- Created by: Rachel Nigriello
- Created on: 05-06-10 09:50
Explain the relationship between classification and phylogeny
Phylogeny is the study of organisms according to their evolutionary history and classification attributes different common features to different groups. From this we can deduce common ancestors and thus study their evolutionary history
What are the 3 domains, 5 kingdoms, phylum, class, order, family, genus and species?
domains - Eubacteria, archaebacteria, Eukaryotes
Eukaryotes are subdivided into 4 other kingdoms, (Eubacteria and archaebacteria make up porkaryotes)
Kindoms - Prokaryotes, Fungi, Animal, Plant, Protoctisa
Kingdoms subdivide into phylum - Cnidaria ( jellyfish) , Platyhelminthes ( flat worms), Annelida ( round worms) , Anthropoda ( 5 classes of insects) , Chordata ( for animals)
Phylum are subdivided into classes - Aves, Reptilia, Mammalia
Classes are subdivided into Orders - Primate
Orders are subdivided into Families - Hominidi
Families are subdivided into Genera - Homo
Genera are subdivided into species - Sapiens
Outline the characteristic features of the following five kingdoms ; Prokaryotae, Protoctista, Fungi, Plantae, Animalia.
Prokaryotes - have no nucleus, have a naked loop of DNA, no membrane bound organelles, 70s ribosomes, no 9 + 2 arrangement of microtubules in flagella, murein cell wall, mesosomes.
Protoctista - All eukaryote unicellular organisms with plant or animal characteristics, algae, amoeba. Some are filamentous, some are autotrophic, some are heterotrophic.
Fungi - Eukaryotes, Saprotrophs, Hetrotrophs. Cell wall made of chitin. Can be unicellular or multicellular, reproduces using spores, no cilia
Plants - Autotrophs, photosynthetic, multicellular, cellulose cell wall, flagella, Eukaryotes, able to make all the amino acids that they need
Animals - Eukaryotes, multicellular, No cell wall, Hetrotrophs, Motile
Outline the binomial system of nomenclature and the use of scientific names for species
Everything is referred to by its genus and its species i.e. homospaiens. Latin is supposed to be a universla language and stopped confusion with common names. The genus has a capital letter and the species has a lower case letter but both are written in italics or underlined if written by hand.
What is a dichotomous key?
It is the means of identifying organisms maybe as far as species levels by a series of questions usually with the answers "yes" or " no" .
What recent developments help us differentiate between species?
Modern techniques such as DNA sequencing show the similarity in the DNA in more closely related organisms. Protein clocks differentiate based on the similarity of amino acid sequences of certain proteins. The greater the similarity of the primary structure of proteins of 2 organisms, the more recent their common ancestor is.
Amino acid sequence is determined by DNA sequence
The more similar the DNA, the more similar the amino acid sequence
Mutation in the DNA would alter the amino acid sequence
Therefore the more similar the sequence, the more closely related the species
Discuss whether the 5 kingdoms and the 3 domain classifications are completely different from one another, or if they could possibly be used together?
The 5 kingdoms make a clear distinction between prokaryotes and eukaryotes and so does the 3 domains so in that way they are similar. However, the 3 domain system is less distinctive between types of eukaryotes so that is when the 5 kingdoms becomes more definitive. Domains show diversity of prokaryotes and that archaebacteria are more closely related to eukaryotes than eubacteria are.
Define the term variation
Variation is the differences between species and differences between individuals of a species
What are the differences between continuous and discontinuous variation?
Continuous variation is different skin colours or hair colours. There are no clear cut categories. Individuals fit somewhere along a spectrum between the extreme values. It forms a normal distribution curve ( bell shaped ). Several genes are involved and the variation may also be affected by the environment
Discontinous variation is like gender or blood group. A few clearly defined groups. There are no intermediates. Controlled by a small number of genes with a few alleles. There is no environmental influence
What are the genetic and environmental causes of variation?
Genetic - mutation , random and unpredictable changes in DNA that can be inherited. It introduces new alleles.
- we all inherit a unique combination of alleles from our parents, genetic information is mixed a reshuffled. Meiosis means that each gamete is genetically unique. Fertilisation is random
Environmental - In utero , differences in oxygen availibility and glucose
- Post utero, smoking, exposure to sun ,diet, education
What are the behavioural, physiological and anatomical adaptations of organisms to their environment. Give examples of all of these
Anatomical - canines have enlarged and sharp teeth to puncture and kill prey
Physiological - desert mice have a long loop of Henle to reabsorb as much water as possible
Behavioural - woolice run towards dark and damp areas and earthworms recoil on touch
Explain the consequences of the four observations made by Darwin in proposing his theory of natural selection.
Darwins 4 observations - There is lots of variation within each species
- Offspring tend to be similar to their parents
- More offspring are born than survive to reproduce
- Population sizes remain fairly stable in nature
Consequences: Some individuals are better adapted to the environment than others. The better adapted organisms are more likely to survive long enough to reproduce as they compete successfully for resources. The less well adapted organisms are more likely to die before reproducing or to produce less offspring. The less well adapted organisms are outcompeted and the population does not grow exponentially. Offspring inherit alleles from their parents and therefore they are similar to their parents and likely to have the characteristics that enabled their parents to survive. Over many generations a species will change and become better adapted to the environment. Eventually a group may become so different from another group that they can no longer interbreed to produce fertile offspring. Speciation has occurred
Define the term speciation
the formation of new species. A species is a group able to breed to produce fertile offspring.
What is the evidence supporting the theory of evolution?
Fossil Record: The preserved remains of organisms that lived and died a long time ago. Fossils provide evidence that some animals have become extinct. They can also show organisms that existed that had features of more than one group e.g. archaeopteryx. They show the evidence of change in organsims over time. It is incomplete and doesn't show "how" the change occured
Homologous structures: Pentadactyl limbs, vertebrates all have a pentadactyl limb with a basic similarity of structure. Points to a common ancestor
Biological Molecules: DNA, same structure in all organisms in prokaryotes and eukaryotes. Suggests all organisms have a common ancestor.
DNA sequencing: More closely related, mutations, DNA of fossils compared with DNA of living organisms
Outline how variation, adaptation and selection occur
Variation and adaptation occurs in a species when a random mutation in the DNA allows an individual to survive better than other members of the species. This special individual is then able to pass on its DNA in reproduction so that its offspring also have the advantageous DNA.
Section occurs when a pressure is applied to the survival of a species e.b. Availibility of suitable foods or Diseases.
Why is variation, adaptation and selection essential for evolution?
These factors give some individuals a competitive advantage over other individuals so some individuals survive better to pass on their alleles to their offspring,
why does the evolution of pesticide resistance in insects and drug resistance in micro-organisms have implications for humans?
If pests are resistant to to pesticides, our crops can be damaged and we will have a shortage of food. Drug resistance means that many illnesses are untreatable and will kill humans. By providing pesticides and antibiotics we provide a selection pressure, encouraging selection
How does speciation occur?
It occurs when there is a reproductive barrier - any factor which prevents different groups from interbreeding.
There are 2 types of speciation: allopatric sectiation - involves geological isolation e.g. a river. There are different selection pressures on each side of the structure so each group adapts to survive in different environments. The allele frequency changes and there are different random mutations. After a long time, the differences accummulate so they are no longer able to reproduce with each other to produce fertile offspring if reintroduced to each other
Sympatic Speciation : Reproductive barrier e.g. behavioural ( different sized beaks affect mating call) or biochemical ( egg and sperm aren't compatible) or physical ( sex organs are incompatible)
What are the reasons for the conservation of animal and plant species?
Economic: There will be plants in the rainforest that hold the secret to undiscovered treatments.
Undiscovered plants may have a natural resistance to certain pests.
Ecological: Nutrient recycling, carbon cycle, nitrogen cycle, no need for fertilizer, natural pollinators, natural predators of other pests, more biodiversity is more stable
Ethical: Every animal has the right to life, removal of rainforests could destroy indigenous habitats.
Aesthetic: Earth looks prettier if the world is more diverse
Pleasure can be derived from bio diverse areas such as rainforests
What are the consequences of global climate change on the biodiversity of plants and animals?
Some organisms may migrate upwards to find cooler temperatures but once they reach the top of a mountain, there is nowhere else to go
There may be a physical barrier stopping organisms from moving to an area of better climate
A manmade barrier could prevent them from moving
Disease is also spreading due to vector spread.
More flooding and drought will kill some species.
Increased number of predators due to warmer weather.
What are the advantages for agriculture of maintaining the biodiversity of animal and plant species?
It's good to have lots of biodiversity because there may be natural predators that eat pests that destroy crops
We need more strains of plants that are grown that have a natural resistance to predators
There may be an undiscovered crop that is a good food source
Economic incentive of EU subsidies and Trusts to maintain biodiversity
What are the advantages of conservation in situ and its disadvantages?
Pros: Some species are reluctant to breed in captivity
No problems of the organisms having an inability to cope with living wild
A natural environment provides ideal conditions for breeding
You can monitor and protect organisms
Cons: Inability to control variables
Can affect local populations of indigenous people.
What are the disadvantages and advantages of ex situ conservation?
Advantages: IVF is advantageous as genetic variation can be ensured
It is easy to transport frozen embryos and sperm
Access to vets
Benefits to public, education, financial support
Disadvantages: Capture can stress animal or injure animal
Transport can be hard
Artificial habitat can be difficult : lack of space, climate, small gene pool, inbreeding
Reintroduction to the wild is difficult: predators, diseases, hunting
Lack of compatibility with partners
How do seed banks and botanic gardens aid the ex situ conservation of rare plant species?
Seeds or cuttings can be extracted from plants in the wild, dried and stored in a cold place to prevent germination. Once germinated, they can be reintroduced into the wild. There is always a source of each plant
Seedbanks can collect specimens of species that may be advantageous and cross them to maintain genetic variation.
What is being done to conserve wildlife internationally?
CITES - convention in international trade of endangered species of flora and fauna.
It ensures that international trade in wildlife doesn't endanger their survival by promoting international collaboration.
They identify which are the most in danger and they prohibit international trade in those species organisms and their products. Lists are updated frequently
Rio Earth Summit - 157 countries signed up to create strategies to protect theri biodiverstiy and aim to provide sustainable developement. It allows countries to share knowledge and technology and genetic resources (wide gene pool). Makes countries make SSSI, grants, greenbelt land, national parks
EIAs - Environmental Impact Assessments, for new developments so that the new project does not adversely impact the biodiversity of the area. It is the responsibility of the developer to submit the EIA to the local planning authority