Classification and Evolution Flashcards
Why do we classify organisms
convenient more manageable to study research easier relationships between species clearer identification of new species possible
What is the classification hierarchy
domain kingdom phylum class order family genus species
What are the 3 domains
Bacteria
Archaea
Eukaryotae
differences between the 3 domains
structure of cell membranes structure of flagella method of RNA synthesis bacteria = naked DNA different mechanisms of DNA replication Archaea share similar features with Eukaryotae Similar RNA polymerase enzyme Similar mechanisms for DNA replication
What is phylum
All organisms with similar body plans (e.g. having a backbone)
what is class
All organisms with similar general traits (e.g. number of limbs)
what is order
Further division (e.g. animals can be Carnivora or Herbivora)
family
A group of closely related genera (plural of genus)
genus
A group of closely related species
species
Basic unit of classification
Binomial naming system
2 names, how we refer to any organisms uses genus name and species name e.g Homo sapiens
How to write binomial naming system
Capitalise first letter of genus
lower case letter of species
underline whole thing
(or italics)
Why do we use the binomial naming system
Avoid long descriptions so it saves time/quicker
Common names for the same organism differ within and between countries.
Translation of languages can result in different names.
The same name may be used for many different species
Define species
A group of organisms that can freely interbreed to produce fertile offspring
What are phylogenetically species
A group of individual organisms that are very similar in appearance anatomy physiology biochemistry and genetics
what is phylogeny
The study of evolutionary relationships between living organisms
What are the 5 kindoms
prokaryotae fungi plantae animalia protoctista
Describe the features of the kingdom prokaryotae
no nucleus loop of DNA no histone proteins (naked DNA) no membrane bound organelles smaller ribosomes smaller cells free living or parasitic
describe the features of the kingdom fungi
eukaryotic single celled/ mycelium of hyphae chitin cell wall multinucleate free living and saprotrophic
Describe the features of the kingdom plantae
eukaryotic multicellular cellulose cell wall autotrophic contain chlorophyll
Describe the features of the domain animalia
eukarotic
multicellular
heterotrophic
Describe the kingdom of protoctista
eukaryotic
mostly free living
some more like plants and some more like animals
What is convergent evolution
• Since organisms adapt to their environment it is possible for two distantly related species to appear very similar (e.g. some sharks and dolphins)
Example of use of biological molecules to classify organisms
Cytochrome c
• A respiratory protein that can be found in all living organisms but isn’t identical in all species.
• Comparing amino acid sequences for cytochrome c in different organisms can tell us how closely related they are:
• The more differences between the sequences, the more distantly related the two organisms are.
DNA
• Another biological molecule found in all living organisms.
• When DNA is replicated mutations can alter the sequence.
• DNA sequences can be compared just like the amino acid sequences in cytochrome c to tell how closely related two organisms are.
What is monophyletic?
species that belong to the same phyletic group
What is artificial classification and what is it used for
used for convenience, based on a few characteristics and does not represent evolutionary history.
What is natural classification based on?
based on many characteristics to reflect evolutionary
relationships and provide useful information for scientists.
What is evolution?
the process by which different kinds of living organism
are believed to have developed from earlier forms during the history of the earth.
What is natural selection?
The process of change in a population due to selective forces from the environment affecting the reproduction of the individuals in the population.
What is the mechanism of natural selection
- Mutation creates a new allele (a different version) of a gene in an organism.
- The environment dictates which version or versions of alleles are beneficial to the
survival of the individuals in a varied population. - Individuals that have beneficial traits are more likely to survive and reproduce,
passing on the advantageous alleles to their offspring. - The next generation will have a greater number of individuals with beneficial
characteristics. - After many generations the whole population will have the beneficial traits and
they will all be better adapted to their environment.
What were the 4 observations that Darwin based his evolutionary theory on?
- Offspring appear to be similar to their parents
- No two individuals are identical
- Organisms have the ability to produce a large number of offspring
- Populations in nature tend to remain fairly stable in size
What did Darwin conclude from those observations
- There is a struggle to survive.
- Better adapted organisms survive and reproduce.
- Given many generations this can result in a new species.
Give examples of evidence for evolution
Fossils
• Showed that in the past the world was inhabited by different species to those alive now.
• The new species that appear are similar to the older ones they replace.
• For some species (e.g. the horse) there is a complete (or mostly complete) record of their evolution from ancestral species to what we have today.
DNA
• DNA from fossil samples and from living species can be used to construct phylogenetic trees showing the evolution of species.
• Closely related species have similar DNA as they have had less time for evolution to occur in them than distantly related species.
Other biological molecules
• The presence of certain molecules in all living organisms is evidence for evolution.
How else did the same molecules get into every living cell if they didn’t all have
acommon ancestor?
• Like with DNA and cytochrome c, more distantly related organisms will have greater differences in their biological molecules.
What is adaptation?
A trait that better enables an organism to survive in its habitat.
Adaptation is also the process by which an organism becomes suited to a habitat.
What are the 3 types of adaption and explain them using the example of marram grass
Anatomical
• Long roots to access water deep underground.
• Curled leaves to reduce water loss.
• Hairs on the lower epidermis to reduce air movement
and therefore water loss.
Behavioural
• When water is especially scarce marram can roll its
leaves more tightly and close its stomata to further
reduce water loss.
Physiological
• Guard cells use water potential to control the
opening and closing of the stomata.
• Low water potential in its cells prevents the uptake
of lots of salts, which marram grass is sensitive to.
• Lignified cells in the leaf provide support to marram
grass even when cell turgidity is lost.
Use the example of moles as an explanation of convergent evolution
Marsupial and placental moles, they both have:
• A cylindrical body
• Small eyes
• Strong front legs with large claws for digging
• Short fur and tails that don’t get in the way when tunnelling
• A highly sensitive nose with a tough layer of skin for protection
Natural selection can result in similar adaptations in different organisms.
• Distantly related organisms that live in the same habitat experience the same
environmental selection forces.
How does evolution of some species have implications on human populations?
insects can be pests that damage crops and spread disease.
chemicals called pesticides that kill insects.
• These chemicals are deadly and so exert a very strong selection pressure on insects.
• Resistant insects form and pose a serious threat to agriculture and human health.
• E.g. DDT resistance in mosquitos
In the same way antibiotics exerts a strong selective force on bacteria.
• Bacteria with random mutations that can give them resistance to antibiotics like penicillin will survive and can reproduce asexually to form a population with all
resistant bacteria.
• MRSA stands for methicillin-resistant Staphylococcus aureus, but this pathogen poses an even bigger threat because it is resistant to many types of antibiotic.
Define variation
the difference between individuals.
What are the two types of variation
Interspecific variation can occur between individuals of different species.
Intraspecific variation can occur between members of the same species.
What is discontinuous variation
2 or more distinct categories • gGender • Blood group • Members may be evenly distributed between different forms • There may be more of one type than another • Nearly always caused by genes • Little or no environmental influence • Unusually few alleles are involved
What is continuous variation
A spectrum with a range of intermediates • Height • Length of leaves • Most individuals are close to the mean value and there are fewer at the extremes. • May be caused by genes and environment acting together. • It is caused by many genes, and often multiple alleles of each gene.
What are genetic causes of variation?
• Independent assortment of chromosomes
• Crossing over, exchanging of alleles between
homologous chromosomes
• Variation is increased by fertilization during
sexual reproduction
• Mutations cause variation in specific genes
What are environmental causes of variation?
Sunbathing causes darkening of the skin
Lack of a balanced diet causes poor growth
Growing a plant in Magnesium deficient soil
results in yellow leaves
