Unit 10 - Classification and Evolution Flashcards
Define classification.
Classification = the process of sorting living organisms into groups
What is classification used for?
- identifying species
- predicting characteristics of species
- finding evolutionary links between species
Define binomial nomenclature.
Binomial nomenclature = Scientific naming of a species using the genus and the species
Define domain.
Domain = highest taxonomic rank in the hierarchical classification system
Define kingdom.
Kingdom = second highest taxonomic rank in the hierarchical classification system
Define species.
Species = organisms which can reproduce to produce fertile offspring, lowest taxonomic rank in the hierarchical classification system
Define prokaryotic.
Prokaryotic = organisms with no membrane-bound organelles
Define eukaryotic.
Eukaryotic = organisms which contain membrane-bound organelles
Define autotrophic.
Autotrophic = an organism which can produce its own food from light, water, carbon dioxide or other chemicals
Define heterotrophic.
Heterotrophic = an organism which eats other organisms for energy and nutrients
Define saprotrophic.
Saprotrophic = an organism which eats non-living organic matter (detritus) at a microscopic level
Who first suggested binomial nomenclature and the hierarchical classification system?
Carl Linnaeus.
Who proposed the protoctista kingdom in addition to animal and plant kingdoms?
Ernst Haeckel.
Who proposed the five kingdom classification system?
Robert Whittaker.
Who proposed the three domain classification system?
Carl Woese.
What are the seven taxonomic groups in the Linnaean classification system?
Kingdom
Phylum
Class
Order
Family
Genus
Species
What are the five kingdoms in the older classification system?
Prokaryotae
Protoctista
Fungi
Plantae
Animalia
What are the features of organisms in the Prokaryotae kingdom?
- Unicellular
- No nucleus or membrane-bound organelles
- Have a single circular chromosome
- Most have a peptidoglycan/murein cell wall which may be associated with a slime layer/capsule
70s ribosomes - No visible feeding mechanism - nutrients are absorbed through the cell wall or produced internally by photosynthesis
- Reproduce by binary fission
What are the features of organisms in the Protoctista kingdom?
- Mainly unicellular
- Have a nucleus and membrane-bound organelles
- Some have chloroplasts
- Some are sessile
- Some move by cilia, flagella or amoeboid mechanisms
- Either autotrophic, heterotrophic or both - some are parasitic
What are the features of organisms in the Fungi kingdom?
- Can be unicellular or multicellular
- Have a nucleus and membrane-bound organelles
- Have a chitin cell wall
- No chloroplasts
- No mechanisms for locomotion
- Most have a body or mycelium made of threads or hyphae
- Saprophytic feeders - some are parasitic
- Most store food as glycogen
What are the features of organisms in the Plantae kingdom?
- Multicellular
- Have a nucleus and membrane-bound organelles, including chloroplasts
- Have a cellulose cell wall
- Most do not move
- Gametes of some plants move using cilia or flagella
- Autotrophic feeders
- Store food as starch
What are the features of organisms in the Animalia kingdom?
- Multicellular
- Have a nucleus and membrane-bound organelles
- No cell wall
- No chloroplasts
- Move using cilia, flagella or contractile proteins, sometimes in the form of muscular organs
- Heterotrophic feeders
- Store food as glycogen
What are the three domains proposed by Woese?
Archaea
Bacteria
Eukarya
What are the features of Archaea?
- 70s ribosomes
- RNA polymerase contains 8-10 proteins
What are the features of Bacteria?
- 70s ribosomes
- RNA polymerase contains 5 proteins
What are the features of Eukarya?
- 80s ribosomes
- RNA polymerase contains 12 proteins
What did Woese divide the Prokaryotae kingdom into?
Archaebacteria and Eubacteria.
What is the difference between Archaebacteria and Eubacteria?
Archaebacteria are known as ancient bacteria, while Eubacteria are known as true bacteria. Eubacteria are found in all environments, whereas Archaebacteria are more likely to be found in environments with extreme conditions.
Define phylogeny.
Phylogeny is the study of the evolutionary relationships between organisms, which shows which organisms are related and how closely related they are.
Define phylogenetic trees.
Phylogenetic or evolutionary trees are branched diagrams representing evolutionary relationships between organisms and showing how different species evolved from a common ancestor.
What are the advantages of phylogeny?
- Phylogeny can be done without reference to Linnaean classification, which is a confusing system because it implies that different groups in each rank are equivalent - e.g. cats and orchids are both families, but orchids have existed far longer than cats
- Unlike the hierarchical system, phylogeny produces a continuous tree - the lack of discrete taxonomic groups means that organisms are not placed into groups they do not fit into
When did Darwin publish his Theory of Evolution by Natural Selection?
Darwin’s theory was originally published with Wallace in 1858, and his book On the Origin of Species, which popularised the theory, was published in 1859.
What were the four key observations that Darwin made about the world?
- Offspring generally appear similar to their parents
- No two individuals are identical
- Organisms have the ability to produce large numbers of offspring
- Populations in nature tend to remain fairly stable in size
Define phenotype.
Phenotype = the observable characteristics of an organism, determined by the organism’s genes and by their environment
Name the environmental factors that cause selection pressure.
- resource availability
- environment
- biological factors
What is natural selection?
The process whereby organisms better adapted to their environment will survive to produce more offspring.
How do advantageous alleles increase in proportion in a population?
The individuals with those alleles will usually survive and produce more offspring, passing the alleles on.
What is a gene?
A unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring.
What did Alfred Russel Wallace come up with?
Wallace had independently created his own theory of evolution. As his theory was similar to Darwin’s, the two theories were published as a joint paper.
How did Darwin and Wallace agree?
- Both believed in natural selection
- Their conclusions on how natural selection causes evolution were the same
How did Darwin and Wallace disagree?
- Darwin thought selection acted on individuals while Wallace thought it acted on groups or species
- Darwin emphasised competition within populations as the driving force for evolution, whereas Wallace put more emphasis on the species meeting the demands of a change in their environment
- Darwin also explained evolution through sexual selection, which Wallace disregarded
Why is Darwin better remembered for the Theory of Evolution by Natural Selection than Wallace?
- Darwin’s book On the Origin of Species popularised the theory
- He was the first to present evidence for the theory
- His version of the theory contains more individual theories than natural selection, like sexual selection
What are fossils?
The remains or impression or a prehistoric plant or animal embedded in rock and preserved in petrified form.
What fossil example is often used to support evolution?
The horse.
How is the fossil record used to support evolution?
- Simple fossils are found in older rocks than fossils of complex organisms
- The sequence in which fossils are found matches the organisms’ ecological links to each other
- By studying similarities in the anatomy of fossils, scientists can show how closely related organisms have evolved from the same ancestor
- Fossils allow relationships between extinct and extant organisms to be investigated
What is a common ancestor?
An ancestral organism shared by two or more descendent lineages.
Explain how DNA evidence is used to support evolution.
Scientists research slight changes occurring in cytochrome C and rRNA. To find out how closely two species are related, the molecular sequence of a molecule is compared. Species that are closely related have the most similar DNA. rRNA is often used because it has a very slow rate of substitution.
How would DNA compare between two organisms with a recent common ancestor?
The DNA would be very similar.
How would DNA compare between two organisms with an ancient common ancestor?
The DNA would be quite different.
Explain the differences between DNA of closely related organisms and DNA of distantly related organisms.
Organisms that are distantly related have had more time since they shared a common ancestor, so mutations have accumulated in their DNA, while more closely related organisms haven’t had time for enough mutations to occur to make their DNA sequences significantly different.
Define variation.
Variation = differences in characteristics between organisms
Define interspecific variation.
Variation between individuals of different species.
Define intraspecific variation.
Variation between individuals of the same species.
What are the different causes of variation?
Genetic causes or environmental causes. Most characteristics are caused by a combination of genetics and environmental factors.
What are the causes of genetic variation?
Mutations - sudden changes in DNA
Fusion of gametes at fertilisation - the offspring will inherit characteristics from both parents and which genes are inherited differs as gamete fusion is random
Meiosis - crossing over and independent assortment lead to variation
Alleles - no organisms will have the same alleles/gene variants
Why will organisms which reproduce sexually have greater variation than organisms which reproduce asexually?
Asexual reproduction produces clones, which have exactly the same genetic material as the parent, so genetic information in those organisms can only be increased through mutations.
Define continuous variation.
Where there are two extremes and a full range of intermediate values. Most individuals are close to the mean and the number of individuals at the extremes is low.
How is continuous variation usually caused?
Continuous variation is usually regulated by multiple genes and can be influenced by the environment in which an organism lives.
Define discontinuous variation.
Where there are two or more distinct categories with no intermediate values. The members of a species may be evenly distributed between the different forms, or there may be more of one type than the other.
How is discontinuous variation usually caused?
Discontinuous variation is usually regulated by a single gene and is not influenced by the environment in which an organism lives.
What type of distribution is usually produced by continuous variation?
A normal distribution.
What are the characteristics of a normal distribution curve?
The mean, median and mode are the same, in the middle of the curve. Most values lie close to the mean, and the number of individuals at the extremes is low.
Define standard deviation.
A measure of the variation within a sample.
How is the standard deviation represented on a normal distribution curve?
Standard deviation is represented by the width of a normal distribution curve.
How do we interpret standard deviation?
If SD is low, there is less variation, and if SD is high, there is more variation.
What is the student’s t test used for?
To compare the means of data values of two populations.
How do you calculate degrees of freedom?
sample size - number of data sets
What are the steps in the student’s t test?
- Calculate the mean for each data set
- Calculate the standard deviation for each data set
- Put the values into the t test equation and calculate the value of t
- Calculate the degrees of freedom
- Compare the t value to the significance table at 5% or 0.05
- If t is lower than the value in the table, there is no significant difference between the means of the data sets and therefore any variation is likely due to chance. If t is greater than the value in the table, there is a significant difference between the means of the data sets and therefore any variation is unlikely to be due to chance.
What are the steps for Spearman’s rank?
- Rank the data from smallest to highest, with 1 being the highest
- Repeat for the second data set
- Find the difference between the ranks and square it (d2)
- Put the values into the equation and calculate the correlation coefficient
- Compare the value to the critical value (using the number of pairs of data as n) - if the value is lower than the critical value, we accept the null hypothesis, and if it is higher, we reject the null hypothesis
Define adaptations.
Adaptations = characteristics which increase an organism’s chances of survival and reproduction in its unique environment
What are the three types of adaptations?
Anatomical, behavioural and physiological.
Give four examples of anatomical adaptations.
Body coverings - in animals could be hair, scales, spines, feathers, shells etc, and waxy layers and spikes in plants
Camouflage - the outer colour of an animal allows it to blend into the environment, making it more invisible to predators
Teeth - the shape and type are related to the animal’s diet; herbivores have consistently growing teeth while carnivores have sharp canine teeth
Mimicry - copying another organism’s appearance or sounds allows a harmless organism to fool predators into thinking it is poisonous or dangerous
Give three examples of behavioural adaptations.
Survival behaviours
Courtship - increases the organism’s chances of reproduction by helping to attract a mate
Seasonal behaviours which help the organism cope with environmental changes, such as:
Migration - moving from region to region for a better climate/food source
Hibernation - a period of inactivity in which an animal’s body temperature, heart rate and breathing rate slow down to conserve energy, reducing the animal’s requirements for food
How are behavioural adaptations caused?
Behavioural adaptations can be innate/instinctive (inherited through genes) or learned through experience or observing other animals.
Give five examples of physiological adaptations.
Poison production - many reptiles produce venom to kill their prey and many plants produce poisons in their leaves to protect themselves from being eaten
Antibiotic production - some bacteria produce antibiotics to kill other species of bacteria in the surrounding area
Water holding - enables organisms to survive for long periods without access to water
Reflexes - e.g. blinking
Temperature regulation
Define convergent evolution.
Convergent evolution = when unrelated species begin to share similar traits
Define analogous structures.
Analogous structures = structures which have a different genetic origin but have adapted to perform the same function
Give an example in plants of convergent evolution.
Aloe and agave - they have both adapted to survive in the desert but evolved entirely separately, with aloe having evolved in sub-Saharan Africa while agave evolved in Mexico and the southern United States.
How are marsupials and placental mammals an example of convergent evolution?
Despite the geographical and temporal separation between marsupials and placental mammals (their last common ancestor was over 100 million years ago) they bear a strong resemblance in overall shape, type of locomotion and feeding techniques because they have adapted to similar climates and food supplies. However, their distinct evolutionary relationships are reflected in their different methods of reproduction. In placental mammals, a placenta connects the embryo to its mother’s circulatory system in the uterus. Marsupials start life in the uterus, but leave and enter the marsupium while they are embryos, completing their development by suckling milk.
Give three examples of marsupial and placental mammals and their similarities.
Marsupial mice and placental mice - both are small, agile climbers that live in dense ground cover and forage at night for small food items
Flying phalangers and flying squirrels - both are gliders which eat insects and plants, and both have skin stretched between their forelimbs and hind limbs to provide a large surface area for gliding between trees
Marsupial moles and placental moles - both burrow through soft soil to find worms and grubs, have a streamlined body shape and forelimbs for digging and have velvety fur to allow smooth movement through the soil, but the marsupial mole ranges in colour from white to orange whereas the placental mole is grey
Define selection pressures.
Selection pressures = external agents that affect an organism’s ability to survive in a given environment
What are the steps of natural selection?
Organisms within a species show variation in their characteristics that are caused by differences in their genes, such as different alleles of a gene for a particular characteristic. New alleles can arise by mutation.
Organisms whose characteristics are best adapted to the selection pressure have an increased chance of surviving and successfully reproducing. Less well-adapted organisms die or fail to reproduce.
Successful organisms pass the allele encoding the advantageous characteristic onto their offspring. Conversely, organisms possessing the disadvantageous allele are less likely to successfully pass it on.
This process is repeated for every generation. Over time, the proportion of individuals with the advantageous adaptation increases. Therefore, the frequency of the allele that codes for this particular characteristic increases in the population’s gene pool.
Over very long periods of time and many generations, often involving multiple genes, this process can lead to the evolution of a new species.
How is MRSA a modern example of evolution?
Methicillin-resistant Staphylococcus aureus (MRSA) has developed resistance to many antibiotics, including methicillin
Bacteria evolve in a short time due to reproducing very quickly
Usually, mutations in bacteria result in their death, but a mutation in S. aureus provided resistance to methicillin
When the bacteria were exposed to methicillin, resistant individuals survived and reproduced, passing the allele for resistance on to their offspring, while non-resistant individuals died
Over time, the number of resistant individuals in the population increased until a resistant strain had evolved
How are peppered moths a modern example of evolution?
Before the industrial revolution, most peppered moths were pale in colour, providing camouflage against tree bark - this increased their chances of survival as darker-coloured moths were eaten by birds
During the industrial revolution, many trees became darker due to being covered in soot or a loss of lichen cover (caused by increased atmospheric pollution) - this meant more dark peppered moths survived and reproduced, passing on the ‘dark’ allele
This increased the frequency of this allele, and of darker peppered moths, in the population
After a few years, there were more dark than light peppered moths in areas close to industrial towns and cities
Since the Clean Air Act of 1956, steps have been taken to improve air quality in towns and cities and to reduce the level of pollution released from factories
The frequency of lighter peppered moths has increased again
How are sheep blowflies a modern example of evolution?
Sheep blowflies cause a condition called flystrike in sheep, which can be fatal
In the 1950s in Australia, the pesticide diazinon was used to kill blowflies, preventing flystrike
Within six years, blowflies had developed high resistance to diazinon, as individuals with resistance had survived exposure, passing on the resistant allele - this allowed a resistant population to evolve
Scientists extracted DNA from a sample of 70-year-old blowflies kept at the Australian Natural Insect Collection
It was found that the older blowflies did not have resistance to diazinon (unlike the modern species), but both the older and modern blowflies had resistance to malathion (a similar pesticide)
The scientists concluded that pre-adaptation contributed to the development of diazinon resistance - the pre-existing resistance to malathion allowed the blowflies to develop first resistance to organophosphate chemicals (the type of chemical which diazinon and malathion are) generally and eventually resistance to diazinon specifically
How is Flavobacterium a modern example of evolution?
Scientists have discovered a new strain of Flavobacterium living in waste water from factories which produce nylon 6 (used to make toothbrushes, violin strings etc.)
This strain of bacteria has evolved to digest nylon using enzymes called nylonases - this is beneficial to humans because it helps clear up factory waste, and to the bacteria because it provides them with another nutrient source
Nylonases are unlike any enzymes found in other strains of Flavobacterium and do not help digest any other known material
Most scientists believe that the mutation producing these enzymes was a result of a gene duplication combined with a frameshift mutation
