CHAPTER 10 - CLASSIFICATION AND EVOLUTION Flashcards
What are the 7 taxonomic groups (linnaean classification)
Kingdom, Phylum, Class, Order, Family, Genus, Species
(Ellis method)
Why do scientists classify organisms
To identify species
To predict characteristics
Find evolutionary links
What is a species defined as
A group of organisms that are able to reproduce to produce fertile offspring
State two reasons why classification is important
Enables scientists to share information / makes communication easy
provides information about an organism, based on members of the same group
allows accurate identification of an organism
Ligers are the offsprings of male lions and female tigers. Suggest two reasons why ligers are not classified as a species but their parents are
Ligers cannot reproduce to produce more ligers therefore they are not a species
Both lions and tigers reproduce to produce fertile offspring, therefore they are species
The loganberry (Rubus loganobaccus) is the fertile offspring of the blackberry (Rubus ursinus) and the raspberry (Rubus idaeus). Explain why the Loganberry is difficult to classify into a taxonomic group
Both parents are members of the same genus (Rubus)
but different species (ursinus and idaeus)
Two different species cannot produce fertile offspring / according to the taxonomic classification system the loganberry should not be fertile
What are the general features of prokaryotae
Unicellular
No nucleus or membrane mound organelles
Rings of ‘naked’ DNA
Small ribosomes
No visible feeding mechanism
What are the general features of protoctista
Mainly unicellular
Nucleus and other membrane bound organelles
Some contain chloroplasts
Some can move using flagella, cilia or amoeboid mechanisms but others are sessile
Nutrients acquired by photosynthesis
What are the general features of fungi
Unicellular or multicellular
A nucleus and other membrane bound organelles, with a chitin cell wall
No chloroplasts
No mechanism for locomotion
Most have a body or mycelium made up of threads or hyphae
Saprophytic - absorb decaying material
Store food as glycogen
What are the general features of plantae
Multicellular
A nucleus and other membrane-bound organelles including chloroplasts
All contain chlorophyll
Most dont move, although gametes of some plants move using cilia or flagella
Autotrophic - organisms make their own food
Store food as starch
What are the general features of Animalia
Multicellular
Nucleus and other membrane bound organelles
No cell wall
No chlorplasts
Move with aid of cilia, flagella or contractile proteins (eg. muscular organs)
Heterotrophic - ingest food
Food stored as glycogen
State two differences between fungi and plants
Plants have chloroplasts / chlorophyll, whereas fungi do not
plants are autotrophs, whereas fungi are heterotrophs
fungi may be unicellular, plants are always multicellular
fungi store food as glycogen, whereas plants store food as starch
plant cell walls are composed of cellulose, whereas fungi cell walls are composed of chitin
Explain why prokaryotes are now classified as two separate domains
Advances in biological techniques have identifies large differences in composition
ribosomes/rRNA differ
cell walls differ – peptidoglycan not found in archaea
Old classification does not show correct phylogeny
What are the three systems of classifying
3 domain system
6 kingdom system
5 kingdom system
(pg 239)
Explain why prokaryotes are now classified as two separate domains
Advances in biological techniques have identifies large differences in composition
ribosomes/rRNA differ
cell walls differ – peptidoglycan not found in archaea
old classification does not show correct phylogeny
Describe how and why classification systems have changed over time
Living organisms classified into two kingdoms based on major differences in characteristics
for example, those that moved and ate (animals) and those that didn’t (plants)
scientific advances/use of microscope allowed smaller details to be observed
organisms divided into five kingdoms
Plants, animals, fungi, protoctista, prokaryotes
Advances in science allowed DNA and proteins to be studied
Provided evidence for evolutionary relationships
Three domain system proposed
Relevant scientists mentioned (Linnaeus, Whittaker, Woese)
What is phylogeny
Evolutionary relationships between organisms
What are some advantages of phylogenetic classification
It takes into account evolutionary relationships that might not be obvious by just looking at characteristics
it forms a continuous tree so organisms do not have to be forced into groups
is not hierarchical therefore different groups on the tree are represented according to their evolutionary position – and can thus be compared
State the main difference between early classification systems and systems based on phylogeny
Historical classification systems based on physical characteristics / niche occupancy, whereas phylogeny based on evolutionary relationships
What is evolution
The way in which organisms evolve or change over many years as a result of natural selection
What evidence is there for evolution
Palaeontology and fossil records
Comparative anatomy
Comparative biochemistry
How are fossils formed
Animal and plant remains are preserved in rocks,
Time of existence can be determined by amount of rock build up on top
What evidence is provided by the fossil record
Timeline, of simpler organisms buried deeper in the rock and more complex higher up
Sequence matches ecological links - eg. plants are found before animals
Anatomy can show how closely related organisms have evolved from the same ancestor eg. zebra/horse and rhino
Allows relationships between extinct and living organisms to be investigated
What is one issue in the fossil record
It is incomplete, partly due to soft bodied organisms decomposing before having a chance to fossilise
What are homologous structures, what is an example, and how does it show divergent evolution
Structure that appears superficially different (and may perform different functions) in different organisms but has the same underlying structure
eg. Pentadactyl limb
Evolved form a common ancestor and have to adapt to new habitats
What are the two most commonly studied biochemistry molecules in comparing species relationships
Cytochrome c - protein in respiration
rRNA - ribosomal RNA
What is the hypothesis of neutral evolution
Most of the variability in the structure of a molecule doesn’t affect its function
Describe what is shown on a phylogenetic tree
A diagram used to show evolutionary relationships between organisms
the closer the branches of the tree the closer the evolutionary relationships - meetings of lines are called nodes
Describe two advantages and two disadvantages of using the fossil record as a source of evidence for evolution
Advantages:
radioisotopes can be used to date fossils
changes can be tracked over time
chronological order apparent in rock strata.
Disadvantages:
many organisms decompose quickly before they have a chance to fossilise/
destroyed by volcanoes/ destroyed by earthquakes
Describe how the work of three scientists was used in the development of the theory of evolution
Lyell – suggested that fossils were actually evidence of animals that had lived millions of years ago.
Hutton – proposed theory of uniformitarianism.
Darwin – came up with theory of evolution by natural selection through observations in Galapagos islands / jointly published theory.
Wallace – came up with theory of evolution by natural selection in Borneo/jointly published theory
Explain how comparative biochemistry provides evidence of evolution
Study of similarities and differences in proteins and nucleic acid/DNA of an organism
changes in highly conserved molecules can help identify evolutionary links
such as cytochrome C / ribosomal RNA
species that are closely related have the most similar DNA and proteins /distantly related have far fewer similarities
What is interspecific variation
Variation between members of different species
What is infraspecific variation
Differences between organisms within a species
What are the factors that cause variation
Differences in the genetic material an organism inherits from its parents leads to genetic variation
Environment in which it lives, this causes environmental variation
What are the Genetic causes of variation
Differing Alleles
Mutations
Meiosis - Independent Assortment and Crossing over
Sexual reproduction - mix of alleles inherited
Chance- many gametes produced by parents
What is an example of environmental causes of variation
pH of soil, which causes changes in flower colour
Name two human characteristics with variation caused solely by the environment
scar, tattoo, dyed hair
Name two human characteristics with variation cause solely by genetics
eye colour, blood group, lobed or lobeless ears
Explain some of the causes of variation of human hair
Caused by a combination of genetics and the environment
Genes determine the natural colour of hair and texture, e.g. curly/straight
Environment affects final appearance, e.g. if hair is cut, dyed, or lightened by sunlight
Explain more genetic variation is more common in organisms that reproduce sexually
Individuals produced by asexual reproduction are clones/genetically identical to parents
no fertilisation so no mixture of genetic material
meiosis does not take place/ no production of gametes
DNA can only be altered as a result of mutation
What is discontinuous variation
value at either end of a spectrum, no middle value
eg. an animal sex either Male or Female
or shape of a bacteria
What is continuous variation
A characteristic which can take any value within a range
eg. weight or height
(can be influenced by environmental factors)
What types of ways are there of showing variation
Distribution curve
Standard deviation
T-tests
Spearman’s rank
what are some adaptations
Anatomical adaptations - physical features
Behavioural adaptations - The way an organism acts, inherited or learnt from their parents
Physiological adaptations - processes that take place inside an organism
What are some examples of anatomical adaptations
Body covering - eg. hair, scales, spines, feathers
Camouflage
Teeth - type of teeth present
Mimicry eg. markings of another species
What are some adaptations of marram grass
Curled or rolled leaves, to minimise surface area of moist tissue
Hairs on the inside surface of leaves to trap moist air
Stomata sunk into pits
Thick waxy cuticle on the leaves and stems
What are some examples of behavioural adaptations
Survival behaviours - eg. rabbit freezing when it has been seen
Courtship - dancing etc…
Seasonal behaviours - migration and hibernation
What categories to behavioural adaptations fall into
Innate behaviour - inherited through genes eg. web building of spiders
Learned behaviour - learnt through experience or observing other animals. otters using stones to hammer shells
What are some examples of physiological adaptations
Poison production - hunting or protection
Antibiotic production - kill off bacteria
Water holding - especially in arid environments
What are analogous structures, what is an example, and how does it prove convergent evolution
they have adapted to perform the same function but have a different genetic origin
Tail fins of whale and a fish perform the same role
Takes place when unrelated species begin to share similar traits, adapting to a niche
State the difference between analogous and homologous structures
Characteristics which show discontinuous variation are purely controlled by genetics/no environmental influence (except scars/tattoos just environment)
Normally controlled by a single gene
Characteristics which show continuous variation are controlled by a combination of genetic and environmental causes
Controlled by a number of genes/ polygenes
Which of the following is an example of convergent evolution, and explain your answer
Insect wing and bird wing
Bat wing and human arm
Insect and bird wing – both have evolved to fly to escape predators/hunt for food
State and explain how marsupial moles and placental moles provide evidence for convergent evolution
They have analogous structures – anatomical features that perform the same function in different organisms, but have a different origin
Any two from: Both burrow through soft soil to find insects
Both have a streamlined body shape, and modified forelimbs for digging
Both have velvety fur which allows smooth movement through the soil
What is the process for natural selection
Variation in an organism from mutation occurs
Organism whose characteristic best suited to selection pressure will survive and reproduce
Successful organisms pass on successful alleles
Process repeated for every generation, increasing frequency of successful allele
Over a long period, this can lead to an evolution of a new species
What are some examples of modern evolution
Antibiotic-resistant bacteria
Peppered moths
Sheep blowflies
Flavobacterium
State three selection pressures that may be experienced by a plant species
availability of light / water / nutrients / carbon dioxide / space, risk of being eaten, disease, ability to cross-pollinate
Describe the process of natural selection
Variations exist within a population
those with the best characteristics survive AND reproduce
characteristics are passed onto their offspring through genes
DDT is a chemical insecticide that was used to kill mosquitoes to prevent the spread of malaria. Several years after its introduction large populations of mosquitoes became DDT resistant. Explain how this occurred.
A mutation occurred / existed in the mosquitos DNA which made them DDT resistant
these organisms survived exposure to DDT and reproduced
mutation which caused resistance is passed onto their offspring
frequency of the DDT-resistant allele increases in the population
Examples state and explain the positive and negative effect on humans of recent examples of evolution in some species
Flavobacterium digests nylon waste
positive – used to clean up factory waste
bacteria e.g. MRSA – antibiotic resistance
negative – no longer killed using current medical treatment
sheep blowfly – insecticide resistant
negative – no longer killed by insecticide so increased sheep death
