Topic 4 Flashcards
biodiversity
the variety of species or organisms in an area
species
- a group of organisms with similar morphology, physiology, and behaviour
- can interbreed to produce fertile offspring
- reproductively isolated from other species
Habitat
- A place within an ecosystem where a community of organisms are found
- characterised by physical conditions and species of organisms present
population
- a group of organisms
- all same species
- all live together in a particular habitat
community
the total of all populations living together in a particular habitat
Low biodiversity
- is not necessarily a cause for concern
- the artic and antarctic naturally have low biodiversity compared to a tropical rain forest
Loss of biodiversity
- is a cause for concern
- ecosystems rely on the interdependence of all organisms to maintain stability
- can cause irreversible damage
species richness
- no. of species present in a given habitat
- takes no account of population size
species evenness
- how close the no. of each species in an environment
- high species evenness = similar no. of each species
species diversity
- a measure of how many different species are present in an area
genetic diversity
- a measure of how many variations there are in the gene pool of individuals of a particular species
habitat diversity
- a measure of how many different habitats in an area
- including biotic and abiotic factors
genetic diversity - phenotype
- different alleles code for different versions of the same characteristic
- by looking at the different phenotypes in a species we can get an idea of the different alleles
- the larger the no. of different phenotypes the greater the genetic diversity
genetic diversity - genotype
- measure the no. of different alleles a species has for one characteristic to see how genetically diverse the species is
- the larger the no. of different alleles the greater the genetic diversity
heterozygosity index
number of heterozygotes/no. of individuals in the population
niche
the way an organism exploits (uses) it’s environment
- interactions with other living things: eats/eaten by
- interactions with non-living environments - shelter site
competition
- when 2 or more individuals strive to obtain the same resources when they are in short supply
- the more similar the two individuals are, the more intense the competition
anatomical adaptations
adaptations that can be observed or seen when an organism is dissected
behavioural adaptations
actions by the organism which help them to survive or reproduce
physiological adaptations
internal workings within an organism which help it to survive/reproduce
adaption
a characteristic of an organism which improves its chances of surviving/reproducing
selection pressure
- such as predation, disease and competition - creates a struggle for survival
- anything that affects an animals chance of survival or reproduction
endemism
when a species evolves in isolation and is only found in one part of the world
genetic drift
when the frequency of an allele varies over many generations - affects smaller populations more
gene pools
consist of all of the alleles of all the genes present in a population
Simpson’s index of diversity symbols
N =
n =
D =
N = total no. of organisms of all species n = total no. of organisms of a particular species D = probability that two randomly selected individuals will belong to the same species
Hardy-Weinberg equation symbols
p =
q =
p^2 =
q^2 =
2pq =
p = dominant q = recessive p^2 = homozygous dominant genotype q^2 = homozygous recessive genotype 2pq = heterozygous genotype
Hardy-Weinberg equation meanings
p+q=1 ?
p^2+2pq+q^2=1 ?
p+q=1 = frequency of all alleles p^2+2pq+q^2=1 = frequency of all genotypes
speciation
- the development of a new species
- occur when populations of the same species become reproductively isolated
- can be due to:
- seasonal changes: different mating seasons
- Mechanical changes: changes in genitalia prevent successful mating
- Behavioural changes: different courtship rituals
- geographical isolation
Geographical isolation
- can lead to speciation
- when a physical barrier divides population of a species
- flood, volcanic eruptions and earthquakes
- different condition and therefore selection pressures can cause speciation
- natural selection - different alleles may be more advantageous on one side than the other
- mutations will only be passed on in one of the populations
Taxonomy
science of classification
classification
- eight levels of groups
- domain, kingdom, phylum, class, order, family, genus, species
- naming and organising organisms based off of similarities and differences
DEAR KING PHILIP CAME OVER FOR GOOD SOUP
5 Kingdoms
Prokaryotae e.g. bacteria
Protocista e.g. algae
Fungu e.g. mushrooms
Plantae e.g. mosses
Animalia e.g. mammals
- based on general features
3 Domains
- based on molecular phylogeny: evolutionary history, looks at DNA to see how closely related species are
Eukaryota
Bacteria
Archaea
- Prokaryote was split into bacteria and archaea because molecular phylogeny suggested that they are more distantly related than originally thought
The work of seedbanks involves
- conserve genetic diversity
- creating the cool, dry conditions required for storage
- allowing seeds to be stored for a long time
- testing seeds for viability –> seeds are planted, grown and new seeds are harvested and put back into storage
advantages of seedbanks
- cheaper than storing fully grown plants
- large numbers can be stored in less space
- less labour is required to look after seeds than plants
- seeds can be stored anywhere as long as conditions are cool and dry whereas plants need the conditions from their original habitat
disadvantages of seed banks
- testing the seeds for viability can be time-consuming and expensive
- too expensive to store all types of seeds and regularly test each for viability
- it is difficult to collect seeds from plants that only grow in remote locations
captive breeding programmes
- breed animals in controlled environments
- for species that are endangered or extinct in the wild they can be bred in captivity to increase their numbers
disadvantages of captive breeding programmes
- animals sometimes have problems breeding outside of their natural habitat
- cruel to keep animals in captivity
reintroduction into the wild
- the reintroduction of seeds from seedbanks or animals from captive breeding programmes can increase their numbers in the wild
- can also help animals who rely on these animals or plants for food or part of their habitat
- restoration of plants and animals also contributes to restoring lost habitats e.g. rainforests that have been cut down
disadvantages of reintroduction to the wild
- can introduce new diseases
- animals may have trouble behaving as they would if they had been raised in the wild –> will have problems finding food or communicating with wild members of their species
seedbanks contribution to scientific research
- allows the study of how to successfully grow plants from seeds –> useful for reintroduction
- can grow endangered plants from seeds to use for medical research or new crops –> they don’t need to be removed from their environment
- limits the study to a small inbred population - research may not represent wild population
zoos contribution to scientific research
- increases knowledge of behaviour, physiology and nutritional needs of animals - contributes to conservation efforts in the wild
- captive animals may act differently to wild animals
xylem function
- transport water and mineral ions up the plant
- provide support
xylem structure
- long, tube-like structures formed from dead cells joined end to end
- hollow lumen and no end walls
- uninterrupted tube allows water and mineral ions to move through the middle easily
- walls are strengthened by lignin - helps support the plant
- water and mineral ions move into and out of the pits where there is no lignin
sclerenchyma fibres function
- provide support
sclerenchyma fibres structure
- bundles of dead cells that run vertically up the stem
- hollow lumen and have end walls
- wall thickened with lignin
- no pits
- contain lots of cellulose
phloem function
- transport organic solutes from where they’re made to where they’re needed
- this is known as translocation
phloem structure
- cells arranged in tubes
- sieve tube elements: live cells joined end to end to form sieve tubes
- sieve part are the end walls which have lots of holes to allow solutes to pass through
- sieve tubes have no nucleus so require a companion cell to survive
- companion cells carry out the living functions for both themselves and their sieve cells
vascular bundles
- in the stem xylem vessels and phloem tissue group together
- sclerenchyma fibres are also there
- from outside to inside:
sclerenchyma fibres –> phloem –> xylem
starch: amylose
- long, unbranched alpha glucose
- coiled structure = compact so good storage molecule (more in small space)
- insoluble - doesn’t swell through osmosis
starch: amylopectin
- long, branched alpha glucose
- good for energy - branches allow enzymes to break down glycosidic bonds easily so glucose can be released quickly
- insoluble - doesn’t swell through osmosis
starch and plants
- cells get energy from glucose
- plants store excess glucose as starch - when they need more energy it breaks down starch and releases it as glucose
cellulose
- long, unbranched beta glucose
- glycosidic bonds are straight so the chains are straight
- between 50 and 80 cellulose chains are linked together by hydrogen bonds to form microfibrils
- these strong threads mean that cellulose provide structural support for cells
Why plant fibres are strong: arrangement of microfibrils
- the cells wall contains microfibrils in a net-like arrangement
- their strength and arrangement gives the plant fibres strength
Why plant fibres are strong: secondary thickening
- when structural plant cells such as sclerenchyma and xylem have finished growing they produce a secondary cell wall between the cell wall and the cell membrane
- the secondary cell wall is thicker and contains more lignin than the normal cell wall
- this growth is called secondary thickening, it makes plant fibres even stronger
sustainability
- using resources in a way that meets the needs of the current generation without using it up for future generation
- in order to make something sustainably you must use renewable resources
renewable resources
- can be used indefinitely without running out
- e.g. plants are a renewable resource because harvested plants can be regrown so there is enough for future generations
- e.g. 2 fossil fuels are a finite resource and are unrenewable - once they’re all used up there is no more
Plant Fibres sustainability
- ropes and fabrics can be made from plastic (oil) but also from plant fibres
- this is more sustainable since fewer fossil fuels are sued up and crops can be regrown for future generations
- plants are biodegradable unlike most oil-based plastics
- plants are easier to grow and process than extracting and processing oil –> cheaper
Starch sustainability
- plastics can be made from oil but also starch: bioplastics
- less fossil fuel is used up and crops from which the starch came from can be regrown
- vehicle fuel is also made from oil but can lose be made from starch: biofuel
- less fossil fuel is used up and crops from which the starch came from can be regrown
plants need water for…
… photosynthesis, to transport minerals, to maintain structural rigidity and to regulate temperature
plants need magnesium ions for…
… the production of chlorophyll - the pigment needed for phtosynthesis
plants need nitrate ions for…
… the production of DNA, proteins (including enzymes) and chlorophyll
They are required for plant growth, fruit and seed production
plants need calcium ions for…
… plant growth
William Withering: Drug testing in the past
- chance observation that digitalis could treat dropsy
- too much = poison
- too little = no effect
- trial and error until he found the right amount
Modern Drug testing
- tested on cells in the lab
- Computer models may also be used to simulate the metabolic pathways that may be taken by the drug
- tested on animals to see the effect on a whole organism
- all new medicines in the UK have to have tests on 2 different animals by law
- Efficiency, toxicity and dosage are tested at this stage
Then human trials:
Phase 1: testing on a small group of healthy individuals –> find out dosage, side effects and how the body reacts
Phase 2: larger group of this time patients –> find out effectiveness of drug
Phase 3: tested on hundreds of patients –> compared to existing drugs –> patients are randomly split into two groups: existing treatment vs new treatment
Placebos
an inactive substance that looks exactly like the drug but does not contain the active ingredient so does not do anything
Double-Blind trial
- neither the doctor nor the patient knows if the patient is getting the active drug or the placebo (or old drug)
- REDUCES BIAS
