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Define the term evolution.
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Define the term evolution.
Evolution refers to changes in the heritable characteristics of a population.
Define the term heritable.
The term heritable is used to describe features that can be passed from parents to offspring; heritable characteristics are controlled by genes.
Lamarck's theory of evolution states that populations evolve when are passed on to .
Lamarck's theory of evolution states that populations evolve when acquired characteristics are passed on to offspring.
What is the difference between Darwin's and Lamarck's theories of evolution?
The difference between Darwin's and Lamarck's theories is that Darwin describes the passing on of advantageous characteristics that exist from birth (i.e. features that are genetically determined) while Lamarck describes the passing on of advantageous characteristics that are acquired during an organism's lifetime.
True or False?
Advantageous characteristics that arise during an organism's lifetime cannot be described as evolution.
True.
Evolution involves changes in heritable characteristics, so cannot be acquired during an organism's lifetime.
Why is the theory of evolution unlikely to ever be falsified? (NOS)
The theory of evolution is unlikely to ever be falsified because it explains many scientific observations and is supported by many different types of evidence. Any new evidence that does not fit the existing theory may result in changes to the theory rather than falsification.
True or False?
The theory of evolution will eventually be formally proved. (NOS)
False.
The theory of evolution is not a mathematical formula that can be proved; the nature of the scientific method means that this type of proof is not possible in this instance.
The theory of evolution is considered to be empirically true on the basis of observation and measurement, and is not awaiting more evidence before it is scientifically accepted.
What are three sources of sequence data?
Sources of sequence data include:
DNA
RNA
proteins
Define the term common ancestor.
A common ancestor is an ancestral individual from which two or more individuals descend, e.g. the common ancestor of two cousins would be their grandparents. The term can also be used to describe an ancestral species.
What does a high similarity in DNA base sequences between species indicate?
A high similarity in DNA base sequences between species indicates that they are close evolutionary relatives that share a recent common ancestor.
True or False?
Comparing the sequences of proteins that are present in many different species can yield useful information about evolutionary relationships.
True.
Comparing amino acid sequences of proteins that are present in many species allows the evolutionary relationships between all of the many species to be studied.
Studying a protein that is unique to a few species will only allow assessment of the relationship between those few species.
Define the term selective breeding.
Selective breeding is the process during which humans choose organisms with desirable characteristics and breed them together repeatedly to increase the expression of these characteristics over many generations.
What is the difference between natural selection and selective breeding?
The difference between natural selection and selective breeding is that:
in selective breeding humans decide which characteristics are desirable and which individuals will breed
in natural selection survival and reproduction are determined by environmental factors
How does selective breeding in domestic animals and crop varieties provide evidence for evolution?
Selective breeding in domestic animals and crop varieties provides evidence for evolution because of the variation that is generated by this process. This variation arises due to the accumulation of genetic differences, just as heritable changes occur in natural selection.
Define the term homologous structure.
Homologous structures are body parts that look and function differently but that share structural similarities. The presence of such structures indicates common ancestry.
True or False?
The human foot, whale flippers and bird wings are examples of pentadactyl limbs.
True.
The human foot, whale flippers, and bird wings are examples of pentadactyl limbs.
How does the pentadactyl limb provide evidence for evolution?
The pentadactyl limb provides evidence for evolution because it is a homologous structure that often differs in form and function but that is structurally similar across species; this indicates that all of these species evolved from a common ancestor.
What is an analogous structure?
Analogous structures are characteristics with similar form and function, but with different evolutionary origins.
What is convergent evolution?
Convergent evolution is the process by which distantly related species independently evolve similar traits as a result of adapting to similar environments or ecological niches.
What causes convergent evolution to occur?
Convergent evolution occurs when two distantly related species live in habitats with similar selection pressures, leading to the passing on of similar advantageous characteristics.
True or False?
Analogous structures provide evidence of shared ancestry.
False.
Analogous structures indicate that two species have evolved in response to similar selection pressures and do not indicate recent shared ancestry.
It is homologous structures that indicate shared ancestry.
True or False?
The presence of streamlined shape in dolphins (a mammal) and sharks (a fish) is an example of convergent evolution.
True.
Dolphins and sharks are both aquatic animals that have evolved to move efficiently in water. Their similarity in body shape does not indicate shared recent common ancestry.
Define the term speciation.
Speciation is the development of new species that occurs when a pre-existing species is split.
True or False?
Speciation increases diversity.
True.
Speciation gives rise to new species, so increases diversity.
True or False?
The splitting of pre-existing species is one of several ways in which new species arise.
False.
The splitting of pre-existing species during speciation is the only way that new species arise.
How does extinction affect biodiversity?
Extinction reduces biodiversity by decreasing the number of species on Earth.
True or False?
Speciation can occur when a species undergoes gradual evolutionary change over time.
False.
Speciation does not occur due to gradual change in a species over time, but only when a split in the pre-existing species occurs.
Define the term reproductive isolation.
Reproductive isolation occurs when two populations are so different from each other that they cannot breed together to produce fertile offspring. Once this point has been reached speciation is said to have occurred.
What is an example of geographical isolation?
Examples of geographical isolation include populations separated by:
ocean
rivers
mountain ranges
desert
True or False?
Geographical isolation can lead to reproductive isolation.
True.
Geographical isolation can lead to reproductive isolation when differential selection occurs on either side of a geographical barrier.
What is differential selection?
Differential selection occurs when different selection pressures act on geographically isolated populations, leading to different evolutionary paths.
What led to the speciation of bonobos and chimpanzees?
Speciation led to the evolution of bonobos and chimpanzees when the Congo River caused geographical isolation, leading to differential selection and eventually speciation of bonobos and chimpanzees.
Define allopatric speciation.
Allopatric speciation is the formation of new species that occurs when populations of a species become separated by geographical barriers, preventing gene flow between them.
Define sympatric speciation.
Sympatric speciation occurs when two groups of the same species become reproductively isolated due to random changes in the alleles, and therefore phenotypes, of some individuals in a population. This can prevent them from successfully breeding with other individuals in the population. The lack of gene flow leads to speciation over time.
True or False?
Sympatric speciation requires geographical barriers.
False.
Sympatric speciation occurs without geographical barriers and instead happens when random changes in alleles prevent individuals from breeding with others in the same area.
What is a hybrid?
A hybrid is the offspring produced from the mating of individuals from two different species.
Define temporal isolation.
Temporal isolation is when populations develop different mating or flowering seasons, preventing them from breeding with each other due to mismatched reproductive timing.
True or False?
Mules are fertile hybrids.
False.
Mules are infertile hybrids because they inherit an odd number of chromosomes which prevents them from carrying out meiosis.
What is behavioural isolation?
Behavioural isolation is when changes in courtship behaviours prevent individuals from successfully attracting mates, leading to reproductive isolation.
Define gene flow.
Gene flow is the transfer of genetic material between populations through successful breeding and reproduction.
State the meaning of courtship behaviour.
Courtship behaviour is a ritual preceding successful breeding that involves visual, chemical, or auditory stimuli to facilitate mating and reproduction between individuals.
What is adaptive radiation?
Adaptive radiation is the rapid evolution of multiple different species from a common ancestor through natural selection.
True or False?
Species that arise through adaptive radiation have no similar features.
False.
Species that arise through adaptive radiation are likely to have some similar features due to their shared ancestry.
What is an ecological niche?
An ecological niche is an organism's role within its ecosystem, including the food it eats, its environmental requirements, and its position in food chains.
Why can species formed through adaptive radiation often live together in one habitat?
Species formed through adaptive radiation can often live together in one habitat because they evolve to fill different ecological niches.
True or False.
Charles Darwin observed several species of finch that showed distinct differences in beak shape, size and function. Darwin's finches provide a real example of adaptive radiation.
True.
Darwin's finches demonstrate adaptive radiation as several species of finch evolved from a common ancestor to fill different niches.
What is polyploidy?
Polyploidy is a condition where cells have more than two sets of chromosomes.
True or False?
Non-disjunction in meiosis can result in polyploidy.
Chromosome nondisjunction is the failure of chromosomes to separate correctly during meiosis. If gametes that have a nondisjunction mutation, fuse together, this can lead to polyploidy.
True or False?
Triploid (3n) plants are typically fertile.
False.
Triploid (3n) plants are typically infertile.
What is the chromosome number of a tetraploid organism?
A tetraploid organism has four sets of chromosomes (4n).
State three advantages of polyploidy in plants.
Three advantages of polyploidy in plants are:
allowing otherwise infertile hybrids to carry out meiosis
producing larger and more vigorous plants
reducing the impact of harmful mutations through multiple gene copies
True or False?
Knotweed is an example of a diploid plant species.
False.
Knotweed is a genus with many examples of species with polyploidy.
Why can't 4n individuals breed successfully with 2n individuals?
4n individuals can't breed successfully with 2n individuals because their fusion would produce infertile 3n offspring, as 2n gametes from 4n plants would fuse with n gametes from 2n plants.