Topic 4 Flashcards
Biodiversity
Variety of living organisms in the area
Species diversity
The no. of different species & abundance of each specie within a given area
Genetic diversity
Variation of alleles within a species (e.g. blood type = three alleles)
Endemism
Species unique to a single place
e.g. Giant tortoise = endemic to Galapagos islands
Anthropogenic affect on biodiversity
Reduced via farming and deforestation
- conservation = important, especially for endemic species
Natural Selection
The pressure that causes groups of organisms to change over time
- > adaptation
- > evolution
Habitat
Where organisms live
Measuring species diversity in a habitat
- count no. of different species = species richness (no. = indication of abundance)
- count no. of different species + abundance of them
- > index of diversity equation to calculate diversity
note: compare + note change
Sampling (method)
- area
- random sample (avoid bias)
- count no. of each species
- plants = quadrat
- insects (flying) = sweepnet (net on a pole)
- insects (ground) = pitfall trap
- aquatics = net - repeat
- estimate
- sample different habitats using same technique
Measuring genetic diversity (within a species)
To measure look at:
- Phenotype = observable characteristics
- different types -> idea of alleles
e. g. greater genetic diversity for eye colour in northern Europe than rest of the world - Genotype = DNA samples taken & sequence of base pairs analysed
- base order in different alleles differs slightly
- sequencing DNA -> look at similarities + differences
- measure no. of different alleles for one characteristic
- look at heterozygosity index
Gene pool
complete set of alleles in population
Diversity within a species
Diversity within a species = variety shown by individuals/population
- variation -> alleles
Genetic diversity
Variety of alleles in gene pool
Heterozygosity Index
Measures genetic diversity
- two different alleles at particular locus
- higher proportion of heterozygotes -> greater genetic diversity
Heterozygosity Index Equation
H = (no. of different alleles at particular locus) / (no. of individuals in population)
- > average value for H at many loci
- estimate diversity in whole genome of population
Index of Diversity
D = ( N ( N-1 )) / ( Σn ( n-1 ))
-> higher number = more diverse; compare different habitats
D = Index of diversity N = total number or organisms of all species n = total number of organisms of one species Σ = sum of
Niche
Role of species within a habitat
Only occupied by one species -> competition
- interactions with living organisms & environment
Niche: Common Pipistrelle Bat
British farmland bat
- open woodland, hedgerows, urban
Flies & catches insects
- echolocation: frequency = 45 kHz
Niche: Soprano Pipistrelle Bat
British woodland bat
- close to lakes + rivers
Flies & catches insects
- echolocation: frequency = 55 kHz
Organism adaptation to niche
- Behavioural
- Physiological
- Anatomical
note: increase survival
Organism adaptation to niche: Behavioural
Ways an organism acts
- Possums -> play dead
- Scorpions -> ‘dance’ before mating
- > ensures (likelihood of) same species mating
Organism adaptation to niche: Physiological
Processes inside an organism’s body
- brown bears -> hibernate (lower metabolic rate) as food scare over winter
- some bacteria are antibiotic resistance (ensures survival over though who are not)
Organism adaptation to niche: Anatomical
Structural features of an organism’s body
- otters = streamlined -> glide through water
- whales = thick blubber layer -> warm in cold sea (location of food source)
Evolution -> increases adaptation
- Mutation -> new alleles -> phenotype variation
- Selection pressure (predation/disease/competition) -> survival struggle
- no advantageous allele -> die -> survival struggle
- > better adaptation -> increased survival -> more likely to reproduce -> pass on allele
- > allele population increases overtime
- > evolution
- > Charles Darwin = natural selection
Evolution: Peppered Moths
Variation in colour (light + dark) 1800's = more light coloured - pollution -> blackened trees - dark = more camouflaged - light -> predation (stood out) -> (overtime) dark moths = more common
Speciation
Development of a new species (genetically distinct),
via:
1. Reproductive isolation
- Seasonal changes = develop different flowering/mating seasons; sexually active at different times
- Mechanical changes = genitalia altered
- Behavioural changes = courtship rituals alter
2. Random mutation
3. Geographical isolation
- physical barrier divides population
- conditions either side of barrier differ slightly
- selection pressure -> different characteristics become more common
-> allele frequencies change
-> independent mutations not spread through population
-> change in phenotype frequencies
Species
Group of similar organisms that can reproduce to produce fertile offspring
Evolution
Change in allele frequency
- percentage calculated by Hardy-Weinberg principle
- new alleles = gene mutation
Hardy-Weinberg principle
Predicts allele frequencies will not change over time
Certain conditions:
- large population
- no immigration
- no migration
- no mutations
- no natural selection
- random mating
Hardy-Weinberg equation (predict allele frequencies)
p + q = 1
- p = frequency of dominant allele
- q = frequency of recessive allele
Hardy-Weinberg equation (Gentotype + Phenotype frequency)
p^2 + 2pq + q^2 = 1
- p^2 = frequency of homozygous dominant genotype
- 2pq = frequency of heterozygous genotype
- q^2 = frequency of homozygous recessive genotype
What is an indication of a population evolving
Allele frequencies
Classification
Grouping together similar organisms
Taxonomy
Science of classification (naming + organising)
8 taxonomic groups
Taxonomic groups
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
Species naming
Binomial word
1st = genus
2nd = species
5 Kingdoms
= all organisms
- Prokaryotae (monera)
- Protoctista
- Fungi
- Plantae
- Animalia
Prokaryotae (monera) Kingdom
Bacteria
- Prokaryotes
- Unicellular
- No nucleus
- x < 5μm
Protoctista Kingdom
Algae, Protozoa
- Eukaryotic Cells
- water (emvironment)
- single-celled
- simple multicellular
Fungi Kingdom
Moulds, Yeast, Mushrooms
- eukaryotic
- chitin cell wall
- saprotrophic
Plantae Kingdom
Moses, Ferns, Flowering plants
- eukaryotes
- multicellular
- cellulose cell wall
- photosynthesise
- chlorophyll
- autotrophic
Animalia Kingdom
Nematodes, Molluscs, Insects, Fish, Reptiles, Birds, Mammals
- Eukaryotes
- Multicellular
- no cell walls
- heterotrophic
Heterotrophic
Consume plants and animals
Autotrophic
Produces own food
Saprotrophic
Absorb substances from dead/decaying organisms
Three domain system
New data (molecular phylogeny) -> new taxonomic groupings
Domains = Superkingdoms, above kingdoms in hierarchy:
- Archaea
- Bacteria
- Eukaryota
Prokaryotae -> Archaea + Bacteria (more distantly related)
Other 4 Kingdoms -> Eukaryota
Molecular Phylogeny
MP = looks at molecules to see how closely related an organism is
Phylogeny = study of molecular history of organism groups
Conservation (reason)
Species extinction (or loss of species genetic diversity) -> loss of global biodiversity Counteract + reintroduce
Seedbanks
Stores seeds from different plant species
Helps to conserve genetic diversity
- cool + dry conditions needed for storage
- Testing for viability (planted -> grown -> seeds harvested)
Seedbanks (+/-)
\+ Cheaper = seeds \+ large number -> less space \+ less labour \+ stored anywhere \+ less likely to be damaged (disease, natural disaster)
- Viability testing -> expensive + time consuming
- too expensive to store all seeds + test regularly
- difficult to collect some seeds (remote locations)
Zoos (captive breeding programs)
Animals bred in controlled environment
- problems breeding outside natural habitat
- > hard to recreate
- e.g. Pandas do not breed as successfully
- considered cruel
Reintroduced into wild
- e.g. Californian Condor = 22 birds left -> 300 (half reintroduced)
- help habitat restoration + reliance of/on other organisms
- could bring new diseases
- may not behave as if raised in the wild (decreased survival likelihood)
Scientific Research + Education (Seedbanks + Zoos)
Seedbanks -> study successful growing methods
- medical research (no removing wild population)
- limits data to interbred population (small)
- > provide training + local seedbanks
- > Millenium seedbanks = in own country
Zoos -> increase knowledge of behaviour, physiology & nutritional needs
- nutritional + reproductive studies (not possible in the wild)
- Captivity -> may act different
- > increase enthusiasm for conservation (up close interactions)
Cell Wall
Rigid structure that surrounds plant cells & supports them
- Mainly made of carbohydrate Cellulose
Middle Lamella
Outer most layer of cells, acting as an adhesive to stick adjacent cells together, giving them stability
Plasmodesmata
Channels in cell walls that link adjacent cells together
- allows transports of substances and communication between cells
Pits
Cell wall regions that are very thin, and arranged in pairs (lined up with adjacent cell)
- allows transport of substances between cells
Chloroplast
Small Flat structures
Double Membrane
Inside = thylakoid membranes (-> stacked = granum)
Grana linked by lamella = thin flat pieces of thylakoid membrane
Stroma = thick fluid inside
- where photosynthesis occurs: grana (light dependent) & stroma (light independent)
Amyloplast
Small organelle enclosed by membrane
Contains starch granules
- stores starch grains
- converts starch -> glucose
Vacuole
Compartment containing cell sap, surrounded by a Tonoplast (membrane)
- cell sap = water, enzymes, minerals, waste
- keeps cell turgid
- breakdown + isolation of unwanted chemicals
Tonoplast
Membrane that surround vacuole
- controls what enters + leaves
Xylem Vessels
- function = water + mineral ion transport (up the plant)
- > provide support - long tube like structures, formed from dead cells joined end to end
- formed in bundles - cells = longer than wide
= hollow lumen (no cytoplasm)
= no end walls
-> unitterupted tube for transport through middle - walls = thickened with woody substance = lignin
- > helps support - Water + mineral ions move in/out via pits in the wall (no lignin present)
Sclerenchyma Fibres
- provide support
- bundles of dead cells running vertically up the stem
- Cells = longer than wide
= hollow lumen
= have end walls - cells thickened with lignin
- more cellulose (than other plant cells)
- no pits
Phloem Tissue
- Transports organic solutes (e.g. sucrose) from where there made in plant -> needed
= TRANSLOCATION - Arranged in tubes (non-supportive)
- Sieve tube elements = living cells with no nucleus
- joined end to end -> sieve tubes
- thin cytoplasm layer
- few organelles - ‘Sieve’ = end wall
- lots of holes -> solutes - Sieve Plates =through which the cytoplasm of adjacent cells is connected via holes in the plates
- Companion cells = living function for themselves & sieve cells
- energy
- active transport
- all sieve tube elements have companion cell as without nucleus + other organelles they cannot survive
Vascular Bundels
Xylem + Phloem grouped together
- sclerenchyma fibers associated
- present in (plant) stem
note: Xylem = inside
Phloem = middle
sclerenchyma = outside
Starch
Main energy source in plants
- Cells = energy from glucose; excess -> starch
- Starch = amylose + amylopectin
- insoluable in water -> good for storage (does not alter osmotic potential
Cellulose
Major component of plant cell walls
- long unbranched chains of Beta glucose
- joined via 1-4 glycosidic bonds
- bonds = straight -> chain = straight
- 50 to 80 chains
- linked via ( many) hydrogen bonds
- > strong threads = Microfibrils
- > structural support
Plant Fibres = Strong, because…
- Arrangement of microfibrils = net like in cell wall
- Secondary thickening of cells walls
- structural (xylem + sclerenchyma) cells finish growing
-> second cell wall between original + cell membrane
= thicker + more lignin
Microfibril
50 to 80 cellulose chains linked via hydrogen bonds
Drug Testing (modern method)
- Computers model potential effects
- Tests carried out on human tissues in lab
- Tested on live animal(s)
- Clinical (human) trials: three phases
Phases of clinical trials
- New drug
- small group of healthy individuals
- safe dosage
- side effects
- body’s reaction - Larger group
- includes patients
- test effectiveness - Drug compared to existing treatment
- tests on hundred to thousands of patients
- > large sample = more reliable results
- patients randomly split into two groups
- > double blind study + placebos
- > new drug + existing drug
note:
double blind study = neither patient nor doctor knows who has what
- reduces bias (perception + want)
Digitalis soup (Trial + Error)
William Withering (1700s) chance observation of patient treated with traditional foxglove remedy
- Foxglove extract -> dropsy treatment (swelling caused via heart failure)
- drug = Digitalis
Foxgloves = poisonous - tested different versions with different concentrations of digitalis = Digitalis Soup -> too much = poison -> too little = no effect -> trial + error -> treatment discovered
