inherited by its offspring. This concept, often summarized as "use and disuse," was one of the early attempts to explain how species change over time, predating Darwin's theory of evolution by natural selection.

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.

Accepted Answer

Mutation is the ultimate source of all genetic variation because it introduces new genetic information into a population by altering DNA sequences. Natural selection, the environment, and sexual recombination can all influence how genetic variation is distributed and maintained within a population, but they do not create new genetic information themselves.

Question 6

Most genetic variation in populations results from
A) mutation.
B) polyploidy.
C) natural selection.
D) environmental pressure.
E) recombination of existing alleles.

Accepted Answer

Recombination of existing alleles during sexual reproduction creates new combinations of genes, leading to genetic variation in populations.

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.

Accepted Answer

Mutations that have no effect on fitness are neutral and can vary in frequency within a population due to genetic drift, a mechanism of evolution that involves random changes in allele frequencies.

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.

Accepted Answer

In Hardy-Weinberg equilibrium, the frequency of alleles in the population remains constant from one generation to the next. If the frequency of the A allele is 50% (or 0.5), then the frequency of the a allele is also 50% (or 0.5). The frequency of aa homozygotes can be calculated using the equation p^2 + 2pq + q^2 = 1, where p is the frequency of one allele (A), q is the frequency of the other allele (a), p^2 is the frequency of AA, 2pq is the frequency of Aa, and q^2 is the frequency of aa. Therefore, the frequency of aa homozygotes is q^2 = 0.5^2 = 0.25.

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

Accepted Answer

The probability of carrying the LN allele is 1 - the probability of carrying the LM allele, which is 1 - 0.3 = 0.7.

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

Accepted Answer

Given that the ability to curl the tongue downwards is a recessive trait, let's denote the recessive allele as "a" and the dominant allele as "A". If 1 in 100 people can curl their tongues downwards, this means that the frequency of the homozygous recessive genotype (aa) is 0.01 (or 1%). According to the Hardy-Weinberg principle, the frequency of the recessive allele "a" can be found by taking the square root of the frequency of the homozygous recessive genotype, which is √0.01 = 0.1 or 10%. The frequency of the dominant allele "A" would then be 1 - 0.1 = 0.9 or 90%. The frequency of carriers (heterozygous genotype Aa) can be calculated as 2pq, where p is the frequency of the dominant allele and q is the frequency of the recessive allele. Substituting the values, we get 2 * 0.9 * 0.1 = 0.18 or 18%. Therefore, 18% of the population is likely to be carriers of the allele but unable to curl their tongues downwards.

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.

Accepted Answer

Genetic drift is a mechanism of evolution that refers to random changes in the frequency of alleles in a small population. In the scenario described, the disappearance of alleles from the island population of wallabies, which is isolated and presumably small, is most likely due to genetic drift. This process can lead to the loss of alleles over time, especially in small, isolated populations where the effects of random events can have a larger impact on allele frequencies.

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.

Accepted Answer

The disappearance of alleles from the island population of wallabies, especially if those alleles were related to the efficient use of a particular food resource, is most likely due to selection. Natural selection would favor individuals with alleles that are advantageous in the island's specific environment, leading to the disappearance of less advantageous alleles over time.

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.

Accepted Answer

The answer of Most marine turtles in a small population...

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.

Accepted Answer

Since the mutation is described as neutral, it does not confer any selective advantage or disadvantage to the seabirds. Therefore, its frequency in the population over time is subject to genetic drift and other evolutionary forces, making it impossible to predict without more specific information about the population size, mating patterns, and other ecological or genetic factors.

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.

Accepted Answer

Drug-resistant bacteria often pre-exist within a population. When a drug is applied, it selectively kills the non-resistant individuals, allowing the resistant ones to survive and reproduce, thereby increasing their proportion in the population over time. This process is an example of natural selection.

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.

Accepted Answer

The answer of Using 'Insecticide A' to control insect pests...

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.

Accepted Answer

The fittest individual, in evolutionary terms, is the one that leaves the most descendants, as this indicates successful reproduction and passing on of genes to the next generation.

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.

Accepted Answer

The biological species concept defines species based on the ability to interbreed and produce fertile offspring. Since parthenogenetic lizards reproduce asexually, this concept cannot be used to distinguish between different species of such lizards.

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.

Accepted Answer

The answer of Two species of yabbies inhabit the same...

Question 20

Which of the following reproductive isolating mechanisms acts after fertilisation?
A) Mechanical.
B) Hybrid breakdown.
C) Temporal.
D) Ethological.
E) Ecological.

Accepted Answer

Hybrid breakdown is a postzygotic barrier where hybrid offspring of two different species may be fertile but when they mate, the next generation is often sterile or inviable. This occurs after fertilization, distinguishing it from prezygotic barriers like mechanical, temporal, ethological, and ecological isolation mechanisms.

Quiz 34: Mechanisms of Evolution

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

In adaptive evolution, selection

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

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

The ultimate source of all genetic variation is

Most genetic variation in populations results from

Mutations that have no effect on fitness

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 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 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

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?

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

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

Which of the following reproductive isolating mechanisms acts after fertilisation?