Definition of binomial system
System that uses genus name and species name to avoid confusion when naming organisms
Definition of classification
Process of placing living things into groups
Modern classification hierarchy order:
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
What are the 3 domains?
Archaea
Eubacteria
Eukaryotae
What are the 5 kingdoms?
Plantae
Animalia
Fungi
Protocistia (all eukaryotes which possess a nuclues)
Prokaryotae (single-celled organisms that don’t possess nucleus)
What’s a phylum?
Subdivision of the kingdom - contains all thegroups of organisms that have same body plan
What's a class?
A group of organisms that all possess same general traits
What's an order?
Subdivision of class using additional info about the organisms
What's a family?
Group of closely related genera
What's a genus?
Group of closely related species
What's a species?
Basic unit if classification. All members of species show variation but all essentially the same
At high levels of ranked system …
Differences between organisms is great
As descend to lower taxonomic groups …
Increasingly more difficult to seperate closely related species as more and more detail needed
What happens as you go down the hierarchy for classification?
Number of organisms in each group decreases
Similarities between organisms increase
What are the reasons for classification?
For convenience
Make the study of living things more manageable
Makes it easier to identify organisms
Helps see relationships between species
What's taxonomy?
The scientific study of classification
What's phylogeny?
Study of evolutionary relationships
Meaning of heirarchial
Keep breaking down into smaller and smaller groups
What's eubacteria sometimes called?
Prokaryota
Why were domains developed?
Sometimes difficult to know which Kingdom to put an organism in
Why was the modern classification hierarchy system proposed?
New evidence showing large differences between the bacteria and archae
How are polar bears adapted?
Sharp teeth - killing
Layer of blubber - insulation
Sharp claws - killing, digging, grip
Large feet - weight distribution and swimming
Strong legs - swimming, running
Large size, small ears (SA:V) - reduces SA where heat can be lost
Black skin - absorb sunlight
Fur - insulation
Human kingdom
Human class
Mammalia
Human order
Primate
Huamn genus
Homo
Human species
Sapiens
What names are used in the binomial system?
Genus and species
Human binomial name
Homo sapiens
Why is the binomial system used instead of common names?
Some organisms have diff common name in diff parts of country
Diff common names in diff countries
Translation of languages may give diff names
Same common name may be used for diff species
What language is used for the binomial system and why?
Latin - avoid confusion (universal name)
Definition of adaptation
A characteristic that enhances survival in habitat
Definition of anatomical adaptations
Structural features (anatomy)
Definition of behavioural adaptations
Ways behaviour is modified for survival
Definition of psychological adaptations
Affect the way processes work
What do adaptations do?
Help organism cope with environmental stress and obtain the things needed to survive
What are well adapted organisms able to do?
Find enough food/photosynthesise well
Find enough water
Gather enough nutrients
Defend itself from predators/diseases
Survive physical conditions of environment
Respond to changes in environment
What are the 3 types of adaptation?
Anatomical
Behavioural
Psychological
Maream grass is a …
Xerophyte
Where's marram grass adapted to living?
On sand dunes with little water available
What are the anatomical adaptations of marram grass?
Long roots
Roots spread over wide areas
Curved leaves
Lower epidermis covered in hairs
Lower epidermis folded to form pits where stomata are positioned
Low density of stomata
Leaf covered in thick waxy cuticle
How do long roots help marram grass survive?
Enables plants to reach water deep underground
How do long roots spread over wide areas help marram grass survive?
Enables to absorb lots of water when available
Helps stabilise sand dune in which lives
How do curved leaves help marram grass survive?
Reduces SA exposed to wind
Traps air inside, against lower epidermis, so moisture can build up in enclosed space
How does a lower epidermis covered in hairs help marram grass survive?
Reduces air movement so water vapours retained close to lower epidermis
How does a lower epidermis folded to create pits where stomata are positioned help marram grass survive?
Water vapour builds up in pits reducing loss of water vapour from inside leaf
How does a low density of stomata help marram grass survive?
Fewer stomata = less water vapour lost
How does a leaf covered in thick waxy cuticle help marram grass survive?
Reduces evaporation of water from cells of leaf
What are the behavioural adaptations of marram grass and how do these help it survive?
Responds to shortage of water by rolling leaves more tightly and closing stomata - both reduce transpiration
When covered by sand, grow more quickly to reach sunlight
What are the psychological adaptations of marram grass?
Ability to roll is due to action of specialised hinge cells in lower epidermis
Guard cells to open and close stomata
Maintains cell water potential lower than other plants
Leaves contain lignified cells
How does the ability to roll it's leaves help marram grass to survive?
It's due to the action of specialised hinge cells in lower epidermis. Cells loose water when water is scarce and loose their turgidity rolling the leaf more tightly
When waters available hinge cells become more turgid opening leaf for easier access for CO2 for photosynthesis
How does maintaining a cell water potential lower than other plants help marram grass to survive?
Enables it to survive in salty conditions found beside sea
How does having leaves containing lignified cells help marram grass survive?
Provides support when turgidity is lost keeping leaf upright when water not available
Polar bear adaptations
Sharp teetch - killing
Large feet - weight distribution, swimming
Large size, small ears - large SA:V to reduce SA where heat lost
What are the similar characteristics between marsupial and placental moles?
Cylindrical body
Small eyes
Strong front legs
Short fur
Short tail
Nose with tough skin for protection
Large claws on front legs
What's convergent evolution?
When two species evolve seperately but have similar characteristics
What's variation produced by?
Inherited differences or differences caused by environment
What's genetic variation caused by?
Mutations: chromosomal mutation, gene mutation
Sexual reproduction: independent assortment, crossing over, random fertilisation
Definition of discontinuous variation
Where there are distinct categories and nothing inbetween
Definition of genetic variation
Caused by possessing a different combination of alleles
Definition of environmental variation
Caused by response to environmental factors e.g light intensity
Definition of continuous variation
Variation where there are two extremes and a full range of values in between
What environmental difference can cause variation?
Climate
Diet
Lifestyle
Culture
Accidents
What type of variation can't be inherited?
Environmental
What is unique that we inherit?
Our combination of alleles (not same as any other organism)
Give an example of how an environmental difference can cause variation
Skin will become darker and tanned when exposed to sunlight
How can combined effects cause variation?
Not all genes are active at some time e.g puberty so changes in environment can affect which genes are active
What causes variation?
Genetic and enviro factors
What's discontinuous variation?
Where there are distinct categories and nothing in between
Examples of discontinuous variation
Gender
Blood groups
What's genetic variation?
Caused by possessing the different combination of alleles
What's environmental variation?
Definition of interspecific variation
The differences between species
Definition of intraspecific variation
Variation between members of the same species
Definition of variation
The presence of variety, differences between individuals
Variation within species
Intraspecific variation
Why may identical twins still show differences?
Start as one celll that divides into 2 so same genetic info but replication of DNA and cell divisions may change DNA or enviro factors
The greater the intraspecific variation…
The greater the genetic diversity of a species
Variation between species
Interspecific variation
What's interspecific variation used for?
Used to seperate members of one species from another
What's discontinuous data regulated by?
Single gene (not influenced by environment)
Describe discontinuous variation
Maybe be evenly distributed or more of one type than another
Continuous variation is usually…
Quantifiable
Describe continuous variation
Most individuals close to mean value, number at extreme lows
What's continuous variation regulated by and what can it be influenced by?
Regulated by more than one gene
Influenced by environment of living
Give examples of continuous variation
Height in humans
Length of leaves on trees
Definition of phylogeny
The study of the evolutionary relationships between organisms
Why do we use artificial classification?
What's artificial classification based on?
Only a few characteristics
What doesn't artificial classification reflect?
Any evolutionary relationships
Artificial classification provides…
Limited info
Artificial selection
What does natural classification involve?
Detailed study of the individuals in a species
Natural classification uses …
Many characteristics
Natural classification reflects …
Evolutionary relationships
Natural classification provides …
Lots of useful info
When may natural classification change?
With advancing knowledge
Where are closely related species and genera placed in natural classification?
Species - placed in genus
Genera - placed into family
What does monophyletic mean?
Belong to the same phylogenetic group
Do common ancestors survive today and where are they found?
No
Found at branch point
What appears at a branch point?
Common ancestors
Branch splits in 2 to show the 2 species which evolve
How many species will have the same common ancestor in the past?
Only 2
The more recent the common ancestors…
The more closely releated the 2 species are
Describe the features of animalia
Eukaryotic
Multicellular
Heterotrophic
Able to move around
Fertilised eggs that form a blastula
Describe the features of plantae
Have cellulose cell wall
Are autotrophic
Contain chlorophyll
Fertilised eggs that for multicellular embryos
Describe the features of fungi
Exist as single cells or have a mycelium that consist of hyphae
Walls made of chitin
Cytoplasm is multinucleate
Most free-living and saprophytic or heterotrophic
What does saprophytic mean?
Causes decay of organic matter
What does heterotrophic mean?
Ingest prey
What does autotrophic mean?
Photosynthesise
Describe the features of protoctista
Mostly single-celled
Show wide variety of forms
Show various plant-like and animal-like features
Mostly free-living
Have autotrophic and heterotrophic nutrition
What's prokaryotae sometimes called?
Monera
Describe the features of Monera/prokaryotae
No nucleus
Loop of DNA not arranged in linear chromosomes
Naked DNA
No membrane-bound organelles
Smaller ribosomes than other groups
Cells smaller than eukaryotes
Respire on mesosomes
Free living it parasitic
Some pathogenic
What's the five kingdom classification based on?
Observable features of anatomy at microscopic level
What's the biological definition of species?
A group of organisms that can freely interbreed to produce fertile offspring
What doesn't the biological definition of species work for?
Organisms that produce asexually
What's the phylogenetic definition of a species?
A group of individual organisms that are very similar in appearance, anatomy, physiology, bichemistry and genetics
In early classification what did Aristotle classify all living things as?
What were animals subdivided into?
Plants or animals
Live and move in water, live and move on land, move through the air
How did Aristotle classify in early classification?
Based on similarities he observed
What was the problem with the early two Kingdom classification systems?
The animal kingdom included single-celled organisms that had some animal-like features and vice versa but when using electron microscopes some had features of both
Definition of correlation coefficient
A measure of how closely 2 sets of data are correlated - value of one means perfect correlation
What's the value of a perfect correlation?
1
Definition of standard deviation
A measure of the spread around a mean
Definition of students t-test
Test used to compare two means
Why do we use statistical tests?
Help to determine whether the differences observed is a significant difference or simply natural variation
Standard deviation is a …
Measure of variation
What does a low standard deviation indicate?
The data has a narrow range and the points are closely grouped to the mean - indicates greater reliability
What does a high standard deviation indicate?
The data points have a lower range and less well grouped - indicates lower reliability
Formula for standard deviation
S =
X =
n =
_
Standard deviation
Individual value
Number of data points
Mean value
What does a students t-test do?
Tests whether the difference between the 2 means is a significant difference
How do you carry out a students t-test?
First state null hypothesis that there's no significant difference between the means of the 2 sets of data. T-test will test whether we can reject or must accept the hypothesis
Formula for students t-test
x1 =
s1²=
n1=
Mean of 1st data set
SD of 1st data set squared
Number of data points in 1st data set
What are the degrees of freedom defined as?
The number of values in a statistical calculation that are free to vary
How is the degree of freedom calculated?
Sample size - no. Data sets
When is the degree of freedom considered to be significant?
Calculated value of t is greater than value at 5% (if <5%, insignificant)
What's the correlation coefficient used for?
To consider the relationships between 2 sets of data
Formula for spearman rho
rs=
d =
Coefficient
Difference between ranks
Number of pairs of values
What are fossils?
Preserve remains of organisms that lived and died long ago
How are fossils formed?
Most formed from hard parts of organisms such as bones and shells that have become mineralized
Some soft parts preserved when right conditions are present
Definition of natural selection
Term used to explain how features of the environment apply to a selective force on the reproduction of individuals in a population
What did Charles Darwin propose?
Natural selection
Charles Darwin was a…
Naturalist
Wallace was a…
Wallis came to…
The same conclusions as Darwin
What four observations did Darwin make?
Offspring generally…
No …
Organisms have the ability to…
Populations in nature…
Appear similar to their parents
Two individuals are identical
Produce large numbers of offspring
Tend to remain fairly stable in size
When too many you are produced =
Competition for food and resources
What were Darwin's conclusions?
There's a struggle to survive
Better adapted individuals survive and pass on their characteristics
Ovetime, number of changes leads to new species
How can fossils be used as evidence for evolution?
Old species have appeared often similar to older ones found in same place
Modern species have variations that meant better adapted to environment
What happens when one species gives rise to another? What does this suggest?
Likely to have same/similar molecules
Suggests all arose from one original ancestor
When are biological molecules likely to differ more?
Species that took seperate evolutionary paths long time ago
Who are likely to have similar/identical molecules?
Closely related species
The greater the number of similarities between gene sequences, …
The more closely related the species and more recent their evolution
How different is our coding to chimps, gorillas and baboons?
Chimps - 1.2%
Gorillas - 1.6%
Baboons - 6.6%
What DNA does mitochondria contain?
Mitochondrial DNA (mDNA)
What happens to the mitochondria during sexual reproduction?
The mitochondria in the egg are passed to offspring, mDNA is passed on from mother
How is mitochondria DNA useful in tracing human history?
History isn't confused by DNA from parental line and mDNA you take more frequently than nuclear DNA as doesn't have same checking system to proofread copies. Lots of variation in sequence of mDNA from different parts of the world
When two unrelated species adapt to their environment in similar ways and therefore look very similar
Following convergent evolution, the two species may be …
Classified in same taxonomic group according to observable features
What does DNA provide?
The genetic code
What word can be used to describe the genetic code and why?
Universal as it's the same for all organisms
What are mutations?
Changes to the sequence of bases in DNA
Mutations are __.
Random
How can DNA be used to classify species?
The more similar the sequence in a part of DNA, the more closely related to species
Cytochrome C is a ..
Protein
What cytochrome C used in?
Process of respiration
If the sequence of AAs making up cytochrome C is the same…
The two species are closely related
If the sequence of AAs making up cytochrome C is different…
Not closely related
The more differences found between the sequences of AAs that make up cytochrome C…
The less closely related the 2 species
What is the protein evidence for classification?
DNA/RNA polymerase
Cytochrome C
Why is DNA/RNA polymerase evidence for classification?
Vital proteins for life
General structure similar across taxonomic groups
Higher organisms have more subunits
Why is cytochrome C evidence for classification?
Sequence of AA varies more as groups get further apart evolutionary as more time for changes to accumulate
Who proposed the three domain classification system?
Can Woese, 1990
Why did Can Woese come up with the three domain classification?
Based ideas on detailed study of rRNA gene. Divided kingdom prokaryotae into bacteria and archeae - division based on fact bacteria are fundamentally different from archeae and eukaryotae
What are the structural differences between bacteria and archeae?
Bacteria have:
Different cell membrane structure
Flagella with different internal structure
Different enzymes for synthesizing RNA
No proteins bound to genetic material
Different mechanisms for DNA replication and for synthesizing RNA
What features do archeae share with eukaryotes?
Similar enzymes for synthesizing RNA
Similar mechanisms for DNA replication and synthesizing RNA
Production of some proteins that bind to their DNA
What’s natural selection?
Indi’s that have characteristics to help it survive in its enviro more likely to live long enough to reproduce
How does the process of evolution work?
Selecting indi’s with particular adaptations to survive and reproduce which then passed down gen’s therefore adaptations selected
Describe the process of natural selection
Muatation
Once variety exists,
Indi’s with advantageous characteristsics
Next generation has
Over time, group of organisms
creates alternative version of gene (allele) - creates genetic variation between indi’s of species (intraspecific variation)
enviro selects. When resources scarce, enviro selects variations that give advanatge - there’s a selection pressure
Survive and reproduce passing on advantageous characteristic (inheritance)
higher proportion of indi’s with successful characteristic
become well adapted to enviro (adaptation)
What type of variation won’t be passed on?
Variation due to enviro factors
What are pesticides?
Chemicals designed to kill pests
What are insecticides?
Chemicasl designed to kill insects
What do insecticides apply?
Strong selection pressure
How do insecticides apply strong selection pressure?
If insect susceptible - it’ll die
If has some resistance - may survive
Allows indi’s with resistance to reproduce adn pass on resistant characteristics so resistance quickly spreads through whole pop
What happens when insects become resistant to pesticides?
Can cause pesticide to accumulate in food chain
Insects eaten by predators -> predators receive larger dose of insecticide-> insecticide moves up chain -> humans may receive large dose of insecticide
Why are multiple antibiotics sometimes prescribed?
Reduce chances of some bacteria surviving
What applies selection pressure on bacteria?
Antibodies
How do antibodies apply selection pressure of bacteria?
When taken, most bacteria killed. Some may be resistant to antibiotic, Once most bacteria killed = feel better = stop taking antibiotic
Describe the levels of resistance before natural selection
Variety of levels. Variation caused by mutations that cause genetic variation within species
Describe the levels of resistance directly after natural selection
Least resistant have been killed
Remain are those with some resistance
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