Topic 4 Flashcards
how has variety of life changed over time
generally increases as new species form
human activity threatens it
define biodiversity
variety of living organisms
can be measured in terms of number of species within a habitat, or by genetic variation within a species
what is endemism
when a species is found in one geographical location and is unable to be found elsewhere
who formulated the natural selection theory
charles darwin and alfred wallace
what is the definition of species
a group of organisms capable of reproducing to create fertile offspring
what is a population
a group of interbreedig individuals of the same species found in an area
what is a community
various populations in a habitat
what is a niche
the way an organism exploits/uses its environment
functional role that it plays within an ecosystem
what happens if there are 2 species fulfilling the same niche - use an example
they will compete directly with each other and the better adapted organism will out-compete the other and exclude it from its habitat
grey squirrels and red squirrels
red squirrels have now been out-competed and replaced by the grey squirrel
what is the hardy-weinberg equation
p^2 + 2pq + q^2 = 1
p + q = 1
what are the 3 types of adaptations
behavioural
physiological
anatomical
what is the difference between physiology and anatomy
physiology is the features of the internal workings of organisms that help them to survive
anatomy is the structures we can see when we observe or dissect an organism
definition of behavioural adaptations and give an example
any actions by organisms that help them to survive or reproduce
agoutis burying Brazil nuts which ensures a future food source
define physiological adaptations
and give an example
features of the internal workings of organisms that help them to survive or reproduce
Danish scurvy grass - able to tolerate very high salt concentrations
define anatomical adaptations and give an example
the structures we can see when we observe or dissect an organism
bumblebees have very long tongues to suck nectar
define co-adaptation
when the plant and pollinator become dependent on each other, and more closely adapted
what kind of adaptation is knocking body to signal food
behavioural
what kind of adaptation is a stinger
anatomical
One type of joint injury is a torn ligament. This may be treated by adding a piece of
tendon to the ligament. This is because after a period of time, the tendon tissue changes and responds in the same way as a ligament.
describe changes in piece of tendon
it shows a change in its phenotype
and is an anatomical and physiological adaptation
The Scottish wildcat can interbreed successfully with domestic cats.
Explain the effect this could have on the genetic diversity of the Scottish wildcat
increase in genetic diversity
because of introduction of new alleles into the population
what is the diversity index equation
D = N (N-1) / Σn (n-1)
Describe what needs to be measured in order to compare the biodiversity of two
rainforests.
counting number of different species
counting number of individuals per species
Explain how two species of snake could have arisen from a common ancestor.
mutation leads to variation in population of snakes
natural selection led to those snakes which were better camouflaged surviving to reproduce
therefore giving rise to two populations with differing allele frequency
the 2 populations become reproductively isolated
sympatric speciation
Name the process that could lead to the Brownsea Island population of
squirrels becoming a new species
natural selection
Describe the features that could be used to identify the prokaryotic cells in the blood sample.
presence of a cell wall
circular DNA
small/70s ribosomes
flagellum
capsule
Explain how molecular phylogeny can be used to show that these two populations are reproductively isolated.
comparing similarities and differences in DNA/proteins
comparison of nucleotides
the greater the number of differences, the more likely they are to be reproductively isolated
Describe how mutations in badgers to the east of the Bosphorus Strait may lead to this population becoming a separate species.
mutations result in production of new alleles
selection pressure can cause the mutations to be advantageous
more individuals with advantageous allele survive and reproduce
after time, population won’t be able to reproduce with other badger species to produce fertile offspring
define species richness
measures number of species in a population
define heterozygosity index
a measure of genetic diversity within a species
Explain why the frequency of this allele may change from one generation to the next
bc allele may undergo mutation
gene flow may cause the allele to be lost or gained from population
due to natural selection
because people with the condition may not have children
Explain how the Hardy-Weinberg equation can be used to show that natural selection is occurring in a population.
shows the allele frequency in a population
if natural selection is occurring there would be a change in allele frequency over time
production of anti-freeze proteins is an example of
a physiological adaptation
The bee orchid, Ophrys apifera, is pollinated by a species of bee, Eucera longicornis, that is
found in parts of the UK.
Males of this species of bee mistake the flower for a female bee.
The bee orchid can also self-pollinate.
The niche of E. longicornis is that it
pollinates the orchid
what is the hierarchy if groups
kingdom phylum class order family genus species
what are the 5 kingdoms
Animalia Plantae Fungi Prokaryotae and Protoctista
what does the animalia kingdom consist of
multicellular eukaryotes that are hetertrophs; organisms thar obtain energy as ‘ready-made’ organic molecules by ingesting material from other organisms
what does the plantae kingdom consist of
multicellular eukaryotes that are autotrophs, organisms that make their own organic molecules by photosynthesis
what does the fungi kingdom consist of
multicellular eukaryotes that are heterotrophs that absorb nutrients from decaying matter after external digestion
what does the Protoctista kingdom consist of
eukaryotes that photosynthesis or feed on organic matter from other sources but are not included in the other kingdoms; includes single-celled protozoa, such as amoeba and algae
what does the Prokaryotae kingdom consist of
prokaryotic organisms; includes bacteria and cyanobacteria
what are the 3 domains
Bacteria, Archaea and Eukaryota
what are some features of a plant cell
ribosomes, tonoplast, chloroplasts, smooth ER, pit, plasmodesma, middle lamella, rER, chromatin, nucleus, nucleolus, nuclear envelope, mitochondria, cell surface membrane, cell wall, amyloplast, golgi
what is tonoplast
vacuolar membrane
what is the function of plasmodesma
form a living bridge between them to allow specific molecules to pass through.
what is the function of the middle lamella
Cementing together the primary cell walls of adjacent plant cells.
Providing structural support and integrity to plant tissues.
Forming barriers that prevent the movement of substances between cells.
Stabilizing cells and forming plasmodesmata between them.
Being the first layer to form during cytokinesis.
what are the plant basics of building strong and tall structures
produce strong cell walls out of cellulose
build columns and tubes rom specialised cells
stiffen some of special cells with lignin
what is cellulose
polymer made out of glucose
how do trees build up wood
they add a ring of stiffened lignin tissue each year - tree rings
what are the fundamental differences between plant and animal cells
plant cells have rigid cell walls and contain chloroplasts
what is the function of the pit in plant cells
Pits are depressions on the cell walls that act as channels for the transport of water and minerals between adjacent cells.
They form a morphological and functional unit called the pit pair.
Pit-pairs allow for communication and transport of substances between adjacent cells, especially in xylem and phloem tissues.
what does the ability of a population to adapt to new conditions depend on
strength of selection pressure
size of gene pool
reproductive rate of the organism
what are the fundamentals of evolution by natural selection
- population has some naturallt occurring genetic variation with new alleles created through mutations
- a change in the environment causes a change in the selection pressures acting on the population
- an allele that was previously of no particular advantage now becomes favourable
- organisms with the allele are more likely to survive, reproduce and so produce offspring,
- offspring are more likely to have allele so becomes more common in population
what contains cellulose in a plant cell
cell wall
what is cellulose made out of
beta glucose monomers
what bonds are in cellulose
beta 1,4 glycosidic bonds
how do you join 2 beta glucose monomers
condensation reaction and 1 monomer is flipped upside down
what are bundles of neighbouring cellulose chains called
microfibrils - bundles of about 60-70 cellulose molecules
what are the components of microfibril glue
hemicelluloses and pectins
they bind to the surface of cellulose and to each other the microfibrils together
where else are pectins important and what is the function of them
important components in the middle lamella and they act as a cement and hold cells together
what bonds form between OH groups in neighbouring cellulose chains and describe their strength
hydrogen bonds
individually weak but collectively strong
why are pectins annoying in fruit juice industry
they thicken the juice and make it difficult to extract
what are the narrow fluid-filled channels between plant cells called
plasmodesmata
Describe how nitrate ions are transported from the root to the leaves
through xylem vessels in water solution
These microfibrils are embedded in a matrix containing calcium pectate.
Calcium pectate can be found in the
middle lamella
Compare and contrast the structure of cellulose and amylopectin.
both are ploysaccharides/ monomers of glucose
both contain 1,4 glycosidic bonds
cellulose contains beta glucose whereas amylopectin contains alpha glucose
cellulose is unbranched
Describe how the tensile strength of these fibres could have been measured.
add 50g bamboo fibre to resin
tensile strength tested by adding masses until fibre breaks
calculate tensile strength by dividing force by cross sectional area
control bamboo species
State one difference between the hexose in cellulose and the hexose in amylopectin.
amylopectin contains alpha glucose
cellulose contains beta glucose
Name the bond between adjacent cellulose molecules in a cellulose microfibril.
hydrogen bonds
Explain why the seedling needs a supply of magnesium ions.
magnesium is needed to make chlorophyll
because chlorophyll is required for photosynthesis
because shoots need to carry out photosynthesis in order to grow
Devise an investigation to determine the effect of nitrate ion concentration on the growth of young peanut plants.
use of plants that are clones of each other
range of at least 5 different nitrate concentrations
use a buffer to control pH
grown for a set period of time
measure height
repeat to calculate mean values
‘The growth of seedlings is affected by the concentration of magnesium ions whereas germination of seeds is not.’
Devise an investigation to obtain valid evidence to support this statement.
range of Mg ion concentrations
measurement of germination rate
use of seedlings germinated in solutions containing all mineral ions
measurement of seedling growth
control temperature
Name a plant tissue that has lignin in its cell wall
xylem
sclerenchyma
Explain the role of the middle lamella when a plant cell completes mitosis.
produced between 2 adjacent new cells
because they hold cells together
explain function of plasmodesmata
cytoplasmic connection in between cells
which allows transport/communication between cells
Explain the effects of a shortage of magnesium ions on a plant.
limits production of chlorophyll
lack of glucose and cellulose due to photosynthesis
plant leaves may be yellow/plants may be small
Give two reasons why a sieve tube element does not require rough endoplasmic reticulum
and ribosomes.
there will be no transcription and no proteins will be synthesised to be processed in endoplasmic reticulum
Cystic fibrosis is a genetically inherited condition. A couple who are both carriers for the condition have a 25% chance of having a baby with cystic fibrosis. In the UK, 1 in 2500 babies born have cystic fibrosis.
Use the Hardy-Weinberg equation to calculate the probability of babies born in
the UK being carriers for cystic fibrosis
(val of q) √1/2500 = 0.02
(val of p) = 1-0.02 = 0.98
(2pq) = 2(0.98 x 0.02) = 0.0392
0.0392 x 100 = 3.92% of population = carriers
Muscular dystrophy is a group of disorders that gradually cause muscles to weaken. One type of muscular dystrophy, caused by a recessive allele, affects 10 people in 100 000 of the population.
Calculate the number of carriers in a population of 17.02 million.
Use the Hardy-Weinberg equation, p2 + 2pq + q2 = 1
p = 0.99 q = 0.01
2pq = (0.99x0.01) x 2 = 0.0198
0.0198 x 17020000 = 336996 carriers
