Topic 4 completed Flashcards
define biodiversity
the variety of living organisms in an area
define habitat/ecosystem diversity
the range of different habitats or ecosystems in an area
what 2 things does biodiversity include?
species diversity- number of species and the abundance of the species in an area
genetic diversity- the variation of alleles within a species
how do you measure genetic diversity?
by looking at genotype and phenotype
how does looking at phenotypes help show genetic diversity?
by looking at physical traits in a population you get an idea of the diversity of the alleles (as the alleles code for the characteristics)
how do you look at genotypes in a population to investigate genetic diversity?
samples of DNA taken, the order of bases in alleles are slightly different, sequence DNA to look at similarities and differences of the alleles, can measure the number of alleles for a characteristic to see how genetically diverse a species is
or can use heterozygosity index
what is the equation of the heterozygosity index?
H=number of heterozygotes/number of individuals in the population
what does the heterozygosity index show?
the proportion of heterozygotes in a population (the higher the proportion, the higher the genetic diversity)
what is the index of diversity?
D= N(N-1)/sum of n(n-1)
what is endemism?
when a species is only found in one geographical location
define niche
the role a species plays within its habitat
what are the 3 types of adaptations?
anatomical, behavioural, physiological
what are behavioural adaptations? give an example
ways an organism acts that increase its chance of survival
possums ‘play dead’
what are physiological adaptations?
processes inside an organism that increases its chance of survival
brown bears hibernate- lower rate of metabolism so energy is conserved
some bacteria produce antibiotics which kill other species of bacteria so there is less competition
what are anatomical adaptations?
structural features of an organisms body that increase its chance of survival
otters have a streamlined shape so they can glide easily through the water
whales have a thick layer of blubber to help keep them warm
what are the stages of natural selection?
1-Natural mutations in DNA cause genetic variation in the population
2-A selection pressure such as predation, disease, competition changes
3-An allele becomes favourable as this gives a characteristic which increases chance of survival under new selection pressure
4- individuals with favourable allele more likely to survive and reproduce
5- over time frequency of the advantageous allele increases
what can natural selection lead to?
adaptation and evolution
define evolution
a change in the allele frequency
what is speciation?
the development of a new species
what are the 2 types of speciation?
allopatric and sympatric
what is allopatric speciation?
1- a species become geographically separated
2- the 2 groups have different selection pressures
3- different advantageous alleles
4- different changes in allele frequency
5-differences in gene pools
6-populations become genetically distinct
7- will have become reproductively isolated
what is sympatric speciation?
a change occurs which results in 2 groups becoming reproductively isolated
- seasonal changes (individuals develop different flowering or mating seasons)
- mechanical changes (changes genitalia prevent successful mating)
- behavioural changes (changes in mating call)
what does the Hardy-Weinberg principle predict?
that the frequencies of allele in a population won’t change from one generation to the next
under what conditions is the hardy Weinberg principle right?
large population, no immigration, no emigration, no mutation and no natural selection
what is the hardy Weinberg principle used to estimate?
the frequency of particular alleles, genotypes and phenotypes within populations
what does p represent in the hardy Weinberg principle?
the frequency of the dominant allele
what does q represent in the hardy Weinberg principle?
the frequency of the recessive allele
in the hardy Weinberg principle why is p+q=1?
the total frequency of all possible alleles for a characteristic in a certain population is 1
what does p squared represent in the hardy Weinberg principle?
the frequency of the homozygous dominant genotype
what does 2pq represent in the hardy Weinberg principle?
the frequency of heterozygous genotype
what does q squared represent in the hardy Weinberg principle?
the frequency of the homozygous recessive genotype
what is taxonomy?
the science of classification
what is classification based on?
similarities and differences in genotype and phenotype
what are the 8 taxonomic groups?
domain, kingdom, phylum, class, order, family, genus, species
what is the structure of the names given by the binomial system?
genus species
what are the 5 kindoms?
prokaryotae, protoctista, fungi, plantae, animalia
what are the 3 domains?
bacteria, archaea, eukaryota
describe the features of the prokaryotae kingdom and give an example
prokaryotes, unicellular, no nucleus, less than 5 um
bacteria
describe the features of the protoctista kingdom and give 2 examples
eukaryotic, usually found in water, single celled or simple multicellular organisms
algae, protozoa
describe the features of the fungi kingdom and give 3 examples
eukaryotic, chitin cell walls, saprotrophic (absorb substances from dead or decaying organisms)
moulds, yeasts, mushrooms
define saprotrophic
absorbs substances from dead or decaying organisms
describe the features of the plantae kingdom and give 3 examples
eukaryotic, multicellular, cellulose cell walls, can photosynthesise, contains chlorophyll, autotrophic
mosses, ferns, flowering plants
describe the features of the animalia kingdom and give 3 examples
eukaryotic, multicellular, no cell walls, heterotrophic
birds, mammals, reptiles
what is molecular phylogeny?
looks at molecules such as DNA and proteins to see how closely related organisms are (closely related organisms have similar molecules)
which domains have prokaryotes?
bacteria and archaea
what conditions are seeds stored in within seed banks?
cool, dry conditions
why are seeds stored in cold and dry conditions?
stops the seeds germinating, reduces enzyme activity, prevents bacterial/fungal growth, prevents decaying
why do seed banks store seeds in ex situ instead of growing plants?
less space required so more species can be stored, most plants produce large amounts of seeds so collecting a small sample will not harm the wild population, easier to store as they are dormant
how are seeds tested for viability in seed banks?
planted, grown and new seeds are harvested and stored
how do seed banks conserve endangered species and their genetic diversity?
conserve genetic diversity as some species have different seeds stored with different alleles, conserves biodiversity by storing seeds of endangered plants, if plants become extinct they can be regrown from the seeds
what are the advantages storing seeds rather than plants?
cheaper than storing plants, large number can be stored, less labour, can be stored anywhere (plants would need conditions of original habitat), less likely to be damaged by disease, natural disaster or vandalism
what are the disadvantages of seed banks?
testing for viability can be expensive and time consuming, would be too expensive to store all types of seeds and test viability regularly, may be difficult to collect seeds for some plants if they grow in remote locations
how do seed banks contribute to scientific research?
scientists can study how plant species can be successfully grown from seeds (useful for reintroducing into the wild), can be used to grow endangered plants needed for medical research (don’t have to remove endangered species from the wild), disadvantage- only studying seeds from banks limits the data size so info gathered may not be represented of wild plants
how do zoos conserve endangered species and genetic diversity?
through captive breeding programmes and reintroducing animals into the wild
what are captive breeding programmes?
endangered or species which are extinct in the wild can be bred together in zoos in controlled environments to increase their numbers
what are the problems with captive breeding programmes?
animals can have problems breeding outside their natural habitat, which can be hard to recreate in a zoo
many people think it is cruel to keep animals in captivity even if its done to prevent them becoming extinct
what are the advantages of reintroduction of animals into the wild?
can increase population numbers in the wild which conserves their numbers or brings them back from extinction
will help to restore habitats and ecosystems
what are the issues with reintroduction?
may introduce new diseases which could harm the organisms already living there
reintroduced animals may not behave as they would if they had been raised in the wild
how do zoos contribute to scientific research?
research in zoos increases knowledge about behaviour, physiology and nutritional needs which an contribute to conservation efforts in the wild
can carry out research not possible in the wild
disadvantage- animals in captivity may act differently to those in the wild
how do zoos educate people?
let people get close to organisms, increasing their enthusiasm for conservation work
what are the 8 features of a plant cell?
cell wall, middle lamella, pits, chloroplasts, plasmodesmata, amyloplasts, vacuole, tonoplast
describe and explain the structure and function of a cell wall in a plant cell
a rigid structure made of cellulose
supports the plant cell
describe and explain the structure and function of the middle lamella in a plant cell
the outermost layer of the cell
acts as an adhesive which sticks adjacent cells together to provide stability
describe and explain the structure and function of the plasmodesmata in a plant cell
channels in the cell wall that link adjacent cells together
allow transport of substances and communication between cells
describe and explain the structure and function of the pits in a plant cell
regions of very thin cell wall- arranged in pairs so the pit of one cell is adjacent to the pit of another
allow transport of substances between cells
describe and explain the structure and function of the chloroplasts in a plant cell
a small flattened organelle with a double membrane
site of photosynthesis
describe and explain the structure and function of the amyloplast in a plant cell
small organelle that contain starch granules
store starch and convert starch back to glucose for release of energy when needed
describe and explain the structure and function of the vacuole in a plant cell
contains cell sap (water, minerals, enzymes, waste products) and involved in the breakdown and isolation of unwanted chemicals in the cell
keeps cell turgid to stop wilting
describe and explain the structure and function of the tonoplast in a plant cell
membrane of the vacuole
controls what enters and leaves the vacuole
what is the function of the xylem vessel?
to transport water and mineral ions up the plant
to provide support
describe the structure of the xylem vessel
very long tube like structures
formed from dead cells that are longer than they are wide
cells have a hollow lumen and no end walls
form uninterrupted tubes
lignified to add support and strength
water and minerals move in and out through pits where there is no lignin
no cytoplasm or organelles
where are xylem vessels found?
on the inside of the vascular bundle
what is the function of the sclerenchyma?
to provide support
describe the structure of the sclerenchyma
made of dead cells that are longer than they are wide
hollow lumen
do have end walls
thickened with lignin
don’t contain pits
cell walls contain lots of cellulose
where are sclerenchyma fibres found?
on the outside of the vascular bundle (not in the vascular bundle)
what is the function of the phloem tissue?
to transport solutes (mainly sugars) from where they are made to where they are needed (this is translocation)
describe the structure of the phloem tissue
cells arranged in tubes
contains sieve cells and companion cells
sieve cells are living and join end to end to form sieve tubes
sieve cells have no nucleus and few organelles
lack of nucleus and organelles means sieve cells cannot survive on their own so each has a companion cell
companion cells carry out living functions for both cells including provide energy for active transport of solutes
where are phloem tissue found?
in the middle of the vascular bundle
describe the position of the xylem, phloem and sclerenchyma in the stem
sclerenchyma found on outside
xylem and phloem are found together in an oval shape with xylem on the inside
what are the 2 ways you can cut a plant stem?
transverse cross section (cut at right angle to its length) and longitudinal cross section (cut along the length)
what is the main energy storage material in plants?
starch
what is starch made of?
alpha glucose
describe the structure of amylose
long, unbranched chain of alpha glucose
the angles of the glycosidic bonds give a coiled structure like a cylinder
makes it compact and therefore good of storage
describe the structure of amylopectin
long branched chain of alpha glucose
side branches allow lots of enzymes to bind and so can be quickly broken down for release of energy
is starch soluble in water? why is this good/bad for storage?
no, good for storage as has no osmotic effect (which would made the cells swell)
describe the structure of cellulose
long, unbranched chains of beta glucose
straight 1-4 glycosidic bonds so chains are straight
chains linked by hydrogen bonds to form strong threads called microfibrils which provide structural support
what are the 2 reasons plant fibres are strong?
cell wall contains cellulose
secondary thickening
why are plant cell walls so strong?
contain cellulose microfibrils arranged in a net-like arrangement
what is secondary thickening?
when sclerenchyma and xylem vessels have finished growing they produce a second cell wall which is thicker and has more lignin- the development of this cell wall is secondary thickening
define sustainability
using resources in a way which meets the needs of the present generation while keeping the resources available for future generations
define renewable resources
resources which can be used indefinitely without running out
what is a disadvantage of using plant fibres in ropes?
they’re generally not as strong as rope made of plastic
what are the advantages of using plant fibres in ropes?
more sustainable as less fossil fuels used and crops can be regrown to maintain supply for the future
biodegradable
plants are easier to grow and process than extracting and processing oil, so plants are cheaper and is easier to use in developing countries
what are plastics made of starch called?
bioplastics
what are the advantages of bioplastics?
more sustainable as less fossil fuels used and crops (which are the source of starch) can be regrown
what 2 things can be made of starch as a sustainable alternative?
plastics and vehicle fuel
what is water needed for in plants?
needed for photosynthesis, provides transport medium for minerals, maintains turgidity in plant cells through pressure in vacuoles, regulates temperature to ensure optimum enzyme activity
what are magnesium ions needed for in plants?
production of chlorophyll (needed for photosynthesis)
what are nitrate ions needed for in plants?
production of DNA, proteins (including enzymes), and chlorophyll
what are calcium ions needed for in plants?
cell walls (middle lamella)- needed for plant growth
what conditions are needed for bacterial growth?
nutrients present which provide materials needed for the bacteria to grow and respire
aerobic bacteria need oxygen supply
temperature and pH must not be too high or too low for enzymes in bacteria to control metabolic processes
who discovered digitalis?
William Withering
what can digitalis treat?
dropsy
where is digitalis found?
foxgloves
how did Withering know how much digitalis to give to patients?
trail and error- too much poisoned patients and too little had no effect
what are the steps of drug testing before phase 1?
computers used to model effects, tests carried out on human tissues, tested on live animals
what happens during phase 1 of clinical trials?
small group of healthy individuals. done to find safe dosages, side effects and how the body reacts
what happens during phase 2 of clinical trials?
large group of patients to see if the treatment works
what happens during phase 3 of clinical trials?
drug is compared to existing treatments, tested on hundreds to thousands of patients. patients split into 2 groups with one receiving placebo
what are the 2 types of clinical trials?
blind and double blind
what is the difference between blind and double blind?
blind- patients don’t know if they are receiving new drug or placebo.
double blind- medical staff don’t know who is receiving new drug or placebo
